铅锌矿产集中发育区土壤重金属背景值及特征分析

Analysis on the Background Value and Characteristic of Soil Heavy Metals in Lead-zinc Mineral Concentrated Development Area

探索铅锌矿产集中发育区土壤重金属背景值及分布特征,并结合受污染耕地、涉重企业分布进行土壤重金属污染成因分析。选取铅锌矿产发育的尤溪县梅仙镇,采用系统均匀布点法,按2.5 km×2.5 km网格布设39个表层土壤监测点位,以土壤环境背景含量顺序统计量的95%分位值获得区域土壤环境背景值,分析高背景值重金属元素的分布特征;结合受污染耕地、涉重企业分布特点,从污染源角度解析农用地的重金属污染分布特征及成因。明确研究区土壤环境背景值为:镉0.294 mg/kg、汞0.181 mg/kg、砷11.0 mg/kg、铅269.1 mg/kg、铬75.2 mg/kg、铜61.3 mg/kg、镍35.6 mg/kg、锌153.0 mg/kg。对比分析显示,铅、铜元素属于区域性高背景重金属元素,同源重金属铅、铜、镉、锌呈现区域性复合污染;从分布上,铅、铜围绕矿产集中分布区富集,铅元素在平面上呈现连片式分布,铜元素在平面上呈现点状式分布。结合高背景值重金属元素分布特征及受污染耕地分布解析,梅仙镇安全利用类耕地分布主要受背景值控制,同时受矿山采选活动叠加影响;严格管控类耕地分布受矿山采选活动影响为主,地质背景的自然因素影响较小。

To explore the background value and distribution characteristics of heavy metals in soil of lead-zinc mineral concentrated development area,the causes of heavy metal pollution in soil combined with the distribution of polluted cultivated land and heavy enterprises are analyzed.Meixian Town,Youxi County,where lead and zinc minerals are well developed,was selected and 39 surface soil monitoring sites were set up according to 2.5 km×2.5 km grid by using the system uniform distribution method.The regional soil environmental background value was obtained by using the 95%quantile of soil environmental background content sequence statistics,and the distribution characteristics of heavy metals with high background value were analyzed.Combined with the distribution characteristics of contaminated farmland and heavy enterprises,the distribution characteristics and causes of heavy metal pollution in agricultural land were analyzed from the perspective of pollution sources.The background values of soil environment in the study area were determined as follows:cadmium 0.294 mg/kg,mercury 0.181 mg/kg,arsenic 11.0 mg/kg,lead 269.1 mg/kg,chromium 75.2 mg/kg,copper 61.3 mg/kg,nickel 35.6 mg/kg,zinc 153.0 mg/kg.Comparative analysis shows that lead and copper belong to regional high background heavy metals,and homologous heavy metals lead,copper,cadmium and zinc present regional compound pollution.From the distribution:lead,copper enrichment around the mineral concentrated distribution area,lead element in the plane showed a contiguous distribution,copper element in the plane show a point distribution.Combined with the distribution characteristics of heavy metal elements with high background value and the distribution analysis of polluted cultivated land,the distribution of safe use cultivated land in Meixian Town was mainly controlled by background value,and was affected by the superposition of mining and selection activities.The distribution of strictly controlled cultivated land is mainly affected by mining and selection activities,and the natural factors of geological background have little influence.