Movement and bioaccumulation of chromium in an artificial freshwater ecosystem.

ABSTRACT

In the present study, a small fresh water aquatic ecosystem was created into a small test tank to evaluate the movement and bioaccumulation of Cr (VI) through water, sediment, a macrophyte Hydrilla, small fish guppy, and few key organs of magur, Clarias batrachus. The Cr (VI) intoxication was imposed of as a single dose of 30 mg/l concentration for a wide range of exposure durations like 1, 7, 14 and 21 days. After 1 day of exposure the total Cr (VI) load was very high in the water and sediment samples (5.187 microg/ml and 23.332 microg/g respectively) which were decreased with increasing exposure durations over their respective controls. In samples of macrophyte, Cr (VI) concentration showed a gradual increasing trend from 6.1797 microg/g in control to 21.1903 microg/g in 1 day exposure and reached up to 24.635 microg/g after 21 days exposure. In guppy, the Cr (VI) bioaccumulation showed an increasing trend but the rate was not statistically significant. However, in magur, the Cr (VI) uptake showed a significant gradual and increasing trend with increasing exposure durations in liver, brain, intestine and muscular tissues than gill and kidney over their respective controls. The movement of the Cr (VI) was found to be from sediment to water during pre-treatment phase, after intoxication, from water to macrophyte and to other phytoplankton and zooplankton. It then accumulated in the primary consumer guppy and finally moved to the secondary consumer the magur following the food web. The results reveal that the rate of movement and bioaccumulation of Cr (VI) varied from organism to organism and in C. batrachus, from tissue to tissue.