Leaching of heavy metals in soil column under irrigation reclaimed water:a simulation experiment
中水灌溉下重金属在土壤中的垂直迁移及其对地下水的污染风险

Irrigation using reclaimed water would be the potentially effective approach to meet the large demand of agriculture. However,the environment risks of reclaimed-water irrigation still remain unknown.To obtain the knowledge of the impact on soil,crops and shallow groundwater,an investigation was undertaken in Tongzhou,Beijing.As one part of the research,soil column experiments(10 100 cm) were conducted to understand the heavy metal transport behaviors in soil profile under reclaimed water leaching condition and the concentrations of As,Cd,Cu,and Pb in the leachate.Soil columns were leached with artificial reclaimed water(As,2 mg kg~(-1);Cd,0.2 mg kg~(-1);Cu,20 mg kg~(-1);Pb,20 mg kg~(-1)) and reclaimed water(As,0.83g kg~(-1);Cd,0.01g kg~(-1);Cu,1.73g kg~(-1);Pb,2.01g kg~(-1)) in different water amount(4 L,12 L).The results indicated that the maximum values of total As,Cd,Cu and Pb in the superficial horizons(0-20 cm) in soil columns are either artificial reclaimed water leaching or reclaimed water leaching.The trends of heavy metals downward movement were showed with the increase of leaching water amount and Cd demonstrated more mobile in soil columns than other heavy metals,while the mobility of As,Cu and Pb were weak.According to the leachate concentrations of As,Cd,Cu and Pb,which did not exceed the values of the Groundwater Quality Standards I,it could be concluded that irrigation with reclaimed water would not result in heavy metals(As,Cd,Cu and Pb) pollution on the shallow groundwater under reclaimed water leaching condition in this study,and As,Cu and Pb indicate a lower pollution risk to the shallow groundwater than Cd under long-term reclaimed water irrigation condition.