上海崇明岛土壤重金属含量空间变异特征研究

Spatial Variability of Soil Heavy Metals in Chongming Island, Shanghai

采用地统计学与GIS相结合的方法,研究分析了上海崇明岛土壤重金属砷(As)、镉(Cd)、铬(Cr)、锌(Zn)、铜(Cu)、汞(Hg)、铅(Pb)、镍(Ni)的空间变异特征并比对国家标准分析了各元素超标概率分布状况。样本数据中的离群值是反应区域局部污染状况的重要信息,但同时离群值又对样本统计量的估计或空间插值造成一定的影响。本文尝试采用去离群值样本的插值模型与包含离群值样本数据进行插值的方式对重金属空间分布特征进行分析。另外,采用概率克立格法对研究区各元素超标概率状况进行了预测。结果表明:基于对离群值特殊处理的重金属含量的空间插值精度明显提高。研究区重金属分布特征为:崇明岛部分区域Cd含量较高;分布相对均匀,但空间向异性较大;新河码头附近、前进农场东、六滧港附近、崇明岛西北角这四大区域大部分重金属元素含量较高、且超标概率也较高。

The spatial variability and distributions of the soil heavy metal elements including As, Cd, Cr, Zn, Cu, Hg, Ph and Ni in the topsoil were estimated in Chongming Island （Shanghai） based on the combination of Geostatistics and Geographic Information System （GIS）. The spatial sampling site with the extra-bigger （smaller） measuring value of heavy metal elements were specially considered and treated in this study because these data of the sampling sites can reflect the status of contamination of the local regions, meanwhile may unfortunately he impractive to the estimation of statistic parameters and the spatial variability. In addition, Probability Kriging was per- formed for predicting the possibility of polluted area. The resuhs indicate that Cd is extremely high on the whole island, while other heavy metals are distributed acceptably. The most probably as well as the most seriously polluted extensions are discerned in the following four regions： nearby Xinhe Dock and Liuyao River, the east of Qianjin Farm and the northwest part of the island.