中水浇灌对土壤重金属污染的影响

Effect of Recycled Water Irrigation on Heavy Metal Pollution in Irrigation Soil

城市化的加快,使缺水问题更为普遍,中水用于冲厕和绿地浇灌将是未来的趋势.为研究特殊行业污水处理后用于绿地浇灌对土壤的重金属污染状况,选取以生活污水和实验室污水为水源,一体式氧化沟为处理单元的出水为浇灌用水,以包括阔叶林、灌木和草坪的小区土壤作为研究对象;采集6个样品点0-20 cm深的土壤进行Cr、Mn等8种重金属检测.结果表明,与自来水浇灌土壤对比,中水浇灌土壤的重金属含量没有显著差异;中水浇灌土壤的重金属主要在表层富集,其中铬、镍、铜、锌、铅浓度低于北京市土壤背景值;浇灌土壤中砷和镉存在轻度污染,值得关注.

With acceleration of urbanization,water shortages will become a serious problem.Usage of reclaimed water for flushing and watering of the green areas will be common in the future.To study the heavy metal contamination of soils after green area irrigation using recycled wastewater from special industries,we selected sewage and laboratory wastewater as water source for integrated oxidation ditch treatment,and the effluent was used as irrigation water of the green area.The irrigation units included broad-leaved forest,bush and lawn.Six samples sites were selected,and 0-20 cm soil of them were collected.Analysis of the heavy metals including Cr,Mn,Ni,Cu,Zn,As,Cd and Pb in the soil showed no significant differences with heavy metals concentration in soil irrigated with tap water.The heavy metals in the soil irrigated with recycled water were mainly enriched in the surface layer,among which the contents of Cr,Ni,Cu,Zn and Pb were below the soil background values of Beijing.A slight pollution of As and Cd was found in the soil irrigated by recycled water,which needs to be noticed.