نویسنده: mitra2--javid

شکل 4-13- نمودار دمای آب در حالت مهکشند شکل 4-12- نمودار دمای آب در حالت مهکشند ایستگاه D در لایه میانی ایستگاه C در لایه میانی در شکل (4-14) تغییرات دمای لایه میانی آب در چهار ایستگاه به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. این شکل نشان می‌دهد وقتی جریان مدی وجود دارد دمای آب در ایستگاه B، و وقتی جریان جزری وجود دارد دمای آب در ایستگاه C از دمای آب در بقیه ایستگاه‌ها بیشتر است. شکل 4-14- نمودار جامع دمای آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه میانی در یک چرخه جزر و مد
شکل 4-16- نمودار دمای آب در حالت مهکشند شکل 4-15- نمودار دمای آب در حالت مهکشند ایستگاه B در لایه زیرین ایستگاه A در لایه زیرین
شکل 4-18- نمودار دمای آب در حالت مهکشند شکل 4-17- نمودار دمای آب در حالت مهکشند ایستگاه D در لایه زیرین ایستگاه C در لایه زیرین
در شکل (4-19) تغییرات دمای لایه زیرین آب در چهار ایستگاه به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. این شکل نشان می‌دهد وقتی جریان مدی وجود دارد دمای آب در ایستگاه B، و وقتی جریان جزری وجود دارد دمای آب در ایستگاه C از دمای آب در بقیه ایستگاه‌ها بیشتر است.
شکل 4-19- نمودار جامع دمای آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه زیرین در یک چرخه جزر و مد
شوری در حالت مهکشند شکل 4-21- نمودار شوری آب در حالت مهکشند شکل 4-20- نمودار شوری آب در حالت مهکشند ایستگاه B در لایه سطح ایستگاه A در لایه سطح
شکل 4-23- نمودار شوری آب در حالت مهکشند شکل 4-22- نمودار شوری آب در حالت مهکشند ایستگاه D در لایه سطح ایستگاه C در لایه سطح در شکل (4-24) شوری آب در لایه سطحی چهار ایستگاه، به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. این شکل نشان میدهد که چهار ایستگاه بیشترین شوری را در جزر کامل و کمترین شوری را در مد کامل دارند. شکل 4-24- نمودار جامع شوری آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه سطح در یک چرخه جزر و مد شکل 4-26- نمودار شوری آب در حالت مهکشند شکل 4-25- نمودار شوری آب در حالت مهکشند ایستگاه B در لایه میانی ایستگاه A در لایه میانی
شکل 4-28- نمودار شوری آب در حالت مهکشند شکل 4-27- نمودار شوری آب در حالت مهکشند ایستگاه D در لایه میانی ایستگاه C در لایه میانی
در شکل (4-29) شوری آب در لایه میانی چهار ایستگاه، به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. این شکل نشان میدهد که چهار ایستگاه بیشترین شوری را در جزر کامل و کمترین شوری را در مد کامل دارند. شکل 4-29- نمودار جامع شوری آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه میانی در یک چرخه جزر و مد
شکل 4-31- نمودار شوری آب در حالت مهکشند شکل 4-30- نمودار شوری آب در حالت مهکشند ایستگاه B در لایه زیرین ایستگاه A در لایه زیرین
شکل 4-33- نمودار شوری آب در حالت مهکشند شکل 4-32- نمودار شوری آب در حالت مهکشند ایستگاه D در لایه زیرین ایستگاه C در لایه زیرین در شکل (4-34) شوری آب در لایه زیرین چهار ایستگاه، به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. این شکل نشان میدهد که چهار ایستگاه بیشترین شوری را در جزر کامل و کمترین شوری را در مد کامل دارند. شکل 4-34- نمودار جامع شوری آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه زیرین در یک چرخه جزر و مد
چگالی در حالت مهکشند شکل 4-36- نمودار چگالی آب در حالت مهکشند شکل 4-35- نمودار چگالی آب در حالت مهکشند ایستگاه B در لایه سطح ایستگاه A در لایه سطح
شکل 4-38- نمودار چگالی آب در حالت مهکشند شکل 4-37- نمودار چگالی آب در حالت مهکشند ایستگاه D در لایه سطح ایستگاه C در لایه سطح
در شکل (4-39) تغییرات چگالی آب در لایه سطحی چهار ایستگاه به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. شکل 4-39- نمودار جامع چگالی آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه سطح در یک چرخه جزر و مد
شکل 4-41- نمودار چگالی آب در حالت مهکشند شکل 4-40- نمودار چگالی آب در حالت مهکشند ایستگاه B در لایه میانی ایستگاه A در لایه میانی
شکل 4-43- نمودار چگالی آب در حالت مهکشند شکل 4-42- نمودار چگالی آب در حالت مهکشند ایستگاه D در لایه میانی ایستگاه C در لایه میانی
در شکل (4-44) تغییرات چگالی آب در لایه میانی چهار ایستگاه به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. شکل 4-44- نمودار جامع چگالی آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه میانی در یک چرخه جزر و مد
شکل 4-46- نمودار چگالی آب در حالت مهکشند شکل 4-45- نمودار چگالی آب در حالت مهکشند ایستگاه B در لایه زیرین ایستگاه A در لایه زیرین
شکل 4-48- نمودار چگالی آب در حالت مهکشند شکل 4-47- نمودار چگالی آب در حالت مهکشند ایستگاه D در لایه زیرین ایستگاه C در لایه زیرین در شکل (4-49) تغییرات چگالی آب در لایه زیرین چهار ایستگاه به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است.
شکل 4-49- نمودار جامع چگالی آب در حالت مهکشند ایستگاه‌های (A,B,C,D) در لایه زیرین در یک چرخه جزر و مد 4-4-2- اندازی گیری در حالت کهکشند
در تاریخ 5/10/92 در موقع کهکشند به مدت یک دوره جزر و مـدی 15 ساعته، مطابق شکل (3-1) با ایجاد چهار ایستگاه (A,B,C,D) در سه لایه سطح، میانی و عمق، دما و شوری و چگالی اندازه‌گیری شد که شکلهای زیر نتایج اندازه گیری را نشان میدهند.
دما در حالت کهکشند شکل 4-51- نمودار دمای آب در حالت کهکشند شکل 4-50- نمودار دمای آب در حالت کهکشند ایستگاه B در لایه سطح ایستگاه A در لایه سطح
شکل 4-53- نمودار دمای آب در حالت کهکشند شکل 4-52- نمودار دمای آب در حالت کهکشند ایستگاه D در لایه سطح ایستگاه C در لایه سطح
در شکل (4-54) تغییرات دمای لایه سطحی آب در چهار ایستگاه به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. این شکل نشان می‌دهد وقتی جریان مدی وجود دارد دمای آب در ایستگاه B، و وقتی جریان جزری وجود دارد دمای آب در ایستگاه C از دمای آب در بقیه ایستگاه‌ها بیشتر است.
شکل 4-54- نمودار جامع دمای آب در حالت کهکشند ایستگاه‌های (A,B,C,D) در لایه سطح در یک چرخه جزر و مد
شکل 4-56- نمودار دمای آب در حالت کهکشند شکل 4-55- نمودار دمای آب در حالت کهکشند ایستگاه B در لایه میانی ایستگاه A در لایه میانی
شکل 4-58- نمودار دمای آب در حالت کهکشند شکل 4-57- نمودار دمای آب در حالت کهکشند ایستگاه D در لایه میانی ایستگاه C در لایه میانی
در شکل (4-59) تغییرات دمای لایه میانی آب در چهار ایستگاه به همراه نوسانات سطح آب در منطقه اندازه‌گیری رسم شده است. این شکل نشان می‌دهد وقتی جریان مدی وجود دارد دمای آب در ایستگاه B، و وقتی جریان جزری وجود دارد دمای آب در ایستگاه C از دمای آب در بقیه ایستگاه‌ها بیشتر است.
شکل 4- 59- نمودار جامع دمای آب در حالت کهکشند ایستگاه‌های (A,B,C,D) در لایه میانی در یک چرخه جزر و مد
شکل 4-61- نمودار دمای آب در حالت کهکشند شکل 4-60- نمودار دمای آب در حالت کهکشند ایستگاه B در لایه زیرین ایستگاه A در لایه زیرین
شکل 4-63- نمودار دمای آب در حالت کهکشند شکل 4-62- نمودار دمای آب در حالت کهکشند ایستگاه D در لایه زیرین ایستگاه C در لایه زیرین
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زمین‌شناسی منطقه
از دیدگاه زمین‌شناسی، خلیج ‌فارس فرونشست زمین ساختی کم‌ژرفایی است که در حاشیه جنوبی رشته‌کوه زاگرس تشکیل‌شده‌ است. درواقع این دریا بازمانده گودال بزرگی است که از دوران گذشته زمین‌شناختی تحت تأثیر فشار ناشی از آتش‌فشان‌های فلات ایران بوده و پایداری فلات عربستان در مقابل این واکنش‌های تکتونیکی سبب ایجاد و توسعه پهنا-ژرفای آن شده ‌است. شدیدترین چین‌خوردگی‌های دوران پلیو پلیستوسن، کرانه‌های شمالی خلیج ‌فارس (زاگرس) را چین داده ‌است. بستر خلیج ‌فارس در مجاورت ایران از شیب نسبتاً تند ( حدود cm⁄km 175 ) برخوردار است. درحالی‌که در سمت کشورهای عربی حوزه خلیج ‌فارس شیب آن کمتر ( حدود cm⁄km 35 ) است. تعداد جزایر خلیج ‌فارس130 جزیره، و بزرگ‌ترین آن‌ها جزیره قشم است. سطح دریا احتمالاً 150 متر بالاتر از سطح کنونی بوده است. این سطح از 100 هزار سال پیش از میلاد مسیح به‌تدریج به سطح کنونی رسیده است. ( رامشت ، 1368 )
اقلیم‌شناسی
