[Cu and Zn pollution and soil enzyme activities in sewage irrigation area near smeltery]

This paper studied the Cu and Zn status in soil and rice plant as well as the soil enzyme activities in the sewage irrigation area near a smeltery. The results showed that the soils near the smeltery were polluted. The soil total and extractable Cu contents at the distance of 100 m were 182.45 and 81.91 mg x kg(-1), respectively, 9.3 and 34 times higher than the control. The Cu concentration in different parts of rice was in order of root > leaf and stem > grain, while the Zn concentration was in order of leaf and stem > root > grain. Zn was more mobile than Cu which was likely to accumulate in rice root. It was considered that root could act as a barrier which retarded the upwards transport of Cu and protected the above ground parts of rice from toxication. The Cu contents of rice stem and leaf had a significant correlation with soil Cu contents in the sewage irrigation area. Among the three test enzymes, urease was the most sensitive one to Cu, and its activity had a significant correlation with soil Cu content. Therefore, it is feasible to use soil urease activity as an indicator of soil Cu pollution in sewage irrigation area near the smeltery.