再生水灌溉对4类土壤Cd生物有效性的影响

根据国家土壤环境质量标准，选取重金属Cd含量为二级水平的4类土壤（红壤、 潮土、 土、 黑土）进行土培试验，研究再生水灌溉与小白菜生物量及Cd含量、 土壤有效态Cd含量、 pH、 微生物群落的关系，以及不同类型土壤间的差异性。结果表明， 再生水灌溉在不同类型土壤上对小白菜生物量及Cd含量、 土壤有效态Cd含量、 土壤pH和微生物数量的影响不同: 1）红壤、 潮土、 土上小白菜生物量增加显著，分别增加9.09%、 16.08%、 9.92%，黑土上增加不显著； 2）小白菜Cd含量在红壤上显著降低，由对照的0.29 mg/kg降低到0.22 mg/kg，在黑土上比对照增加了18.75%，在潮土和土上影响不大； 3）有效态Cd含量在红壤没有变化，但在潮土、 土、 黑土上增加显著； 4） 4类土壤微生物数量增加显著； 5）潮土、 土、 黑土的pH值有所降低。

Effects of recycled municipal wastewater irrigation on the bioavailability of Cd in different soils

Pot culture experiments were used to study the effects of recycled municipal wastewater irrigation on the bioavailability of Cd in different soils in green house: Red Soil, Fluvo-aquic Soil, Loess Soil and Black Soil. The dry weights (DW) and Cd contents of vegetables, soil available Cd contents, soil pH and the population of bacteria, fungi and actinomycetes in the four soils were analyzed. Different results were obtained in the analyzed items among the four soils when irrigated with recycled municipal wastewater. When irrigated with recycled municipal wastewater, the dry weights of vegetables irrigated with increased significantly by 9.09%, 16.08% and 9.92% in Red Soil, Fluvo-aquic Soil and Loess Soil respectively, slightly increased in Black Soil; the Cd contents of vegetables decreased significantly from 0.29 mg/kg to 0.22 mg/kg in Red Soil, but increased by 18.75% in Black Soil and kept similar in Fluvo-aquic Soil and Loess Soil; the available Cd contents in Fluvo-aquic Soil, Loess Soil and Black Soil increased significantly, not significantly in Red Soil; the population of bacteria, fungi and actinomycetes were increased obviously in all the four soils, the soil pH of Fluvo-aquic Soil, Loess Soil and Black Soil decreased, not decreased in Red Soil.