铅锌矿区稻田土壤中重金属形态分析及生态风险评价

Speciation analysis and ecological risk assessment of heavy metals inpaddy soil surrounding lead-zinc mine area

以黔西北某锌冶炼区周边稻田土壤为研究对象,采集土壤样品52个,采用电感耦合等离子体质谱法测定土壤中重金属Cr、Ni、Cu、Zn、Cd、Pb总量和可提取态含量。并采用单因子污染指数法和内梅罗综合指数法评价了稻田土壤重金属污染状况,利用地累积指数法和潜在生态危害指数法评价土壤生态风险,并对重金属总量与对应可提取态作相关性分析。结果表明:(1)研究区稻田土壤受到Cd和Cu的污染,单项污染指数分别为3.31、2.59;内梅罗污染指数结果显示研究区土壤已受到重金属严重污染,Cd、Cu污染等级为重度污染,Zn为轻度污染,Pb达到警戒线。(2) Cr、Ni、Cd、Pb地累积指数级数为0,无污染;Zn地累积指数0.14,为轻度污染;Cu地累积指数1.43,为偏中度污染。(3)研究区主要生态风险因子为Cd、Cu,6种重金属潜在生态危害大小顺序为:Cd>Cu> Ni> Pb> Zn> Cr;其中轻微生态风险样点数占比19.2%,中等生态风险占比80.8%。(4)相关性分析表明全量元素与可提取态之间无显著相关性。

52 soil samples were collected from paddy soil around lead-zinc mining area in Northwestern Guizhou,and the contents of Cr,Ni,Cu,Zn,Cd and Pb in the soil and their extractable states were determined by inductively coupled plasma mass spectrometry(ICP-MS).The pollution status of heavy metals in surface soils were evaluated by single factor pollution index method and Nemerow comprehensive pollution index method,and the ecological risk of paddy soil was evaluated by geo-accumulation index method and potential ecological risk index method.The results showed that:(1)the paddy surface soil of the study area was polluted by Cd and Cu,and the single pollution index was 3.31 and 2.59,respectively.The results of Nemerow pollution index showed that the soil was seriously polluted,Cd and Cu was in heavy pollution level,Zn was in light pollution,and Pb reached the warning line.(2)The geo-accumulation index of Cr,Ni,Cd,Pb was 0,indicating no pollution of these elements;the geo-accumulation index of Zn was 0.14, indicating that the paddy soil was in light Zn pollution;and the geo-accumulation index of Cu was 1.43, indicating in moderate Cu pollution. (3) The main ecological risk factors of the study area were Cd and Cu. The order of potential ecological risk of six heavy metals was as follows: Cd>Cu>Ni>Pb>Zn>Cr. Among them, the number of samples with slight ecological risk accounted for 19.2%, and the number with moderate ecological risk accounted for 80.8%. (4) Correlation analysis showed that there was no significant correlation between total contents and extractable states of heavy metals.