Sains Malaysiana 40(8)(2011): 821–825

 

Effects of Thermal Stratification on the Concentration of Iron and Manganese

in a Tropical Water Supply Reservoir

(Kesan Perlintapan Haba ke atas Kepekatan Ferum dan Mangan di dalam Takungan Air Bekalan Tropika)

 

Noor Halini Baharim*

Faculty of Science and Environmental Technology, Universiti Industri Selangor, Jalan Timur Tambahan

45600 Bestari Jaya, Selangor, Malaysia

 

Razali Ismail

Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia

 

Mohamad Hanif Omar

Jabatan Kimia Malaysia, 46100 Petaling Jaya, Selangor, Malaysia

 

Diserahkan: 10 Mei 2010 / Diterima: 22 Disember 2010

 

 

ABSTRACT

Thermal stratification in lakes is an important natural process that can have a significant effect on the water resource quality. The potential changes in chemical contents in water resulting from stratification are the production of ammonia, sulphides and algal nutrients and the increasing concentrations of iron and manganese. One of the water supply reservoirs located in Johor, Malaysia facing with high iron and manganese concentrations associated with the period of stratifications. This study showed that the level of thermal stratification in the reservoir varied at different time of the year. During the strongest period of stratification, the dissolved oxygen content was found to diminish significantly with depth and iron and manganese were recorded at the highest concentrations. Although significant period of rainfalls contributed to the natural destratification of reservoir, lower concentrations of iron and manganese only remained for a shorter period before the concentrations continued to increase with the onset of the thermal stratification. A good understanding on the behaviour of the reservoir may help to identify several measures for the improvement of water quality.

 

Keywords: Iron; manganese; thermal stratification; water quality

 

ABSTRAK

Perlintapan haba yang berlaku di dalam tasik merupakan suatu proses semula jadi yang memainkan peranan penting terhadap kualiti air bekalan. Antara perubahan kimia yang berlaku di dalam air hasil daripada perlintapan haba adalah penghasilan ammonia, ion sulfida dan nutrisi alga serta peningkatan kepekatan ferum dan mangan. Sebuah tasik takungan tropika yang membekalkan air mentah kepada loji air minuman di Johor, Malaysia menghadapi masalah kepekatan ferum dan mangan yang tinggi disebabkan oleh perlintapan yang berlaku. Kajian ini menunjukkan tahap kewujudan perlintapan haba dalam tasik takungan tropika berubah-ubah sepanjang tahun. Pada tahap perlintapan haba yang tinggi, kandungan oksigen terlarut berkurangan mengikut kedalaman tasik menyebabkan kepekatan yang tinggi bagi ferum dan mangan. Walaupun musim hujan mempengaruhi penyahlintapan haba secara semula jadi di dalam tasik, bacaan kepekatan ferum dan mangan yang rendah hanya mampu bertahan dalam tempoh masa yang pendek dan akan kembali meningkat apabila perlintapan berlaku semula. Pemahaman yang baik terhadap keadaan tasik takungan tropika ini dapat digunakan untuk mengenalpasti beberapa kaedah yang boleh diambil bagi tujuan peningkatan kualiti air.

 

Kata kunci: Ferum; kualiti air; mangan; perlintapan haba

RUJUKAN

 

American Public Health Association 1998. Standard Methods for the Examination of Water and Waste Water. 15th Edition. Washington D.C.: APHA-AWWA-WPCF.

Davidson, W. 1993. Iron and manganese in lakes. Earth Science Reviews 34(2): 119-163.

Lawson, R. & Anderson, M.A. 2007. Stratification and mixing in Lake Elsinore, California: An assessment of axial flow pumps for improving water quality in a shallow eutrophic lake. Water Research 41(19): 4457-4467.

Lukatelich, R., Robertson, D., Boland, K., Imberger, J. & Patterson, J. 1999. Stratification, mixing and water quality in Darwin water supply reservoir, Urban Water Research Association of Australia 34: 1-60.

Palancar, M.C., Aragon, J.M., Sanchez, F. & Gil, R. 2006. Effects on warm water inflows on the dispersion of pollutant in small reservoir. Journal of Environmental Management 81(3): 210-222.

Wetzel, R. 1983. Limnology. Philadelphia: Saunders College Publishing.

Zaw, M. & Chiswell, B. 1999. Iron and manganese dynamics in lake water. Water Research 33(8): 1900-1910.

 

 

*Pengarang untuk surat-menyurat; email: halini@unisel.edu.my

 

 

 

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