ABSTRACT
Tannery effluent contributes significantly to pollution of the environment. In this study, phytotoxic and genotoxic effects of tannery effluent and chromium (Cr) were investigated in Allium cepa. For this purpose, tannery effluent was collected from “Up flow Anaerobic Sludge Blanket” (U.A.S.B) Jajmau, Kanpur. A. cepa were exposed to various concentrations of tannery effluent (0.0, 3.125, 6.25, 12.50, 25.0%) and Cr (0.0, 1.0, 2.0, 4.0, 8.0 mg l-1) for 48 and 168 hr. The perusal of data revealed that the physico-chemical characteristics of tannery effluent viz. pH (8.5), EC (11.94 dSm-1), BOD (499 mg l-1), COD (1382 mgl-1) and Cr content (2.32 mg l-1) were much higher than the prescribed permissible limit for industrial effluent discharged into inland waters. These substances provoked phytotoxic and genotoxic effects in A. cepa. Total chlorophyll and protein content in leaves of tannery effluent and Cr treated plants decreased significantly in dose-duration dependent manner. A maximum decrease of 86.29 and 84.26% in total chlorophyll and 81.27 and 76.16% in protein content was observed after 168 hr of exposure while carotenoid content increased up to 6.25% effluent and 2.0 mgl-1Cr treatment and decreased further. In all treated plants, a significant (p>0.05) reduction in root length, mitotic index (MI) and induction in chromosomal (CA)/mitotic (MA) aberration and micronuclei (MNC) were observed as compared to unstressed plants. A maximum reduction of 81.15 and 79.71% in MI, and induction of 6.8 and 4.8% in CA, 29.24 and 26.66% in MA and 0.52 and 0.43% in MNC were found at 12.50% effluent and 4 mgl-1 Cr treated plants as compared to unstressed plants, however at highest effluent and Cr concentration both the plants showed pyknosis condition after 168 hr.
ABSTRACT
Aquatic macrophytes have been widely studied because of their capability of absorbing contaminants from water and their subsequent use in biomonitoring. This study presents a comparison of Cr accumulating potential of submerged aquatic plants viz Vallisneria spiralis and Hydrilla verticillata. These plants were treated with various concentrations of treated tannery effluent collected from UASB, Jajmau, Kanpur under repeated exposure in controlled laboratory conditions in order to assess their maximum bioaccumulation potential. The maximum accumulation of 385.6 and 201.6 μg g-1 dry weight was found in roots of V. spiralis and the whole plants of H. verticillata, respectively at 100% concentration after 9th day of effluent exposure. The chlorophyll and protein content of both species decreased with increase in effluent concentration and duration. At highest concentration and duration a maximum reduction of 67.4 and 62.66% in total chlorophyll content, 9.97 and 4.66% in carotenoid content and 62.66 and 59.36% in protein content was found in V. spiralis and H. verticillata respectively. Anatomical studies in both V. spiralis and H. verticillata was carried out to assess the effects of metal accumulation within the plants. Changes in the anatomical structures of both plants exhibits the capacity of these species to act as indicator of effluent toxicity. The high accumulation potential of Cr by both plants revealed their capability to remove pollutants from effluent.
ABSTRACT
Physico-chemical parameter and metal concentration in effluents of two industries i.e. Tannery industry, Jajmau, Kanpur and Electroplating industry, Scooter India Limited (SIL), Lucknow were determined to assess the toxicity of chromium. Metal accumulation in Eichhornia crassipes growing in these contaminated sites were also determined. For laboratory toxicity testing the plants were exposed to nutrient solution containing Cr concentration ranging from 0.01-10 μg ml-1 for 24-96 hr. Accumulation of chromium was observed to be dependent on its concentration and time of exposure and was greater in roots (789.3 mg g-1 d.wt.) than in leaves (335.6 mg g-1 d.wt.) after 96 hr at 10 μg ml-1 concentration. Under field conditions the accumulation of Cr was 1258 and 733.3 in roots and 94 and 53 μg g-1 d.wt. in leaves of E. crassipes growing in Jajmau, Kanpur tanning industry and SIL effluents, respectively. It was found that lower doses (0.01-0.1 μg ml-1) of chromium had stimulatory effect on various metabolic activities in plants including chlorophyll a, b and total chlorophyll, protein, nitrate reductase and mitotic index. Whereas higher doses of chromium had inhibitory effect. The carotenoid content and number of micronuclei was found directly proportional to the concentration of chromium and increased with increase in concentration of chromium to which plants were exposed. It may be concluded from the present study that E. crassipes is tolerant to the elevated Cr concentration as there is no inhibition of chlorophyll and carotenoid upto 0.1 μg ml-1 at 24 and 48 hr exhibiting phytotoxicity at higher concentration. Therefore, E. crassipes may be used as bioassay for biomonitoring and control of Cr pollution in the environment.