工业城市农田土壤重金属时空变异及来源解析

环境政策调控对农田土壤重金属富集趋势影响显著.本研究以典型工业城区周边农田为例,采用经典统计与地统计方法分析土壤Cd、 Pb、 Cu和Zn含量变化及时空分布特征,并采用PCA/APCS模型对土壤Cd、 Pb、 Cu和Zn污染来源及变化进行分析.结果表明,与2011年相比, 2017年研究区土壤Cd、 Pb、 Cu和Zn含量整体呈增加趋势.空间分布上Cd和Pb含量在2个时期均表现为从西北向东南逐渐降低,Cu和Zn含量在2011年表现为从北向南逐渐降低, 2017年表现为从西北向东南逐渐降低.与2011年相比, 2017年工业污染源对Cd、 Cu和Zn贡献率分别增加5.58%、 10.4%和20.4%,对Pb贡献率降低19.7%;其它源对Cd和Pb贡献率分别增加3.76%和24.8%,对Cu和Zn贡献率分别降低9.27%和4.31%.相关举措降低了工业污染源带来的区域土壤Pb累积,但对Cd、 Cu和Zn污染防控并不明显,新的Cd和Pb污染源需引起重视.

Spatial-temporal Variation and Source Change of Heavy Metals in the Cropland Soil in the Industrial City

Environmental policy regulation affects the accumulation of heavy metals in soil. Two soil surveys were conducted in farmland in industrial cities. Classical statistical and geostatistical methods were applied to examine the content changes and spatial-temporal distribution characteristics of Cd, Pb, Cu, and Zn in soil. The pollution sources and their contribution rates were further analyzed by a principal component analysis/absolute principal component scores (PCA/APCS) model. The results indicated that the concentrations of Cd, Pb, Cu, and Zn increased during the two periods. The content of Cd and Pb in the spatial distribution decreased from northwest to southeast in both periods. The content of Cu and Zn decreased from north to south in 2011, and gradually decreased from northwest to southeast in 2017. Compared with 2011, the contribution rate of industrial activities increased by 5.58%, 10.4%, and 20.4% for Cd, Cu, and Zn, respectively, but decreased by 19.7% for Pb. The contribution rates of the other factors to Cd and Pb increased by 3.76% and 24.83%, respectively, and decreased by 9.27% and 4.31% for Cu and Zn, respectively. Relevant measures have reduced the accumulation of Pb in regional soil caused by industrial activities, but not Cd, Cu, or Zn. In addition, new Cd and Pb pollution sources need to be paid attention to.