科研之友
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摘要
Effect of wastewater irrigation on the changes of some soil properties, distribution and fractionation of heavy metals (Cu, Pb and Cd) in soil profiles was investigated by monitoring different plots from Pengzhou, China, which had been irrigated with wastewater for varying periods of time (5, 12 and 20 years, respectively). The non-wastewater-irrigated plot served as the control. Total concentrations of heavy metals at different soil depths were analyzed by acid digestion, and their fractions were partitioned by a sequential extraction procedure, where the speciation of metals was experimentally defined as exchangeable, carbonate-, Fe-Mn oxide-, organic matter-bound and residual fraction. Results showed that soil pH values were significantly (p < 0.05) lowered in plots with more than 12-year irrigation to a depth of 80 cm, while electrical conductivity was elevated for all three plots compared with control, and soil organic matter increased in top 40 cm layers in plots with 12- and 20-year wastewater irrigation. Longterm irrigation with wastewater (12 and 20 years) has led to significant increases in heavy metals' total amounts in surface layer (0-40 cm), in which it also resulted in a marked increase in heavy metal concentrations in the all non-residual fractions, and correspondingly affected the relative binding capacity of heavy metals (except for Pb in soil profile from plot with 20-year irrigation). It was also found that the amounts of heavy metals in residual fractions kept almost unchanged in all plots. The study concludes that long-term wastewater irrigation might give rise to the accumulation and mobilization of heavy metals in upper soil horizons, which may limit the use of wastewater for landscape and agriculture.
- 出版日期2012
- 单位天津城建大学