آب‌وهوای خلیج ‌فارس خشک و نیمه استوایی است. در تابستان، دما گاهی تا ۵۰ درجه سانتیگراد می‌رسد و میزان تبخیر بیشتر از میزان آب‌های وارده می‌شود. در زمستان دما تا ۳ درجه سانتی‌گراد هم گزارش شده ‌است. در عین شوری زیاد آب خلیج ‌فارس، ۲۰۰ چشمه آب شیرین در کف و ۲۵ چشمه آب کاملاً شیرین در سواحل آن جریان دارند که منشأ همگی آن‌ها از کوه‌های زاگرس در ایران است. آب‌های شیرینی که وارد خلیج ‌فارس می‌شوند عمدتاً محدود به روان آب‌های کوه‌های زاگرس در ایران و کوه‌های ترکیه و عراق است. رودخانه‌های اروند، کارون، جراحی، مند، دالکی و میناب بزرگ‌ترین و پرآب‌ترین رودخانه‌هایی هستند که به خلیج ‌فارس می‌ریزند که بیشتر سرچشمه‌های آن‌ها در کوه‌های زاگرس قرار دارند. در کرانه جنوبی آب‌های ورودی به خلیج ‌فارس بسیار کم است که موجب بالا بودن رسوبات کربناتی در این بخش شده است. به دلیل محصور بودن، اثر اقیانوس بر خلیج ‌فارس بسیار ناچیز است و به همین علت سرعت جریان‌های زیرین و افقی آن بسیار کم و در حدود ۱۰ سانتی‌متر در ثانیه ‌است. ( فیاض محمدی، 1388) شوری بیشتر خلیج ‌فارس نسبت به اقیانوس موجب پیدایش جریان آبی از اقیانوس هند به خلیج ‌فارس می‌شود که به‌موازات ساحل ایران و در جهت پادساعت‌گرد است. ( Kampf and sadrinasab, 2004 ) جریان ذکرشده با افزایش شوری همراه است، به‌طوری‌که در تنگه هرمز مقدار نمک 6/36 گرم در لیتر و در سواحل امارات متحده عربی در حدود 45 گرم در لیتر است. میزان بارندگی در سواحل جنوبی کمتر از ۵ سانتی‌متر در سال و در سواحل شمالی بین ۲۰ تا ۵۰ سانتی‌متر در سال است. ( johns,2003 )
اهمیت خلیج ‌فارس
خلیج ‌فارس درواقع محور ارتباط بین اروپا، آفریقا، آسیای جنوبی و جنوب شرقی است. ازنظر راهبردی در منطقه خاورمیانه، به‌عنوان بزرگ‌ترین و مهم‌ترین مرکز ارتباطی بین این سه قاره است و بخشی از یک سیستم ارتباطی شامل اقیانوس اطلس، دریای مدیترانه، دریای سرخ و اقیانوس هند است. به همین دلیل از دیرباز موردتوجه قدرت‌های جهانی و هم‌چنین بازرگانان و تجار دنیا بوده است. هم‌چنین این منطقه منبع مهم انرژی جهان می‌باشد. درمجموع خلیج ‌فارس ازنظر جغرافیای سیاسی، استراتژیک، انرژی و تاریخ و تمدن یک پهنه آبی مهم و حساس در دنیا محسوب می‌شود. ( معروف ، 1389 )
افق خلیج ‌فارس در منطقه پارس جنوبی
بزرگ‌ترین عامل اهمیت خلیج ‌فارس وجود معادن سرشار نفت و گاز در کف بستر و سواحل آن است به‌طوری‌که این منطقه را «مخزن نفت جهان» نام نهاده‌اند. خلیج ‌فارس مسیر انتقال نفت کشورهای ایران، عراق، کویت، عربستان و امارات متحده عربی است و به همین سبب، منطقه‌ای مهم و راهبردی به شمار می‌آید. در حدود ۳۰ درصد نفت جهان از منطقه خلیج ‌فارس تأمین می‌شود که این مقدار گاهی افزایش و گاهی کاهش می‌یابد. نفت تولیدشده در حوزه خلیج ‌فارس باید از طریق این پهنه آبی و از راه تنگه هرمز به سایر نقاط جهان حمل شود. خلیج ‌فارس ازنظر ذخایر نفتی در مقایسه با سایر نقاط جهان دارای مزایای زیادی مانند سهولت استخراج، هزینه پایین تولید، مازاد ظرفیت تولید، کیفیت بالای نفت خام منطقه، سهولت حمل‌ونقل، توان بالای تولید چاه‌ها و امکان کشف ذخایر جدید نفتی وسیع در منطقه می‌باشد. طبق آخرین برآوردهای انجام‌شده حوزه خلیج ‌فارس در حدود ۷۳۰ میلیارد بشکه ذخیره نفت اثبات شده و بیش از ۷۰ تریلیون مترمکعب گاز طبیعی را در خود جای‌داده ‌است. همچنین بندرهای مهمی در حاشیه خلیج ‌فارس وجود دارد که از آن‌ها می‌توان ب ندرعباس، بوشهر، بندرلنگه، کیش، خرمشهر و بندر ماهشهر در ایران و شارجه، دوبی و ابوظبی را در امارات متحده عربی و بندر بصره و فاو در عراق را نام برد. ( معروف ، 1389 )
استان بوشهر
شکل 1-10- نقشه استان بوشهر
1-15-1- مختصات جغرافیائی استان
استان بوشهر با مساحتی در حدود 27653 کیلومترمربع بین 27درجه و 17 دقیقه تا 30 درجه و 17 دقیقه عرض جغرافیایی و 50 درجه و 8 دقیقه تا 52 درجه و 58 دقیقه طول جغرافیایی، در جنوب ایران و در حاشیه زیبای خلیج‌ همیشه فارس قرار دارد. این استان از شرق به استان فارس و از غرب به خلیج ‌فارس، از جنوب به خلیج ‌فارس و قسمتی از استان هرمزگان ، از شمال به استان خوزستان و قسمتی از کهگیلویه و بویراحمد، محدود است. استان بوشهر با خلیج ‌فارس بیش از 600 کیلومتر مرز دریایی دارد. بر اساس آخرین تقسیمات سیاسی کشور، استان بوشهر مشتمل بر 8 شهرستان، 17 بخش، 13 شهر، 36 دهستان و 706 آبادی دارای سکنه است. ( عبدلی و همکاران ، 1388 )
شهرستان‌های استان بوشهر عبارت‌اند از : بوشهر، تنگستان، دشتستان، دشتی، دیر، دیلم، کنگان و گناوه.
1-15-2- جریانات جوی زمستانه در استان بوشهر
توده‌هوای مدیترانه‌ای که در شمال اقیانوس اطلس و جنوب ایسلند شکل میگیرد بعد از عبور از روی اروپا از طریق دریای سیاه به شرق دریای مدیترانه وارد و سپس از طریق ترکیه نواحی شمال و شمال غرب ایران را مورد تأثیر قرار میدهد . این توده‌هوا به دلیل عبور از خشکی‌های فراوان ماهیت خود را از دست میدهد. توده‌هوای مدیترانه‌ای که از طریق اروپای غربی وارد شرق مدیترانه می‌شود بعد از تقویت در منطقه و پیدایش جبهه قطبی با حرکت به سمت شرق ، ایران را موردتهاجم قرار می‌دهند که اکثر بارانهای ایران ناشی از این توده‌هوا است. گاهی این توده‌هوا به عرض‌های پایین نیز کشیده میشود و جنوب ایران و استان بوشهر را تحت تأثیر قرار میدهند. توده‌هوای دیگری که در زمستان استان بوشهر را تحت تأثیر قرار می‌دهند، توده هوایی با منشأ اسکاندیناوی و اقیانوس اطلس است که با عبور از روی اروپا و از دست دادن رطوبت مجدداً از دریای سیاه رطوبت کسب کرده و از طریق ترکیه و عراق ، غرب ایران را مورد تأثیر قرار میدهند.
توده هوایی با منشأ نواحی صحرای شمال آفریقا ( سودانی ) بعد از عبور از عربستان، نواحی غربی و جنوب غرب ایران را موردتهاجم قرار میدهد. با استقرار این توده‌هوا بر روی دریای عمان و خلیج ‌فارس و کسب رطوبت سبب بارندگی‌هایی از نوع ناپایدار شدید شده و حتی باران‌های سیل‌آسا ایجاد میکند ( این سامانه به‌دفعات استان بوشهر را تحت تأثیر قرار داده و باعث جاری شدن سیل شده است ). ولی اگر رطوبت کافی نباشد همراه با گردوخاک و بارندگی خفیف خواهد بود. ( سالنامه جوی و دریایی اداره کل هواشناسی بوشهر) 1-15-3- جریانات جوی تابستانه در استان بوشهر
توده‌هوا با منشأ جنوب شرقی اقیانوس اطلس و جنوب غربی اروپا بعد از عبور از دریای مدیترانه و جنوب اروپا یا شمال آفریقا و عربستان صعودی نواحی جنوب کشور را تحت تأثیر قرار می‌دهد. کم‌فشارهای حرارتی صحرای عربستان موجب افزایش دما و انتقال رطوبت از دریا و شرجی شدن هوا در استان بوشهر میگردد. مونسون هند نیز گاها استان بوشهر را تحت تأثیر قرار می‌دهد. ( سالنامه جوی و دریایی اداره کل هواشناسی بوشهر ) فصل دوم
پیشینه تحقیق 2-1- مقدمه
ازآنجاکه مدت زیادی از راه‌اندازی نیروگاه اتمی بوشهر نمیگذرد، هیچ‌گونه کار میدانی پس از راه‌اندازی نیروگاه انجام نشده است . البته برخی مدل‌سازی‌ها برای بررسی آلودگی‌های حرارتی نیروگاه‌های فرضی انجام‌شده که هیچ‌یک نمی‌تواند جای یک کار میدانی برای بررسی یک نیروگاه واقعی را بگیرد.
2-2- پیشینه تحقیق
در اینجا به چند مورد مدل‌سازی که به بررسی آلودگی حرارتی ناشی از نیروگاه‌ها می‌پردازد اشاره میشود:
– آرش رزاقی ،1378 ، مدل دوبعدی توزیع حرارت ناشی از نیروگاه‌ها در آب دریا را موردبررسی قرار داده و برای انجام این طرح از روش ADI 13 بهره گرفته شد و آنچه در این طرح محاسبه شد، ضریب انتشار حرارت در آب دریا بوده و از روش‌های مختلفی ازجمله ضریب انتشار با مقدار ثابت و ضریب انتشار با استفاده از سرعت برشی برای انجام این تحقیق استفاده‌شده است.
– Menlo و همکاران، آلودگی گرمایی را در ساحل شعربا در کویت بررسی کردند. یک مدل فیزیکی غیر پیچیده با مقیاس 1 به 50 ساخته‌شده و با فراسنج های اساسی تعیین‌کننده دما در منطقه ساحلی شعربا امتحان گردید که بر اساس نتایج آن دمای آب دریا در منطقه موردنظر 7/1 تا 5/2 واحد نسبت به گذشته افزایش داشته است. ( Menlo and Eseni,1987 )
– مقیمی و همکاران ، آلودگی حرارتی طرح توسعه نیروگاه بندرعباس را با استفاده از مدل 14 MIKE21 بررسی کردند و به این نتیجه رسیدند که برای توسعه و افزایش راندمان نیروگاه باید به تعداد و فاصله کانال‌های خروجی توجه شود. ( مقیمی و همکاران، 1383 )
– نصیری و همکاران، مدل سه‌بعدی از انتقال حرارت مجتمع پالایشگاه‌های پارس را ارائه کردند در بررسی آنان از مدل سه‌بعدی POM15 استفاده میشود. بنا بر نتیجه این مدل‌سازی استانداردهای زیست‌محیطی رعایت شدهاند. ( نصیری و همکاران ، 1383 )
– جوکار، آلودگی حرارتی نیروگاه اتمی بوشهر را مدل‌سازی کرد. آنچه که از این محاسبات و بررسیهای به‌عمل‌آمده نتیجه شده، تغییرات حرارتی محدود به نقاط نزدیک به نقطه خروج پساب است که اثرات بسیار جزئی بر روی سطح و کف آب خلیج‌فارس دارد و این اطمینان را میدهد که اثرات سوء در شرایط زیست‌محیطی، در مقیاس کلان بر جانوران منطقه نخواهد داشت. همچنین هیچ‌گونه نشانهای دال بر انتقال آب گرم خروجی به ورودی آب نیروگاه ( تشکیل مداربسته ) دیده نمیشود. ( جوکار، 1386 )
– در سال 1391 اکبری از دانشگاه علوم و فنون دریایی خرمشهر ورود آب گرم به یک خلیج فرضی را مدلسازی کرد که بر اساس آن در موارد مشابه نیروگاه اتمی بوشهر امکان این که در اطراف نقطه خروجی پساب دما از مقدار استاندارد بیشتر شود، وجود دارد. اما سیکل بسته آب بین نقطه خروجی پساب و ورودی آب به نیروگاه به وجود نمیآید. ( اکبری، 1391 )
– در سال 1391 پایان‌نامه‌ای با موضوع بررسی تأثیر پساب نیروگاه رامین بر کیفیت آب رودخانه کارون توسط آقای مهران افخمی صورت گرفت که به نتایج زیر رسیدند .
