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.