Impact of Long-Term Irrigation with Sewage on Heavy Metals in Soils, Crops, and Groundwater – a Case Study in Beijing
Zhe Bao1, Wenyong Wu2,3, Honglu Liu2,3, Honghan Chen1, Shiyang Yin2,3
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1School of Water resources & Environment, China University of Geosciences, Beijing 100083, China
2Beijing Hydraulic Research Institute, Beijing 100048, China
3Engineering Technique Research Center for the Exploration and Utilization
of Non-Conventional Water Resources and Water Use Efficiency, Beijing 100048, China
Pol. J. Environ. Stud. 2014;23(2):309–318
The effect of sewage irrigation on the accumulation of heavy metals (HMs) in soil profiles, crops, and, groundwater was investigated by monitoring zones with wastewater for various lengths of time (20, 30, and 40 years) in the southeastern suburbs of Beijing. The non-sewage-irrigated region served as the control. Results show that long-term sewage irrigation increased the soil organic matter content. The zone irrigated for 40 years exhibited the greatest accumulations of Hg, Pb, and Cu in the topsoils (0-30 cm). The Cd, Cu, and Zn enrichment was evident in deeper soil layers (40-70 cm) near the sewage waterway. The transfer factors of the various examined HMs in the crop-soil system ranged from 0.002 to 0.491. The HMs of crop grains and kernels in sewage-irrigated zones did not exceed established limits. Long-term sewage irrigation does not constitute HM pollution in soil and shadow groundwater. However, the monitoring of Hg, Pb, and Cu concentrations should be emphasized in areas that engage in treated sewage irrigation to prevent these HMs from entering the food chain and posing health risks.