بررسی‌های آماری بر روی نتایج حاصل از نمونه‌برداری از ایستگاه‌های مورد مطالعه نشان داد که ورود پساب نیروگاه در ایستگاه‌ها در طی ماه‌های نمونه‌برداری تغییر معنی‌داری ازلحاظ فاکتورهای موردنظر نشان نداده و مشخص شد که پساب خروجی نیروگاه با توجه به حجم آبگذر رودخانه و دبی فاضلاب خروجی، تأثیر قابل‌ملاحظه‌ای بر روی کیفیت آب رودخانه کارون ندارد.
ورود پساب‌های صنعتی از نیروگاه‌ها سبب افزایش دما، مواد آلی، معدنی و ترکیبات خطرناک فلزات سنگین در آب شده و این امر علاوه بر آلودگی محیط‌زیست آبزیان، سبب برهم خوردن تعادل ترکیبات موجود در آب می‌گردد.
از میان منابع مختلف طبیعی از قبیل خاک، جنگل، مرتع و آب، مورد اخیر در ایران به دلایل فراوان از اهمیت خاصی برخوردار بوده و به‌ویژه به دلیل محدودیت‌های طبیعی و شرایط خاص اقلیمی کشور از یکسو و اهمیت روزافزون بین‌المللی منابع آب از سوی دیگر در مطالعات پیشرو توجه خاصی را می‌طلبد.
مطالعات پیرامون منابع آبی میتواند شامل تعیین شرایط هیدرولوژیکی، اقلیمی، آبدهی، وسعت حوزه آبریز، بررسی امکانات بهره‌برداری مستقیم و غیرمستقیم از منابع و نهایتاً بررسی وضعیت آلودگی و ویژگی‌های منابع آلاینده آن‌ها باشد.
رودخانه کارون با طی مسیری حدود هزار کیلومتر از مهم‌ترین منابع آب‌های جاری استان و کشور بوده و در محدوده استانی و ملی دارای اهمیت بسزایی است و هرچند با استفاده از آب این رودخانه و احداث تأسیسات برق‌آبی، نیازهای بسیاری از صنایع و مراکز شهری و کشاورزی استان و کشور ازنظر تأمین آب و انرژی برطرف میگردد، اما به دلیل ورود مازاد آب کشاورزی و پساب‌های اکثر صنایع مهم فلزی، شیمیایی، نفت، غذایی، سلولزی، نیروگاه‌ها و فاضلاب‌های شهرهای مسیر، در رودخانه آلودگی‌های متعددی بروز کرده و هزینه‌های تصفیه و بهسازی آب رودخانه جهت مصارف گوناگون به‌صورت روزافزون افزایش یافته و تبعات منفی ناشی از این آلودگیها بر سلامت مردم منطقه رو به فزونی است. نظر به جایگاه ویژهای که مسئولین مملکتی در سیاست‌های توسعه کلان اقتصادی اجتماعی کشور برای رودخانه کارون ازجمله تأمین آب مصرفی صنایع، شهرها و طرح‌های تولید کشاورزی مهم از قبیل طرح توسعه نیشکر و صنایع جانبی در نظر گرفتهاند، انجام مطالعات پیرامون شرایط]]>

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Vahdani, M. (1990). The Effects of Structural simplification on graded Readers. A thesis submitted to the Tehran University in partial fulfillment of the requirements for the degree of Master of Arts Department. W.Carroll, D. (2008). Psychology of Language. Thomson, Wadsworth. Pp, 132-135 Wallace, C. (1992). Reading. Oxford University Press. Widdowson, H.G. (1979). Explorations in Applied Linguistics. Oxford University Press. Widdowson, H.G. (1990). Aspects of Language Teaching. Oxford University Press. Widdowson, H.G. (1996). Authenticity and Autonomy in ELT. ELT Journal 50(1), 67-68. Williams, E. (1996). Reading in Two Languages at Year Five in African Primary Schools. Applied Linguistics, 17(2), 182-209. Yano, Y., Michael, H.L., & Steven, R. (1994). The Effects of Simplified and Elaborated Texts on Foreign Language Reading Comprehension. In Language Learning 44(2). Young, D. (1999). Linguistic Simplification of SL Reading Material: Effective Instructional Practice. The Modern Language Journal, 83, 350-366. APPENDICES:
Appendix A: Placement test
English Proficiency Test
MELAB
For problems 1-30, choose the word or phrase that correctly completes the sentence.
1. “In America, are most scientist well paid?”
“Yes, the________ are paid very well.”
a. majority of scientists
b. majority of scientists
c. scientists of majority
d. scientists majority 2. “What is your job at the factory?”
“My job is________ all the doors at the end of the day.”
a. locking
b. to be locking
c. locks
d. the locked 3. “I paid $30 for a taxi from the airport last night.”
“You ________me for a ride.”
a. would have asked be
b. could asked
c. could ask
d. could have asked 4. “Let’s take the elevator to the 25th floor”
“Never! Elevators are something ________. “
a. Which I’m afraid
b. I’m afraid of
c. Which I’m afraid of it
d. Which I’m afraid of them 5.“Why did John quit school?”
“He told me it was because of ________. “
a. his failure constantly
b. his constantly failure
c. he failed constantly
d. his constant failure 6. “We need more art clas ses.”
“I don’t think so. The students ________ in art.”
a. are not interesting
b. have not interested
c. are not interested
d. have not interest 7. “I can’t do all this work.”
“_______ I helped you with it?”
a. What if
b. That if
c. As if
d. However 8. “Groceries are certainly expensive.”
“Yes, each time I go shopping, I seem_______ more.”
a. spending
b. be spending
c. to spending
d. to be spending 9. “The children want to play.”
“Yes, but ________ do is their homework.”
a. what should they
b. what they should
c. they should
d. that they should they
10. “Can you give me a receipt?”
“Yes, that can be _______. “
a. easy done
b. easy doing
c. easily done
d. easy to be done
11. “Did John finish his homework?”
“Yes; although he was tired, _______ it all.”
a. but he did
b. despite he did
c. he did
d. that he did 12.”Do you always believe Donald?”
“Yes, I have complete trust ________ whatever he says.”
a. on
b. to
c. in
d. at 13. “Why is the front door open?”
“Oh, I’m sorry. I_______ forgotten to lock it.”
a. should have
b. must have
c. ought to have
d. had to have 14. “Do you like that cake?”
“Well, it has too much sugar in it, but ________ it’s ok.
a. other than that
b. another of that
c. that other
d. none other than 15. “What did you think when you met Robert’s mother?”
“I was very impressed _______her friendliness.”
a. on
b. of
c. by
d. at 16. “What do you want Phil for?”
“I want him the house while I’m away.”
a. guard
b. guarded
c. the guard of
d. guarding 17. “Why don’t you paint_______ blue?”
“Oh, I never thought_______ that.”
a. to be done
b. of doing
c. to have done
d. to do 18. “Can you help me choose my wife’s gift?”
“Certainly; first tell me_______ expensive a gift you would like to buy?”
a. how
b. how much
c. as
d. as much as 19. “I took your books back to the library.”
“Oh, no! I wish you_______ that.”
a. didn’t do
b. didn’t have done
c. haven’t done
d. hadn’t done
20.” What’s so interesting about the San Marcos River?”
“It has plant life which you can’t _______any other place.”
a. find
b. find it
c. find them
d. be found
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This finding is in contrast with the results of an experiment by Ulijn and Strother (1990) who found that syntactic simplification of a text is not a real simplification, and as a result writers and teachers should give priority to other more conceptual ways of rewriting texts.
Ciapuscio (1993) found that cognitive simplification does not lead to syntactic simplification, as the target text often displays more complex syntactic structures than the source text.
Furthermore, Cervantes and Gainer (1992) examined the effects of syntactic simplification and repetition on listening comprehension in two experiments with non – native speakers. Subjects who heard the simplified syntax version score significantly higher in recall than those who heard the more complex version.
Apart from the result of the studies and whether simplified versions of this kind (syntactically and lexically simplified) have a positive impact on reading comprehension of FL readers the lack of authenticity of simplified versions needs to be addressed. 2.9) Simplification and Authenticity
Realization that even a simplified text can be relevant to its audience throws light on the issue of authenticity in language teaching materials. Simplified materials often find acceptance because they prepare the reader for eventual control of authentic texts.
Authentic (like simplified) is a term that occurs in the literature of language teaching and applied linguistics but not in theoretical linguistics (Davis, 1984; Breen, 1987; Wallace, 1992; Widowson, 1990). In discussions on authenticity of language data for language for language teaching purposes, doubts as to what authenticity might mean have already been expressed by Widdowson, who writes (1979):
“I am not sure that it is meaningful to talk about authentic language as such at all. I think it is probably better to consider authenticity not as a faculty residing in instances of language but as a quality which is bestowed upon them, created by the response of the receiver. Authenticity in this view is the function of the interaction between the reader / hearer and the text which incorporates the intentions of the winter / speaker.”
In further discussion of simplification, Widdowson (1979) remarks the linguist’s idealization of data:
“…the teacher simplifies by selecting and ordering the linguistic phenomena he is deal with so as to ease the task of learning and the linguist idealize by selecting and ordering the linguistic phenomena he is to deal with to ease the task of analysis.”
And, making the connection between authenticity and Simplification direct, Lautamatti (1978) argues that simplified texts are used in the teaching of foreign language reading comprehension as a ladder towards less simplified and finally authentic texts. In fact, Lautamatti sees simplification and authenticity as ends of the same continuum.
In teaching, one selects texts on the basis of how simple they are, i.e., whether or not they are comprehensible to the addressee. As a matter of fact, one cannot speak of simplified texts without taking into account the understanding of the addressee. It is that understanding that allows us to rank texts on a scale of readability. In other words, while the writer of simplified texts is conceived with the process of simplifying, that process will be effective only if matched by the reader’s own involvement. That involvement makes the text authentic for the reader. In fact, it is not that a text is understood because it is authentic but that it is authentic because it is understood (Davis, 1987).
It is thus concluded that the teacher and the learner can act as authenticator and simplifier of texts, respectively (Davis, 1984; Corder, 1981). In teaching our concern is with simplification, not with authenticity. Everything the learner understands is authentic for him. It is the teacher who simplifies, the learner who authenticates. In the teaching of reading as in all language teaching the fundamental task of the teacher is that of selection or judging relevance (Davies, 1984). 2.10) Summary
In this chapter the literature related to reading comprehension and simplification has been reviewed. At first, in “Theoretical framework” section some related studies have been reviewed. In the second section ”Reading Comprehension, Past and present”, the literature on approaches to reading, its different definitions, models and theories of reading comprehension has been examined and reviewed, followed by different processes involved in reading. The other section, “Reading Materials”, has investigated the literature on appropriate reading material followed by components of appropriacy. Then, some sources of syntactic complexity have been mentioned. The other section has investigated the relationship between syntactic complexity and reading comprehension. Then, we’ve discussed simplification of reading materials. At the end the relationship between simplification and authenticity has been discussed.
