Heavy metal concentration in water, sediment, shrimp (Penaeus monodon) and Mullet (Liza parsia) in some brackish water ponds of Sunderban, India

Concentrations of Cd, Zn, Pb and Fe were determined in the brackish water ponds of Sunderban mangrove system of India at five different localities. Concentration of the metals in pond water ranged as follows: Cd 0.04-0.10; Zn < 0.01-9.66; Pb 0.03-0.16; Fe 14.3-170.0 g ml(-1). The metals were found highly concentrated in the pond sediment, There was a significant variation of Zn and Fe concentrations in the sediment among the localities. Concentration of Zn in the surface layer of the sediment (upto 10.0 cm depth) ranged from 40.8 to 3348.3 mug g(-1) while that of Fe ranged from 7155.0 to 10068.8 mug g(-1). Background concentration of Fe in the sediment (30.0 cm deep stratum) was very high in all the localities. All the metals in the surface layer of sediment showed a characteristic pattern of partitioning among various chemical fractions of the sediment. Tiger shrimp (Penaeus monodon) and Mullet (Liza par sia) reared in the ponds accumulated all the metals at a high rate, Concentration of the metals in shrimp muscle ranged as follows: Cd 0.11-3.2; Zn 7.3-4809.5; Pb 22.9-42.1; Fe 5.0-495.0 mug g(-1) Except for Pb the metals in shrimp muscle varied significantly among the localities, Concentration of the metals in whole body of mullet ranged as follows: Cd 0.11-0.15; Zn 1.4-272.2; Pb 29.7-44.8; Fe 185.0)-215.0 mug g(-1). Only Zn concentration of the mullet varied significantly among the localities, Neither total metal of the sediment nor metal belonging to any chemical fraction of the sediment did show a correlation with the metal in shrimp muscle or whole body of mullet, Salinity of water showed a positive and significant correlation with Cd and Zn concentrations of shrimp muscle while nitrite concentration of water showed a significant positive correlation with Zn concentration of shrimp muscle. The results indicate that mangrove environments of Sunderbans are being affected by huge loads of Zn and Fe brought about by drainage of the neighbouring river. (C) 2000 Elsevier Science Ltd, All rights reserved.