Assessment of occurrence and concentrations of paraquat dichloride in water, sediments and fish from Warri River Basin, Niger Delta, Nigeria.

The distribution of Paraquat dichloride in different matrices of Warri River, Western Niger Delta, Nigeria was examined. The samplings and physicochemical parameters of the river were carried out during the dry and wet seasons, and stations were visited on monthly basis. The downstream stations had significant (p < 0.05) higher values than the control station. Seasonal variation revealed that, in water, the pesticide level was higher in the dry season than in wet season, and there was no significant difference between the seasons (p > 0.05). The reverse was the case for sediments and fish. The physicochemical parameters of the river's water were within the recommended limits accepted by Federal Environmental Protection Agency, Nigeria. The observed Paraquat dichloride concentrations were above ecological bench, an observation that calls for regular monitoring and strict law enforcement to develop a strategy to manage environmental hazards and to improve environmental protection of this area.

Distribution of lindane in water, sediment, and fish from the warri river of the niger delta, Nigeria.

This paper is the first attempt to quantify the levels and the distribution pattern of lindane in the surface water, sediment and fish (Chrysichthys furcatus and Tilapia zilli). The samples were collected from three stations (Ovwian, Ekakpamre, and Ovu) of the Warri River in the western Niger Delta of Nigeria in 2006: during the dry (January-April) and wet seasons (May-August). The analysis included a total of 96 samples made up of 24 samples each for water, sediment, and fish. The pesticide levels were analysed using high performance liquid chromatography to elucidate its distribution in various environmental compartments. Residue levels in the matrices ranged from below the detection limit (BDL) to 1.37microg L(-1) in water, BDL to 12.66 microg g(-1) dry weight (dw) in sediment, BDL to 16.67 microg g(-1)dw in Chrysichthys furcatus, and BDL to 0.15 microg g(-1)dw in Tilapia zilli. The observed values were above the ecological benchmarks (0.01 microg L(-1)) recommended by the Nigerian Environmental Protection Agency and European Union. They were also relatively higher than in previous studies on the Nigerian environment, which calls for regular monitoring of the Niger Delta water bodies.