CHAPTER 3
METHODOLOGY
3.0) Introduction
As it is said earlier in the previous chapter the present study was conducted to ameliorate the pedagogical and practical effect of textual modification on reading comprehension. So this part aimed at paying attention to the methodology of the research as follows: the design of the study, pilot study, participants of the study, materials, procedures and the statistical analysis. 3.1) The Design of the Study
This part included the design of the study that focused on tests of participants, participants themselves and the way of treatment, which is explained here. The treatment lasted 10 sessions. The procedure was pre-test, post-test based on the nature and the purpose of the study. There were both control and experimental groups. The experimental group was under treatment by giving them instructions and performing tests. The design of the study is quasi experimental which is included pre-test and post-test design. Basically three types of tests were used in this study. MELAB test which was included general tests of English for homogenizing students, pre-test and post-test. The schematic representation of the design is as follows: C1 Control group T1C T2C
X1 Experimental group T1X T2X
T1 Pretest
T2 Post test
3.2) Participants of the Study
The participants of the study were 115 upper-intermediate students both male and female, aged between 15 and 21, After administration of MELAB test, 60 upper-intermediate students whose scores were between 32 and 79 were selected. They were divided into 2 groups control and experimental group. Both groups sat for the pre-test of reading comprehension test to take their initial knowledge of reading comprehension ability. Then the control group received no treatment. However, the experimental group received treatment based on textual modification technique and finally both groups sat for the post-test, which is the same reading comprehension test. 3.3) Materials of the Study
The following materials were employed throughout the course of this study. An MELAB test was used for the purpose of homogenizing the proficiency of the learners. Another type of the test which was used for the purpose of the study was reading comprehension test. This type of test was used as a pre-test to measure the learners’ initial subject knowledge in two groups. And finally a reading comprehension test was used as a post-test. 3.4) Procedures of the Study
The following steps were taken in the course of present study:
1. A M ELAB test was administered among 115 students in order to make them homogeneous.
2. After dividing the students into three groups of low, intermediate and high, forty upper-intermediate students were selected to take part in the investigation.
3. Sixty upper-intermediate students were divided into control and experimental group randomly.
4. Both groups took the same pre-test; a reading comprehension test from Nelson Reading Tests. It was taken to show participants’ current level of knowledge.
5. In Experimental group, researcher used textual modification techniques mentioned in chapter two, such as breaking the complex and compound sentences, using active voice, changing discourse marker, inversion of clause ordering, rearranging the sentence order, topicalization and detopicalization and etc.
6. In control group none of the above-mentioned techniques were used by researcher. Instead like traditional reading classes texts were translated only.
7. After 10 sessions, both groups took the same post-test. This test was also selected from Nelson Reading Test. 3.5) Statistical Collection
After administrating pre-test and post-test from experimental and control group, four sets of scores were available. Scores obtained from pre-test, show participants’ status before any treatment. On the other hand, post-test shows the difference between experimental and control group after using textual modification techniques in experimental group.
The data was analyzed through SPSS, an ANCOVA was run to analyze the data of the study. 3.6) Summary
In this chapter, after discussing pilot study, procedures used to conduct the research were covered. It consisted of three main points; first of all, the participants of the study and their demographic features were discussed. Then the researcher presented a brief explanation of the steps followed to design the instrument of the study and its component parts. Finally, the procedures followed by the researcher to conduct the study, including how the data were collected and how they were analyzed, were presented.
CHAPTER 4
Result
4.0. Data Analysis and Findings
In order to ensure that the control and experimental groups were in equal conditions before the treatment began, it was thought to compare the mean scores of both groups. A pre-requisite to any comparison of two independent means is equality of variances. Equality of variances was investigated and calculated using Levin’s test. The p-value turned out to be 0.051, which is bigger than 0.05, so the variances were assumed as equal with 95% confidence. To investigate equality of means for two independent populations, an independent samples t-test was the best statistical test, so the means were compared using a two tailed t-test.
Table 4.1. Group Statistics group
N
Mean
Std. Deviation
Std. Error Mean
score_ pretest
control
30
61.2333
14.73603
2.69042 exprimental
30
64.0333
15.21679
2.77819 Table 4.2. Independent Samples Test Levene’s Test for Equality of Variances
t-test for Equality of Means F
Sig.
t
df
Sig. (2-tailed)
Mean Difference
Std. Error Difference
95% Confidence Interval of the Difference
Lower
Upper score_ pretest
Equal variances assumed
.045
.833
-.654
58
.516
-2.53333
3.87280
-10.28558
5.21891 Equal variances not assumed
-.654
57.930
.516
-2.53333
3.87280
-10.28578
5.21911 The p-value was 0.516, which is bigger than 0.05; therefore, it was concluded that there was no significant difference between the mean scores of two groups. The following table presents a summary of statistical analysis utilized to investigate the equality of means.
Table 4.3. Descriptive statistics and independent t-test for the comparison of pre-test results
Pre-test results
N
Mean
SD
df
t
sig
Experimental group
30
64
15.21
58
0.654
0.516
Control group
30
63.21
14.73
Therefore, it can be concluded that the two groups were homogenous in terms of]]>

A useful distinction is made by Widdowson (1978) in discussing simplification between what the calls simplified versions and simple accounts. Simplified versions are, he suggests, passages which are derived from genuine instances of discourse by a process of lexical and syntactic substitution.
A simplified version, according to Widdowson, is a simplification of the language code . The original propositions are retained and what is changed is the linguistic connections between them.
A simple account, on the other hand, represents not an alternative textualization of a given discourse but different discourse altogether. In a simple account it is use of the code, the discourse itself that is changed; recast to suit a particular kind of reader. Widdowson makes clear that simple accounts are to be preferred to simplified version in that “…a simple account is a genuine instance of discourse, designed to meet a communicative purpose… a simplified version … is not genuine discourse, it is a contrivance for teaching language.”
Most helpful is the further distinction Widdowson hints at that simplified versions always have a source script which has been changed, whereas simple accounts have a source but no script (Davis, 1984).
A more general view of simplification is that it is used to make information available to an audience other than the one originally intended. All discourse even simplified versions, must be relevant to audience (ibid).
Simplification, thus, can be carried out at different levels. On the one hand, the simplifier can concentrate on replacing words and structures with approximate semantic equivalents in the learner’s inter language omitting whichever items prove intractable, thereby bringing the language of the original within the scope of the learners transitional linguistic competence .This kind of simplification focuses on the way in which the language system is manifested: It is an operation on usage. On the other hand, the simplifier can concentrate on making explicit in different terms the propositional content of the original and the ways in which it is presented in order to bring what is communicated in the original within the scope of the learner’s transitional communicative competence. In this case, Simplification focuses on the way in which the language system is realized for the expression of proposition and the performance of illocutionary acts: it is an operation on use (Widdowson, 1979).
Candido.et.al (2010) proposes a series of possible simplification operations to be applied: 2.8.1) Splitting the sentence
This operation is the most frequent one. It requires finding the split point in the original sentence (such as the boundaries of relative clauses and appositions, the position of coordinate or subordinate conjunctions) and the creation of a new sentence, whose subject corresponds to the replication of a noun phrase in the original sentence. This operation increases the text length, but decreases the length of the sentences. With the duplication of the term from the original sentence (as subject of the new sentence), the resulting text contains redundant information, but it is very helpful for students especially those with lower proficiency. When splitting sentences due to the presence of apposition, we need to choose the element in the original sentence to which it is referring, so that this element can be the subject of the new sentence. At the moment we analyze all NPs that precede the apposition and check for gender and number agreement. If more than one candidate passes the agreement test, we choose the closest one among these; if none does, we choose the closest among all candidates. In both cases we can also pass the decision on to the user. For treating relative clauses there is the same problem as for apposition (finding the NP to which the relative clause is anchored) and an additional one: we need to choose if the referent found should be considered the subject or the object of the new sentence.
Currently, the parser indicates the syntactic function of the relative pronoun and that serves as a clue. 2.8.2) Changing discourse marker
In most cases of subordination and coordination, discourse markers are replaced by most commonly used ones, which are more easily understood. The selection of discourse markers to be replaced and the choice of new markers are done based on the study of Pardo and Nunes (2008). 2.8.3) Transformation to active voice
Clauses in the passive voice are turned into active voice, with the reordering of the elements in the clause and the modification of the tense and form of the verb. Any other phrases attached to the object of the original sentence have to be carried with it when it moves to the subject position, since the voice changing operation is the first to be performed. For instance, the sentence:
“More than 20 people have been bitten by gold piranhas (Serrasalmus Spilopleura), which live in the waters of the Sanchuri dam, next to the BR-720 highway, 40 km from the city.”
is simplified to: “Gold piranhas (Serrasalmus Spilopleura), which live in the waters of the Sanchuri dam, next to the BR-720 highway, 40 km from the city, have bitten more than 20 people.”
After simplification of the relative clause and apposition, the final sentence is:
“Gold piranhas have bitten more than 20 people. Gold piranhas live in the waters of the Sanchuri dam, next to the BR-720 highway, 40 km from the city. Gold piranhas are Serrasalmus Spilopleura.” 2.8.4) Inversion of clause ordering
This operation was primarily designed to handle subordinate clauses, by moving the main clause to the beginning of the sentence, in order to help the reader processing it on their working memory (Graesser et al., 2004). Each of the subordination cases has a more appropriate order for main and subordinate clauses, so that “independent” information is placed before the information that depends on it. In the case of concessive subordinate clauses, for example, the subordinate clause is placed before the main clause. This gives the sentence a logical order of the expressed ideas. See the example below, in which there is also a change of discourse marker and sentence splitting, all operations assigned to concessive subordinate clauses:
“The building hosting the Brazilian Consulate was also evacuated, although the diplomats have obtained permission to carry on working.”
Its simplified version becomes: “The diplomats have obtained permission to carry on working. But the building hosting the Brazilian Consulate was also evacuated.” 2.8.5) Subject-Verb-Object ordering
If a sentence is not in the form of subject-verb-object, it should be rearranged. This operation is based only on information from the syntactic parser. The example below shows a case in which the subject is after the verb: “On the 9th of November of 1989, fell the wall that for almost three decades divided Germany.”
Its simplified version is: “On the 9th of November of 1989, the wall that for almost three decades divided Germany fell.” 2.8.6) Topicalization and detopicalization
This operation is used to topicalize or detopicalize an adverbial phrase. It has been observed that moving adverbial phrases to the end or to the front of sentences can make them simpler in some cases. For instance, the sentence in the last example would become:
“The wall that for almost three decades divided Germany fell on the 9th of November of 1989.”
Although through the process of simplifying a passage, individual lexical items and structures are brought within the scope of the learner’s linguistic competence, it does not necessarily make it easier for him to understand the passage as a whole. There are certa in features of use which this process cannot, of its nature, account for. For instance, to understand the value that some words and items assume, the reader has to be able to associate them with what they refer to in the passage. So to simplify a passage, one may need to provide referential value for anaphoric elements where necessary. It is thus suggested that once an instance of use is interpreted, one can then proceed to restate it in a way which will make such an interpretation more accessible. This may incidentally involve simplifying usage, of course, but as a means to an alternative instance of use not as an end in itself (ibid).
In fact, simplification is defined as the process whereby a language user adjusts his language behavior in the interest of communicative effectiveness. The adjustment may involve either the increase or decrease in complexity of usage. This might appear to be perversely paradoxical. How can one talk of simplification which involves linguistic complexity? One can do so because effectiveness of use in a particular communicative situation might well require explicitness or conformity to accepted convention which calls for linguistic elaboration. This is a point which is frequently ignored by the authors of simplified readers and language teaching textbooks: the simplifying of usage does not necessarily result in the simplification of use, that is to say, it does not necessarily facilitate communication. On the contrary it very often makes communication less effective. As a matter of fact, the language teacher’s simplification of language data in the form of the conventional structural syllabus does not correspond with the learner’s simplification (ibid).
