Bioconcentration and phytotoxicity of chromium in Eichhornia crassipes
Kumkum Mishra1, Kiran Gupta1
and Upendra Nath Rai2
1Plant Genetic Unit, Botany Department, Lucknow
University, Lucknow
- 226 007, India
2Ecotoxicology
and Bioremediation Group, National Botanical Research Institute, Lucknow - 226 001, India
(Received:
August 09, 2007;
Revised received: January
08, 2008; Accepted: February 12, 2008)
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 mg 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 mg ml-1
concentration. Under field conditions the accumulation of Cr was 1258 and 733.3
in roots and 94 and 53 mg 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 mg 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 mg 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.
Key
words: Eichhornia crassipes, Chromium, Phytoremediation,
Biomonitoring
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