کاهش تبخیر سطحی آب‌های ساکن به‌وسیله پوشش زنده و غیر زنده گیاه عدسک آبی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکترای تخصصی شیمی کاربردی، دانشکده علوم پایه، واحد اراک، دانشگاه آزاد اسلامی، اراک، ایران

2 استادیار، گروه شیمی و مهندسی شیمی، واحد میانه، دانشگاه آزاد اسلامی، میانه، ایران

3 استادیار، دانشکده علوم پایه، واحد اراک، دانشگاه آزاد اسلامی، اراک، ایران

4 دانشیار، دانشکده علوم پایه، واحد اراک، دانشگاه آزاد اسلامی، اراک، ایران

10.22093/wwj.2019.169339.2834

چکیده

میزان زیاد تبخیر از سطح آب، باعث کاهش قابل توجه استفاده بهینه از مخازن آب می‌شود. یکی از بزرگ‌ترین مشکلات آب سدها در ایران، از دست رفتن مقدار زیادی از آب از طریق تبخیر سطحی، به‌علت بالا بودن سرعت تبخیر است. در این پژوهش، کارایی گیاه عدسک آبی به‌عنوان یک پوشش دوستدار محیط‌زیست روی آب در کاهش تبخیر سطحی آب مورد بررسی قرار گرفت. برای این منظور، یک سیستم پایلوت طراحی شد که شامل دو حوضچه‌ شیشه‌ای (آکواریوم) بود. یک حوضچه (حوضچه‌ گیاهی) به‌عنوان آکواریوم کشت گیاه و ایجاد پوشش گیاهی از آب سد بدون هیچ‌گونه افزودنی از مواد مغذی گیاهی پر شد و یک حوضچه دیگر (حوضچه‌ غیر گیاهی) از آب سد بدون گیاه پر شد. دیواره‌ آکواریوم‌ها با ورق آلومینیومی پوشانده شد تا نور فقط از بالای آکواریوم به آن تابیده شود. دو لامپ فلورسنت به‌عنوان منبع نور در بالای هر حوضچه قرار گرفت. دمای اتاق در 25 درجه سلسیوس ثابت و مدت زمان نوردهی در طول یک شبانه‌روز، روی 14 ساعت تنظیم شد و به‌مدت یک ماه، هر 24 ساعت میزان تبخیر آب با استفاده از مقدار تغییر ارتفاع آب در حوضچه‌ها اندازه‌گیری شد و اثر پوشش گیاهی، هوادهی و مقایسه‌ پوشش زنده و غیرزنده‌‌ عدسک آبی بررسی شد. نتایج نشان داد که میزان تبخیر در حوضچه‌ گیاهی کمتر از حوضچه‌ غیر گیاهی است. میزان تبخیر در حوضچه‌ گیاهی و غیر گیاهی به‌ترتیب برابر با 75/23 و 60/32 درصد بود. همچنین اثر هوادهی بر کاهش تبخیر بررسی شد. هوادهی، رشد عدسک آبی را افزایش و میزان تبخیر را کاهش داد. همچنین نتایج نشان داد که عدسک آبی غیر زنده می‌تواند به‌عنوان پوشش روی آب برای کاهش تبخیر استفاده شود. مقایسه نتایج به‌دست آمده در محیط آزمایشگاه و هوای آزاد نشان داد که میزان تبخیر در هر دو آکواریوم گیاهی و غیر گیاهی در هوای آزاد نسبت به محیط آزمایشگاه بیشتر است.

کلیدواژه‌ها


عنوان مقاله [English]

Reducing Evaporation of Standing Waters by Fresh and Non-Living Duckweed Covering

نویسندگان [English]

  • Zahra Soltani 1
  • Ali Khani 2
  • Kazem Mahanpoor 3
  • Azam Marjani 4
1 PhD Student of Applied Chemistry, Faculty of Basic Sciences, Arak Branch, Islamic Azad University, Arak, Iran
2 Assist. Prof., Dept. of Chemistry and Chemical Engineering, Miyaneh Branch, Islamic Azad University, Miyaneh, Iran
3 Assist. Prof., Faculty of Basic Sciences, Arak Branch, Islamic Azad University, Arak, Iran
4 Assoc. Prof., Faculty of Basic Sciences, Arak Branch, Islamic Azad University, Arak, Iran
چکیده [English]

The extremely high rate of evaporation from water surfaces greatly reduces optimal utilization of water reservoirs. One of the biggest problems of water in dams in Iran is the huge amount of water loss through evaporation due to high evaporation rate. In this study, the efficiency of duckweed (Lemna gibba L.) as an environmentally friendly cover on water in reducing water evaporation has been investigated. For this purpose, a pilot system was designed that consisted of two glassy ponds. One pond as duckweed culture medium filled with raw water of the dam without the addition of any duckweed nutrients (plant pond), and another pond filled with raw water of the dam without duckweed (unplanted pond). Duckweed (Lemna gibba L.) was purchased from a typical aquarium market, and it was then cultured and used for batch experiments. The raw water of Aydoghmush dam (Miyaneh, Iran) was used for culture medium. The walls of the ponds were covered to prevent light from entering except at the top and the tow fluorescent lamps (36 W, Pars Co.) as artificial light at the top of each pond were also located (simulating natural climatic conditions). Temperature was maintained at 25 °C, and 14 hours of photoperiod was applied to duckweed. Both ponds were also equipped with an aeration system installed at the bottom of the pond. One of the aquariums as a growth medium and plant covering (planted aquarium) and the other without duckweed as unplanted aquarium were selected (both aquariums were filled with the raw water of the dam without the addition of any duckweed nutrients). For one month, every 24 hours, the amount of water evaporation was measured using the amount of change of water height in the ponds. The effect of plant covering, aeration and comparison of fresh and non-living duckweed covering on reducing surface water evaporation were studied. The effect of plant covering on reducing surface water evaporation in open air (outside) was also investigated.  The results showed that the rate of evaporation in the plant pond is lower than unplanted pond. The content of evaporation in the plant and unplanted ponds is 23.75 and 32.60%, respectively. So, plant growth and creating coverage on the water’s surface can be effective in reducing the surface evaporation of water storages such as dams. The effect of aeration on reduction of evaporation was also investigated. The results indicated that aeration enhanced growth rate of the plant and consequently, reduced the water evaporation. This can be due to the following main reasons: 1) increasing the growth rate of the plant and the formation of more plant covering on the surface of the water; 2) the formation of turbulent flow in the surface layer of water and the replacement of water molecules with those molecules that have the potential to escape from the surface of the water. The results also showed that non-living duckweed can be used as a cover on water to reduce water evaporation, and in the open air, by creating plant covering on the surface of the water, 23.53% of the surface water evaporation can be prevented. By comparing the results obtained in the laboratory and in the open air, it is evident that the evaporation rate in both plant and unplanted aquariums is higher than in the laboratory environment, which can be due to exposure to sunlight and wind.

کلیدواژه‌ها [English]

  • Duckweed
  • Evaporation
  • cover
  • Dam Water
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