Parker and Chadron (1987) review 12 experimental studies ( including Johnson , 1981;Blau, 1982; Cervantes,1983; Brown , 1987; Haudron & Richards , 1986_Cited in Barzegar,1997) of the effect of input modifications on comprehension and conclude that although linguistic modifications (for example simple syntax) helped comprehension they did not do so consistently . It has also been shown that revising a text to make the sentences shorter and the words simpler , does not increase comprehension , and the studies show that the same factors , complex morphology and sentence connective , actually convey information about meaning in an explicit may , and so are not barriers to comprehension for most readers (Anderson & Davison ,1983).
On the other hand, Berman (1984) concluded that readers who read the syntactically adapted version did consistently better on all types of questions. He, Furthermore, adds that efficient FL readers must rely in part on syntactic devices to get at text meaning. It is also suggested that the reader should be helped in terms of vocabulary by the provision of some form of familiarization (context clue, illustration, translation, definition, etc) where necessary (Williams, 1996).
Petersen (2007) addresses the task of text simplification in the context of second-language learning. A data-driven approach to simplification is proposed using a corpus of paired articles in which each original sentence does not necessarily have a corresponding simplified sentence, making it possible to learn where writers have dropped or simplified sentences. A classifier is used to select the sentences to simplify, and Siddharthan’s syntactic simplification system (Siddharthan, 2003) is used to split the selected sentences.
In this study, the researcher does not drop sentences, since she believes that all the content must be kept in the text.
Yano, Long and Ross (1994), conclude that linguistic simplification of written texts can increase their comprehensibility for non-native speakers, but reduce their utility for language learning in other ways, for example, through the removal of linguistic items that learners do not know but need to learn. Referring to the results of their experiment, Yano, et .al (1994) state: “Comprehension]]>

After it was proved that the two groups were at the same level of language proficiency before the treatment, the time had come to see whether any change had occurred in the proficiency of the experimental group after the treatment. In order to arrive at a conclusion, the mean scores of the reading comprehension test administered after the treatment were compared. Table 4.2.4 presents the results of the statistical analysis performed to see whether there is any significant difference between mean scores of experimental and control groups. by conducting a Levin’s test, it was found that the variances of both groups are equal. The p-value was calculated to be 0.084, which was bigger than 0.05; as a result, the hypothesis concerning the equality of variances was not rejected. The mean scores were compared with an independent t-test. The p-value turned out to be 0.048 which is smaller than 0.05; therefore, the hypothesis concerning the equality of means was rejected and there was a significant difference between the performance of experimental and control groups. Table 4.4. Independent Samples Test Levene’s Test for Equality of Variances
t-test for Equality of Means F
Sig.
t
df
Sig. (2-tailed)
Mean Difference
Std. Error Difference
95% Confidence Interval of the Difference
Lower
Upper
posttest
Equal variances assumed
.048
.814
-1.760
58
.084
-6.73333
3.82666
-14.39322
.92655 Equal variances not assumed
-1.760
57.833
.084
-6.73333
3.82666
-14.39369
.92702
In order to find out about the experimental group progress after the treatment, it was decided that the participants’ initial scores would be compared to the final ones. A paired t-test was performed to compare the mean scores of students before and after the treatment. As shown in table 4.2.5, the p-value was calculated to be 0.000, which is smaller than 0.05, indicating that there was a significant difference between the means of the experimental group before and after the treatment. Table 4.5. Paired Samples Test Paired Differences
t
df
Sig. (2-tailed) Mean
Std. Deviation
Std. Error Mean
95% Confidence Interval of the Difference Lower
Upper Pair 1
score_pretest – posttest
-3.43333
3.15888
.40781
-4.24936
-2.61731
-8.419
59
.000
4.1. Results of Hypothesis Testing
The result of statistical analysis cleared that the experimental group outperformed the control group after the treatment sessions. 4.2. Summary
The result of this study suggests that textual modification on the whole contributes to improving the students’ reading comprehension.
When the students are trained how to learn, they will become effective learners and know how to comprehend the text better.
The results of this study reveal that textual modification has a positive effect on the reading comprehension of the students. CHAPTER 5
DISCUSSION AND IMPLICATION
5.1) Discussion
Textual modification for second language learners is an important but somewhat controversial issue in the education community.
Some experts prefer the use of “authentic” texts, i.e., texts which are written for native speakers for a purpose other than instruction, while simplified texts are also very common in educational use.
Proponents of authentic texts tout positive effects on student interest and motivation and advantages of exposing students to “real” language and culture.
However, authentic materials are often too hard for students who read at lower levels, as they may contain more complex language structures and vocabulary than texts intended for learners [8, 13]. Studies of the lexical and syntactic differences between authentic and simplified texts, and their effects on student comprehension, show mixed results [14, 6], suggesting that both types of texts can have a place in education. Further, authentic texts are not always available for students whose reading level does not match their intellectual level and interests.
Since teachers report, spending substantial amounts of time adapting texts by hand, automatic simplification could be a useful tool to help teachers adapt texts for these students.
This paper presents an analysis of a corpus of original and manually simplified news articles with the goal of gaining insight into what people most often do to simplify text in order to develop better automatic tools. When creating simplified or abridged texts, authors may drop sentences or phrases, split long sentences into multiple sentences, modify vocabulary, shorten long descriptive phrases, etc.
5.2) Pedagogical Implication
Textual Modification is the process of reducing the grammatical complexity of a text, while retaining its information content and meaning. The aim of textual Modification is to make text easier to comprehend for human readers or process by programs.
In this thesis, it was described how textual Modification can be achieved using shallow robust analysis, a small set of handcrafted simplification rules and a detailed analysis of the discourse-level aspects of syntactically rewriting text. It was offered a treatment of relative clauses, apposition, coordination and subordination.
It was presented novel techniques for relative clause and appositive attachment. It was argued that these attachment decisions are not purely syntactic. This technique relied on a shallow discourse model and on animacy information obtained from a lexical knowledge base.
It was also showed how clause and appositive boundaries can be determined reliably using a decision procedure based on local context, represented by part-of-speech tags and noun chunks.
It was then formalized the interactions that take place between syntax and discourse during the simplification process. This is important because the usefulness of textual Modification in making a text accessible to a wider audience can be undermined if the rewritten text lacks cohesion. It was described how various generation issues like sentence ordering, cue-word selection, referring-expression generation, determiner choice and pronominal use can be resolved to preserve conjunctive and anaphoric cohesive-relations during textual Modification.
In order to perform textual Modification, It was addressed various natural language processing problems, including clause and appositive identification and attachment, pronoun resolution and referring-expression generation. This approach was evaluated to solving each problem individually, and also present a holistic evaluation of my textual Modification system. 5.3) Implication for teaching
Modified texts are commonly used by teachers and students in bilingual education and other language-learning contexts. These texts are usually manually adapted, and teachers say this is a time consuming and sometimes challenging task. Our goal is the development of tools to aid teachers by automatically proposing ways to modify texts. As a first step, this paper presents a detailed analysis of a corpus of news articles and abridged versions written by a literacy organization in order to learn what kinds of changes people make when modifying texts for language learners. 5.4 ) limitations of The Study
For one thing, this study is limited to the reading skill. Moreover, only syntax is being tackled in modifying the related texts. In addition the supposedly difficult syntactic structures are modified according to six steps of splitting the sentence, changing discourse marker, transformation to active voice, inversion of clause ordering, subject verb-o bject ordering, and topicalization and detopicalization, not by other theories. Finally, only intermediate subjects at university level are being investigated. 5.5) Suggestions for Further Research
The focus of this study was on the effectiveness of strategy-based instruction of textual modification and its effect on EFL university students’ reading comprehension ability at intermediate level. Vocabulary was held constant here and only syntax of the text was simplified. Further investigations could be directed towards other types of modification such as lexical or discourse modification.
On the other hand, different types of modification could be studied in terms of their effect on students at elementary and advanced levels, both at the university or high school.
Furthermore, other studies could shed light on the relationship between modification and other language skills and sub-skills such as listening.
Moreover, the suggestion for further research in psycholinguistics would be to get more accurate and comprehensive insight into the process of reading comprehension and see what kind of textual modification can improve its readability more.
Finally, as a suggestion for further research in testing reading it is worth pointing out that reading tests in use generally suffer from a major problem; they are product-oriented. As reading has been proven to be a process that may succeed or fail at different levels, it would be ideal if testers could develop tests which can observe readers in the process of reading rather than focusing on the final product. REFERENCES:
Anderson, R. & Davison, A. (1988). Conceptual and Empirical Bases of Readability Formulas. In Davison & green (eds). Linguistic Complexity and Text Comprehension. New Jersey: Lawrence Erlbaum Associates, Inc. Bartlett, C. (1983). Remembering: A Study in Experimental University Psychology. Cambridge: Cambridge University Press. Barzegar, GH. (1997). The Effect of lexical and Syntactic Simplification on EFL Learners Reading Comprehension Proficiency. A thesis submitted to Tehran University in partial fulfillment of the requirements for the degree of Master of Arts Department. Beaumont, C. (1982). Language and School Failure: Some speculations about the relationship between oral and written language. In M.M. Clark (eds.). New Directions in the Study of Reading. London: Falmer Press. Beck, I., McKeown, M., Omanson, R. & Pople, M. (1984). Improving the Comprehensibility of Stories: The Effects of Revisions That Improve Coherence. Reading Research Quarterly, 19(3), 263-277. Berman, R.A. (1984). Applied Linguistics and Language Study. New York: Holt, Rinehart and Winston, Inc. Birjandi, P., Mosallanejad, P., & Bagheridoust, E. (2006). Principles of Teaching Foreign Languages. Tehran, Rahrovan Publications. pp, 210-219. Boulware-Gooden, R., Carreker, S., Thornhill, A., & Joshi, R.M. (2007). Instruction of Metacognitive Strategies Enhances Reading Comprehension and Vocabulary Achievement of Third – Grade Students. The Reader Teacher, 61 (1), 70-77. In Roshd Quarterly, 25 (2),53. Brewer, B (2008). Effects of Lexical Simplification and Elaboration on ESL Readers’ Local-Level Received Comprehension. A thesis submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Master of Arts Department. Breen, M. (1985). Authenticity in the Language Classroom. Applied Linguistics. Buck, C. (1973). The Effect of Transformed Syntactic Structure on Reading. In Goodman, K. (ed.). Miscue Analysis: Application to Reading Instruction. Urbana: National Council of Teachers of English. Byrne, B. (1985). Deficient Syntactic Control in Poor Readers. Applied Psycholinguistic, 2. Pp. 201-212 Carrell, P. (1984). Evidence of a Formal Schema in Second Language Comprehension. Language Learning, 34, 87-111. Carrell, P. & Eisterhold, J.C. (1987). Schemata Theory an ESL Reading Pedagogy. In M.H. Long & J.C. Richards (eds.). Methodology in TESOL. New York: Newbury House Publishers. Carrell, P., Devine, J. & Eskey, D. (eds.). (1984). Interactive Approaches to Second Language Reading. Cambridge: Cambridge University Press. Cervantes, R. & Gainer, G. (1992). The Effect of Syntactic]]>

1 Beaumont (1982) suggests that children of 7 would find at least some types of
2 relative clauses difficult to read. She tested children’s ability to understand both subject relative and object relative clauses with and without a relative pronoun, that. Interestingly and contrary to previous findings, the children found the object relative pronouns slightly easier than the subject relatives. With the subject relatives, inclusion or omission of the relative pronoun made no difference. Subject-relative when misunderstood tended to be interpreted as two overlapping NVN constructions. For example: The woman following the man is carrying a dog. would be interpreted as:
The woman is following the man … The man is carrying a dog.
