城市污水回用于山地绿化灌溉土壤重金属的空间变异性

Spatial Variability of Heavy Metals in Mountainous Soil of Reused Urban Sewage Virescence Irrigation Area

新疆乌鲁木齐市雅玛里克山国家级绿化示范基地的灌溉用水为雅玛里克山污水厂一级出水（乌鲁木齐生活污水出水）．在面积为59hm^2的污灌区布设了61个采样点，测定了表土（0～20cm）中Cu，Zn，Ni，Cr，Pb，Cd的含量和pH，有机质（OM）含量，阳离子交换量（CEC）等土壤理化参数，并在此基础上进行了尼梅罗综合污染指数评价和基于地理信息系统（GIS）及地统计学的研究．结果表明，6种重金属的平均含量均低于国家二级标准（GBl5168—1995）限值；采样区的土壤重金属总体上属于轻度污染．Zn，Cr，Pb和Cd含量变异函数曲线的理论模型符合指数模型；Ni和OM含量及CEC的理论模型表现为高斯模型；Cu含量和pH的理论模型为球状模型．Pb，Ni，Cr，OM含量和pH，CEC表现为中等强度的空间自相关，Cu，Zn和Cd含量均表现出强烈的空间自相关．重金属。值最大的是Pb（450m），而其他重金属的。值多集中在100～200m，采用普通克立格最优内插法对未测点重金属，pH，OM含量和CEC进行最优估计，绘制了空间分布图，更直观地反映出了重金属元素及土壤理化参数的空间变异特征．

A research has been made in the state virescence demonstration base of Yamanik Mountain in Urumqi, Xinjiang. The virescence base was irrigated with primary municipal effluents, which was taken from Yamanik Mountain Wastewater Treatment Plant （ MWTP）. Sixty-one soll samplers were collected from 59 hm2 of sewage irrigation region, the contents of six heavy metals （Cu, Zn, Ni, Cr, Pb, Cd） and three physiochemical parameters, i.e. pH, cation exchange capacity （CEC） and organic matter （OM）, of surface soil （0 ～ 20 cm） were analysed. According to the Standard of Soil Environment Quality （GB15168-1995）, the statistical result showed that the average concentrations of the six heavy metals did not exceed the secohdary standard limits. The Nemeiow Synthetical Pollution Index Method was adopted to assess the heavy metal pollution of soil, and the majority part of research area reach subtle polluted level. Based on Geostatistics and GIS, the result showed that the semivariograms of Zn, Cr, Pb, Cd were best described by exponential model, the models of Ni, OM, CEC were best fitted by Gauss model, the theory models of Cu, pH are spherical model. The results also indicated that the spatial correlation of Pb, Ni, Cr, pH, OM, CEC was moderately dependent, while that of Cu, Zn, Cd was strongly dependent. The spatial variability range of Pb was 450 m, while the ranges of other heavy metals mainly located in between 100 m to 200 m. Ordinary Kriging method was applied to estimate the unobserved points of heavy metals, pH, OM and CEC. Their distribution maps were obtained which factually reflected their spatial variability.