Single and joint effects of pesticides and mercury on soil urease
YANG Chun-lu , SUN Tie-hang , HE Wen-xiang , ZHOU Qi-xing , CHEN Su
DOI:
Received January 10, 2006,Revised May 10, 2006, Accepted , Available online
Volume 19,2007,Pages 210-216
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The influence of two pesticides chlorimuron-ethyl and furadan, and one heavy metal mercury (Hg) on the urease activity in two meadow burozem and two phaeozem soils was investigated. Soils were exposed to various concentrations of the two pesticides and Hg individually or simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in the same type of soil. Chlorimuron-ethyl and furadan could both activate urease in all of the four soils. The maximum increase of urease activity by chlorimuron-ethyl was up to 14%-18% in the different soils. There was almost an equal increase (up to 13%-21%) in the urease activity by furadan. On the contrary, Hg could markedly inhibit soil urease activity. A logarithmic equation was used to describe the relationship (P < 0.05) between the concentration of Hg and the activity of soil urease in all of the tested soils. Semi-effect dose (ED50) values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with Hg on soil urease was mainly synergic at their high concentration exposure.