With the object-relative, however, the presence of the relative pronoun was important. Understanding was significantly better when the pronoun was included. The marking function of that guided the children’s interpretations. Also, the children tended to match up the nouns and verbs according to word order and distance principle (Oakhill and Garnham, 1988: 47).
Furthermore, in a study of children’s spontaneous production of relative clauses, Romaine (1984) showed an overwhelming preference for right branching (object relative) clauses in all the ages. She tested 6, 8 and 10-year-olds. This preference, according to Oakhill and Garnham (1988) reflects the fact that RB structures are systematically less complex that CE structures.
The implication for syntactic simplification would be: substitute RB structures for CE ones as much as possible. 2.6.3.5) A Proposition-based Measure of Comprehensibility
There have been several attempts to develop text analysis schemes more appropriate to the active processing model of reading. The best known of these are the approaches of Miller and Kintsch (1980) and Meyer (1975). In Miller and Kintsche’s model, texts are analyzed into propositions and it is these propositions which are used to build a meaning structure. An initial text structure or scheme is imposed based on the initial propositions. That structure is expanded, modified, or abandoned as the reader attempts to interpret successive propositions in terms of it. Frequency of occurrence of propositions and the limits of short-term memory in holding sequences of propositions play important roles in determining comprehensibility.
Meyer’s (1975) approach is also based on a propositional analysis of the text and the identification of the coherence relations between the propositions. From her perspective, the reader builds a hierarchical structure of the propositions. Propositions higher in the structure or supporting the higher order propositions will be better recalled.
Meyer maintains that the structure imposed by the writer may not be adopted by the reader. Such a failure may be due to inadequate signaling of the structure by the writer, lack of skill on the part of the reader, or a difference in goals (information requirements) between the two.
The implications for syntactic simplification would be: state explicitly, with proper clues, the structure of propositions and, as far as possible, decrease the number of propositions in each sentence. 2.7) Syntactic Complexity and Reading
Many experts in the field agree that the students of English as a second or foreign language cannot make reasonable prediction about the material they are reading unless they are familiar with the English grammatical patterns (Buck, 1973). The effect of syntax on reading comprehension has attracted attention of quite a number of researchers during the past decade (Smith, 1971). To understand a sentence, one must work out its ingredient: morphemes, words, phrases, and clauses-their boundaries, their meanings (grammatical, lexical, or both), and their relationships to each other as constituents of larger units, up to and including the sentence itself (Ives, 1964).
It is a widely accepted principle that the simple declarative sentence is in a sense the canonical from of a sentence, in terms of which other sentence types, both complex and reduced, may be explained by reference to such operations as conjunction, insertion, inversion, substitution and transportation (Quirk, Greenbaum, Leech, and Svartvik, 1985).
Quirk, et al. (1985) propose the following sources for syntactic complexity:
1. Combining subordination devices within a sentence.
2. Positions of subordination clauses: subordinate clauses may be positioned initially, medially, or at the end of their super ordinate clauses. Right-branching clauses are the easiest to comprehend; however, comprehension becomes more difficult as the complexity of the left-branching increases.
3. Self embedding: the medial subordination of one constituent with another constituent of the same kind.
4. Subordination versus coordination: coordination is the kind of link most used foroptimum ease of comprehension.
5. Structural ambiguity: A change in the typical word order that is familiar to FL readers could also be a cause of complexity. FL readers are mostly familiar with the SVO or NVO of the surface structure, so when their expectations are violated in the foreign language, their fluency may be disrupted, and hence comprehension hindered. According to many researchers (Wood, 1974; Clark and Clark, 1977) parsing sentences into their natural structure constituents clearly facilitates the rate at which sentences can be processed, regardless of the level or the skill of the reader (Cited in Barzegar, 1997).
Anderson and Davison (1988) have demonstrated that difficulty of comprehension is not linked in a simple way to complex features of sentence syntax. However, they state that if the processing of a complex structure in some way exceeds the attentional resources of the reader, it will be difficult for the reader to continue with processingthe structure. Crain and Shankweiler (1988) propose two hypotheses regarding reading acquisition:
1. The structural deficit hypothesis, which proposes that some syntactic structures are inherently more complex than others; for instance, it is claimed that a sentence containing both a main clause and a subordinating clause is more complex than a coordinate structure.
2. The processing deficit hypothesis, which postulates that reading, demands a number of secondary processing mechanisms to interface spoken language and an orthographic system of representation. These subsidiary mechanisms include verbal working memory, routines for identification of printed words, and the syntactic, semantic and pragmatic processors.
Furthermore, word recognition, parsing, and semantic composition of word meanings that are all highly automatic in speech processing, must be reshaped in reading to interface with a new input source.
In essence, these two views hinge upon the distinction between structure and process. On the first view, there is a structural deficit, i.e., a deficit in stored knowledge. On another view, the problem is one of process, i.e., access and use of this stored knowledge.
What is common to these hypotheses is that each attempts to locate the causes of difficulty in reading. It thus indicates that it is not the structures themselves that make comprehension difficult, but the demands these structures make on the subsidiary processing mechanisms, especially verbal working memory (Crain and Shankweiler, 1988).
On the other hand, Frazier (1988) suggests that syntactic ambiguity poses a difficult problem for the readers. There are indefinitely many sentences in a natural language and thus it is in principle impossible for each sentence to be prestored in memory. Hence, we will assume the processor uses the syntactic well-formedness constraints of the language to assign a syntactic structure to a sentence. Therefore, it will be assumed that the point of assigning a syntactic structure to an input is to determine what a sentence actually mean s,
i.e., to distinguish the permissible meanings of a sentence from the larger sets of meanings that result from randomly combining the meaning of the lexical items in the sentence. All this should impose memory and computational demands on the processor that are larger than the demands imposed by a corresponding unambiguous sentence (Crain and Shankweiler, 1988).
Furthermore, the complexity of processing ambiguous inputs will persist regardless of whether the input is fully ambiguous, and ultimately open to more than one analysis, or only temporarily ambiguous, i.e., the initial portion of a sentence may be open to more than one analysis but sequence items may be consistent with only one of these analyses (Crain and Shankweiler, 1988; Frazier, 1988).
Thus, two types of temporary ambiguity are distinguished: horizontal ambiguity which persists even when all information has been extracted from the preceding sentence and discourse context like: John told the girl that Bill liked the story
and vertical ambiguity due to delayed use of information which in principle may be extracted from material preceding the ambiguous string but which is in fact not exploited by the processor until sometime after the initial syntactic analysis of the string (Frazier, 1988). One further source of processing complexity derives from the operations needed to revise an initial incorrect analysis of a sentence, e.g.:
Lydia knew the answer was correct.
The processor deals with temporary ambiguity by initially pursuing the analysis which requires the fewest syntactic nodes. In the above example, “the answer” must be taken to be the object of a sentential complement to “know” not requiring the insertion of an extra S-node dominating the temporarily ambiguous noun-phrase (Frazier, 1988).
In addition to processing difficulty due to syntactic ambiguities, increases in complexity are associated with differences in the memory burden imposed by different sentences structure (Wanner and Maratsos, 1978). Moreover, the complexity of syntactic processing appears to be greater when many syntactic decisions are clustered together (associated with a local region of the sentence) rather than distributed evenly over the input string (Frazier, 1988). As a matter of fact, it is hard to imagine that linguistic structure has no effect at all on performance, and in fact such a view is not generally held (Smith, 1988).
All the above mentioned sources of syntactic complexity and their effect on reading comprehension suggest that an efficient reader, especially at the university level , should rely partially on syntactic elements to get at the meaning of a given text, and that the matter of vocabulary is not as difficult as that of syntax for university students (Cojocaru,1977). 2.8) Simplification of Reading Materials
Researchers have asked whether it is possible to assess the difficulty of a text by looking at some features of the text, especially those which can be measured objectively. Do features of the text reflect its difficulty, and do linguistic features, such as word difficulty and sentence complexity in themselves present barriers to comprehension? Why do some readers and not others, find a text difficult to comprehend – is it because of a deficit of knowledge, or of language or of attentional capacity for efficient processing of language?
These are questions which should be investigated both by educational and cognitive psychologists as well as educators, writers and publishers concerned with very practical problems of matching texts and readers (Davis, 1995).
All pedagogy involves simplification in that it aims at expressing concepts, beliefs, attitudes, and so on in a way which is judged to be in accord with the knowledge and experience of learners. In language teaching, simplification usually refers to a kind of intra lingual translation whereby a piece of discourse is reduced to a version written]]>

Linguistics has had, as one of its goals, describing linguistic complexity that is determining which structures are complex. To achieve this objective, linguists tried to develop scientific criteria to measure linguistic complexity, and later, along with psycholinguists, they attempted to figure out how linguistically complex structures affect performance. As Smith (1988) argues it is hard to imagine that linguistic structure has no effect at all on performance and in fact such a view is not generally held (p.217).
Miller and Chomsky (1963), for instance, discuss the processing difficulty of sentences with multiple embedding and Chomsky’s early papers point out that transformations tend to reduce abstract structure, and thereby simplify the task of speaker or hearer (Cited in Miller, 1976).
Nevertheless, linguistic complexity as a component in linguistic processing and language development has been tried to be studied autonomously; that is, independent of performance factors. This attempt was carried out by Chomsky (1981) in his well-known Government and Binding (GB) Theory. Smith (1988) delineates GB Theory as follows:
“It has a modular organization: it is composed of separate, interacting modules that account for lexical, syntactic, interpretive, and phonological properties of linguistic structure. ”
Within the modular framework of GB Theory, Smith (1988) postulates some criteria to determine structural complexity. He proposes that linguistic complexity is a property of individual sentences, and is a result of several factors in combination. He suggests that:
“For a given sentence, a complexity profile is constructed, that indicates its complexity at each level. A sentence may have high complexity of one type and low complexity of another …. Perhaps, the most complex sentences are high in complexity of all kinds. ”
Smith proposes three types of complexity:
1. Surface syntactic complexity
2. Interpretive complexity
3. Systematic complexity
As this proposal can hare some implications for syntactic simplification, a brief explanation of each is given below. 2.6.1) Surface complexity
Surface complexity assesses at surface structure, which is the linguistic level at which all syntactic rules have applied.
The determiners of surface complexity are “Amount”, “Density” and “Ambiguity”. 2.6.1.1) Amount
It refers to the number of linguistic units in a sentence:
it involves words and morphemes. The longer and more morphologically
complex a sentence, the higher its complexity.
2.6.1.2) Density
It refers to the way linguistic material is distributed in a sentence.
Materials may be distributed quite evenly among the units of a sentence (that is,
NP, PP, etc); or many words may appear in one unit which makes it dense.
Example (1) [Mary wrote NP [a letter] PP [to her family] ]
Example (2) [Mary wrote NP [a letter] PP [about the meeting] ]
(1) has a simple object NP followed by a PP; (2) has a complex object NP, consisting of an NP and a PP. The object of (2) is denser on two counts: it has both more words and more non-terminal node structures within a phrase. 2.6.1.3) Ambiguity
It involves the surface structure interpretation of a sentence. Sentences with more than one bracketing, or category interpretations, are ambiguous.
Example: Visiting relatives can be boring.
The subject noun phrase has two interpretations:
a) (Adj Noun) the relatives who visit
b) (Ving Noun) to visit one’s) relatives 2.6.2) Interpretive Complexity
It arises when the semantic structure that shows scope relations of a sentence is not congruent with its surface structure. It differs from other types of complexity considered here because it involves a comparison between two levels of structure, rather than properties of one level. At least three type of interpretive complexity can be identified: Empty Categories, Discontinuous Constituents, and Semantic Scope. 2.6.3) Systematic Complexity
It deals with the constraints on the rules that produce syntactic structures. Generally speaking, the rules operate without constraints, producing the full range of possible structures. But some words or phrases add to the complexity of a sentence because they constrain the rules. For example, there is a well-known set of words and phrases known as negative polarityitems; they do not appear freely but require a negative of some kind in sentences in which they appear, like left a finger below:
a) I didn’t lift a finger to help her.
