湖北某铅锌矿区农用地重金属调查与类别划分

以鄂东南某铅锌矿区147.3 hm2农用地土壤为研究对象,通过现场采样及实验室测试,对土壤重金属Cu、Cr、Ni、Zn、Pb、Cd、As和Hg含量进行分析和评价。结果表明:Cu、Zn、Pb、Cd和As的点位超标率分别为33.7%、49.0%、73.5%、95.9%和85.7%,单因子污染指数顺序为Cd>As>Pb>Zn>Cu;通过内梅罗综合污染指数评价,重度污染、中度污染、轻微污染的点位比例分别为59.18%、12.24%、27.55%;通过土壤和农产品综合质量指数法评价,矿区农用地土壤大部分呈重度污染状态(土壤综合质量影响指数IICQ_S>5),与Pb、Cd和As含量高值并集区域分布一致;而农产品大部分属于清洁或轻微污染状态(农产品综合质量影响指数IICQ_AP<2),超标点位分布无明显规律;IICQ_S值与IICQ_AP值无显著相关性;IICQ值与IICQ_S值的分布相一致,研究区内农用地IICQ均值为7.84,属于重度污染。结合现场调查及数据分析,对矿区农用地土壤污染概念模型提出了初步构想。根据《农用地土壤环境质量类别划分技术指南(试行)》,结合农产品调查结果,将矿区农用地中的耕地划分为优先保护Ⅱ类(21.4 hm2)、安全利用Ⅰ类(57.8 hm2)、安全利用类荒地(29 hm2)、安全利用Ⅱ类(1.2 hm2)、严格管控类(37.9 hm2)。

INVESTIGATION AND CLASSIFICATION OF HEAVY METALS IN AGRICULTURAL LAND IN A LEAD-ZINC MINING AREA IN HUBEI PROVINCE

The soil of 147.3 hm2 agricultural land in a lead-zinc mining area in Southeast Hubei Province was studied, through field sampling and laboratory test. The contents of heavy metals Cu, Cr, Ni, Zn, Pb, Cd, As and Hg in soil were evaluated. The results showed that: The over-standard rates of Cu, Zn, Pb, Cd and As were 33.7%, 49.0%, 73.5%, 95.9% and 85.7%, respectively. The order of single factor pollution index was Cd>As>Pb>Zn>Cu; through the Nemerow Comprehensive Pollution Index evaluation, the proportion of severe pollution, moderate pollution and slight pollution was 59.18%, 12.24% and 27.55%, respectively. Through the comprehensive index combined soil environmental quality and agricultural products quality, most of the soil of agricultural land in the lead-zinc mining area was heavily polluted(IICQ_S>5), which was consistent with the regional distribution of Pb, Cd and As. However, most of the agricultural products were clean or slightly polluted(IICQ_AP<2), and there was no obvious law in distribution of the over-standard points. There was no significant correlation between IICQs and IICQap. The distribution of IICQ value and IICQs value was consistent. Average IICQ of agricultural land in the study area was 7.84, which was heavily polluted. Combined with field investigation and data analysis, the conceptual model of soil pollution in the lead-zinc mining area was preliminarily conceived. According to Technical Guide for the Classification of Soil Environmental Quality of Agricultural Land, combined with the survey result on agricultural products, the cultivated land in the agricultural land in the lead-zinc mining area was divided into priority protection type Ⅱ(21.4 hm2), safe use type Ⅰ(57.8 hm2), safe use type wasteland(29 hm2), safe use type Ⅱ(1.2 hm2) and strict control type(37.9 hm2).