The influence of phytoextraction effectors on enzyme activity of soil polluted with heavy metals.

摘要

The effects on dehydrogenase (DHG), catalase (CTL) and cellulase (CEL) activity of 1-20 mmol ethylenediaminetetraacetate (EDTA)/kg of soil polluted with Zn, Pb and Cd was investigated. EDTA was also used in conjunction with 10-50 mmol of citric, acetic or nitric acid/kg of soil. Polluted soil originated from the Katowice region of Poland. CTL activity of soil treated with 1-20 mmol EDTA increased by ?8.3% as compared to controls, over a 2-week experimental period. DHG activity of soil treated with10 mmol EDTA increased by ?8.5%, but maximum doses of EDTA gave ambiguous results, with sharp decreases in enzyme activity on day 7. Treatments of 5 mmol EDTA in conjunction with 10 and 50 mmol nitric acid resulted in sustained and irreversible inhibition of CTL and DHG activity, by ?0 and ?2.5% respectively. Sludge from liquid manure inhibited CTL activity by ?4.2%, but increased DHG activity by ?9.4%. EDTA in combination with citric acid increased DHG activity by ?8.3%. EDTA in combination withacetic acid inhibited DHG activity by ?5.7%. Over a 2-month experimental period, treatment with 1-10 mmol EDTA led to prolonged CTL activity, contrasting with DHG activity, which decreased towards the end of the experimental period. Effects of EDTA incombination with nitric acid were similar to those of the 2-week experimental period. CEL activity increased with 1-10 mmol EDTA, and particularly with 5 mmol EDTA combined with 50 mmol nitric acid, increasing by ?9.2 and ?27.3% respectively. With increasing doses of EDTA (1-20 mmol) contents of soluble Zn, Pb and Cd compounds increased respectively by an average of 11, 74 and 22 times. Contents of soluble compounds of heavy metals did not differ between treatments consisting either solely of 5 mmol EDTA, or of 5 mmol EDTA in combination with various acids. In the 2-month experimental period, contents of soluble compounds of Zn, Pb and Cd did not change significantly either during treatment with 1-10 mmol EDTA or during treatment with 5 mmol EDTA and50 mmol nitric acid.