*b) I lifted a finger to help her.
The second sentence is odd at best as a literally meant sentence, and ungrammatical on the idiomatic interpretation … to present a proposal for systematic complexity it would be necessary to consider, closely, the form and range of lexical entries. 2.6.3.1) Sentence Length
“The Longer the sentence the more difficult it would be to understand; this has been a major assumption in readability formulas. While this assertion is not counter-intuitive, it does not necessarily prove true all the times. In fact, in some cases, the opposite has been proven. For example, it has been shown that elliptical sentences, though shorter, are difficult because filling in ellipted words demand greater semantico-syntactic and discourse control.
Moreover, length by itself cannot be considered as an independent criterion for sentence difficulty. Rather, its impact should be measured in interaction with other linguistic and extra-linguistic features.
As Anderson and Davison (1988) contend no recent study has focused specifically on the contribution of sentence length per se to comprehension (P.23). Preliminary findings from a study by Davison, Wilson, and Hermon (1985) show that sentence length alone accounts for a very small percentage of variance in the comprehension of text. They suggest that texts with long sentences are comprehended as well as short sentences, except for poor readers.
One evidence demonstrating that long sentences may be easier to understand comes from Davison and Green (1988). They hold that long sentences are usually characterized by connectives which actually facilitate comprehension, especially in a reversible way.
They provide some examples as follows:
1) I moved the switch. The lights went off.
2a) I moved the switch, because the lights went off.
2b) The lights went off, because I moved the switch.
The two sentences in (1) may bear more than one relation to one another. These different interpretations are paraphrased in (2a) and (2b), in which an explicit connective is used.
Therefore, if there is no connective, the reader is not always able to make the correct inference, especially, if it is not clear from the context, which interference, if any, should be made.
The implication for structural simplification would be that sentence length should be observed in context. If a long sentence overrides reader’s short-term memory and makes comprehension difficult, making it shorter or splitting it can be justified. If, on the other hand, sentence length eliminates ambiguity or facilitates comprehension it is better to be left intact. 2.6.3.2) Preposed Clause
It has been shown that preposed clause to be more complex than a similar clause which follows the main verb and its object. Irwin and Pulver (1977) used sentence pairs, like the following, in their research:
A-Because Mexico allowed slavery, many Americans and their slaves moved to Mexico during that time.
B-Many Americans and their slaves moved to Mexico during that time, because Mexico allowed slavery.
It was surprising that the version with the preposed adverbial clause was difficult for the younger subjects. It was predicted that (A) would always be easier that (B), bec ause the order in which the clauses are mentioned coincides with the general cause-and-effect ordering that is generally preferred. This was the case for older and more skilled readers. This finding has also been supported by another type of reasoning. Yngve (1960), states that words like “the” occur only in phrases with nouns, and precede the noun. This word is a left-branch within a noun phrase and its appearance signals the beginning of a phrase of the NP category. Hence it is stored in working memory while the next constituents are searched for, including the noun. Yngve proposes that for this reason, left branches always require more memory capacity to produce or understand that right branches. Preposed adverbial clauses are left branches, large phrases which mustbe held in working memory until the main clause constituents are found (Bever and Townshend, 1979). Anderson and Davison (1988) remark that the tendency of left branching structure to make a sentence hard to understand is the result of an interaction between the demands on short-term memory caused by left branching structures and a number of other factors.
The implication for syntactic simplification would be: substitute right branching for left branching structures as far as possible. 2.6.3.3) Passive Sentences
The large literature on children’s comprehension of passives (Turner and Rommetveit, 1967; Buldie, 1976; Horgan, 1978; Harris, 1978) has shown that a number of factors reversibility, agent, pragmatic consideration, context, etc-influence the way that such sentences are understood. Slobin (1966) is one of the first researchers who studied how children interpret passives. He gave 6, 8, 10 and 12 year-olds and adults a sentence-picture verification task in which they were presented with a picture and a sentence, and had to say whether the sentences correctly described the picture. He found that, at all ages, reversible passive took longer to verify than non-reversible ones (Cited in Vahdani,1995).
Many experiments, also, have shown (Gluchsberg, Trabasso, and Wald, 1973; Olson and Filby, 1992) passive sentences require less processing time and are more accurately comprehended when the preceding verbal context contains an antecedentfor the passive subjects, which is the topic of the target (Passive) sentences (Vahdani, 1995).
The implication for syntactic simplification would be: when dealing with the passive sentences, pay attention to the kind of passive and its context of use. 2.6.3.4) Relative clause and Embedding
There have been many studies of students’ understanding of relative clauses and a number of theories about why students find them difficult. De Villiers, et al. (1979) identifies two factors that contribute to the structure of relative clauses: a) Embeddedness: It depends on the position of relative clause within a sentence, or more specifically, which part of the main clause it modifies. If the clause modifies the superficial subject NP, it is center-embedded (CE). If it modifies the object NP, it is right branching (RB). b) The focus: It refers to the function that the head noun phrase _the noun phrase in the main clause that is modified by the relative clause _ plays in the relative clause (subject, object, or indirect object). Subject-focus relative clauses are often termed subject relative and object-focus are termed object relative. Examples of each type are given below:
1. The cat that bit the dog chased the rat. (CE _ subject-relative)
2. The cat that the dog bit chased the rat. (CE_ object-relative)
3. The cat bit the dog that chased the rat. (RB_ subject-relative)
4. The cat bit the dog that rat chased. (RB_ object-relative)
Sheldon (1974) carried out an influential early study of relative clauses on 3 to 5 year olds and found that neither factors alone could account for the comparative difficulty of different types of relative clause. She proposed the Parallel Function Hypothesis, stating that sentences in which the head NP has the same function (subject or object) in both clauses are easier. Thus (1) and]]>

4. Perception of syntax for a given word depends upon the context in which the word is embedded (syntactic knowledge).
5. Our interpretation of what we read depends upon the context in which a text segment is embedded (lexical knowledge). All the aforementioned knowledge sources provide input simultaneously. These sources need to communicate and interact with each other, and the higher-order stages should be able to influence the processing of lower-order stages.
According to Stanovich’s interactive-compensatory model:
1. Top-down processing may be easier for the poor reader who may be slow at word recognition but has knowledge of the text topic.
2. Bottom-up processing may be easier for the reader who is skilled at word
recognition but does not know much about the text topic.
3. As a result, Stanovich’s model states that any stage may communicate with any other and any reader may rely on better developed knowledge sources when other sources are temporarily weak.
To properly achieve fluency and accuracy, developing readers must work at perfecting both their bottom-up recognition skills and their top-down interpretation strategies. Good reading (that is fluent and accurate reading) can result only from a constant interaction between these processes. Eskey states that fluent reading entails both skillful decoding and relating information to prior knowledge (Eskey, 1988). This interactive model, in essence is rooted in a well-known theory in reading comprehension called schema theory. 2.3) Schema theory
As a more process-oriented approach to reading comprehension is adopted, more and more attention is directed to the reader, rather than the text. In other words, in-the-hand factors gains predominance over in-the-text factors. It is acknowledged that what reader brings with him to the text and the way he interacts with the material determines the degree of comprehension. As a result, one of the factors, which is given tremendous importance, becomes the reader’s related background knowledge. According to Clarke and Silberstein (1977):
“The reader brings to the task a formidable amount of information and ideas, attitudes and beliefs. This knowledge coupled with the ability to make linguistic predictions, determines the expectations the reader will develops on as he reads. Skill in reading depends on the efficient interaction between linguistic knowledge and knowledge of the words (P.136).”
In fact, the role of background knowledge in language comprehension has been formalized as Schema Theory (Bartlett, 1983; Rumelhart, 1980). Clarke and Silberstein (1977) explain Schema Theory as follows:
“The previous knowledge structure is called schemata. According to the schema theory comprehending a text is an interactive process between the reader’s background knowledge and the text. Efficient comprehension requires the ability to relate the textual material to one’s own knowledge (1987).”
The theory envisions an information-processing model of the mind in which knowledge is stored in related units that can be recalled and activated to operate incoming information (Anderson, 1988). According to Perkins (1983) Schema Theory assumes that readers use a process of semantic productivity to create meaning from a written or spoken text, which itself has no meaning (Cited in Vahdani, 1995). This Theory also predicts that as readers read, they are able to go beyond the word and sentence level to the overall organization and discourse level of the reading because their background knowledge or schemata enables them to expect and predict the way in which the writer has organized the material (Carrell, 1984). Chastain (1988) calls this “knowledge of story schemata”, or writing patterns” which makes it possible for the readers to use the conventions of their language to comprehend the text. 2.4) Parsing
A first step in the process of understanding a sentence is to assign elements of its surface structure to linguistic categories, a procedure known as parsing (Carroll, 2008; p.132). The result of parsing is an internal representation of the linguistic relationships within a sentence, usually in the form of tree structure or phrase marker (ibid). Parsing may be thought as a form of problem solving or decision making in the sense that we are making decisions (although not necessarily in a conscious manner) about where to place incoming words into the phrase marker we’re building. According to Just and Carpenter (1980) these suggestions are made immediately as the reader encounters a word, principle called immediacy principle. According to this principle, when the reader first hear or see a word , access its meaning from permanent memory, identify its likely referent , and fit it into the syntactic structure of the sentence. The alternative one is to take a “wait-and-see” approach: to postpone interpreting a word or phrase until it is clearer where a sentence is going. Considerable evidence for the immediacy principle is available. The primary reason is that the number of decisions involved in understanding even a single sentence can be quite large and thus can overload our cognitive resources.
There are two parsing strategies. One of them is called the late closure strategy. The strategy states that, whenever possible, the reader prefer to attach new items to the current constituent (Frazier, 1987).It reduces the burden on working memory during parsing (ibid). A second strategy is referred to as the minimal attachment strategy, which states that the reader prefers attaching new items into the phrase marker being constructed using the fewest syntactic nodes consistent with the rules of the language (Carroll, 2008). 2.5) Reading materials
The importance of appropriate material has been mentioned before. However the following quotation by Chastain (1988) leaves no doubt in this regard: “Selection of appropriate reading material is a crucial component in the establishment of a productive reading program. Given good reading materials, capable students can manage to compensate for inadequate reading instruction and inappropriate post–reading activities, but they cannot learn to read if they do not have authentic materials with worthwhile content (p. 231).”
Here Chastain believes that appropriate reading materials are so important that without them students would be bogged down in learning to read , whereas with appropriate materials students can improve their reading proficiency without further help from the teacher , provided they have been taught how .
However, just saying that material should be appropriate does not mean anything. In other words, appropriacy of materials should be operationally defined. A difficult task though it is, appropriacy could be broken down to definable components so as to make the development and selection of appropriate materials an easier task for teachers to accomplish. Therefore, the remainder of this section will be devoted to elucidating the components of appropriacy.
2.5.1) Interest
The reader’s willingness to process the printed page until the message is fully understood is a central point. No reading will indeed take place if readers are not interested enough to continue reading. However if they are really interested in knowing what the author has to say, they will make every effort to understand the reading (Chastain, 1988). Along the same lines, Thonis (1970) states: ” The interests of pupils , too , have an important bearing on the choice of materials we may offer … Primary pupils may enjoy the practice of Twinkle , Twinkle , Little star … Older pupils would enjoy , I Must Go Down To The Sea Again … ( p . 198 ).”
