ICP-MS对再生水灌溉区土壤重金属含量的测定

采用ICP-MS(电感耦合等离子光谱)对北京市3个再生水灌溉区8种土壤重金属含量进行分析测定,并将其分别与当地井灌区土壤重金属含量作对比,探究再生水灌溉对土壤重金属含量的影响。结果表明:3个再生水灌区均存在不同程度的汞污染,土壤中的Cd、Ni、Cu和As含量均符合国家土壤环境质量一级标准,而Pb、Zn和Cr含量的最大值(39.90、103.1和120.3 mg/kg)未超过国家土壤环境质量二级标准;Ni和Hg在多数采样点出现重金属向土壤深层移动的趋势;与对照区(井灌区)相比,Cd在3个再生水灌区的土壤中含量均无显著变化,Hg含量仅在通州区大北关井灌区超过再生水灌区,其余6种重金属则呈现不同程度的重金属累积现象。再生水灌溉区土壤重金属污染并非一定由再生水灌溉所致,早期的污水灌溉和有机肥施用等也是不可忽视的因素。

The Determination of Heavy Metals Concentration in Reclaimed Water Irrigated Soils by ICP-MS

With the ICP-MS(inductively coupled plasma mass spectrometry),the concentrations of eight kinds of heavy metals in reclaimed water irrigated soils in three different areas in Beijing were measured.And they were compared with those of groundwater irrigated soils of the corresponding area to research the impact of reclaimed water irrigation on heavy metals concentration in soils respectively.The results showed that: the three reclaimed water irrigated areas were contaminated by mercury to different degrees.The concentrations of Cd,Ni,Cu and As in soil were all in line with the primary grade of Environmental Quality Standard for Soils in China.The maximum concentration of Pb,Zn and Cr(39.90、103.1and 120.3 mg/kg) was even less than the second grade of Environmental Quality Standard for Soils.There was a tendency of Ni and Hg transporting to deep soil layers in most of the sampling points.There was no significant difference of the concentrations of Cd in soils between the reclaimed water irrigated areas and the corresponding groundwater irrigated areas.Only in Dabeiguan,Tongzhou district,the concentration of Hg in soils of groundwater irrigated areas was larger than reclaimed water irrigated areas.Additionally,the concentrations of other six kinds of heavy metals indicated that they were accumulated at varying degrees.Research showed that heavy metal pollution in soils of reclaimed water irrigated areas did not always come from reclaimed water irrigation,and early wastewater irrigation(sewage sludge),organic fertilizer application and the like should not be ignored.