Environmental Science
N.J. Mensah; S. Antwi-Akomeah; E.J.D. Belford; G.E. Sebiawu; R. Aabeyir
Abstract
BACKGROUND AND OBJECTIVES: The vulnerability of the Sankana dam to organochlorine pesticide contamination is a major cause for concern. Indigenes rely on the dam for drinking water and irrigation of their farmlands as well as for fish and other aquatic delicacies. Virtually there exists no study on the ...
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BACKGROUND AND OBJECTIVES: The vulnerability of the Sankana dam to organochlorine pesticide contamination is a major cause for concern. Indigenes rely on the dam for drinking water and irrigation of their farmlands as well as for fish and other aquatic delicacies. Virtually there exists no study on the residual levels of organochlorine or other pesticide contaminants in the dam despite its susceptibility to pesticide contamination. In the present study, the levels of organochlorine residues in fish and sediments from the Sankana dam were assessed.METHODS: Pesticide residue extraction was achieved using acetonitrile containing 1% (v/v) acetic acid in the presence of sodium acetate, sodium citrate and magnesium sulphate followed by purification over activated florisil and sodium sulphate. Identification and quantification of residue extracts was done using a gas chromatograph conjugated with mass spectrometer.FINDING: In all, varying levels of 13 organochlorine residues were detected, 11 of which were found in fish and 12 in sediment. Average mean levels of organochlorine residues found in fish ranged from 0.001 - 0.277 mg/kg. Residual levels of beta-hexachlorocyclohexane, delta-hexachlorocyclohexane, gamma-hexachlorocyclohexane, endosulfan-A and dichlorodiphenyldichloroethane in fish were relatively higher than their respective levels in sediment. Organochlorine residues found in sediment also ranged from 0.001 - 0.091 mg/kg. Dichlorodiphenyldichloroethylene, aldrin, dieldrin, endrin, methoxychlor, heptachlor, gamma-chlordane and endosulfan-B residual levels in sediment were higher than the corresponding levels in fish.CONCLUSION: The study provides a baseline for continuous/regular monitoring of organochlorine contaminants in the Sankana dam and other waterbodies upstream and downstream. Where organochlorine residues exceeded their recommended permissible thresholds typically suggests possible recent/continuous use of such pesticides within the catchment area. There is therefore the need for appropriate measures and/or need to strengthen existing policies that bans the importation, sale and use of organochlorine pesticides via strict enforcement.
S. Afshar; B. Saghafian; H.R. Vosoughifar
Abstract
The present study was carried out to determine the possible origins of sediments entering Taleghan Dam in northern part of Iran, in order to avoid further sedimentation and helping in extension of the useful life of the proposed dam. This was performed by XRD analysis. To do so, first of all, sediment ...
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The present study was carried out to determine the possible origins of sediments entering Taleghan Dam in northern part of Iran, in order to avoid further sedimentation and helping in extension of the useful life of the proposed dam. This was performed by XRD analysis. To do so, first of all, sediment sampling points were positioned along the Taleghan River. The collected samples, after coding, were transferred to the laboratory for mineralogical testing. Then, the samples were exposed to X-ray diffraction analysis. The experimental results were compared with data from geology, land cover land use and slope maps in order to find the possible primary origins of deposits in the Taleghan Dam. Furthermore, the geological formations and physiographical parameter such as slope were also analyzed to test erodibility of the formations. The results showed that most sediment samples in Taleghan are of sedimentary sandstone, mainly containing the quartz and plagioclase minerals (quartz sandstone and arkose sandstone). The findings also showed that calcite and dolomite were abundant in the collected samples, while aragonite and anthracite were found to a lesser extent in the samples. Accordingly, acidic and alkaline formations, mudstone, and siltstone of Karaj area formations, the gypsum of upper red formation, particularly at places with steep slope with a dominance of rangeland land use type, are main origins of sediments in the Taleghan reservoir. In another hand, the control of sediments at these areas would substantially decrease total sediment yields of the entire basin as in the dam reservoir.
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