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Assessment of heavy metal pollution in soil and their implications within and around mechanic villages
Zhao, Y. C.; Yi, X. Y.; Zhang, M.; Liu, L. & Ma, W. J.
Abstract
This research describes application of laccase from white-rot fungi (polyporus) to remove
dichlorodiphenyltrichloroethane in soil. The degradation kinetics of dichlorodiphenyltrichloroethane in soil was also
investigated by laboratory batch experiments. The results showed that laccase from white-rot fungi can effectively
degrade dichlorodiphenyltrichloroethane and the degradation of total dichlorodiphenyltrichloroethane (the sum of the
four dichlorodiphenyltrichloroethane compounds in a sample) was pseudo-first-order kinetics. The residues of almost all
the dichlorodiphenyltrichloroethane components and total dichlorodiphenyltrichloroethane in soils treated with laccase
decreased rapidly during first 15 days and then kept at a stable level during next 10 days. The residues of total
dichlorodiphenyltrichloroethane in soils with different dosages laccase decreased by about 21-32 %, 29-45%, 35-51 %
and 36-51 % after 5, 10, 15 and 25 days of incubation, respectively. The half-life of total dichlorodiphenyltrichloroethane
in soils with different dosages laccase ranged from 24.75 to 41.75 days. The residues of total dichlorodiphenyltrichloroethane
in three different types of soils decreased by 25-29 %, 39-43 %, 44-47 % and 47-52 % after 5, 10, 15 and 25 days of
incubation with laccase, respectively. The half-life of total dichlorodiphenyltrichloroethane in different types of soil
ranged from 24.71 to 27.68 days. The residues of total dichlorodiphenyltrichloroethane in soils with different pH levels
decreased by 18-24 %, 29-39 %, 36-39 % and 39-50% after 5, 10, 15 and 25 days of incubation with laccase, respectively.
The half-life of total dichlorodiphenyltrichloroethane ranged from 25.63 to 36.42 days. Laccase can be an efficient and
safe agent for remediation of dichlorodiphenyltrichloroethane-contaminated soil.
Keywords
Bioremediation; Enzyme; Half-life; Organochlorine pesticide; Residue
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