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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