The level and distribution of selected organochlorine pesticides in sediments from River Chenab,Pakistan |
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Authors: | Syed Ali-Musstjab-Akber-Shah Eqani Riffat Naseem Malik Ashiq Mohammad |
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Institution: | (1) Environmental Biology Laboratory, Department of Plant Sciences, Quaid-i-Azam University, Islamabad, 46000, Pakistan;(2) Ecotoxicology Research Program, National Agricultural Research Center, Park Road, Islamabad, 45500, Pakistan; |
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Abstract: | Organochlorine pesticides (OCPs), viz. β-hexachlorocyclohexane (β-HCH), γ-HCH, aldrin, dieldrin, endrin, heptachlor, endosulfan-I,
endosulfan-II, heptachlor endoepoxide, heptachlor exoepoxide, mirex, dicofol, o,p′-dichlorodiphenyltrichloroethane (o,p′-DDT), p,p′-dichlorodiphenyltrichloroethane (p,p′-DDT), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyltrichloroethylene (DDE) and 12 other physicochemical parameters
were measured in surface sediments from River Chenab during two sampling seasons (summer and winter, 2007) to evaluate spatial
and temporal trends of sediment pollution. Hierarchical agglomerative cluster analysis identified three groups of sites based
on spatial similarities in physicochemical parameters and OCP residual concentrations. Spatial discriminant function analysis
(DFA) segregated 14 parameters, viz. dicofol, endosulfan-I, heptachlor endoepoxide, dieldrin, DDD, DDE, endosulfan-II, o,p′-DDT, p,p′-DDT, pH, electrical conductivity (EC), Cl−1, total P (%), and silt, which explained 96% of total variance between spatial groups. γ-HCH was the most frequently detected
(63%) pesticide, followed by DDD (56%). The ratio of DDTs to their metabolites indicated current input and anaerobic biodegradation.
Temporal DFA highlighted aldrin, heptachlor endoepoxide, Cl−1, total P, and EC as important variables which caused variations between summer and winter. DDTs were relatively more prevalent
as compared to other OCPs in the sediments samples during both seasons. DDT metabolites were detected at greater frequencies
and concentrations in winter, whereas DDT isomers were more prevalent in summer sediment samples. Factor analysis identified
agricultural and industrial activities as major sources of sediment OCP contamination. Concentrations of γ-HCH, heptachlor
endoepoxide, dieldrin, and DDTs (isomers and metabolites) in all sediment samples were well above interim sediment quality
guidelines (ISQGs) and probable effect limits (PEL) given by Canadian Sediment Quality Guidelines (CSQGs). |
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