All this implies, therefore, that in the preparation and selection of materials, an important factor to take into account is the interests of the students. 2.5.2) Objectives
The selection of materials should also be based upon the object ives of the reading program (Thonis, 1970). Without clarifying the objectives, confusion may arise both for the teacher and for the learners. As Chastain (1988) holds:
“Students’ goals vary from no particular objective, common to students in elementary language courses, to very specific goals, such as those held by students with definite career plans (p.232).”
In the same vein, Thonis (1970) holds:
“We need to specify what exactly the present nature of our pupil is, including his language ability and his past educational experiences and to describe precisely what he should be able to do as a result of his exposure to the materials . This exact and precise description of our instructional objectives, in terms of how the learner is expected to perform, serves an excellent guide to our choice of materials (p.197).”
Therefore, another criterion for preparing and selecting appropriate reading materials is that they should fit the objectives of the learners. 2.5.3) Readability
Readability of reading materials, estimated on the basis of linguistic elements in a text, has often been considered a cause of difficulty for students at different levels. However, Beaumont (1982) found that students do not necessarily understand better materials with a lower readability score.
Therefore, scholars conclude that more important factors are at work here. The two most important are background knowledge and interest, considered by Baldwin et al. (1984) to be separate factors in reading comprehension (Chastain, 1988).
Another significant factor affecting comprehensibility in language classes is the lack of familiarity students may have with the foreign culture (Johnson, 1981).
Therefore, in addition to readability, factors such as background knowledge, interest and cultural load must be taken into account when preparing or selecting reading materials. 2.5.4) Authenticity
Robinson (1991) approaches authenticity in the following terms: “A key concept within the communicative approach, and one felt to be particularly relevant for ESP is that of authenticity … basically, when we refer to the use of print, audio, video and pictorial material originally produced for a purpose other than the teaching of language (p.54).”
However, Widdowson (1990) argues differently with regard to authenticity. He states: “Authenticity of language in the classroom is bound to be, to some extent, an illusion. This is because it does not depend on the source from which the language as an object is drawn but on the learners’ engagement with it (pp. 44, 45).”
He further adds that if authenticity is to be defined as natural language behavior, there is also difficulty that learner will naturally incline to draw on their own languagein any situation that calls for uncontrived linguistic communication.
Recently, Widdowson (1996) holds:
“Authenticity concerns the reality of native – speaker language use … But the language which is read for native speakers is not likely to be read for learners … They belong to another community and do not have the necessary knowledge of the contextual conditions which would enable them to authentic English in native speaker terms.”
Lee (1995) distinguishes between text and learner authenticity:
“Text authenticity is defined in terms of origin of the materials, while learner authenticity refers to the interaction with them, in terms of appropriate responses and positive psychological reaction (p. 323).”
Looking at authenticity in this way, we can conclude that textually authentic non-text book materials will not necessarily be learner unauthentic. On the contrary, Byrnes (1985) argues material written by native speakers for language students as being authentic. But, all in all, authenticity is definitely one important factor to be taken into account in preparing and selecting materials, although no general agreement has yet been reached as to what authenticity indeed is and how it is]]>

In the light of new orientation, the idea that reading proceeds word-by-word is rejected. In the early seventies, Goodman’s psycholinguistic model of reading (later named the top-down or concept-driven model) began to have an impact on views of second language reading. In this model the reader is active; makes predictions, processes information, and reconstruct a message encoded by a writer. As Clark and Silberstein (1987) denote: “Reading is an active process. The reader forms a preliminary expectation about the material, and then selects the fewest, most productive cues necessary to confirm or reject the expectation. This is a sampling process in which the reader takes advantage of his knowledge of vocabulary, syntax, discourse, and the real world.”
The top-down processing perspective into reading comprehension had a profound impact on the field, to an extent that it was viewed as a substitute for the bottom-up perspective, rather than its complement. Alderson and Urquhart (1984) contrast the two approaches as follows:
“A product view relates only to what the reader has got out of the text while process view investigates how the reader may arrive at a particular interpretation (p.150).” Smith (1973) emphasizes two important psycholinguistics contributions against word-by-word processing; first, it has been established that there is a severe limit to the amount of information that we are able to receive, process, and remember. Therefore, the reader does not use all of the information in the printed page, but he must select the most productive language cues in determining the message of the writer. As a result, the reading should necessarily be a rapid process which does not precede word-by-word.
Second, Smith holds, research has shown that actually reading is incidentally visual. More information is contributed by the reader than by the print on the page. In fact such a wordby-word reading has been recognized as a defective strategy used by native readers. Varzegar (1978), for instance, talks about the destroying effect of word-by-word reading on fluent reading. He regards reading as a multi-faceted process which entails different activities to be performed; a complex process of identification of letters, recognition of words, visual identification, and thereby sampling of ideas, predicting of forthcoming content and decoding the intended meaning of passage . Goodman (1971) considers reading as a psycholinguistic guessing game in which the reader constructs, as best he can, a message which has been encoded by a writer as a graphic display. The fact that reading is a selective process has been emphasized by Goodman (1973): “The reader does not use all the information available to him. Reading is a process in which reader picks and choose from the available information only enough to select and predict a language structure which is decodable.”
In this approach, reading is a process in which readers sample the text, make hypotheses about what is coming next, sample the text again in order to test their hypotheses, confirm or reject them, make new hypotheses, and so forth. The theory claims that this process of reading is a universal process, and posits the reading universal hypothesis which says that this model has been built through the study of English reading, but it must be applicable to reading in all languages and all orthographies (Goodman, 1975).
Smith (1971) describes reading as “the reduction of uncertainty”. Wallace (1992) elucidates that “as we progress through a text, our choices of what to select are constrained, often heavily, both by features within the text and those external to it”. He describes reading as a unitary aptitude, which is consistent with Smith’s and Goodman’s approach. They hypothesize that it is not possible to identify specific skills which can be built up in any hierarchical way. They believe that effective readers are characterized by ability and willingness to reflect on what they are reading. This unitary view of reading process, as Wallace (1992) contends, has led researchers to talk of reading strategies rather than distinctive skills. He states that “effective readers draw selectively on a range of strategies which are determined by reader purpose, text-type, and context”.
Finally Wallace (1992) proposes an interactive model of reading comprehension as follows: “Texts do not contain meaning; rather they have potential for meaning. This potential is realized only in interaction between text and reader. That is, meaning is created in the course of reading as the reader draws both on existing linguistic and semantic knowledge and input provided by the printed or written text. ”
However, as schema theory research has attempted to make clear, efficient and effective reading in L1 and L2 requires both top-down and bottom-up strategies operating interactively; that is interactive model (Rumelhart, 1977). Both top-down and bottom-up processes, functioning interactively, are necessary to an adequate understanding of second language reading and reading comprehension (Carrell, 1988).
As a matter of fact, the approaches that teachers employ to teach reading and students employ to read the reading materials depend on their functional definition of the reading, learning and language (Chastain, 1988). This means that there might be as many approaches as there are teachers, students, objectives, setting, and so on. But to save space, the major ones will be discussed briefly: 2.2.1) The Top down (Concept-Driven) Approach
The “top down” approach emphasizes readers bringing meaning to text based on their experiential background and interpreting text based on their prior knowledge (whole language).The word “top” refers to higher order mental concepts such as the knowledge and expectations of the reader, and “bottom” refers to the physical text on the page.
The top-down model of reading focuses on what the readers bring to the process (Goodman, 1967; Smith, 1971). The readers sample the text for information and contrast it with their world knowledge, helping to make sense of what is written. The focus here is on the readers as they interact with the text. This model starts with the hypotheses and predictions then attempts to verify them by working down to the printed stimuli.
Carrell and Eisterhold (1987) consider top-down processing as conceptually driven because:
“Top-down processing occurs as the system makes general predictions based on higher level, general schemata, and then searches the input for information to fit into these partially satisfied, higher order schemata. Top-down processing is therefore called conceptually driven (cited in Long & Richards, 1987, p. 221).”This view of reading was called the psycholinguistic guessing game (Goodman, 1967). According to Goodman (1967), readers employ 5 processes in reading:
1. Recognition-initiation
2. Prediction
3. Confirmation
4. Correction
5. Termination
Impact of Goodman’s model:
This model which has recently been characterized as a concept-driven, top-down pattern had the greatest impact on conceptions about native and second language reading instruction: it made the reader an active participant in the reading process ; from earlier views of SL reading as a passive linguistic decoding process to more contemporary views of SL reading as an active predictive process.
According to Stanovich (1980), this model has some disadvantages:
1. For many texts, the reader has little knowledge of the topic and cannot generate predictions.
2. Even i f a skilled reader can generate predictions, this would take much longer than it would to recognize the words.
According to Eskey (1988), a top-down model of reading is essentially a model of the fluent reader and does not account for all the needs of students who are acquiring reading skills. 2.2.2) The Bottom up (Serial) Approach (Text-based)
The “bottom up” approach stipulates that the meaning of any text must be “decoded” by the reader and that students are “reading” when they can “sound out” words on a page. It emphasizes the ability to de-code or put into sound what is seen in a text. It ignores helping emerging readers to recognize what they, as readers, bring to the information on the page.
This model starts with the printed stimuli and works its way up to the higher level stages. The sequence of processing proceeds from the incoming data to higher level encodings.
Carrell and Eisterhold (1987) explain why bottom-up process is called data-driven: “Bottom-up process is evoked by the incoming data ; the features of the data enter the system through the best fitting, bottom-up schemata. Schemata are hierarchically organized from most general at the top to the most specific at the bottom. As these bottom-up schemata coverage into higher level, more general schemata, these too become activated. Bottom-up processing is, therefore, called data-driven. ” According to Stanovich (1980), this model has some problems:
1. This model has a tendency to depict the information flow in a series of discrete stages, with each stage transforming the input and then passing the recorded information on to the next higher stage.
2. An important shortcoming of this model is the fact that it is difficult to account for sentence-context effects and the role of prior knowledge of text topic as facilitating variables in word recognition and comprehension (because of lack of feedback).
According to Eskey (1988), the decoding model is inadequate because it underestimates the contribution of the reader who makes predictions and processes information. It fails to recognize that students utilize their expectations about the text, based on their knowledge of language and how it works (p. 3). 2.2.3) The Interactive Approach
For those reading theorists who recognized the importance of both the text and the reader in the reading process, an amalgamation of the two emerged the interactive approach. Reading here is the process of combining textual information with the information the reader brings to a text.
The interactive model (Rumelhart 1977; Stanovich 1980) stresses both what is on the written page and what a reader brings to it using both top-down and bottom-up skills. It considers reading as the interaction between reader and text. The overreliance on either mode of processing to the neglect of the other mode has been found to cause reading difficulties for SL learners (Carrell 1988, p. 239) The interactive models of reading assume that skills at all levels are interactively available to process and interpret the text (Grabe 1988). In this model, good readers are good decoders and also, good interpreters of text, their decoding skills becoming more automatic but no less important as their reading skill develops (Eskey 1988).
According to Rumelhart’s interactive model:
1. Linear models which pass information only in one direction and which do not permit the information contained in a higher stage to influence the processing of a lower stage contain a serious deficiency. Hence the need for an interactive model which permits the information contained in a higher stage of processing to influence the analysis that occurs at a lower stage.
2. When an error in word recognition is made, the word substitution will maintain the same part of speech as the word for which it was substituted, which will make it difficult for the reader to understand (Orthographic knowledge)
3. Semantic]]>