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大兴安岭森林土壤重金属含量空间变异与污染评价

张继舟1,吕品1,2**,王立民1,于志民1   

  1. (1黑龙江省科学院自然与生态研究所, 湿地与生态保育国家地方联合工程实验室, 哈尔滨 150040; 2东北农业大学生命科学学院, 哈尔滨 150030)
  • 出版日期:2015-03-10 发布日期:2015-03-10

Spatial variability of heavy metal contents and contamination assessment in forest soils of Daxing’an Mountains.

ZHANG Ji-zhou1, LU Pin1,2**, WANG Li-min1, YU Zhi-min1   

  1. (1Institute of Natural Resources and Ecology, Heilongjiang Academy of Sciences, National and Provincial Joint Engineering Laboratory of Wetlands and Ecological Conservation, Harbin 150040, China; 2College of Life Science, Northeast Agricultural University, Harbin 150030, China)
  • Online:2015-03-10 Published:2015-03-10

摘要:

重金属是危害森林生态健康的主要污染物之一,迄今有关大兴安岭森林土壤重金属含量、空间变异和污染程度鲜见报道。本文通过野外调查采样,应用GIS空间分析技术,结合经典重金属污染评价方法,分析了大兴安岭森林土壤Cd、Cr、Pb、Cu、Zn、Ni、Hg及As含量的空间变异与污染程度。结果表明:(1)研究区8种重金属含量具有中等空间异质性,变异系数在16.67%~35.39%。Cd、Cr、Pb、Zn、Hg、As的块金值/基台值\[C0/(C0+C)\]<25%,其空间变异主要由母质、地形等结构性变异引起,Cu和Ni的C0/(C0+C)在25%~75%,即非结构性因素人类活动对二者的影响较大。土壤重金属含量呈斑块状、条带状和岛状分布。(2)大兴安岭森林土壤8种重金属含量主要表现为累积的特征。8种重金属含量的平均值与最大值均未超过《国家土壤环境质量标准》(GB 15618—1995)二级标准限值,其中Cu、Zn、As的最大值超过一级标准,而其他5种元素的最大值均未超过一级标准。(3)地积累指数表明,土壤Cr、Pb、Ni无污染风险,其他5种元素污染风险较低。内梅罗综合污染指数表明,土壤整体质量已经处于轻污染状态。单因子潜在生态风险指数分析表明,Cu、Ni、Pb、Cr、Zn、As不具有潜在生态风险,Hg、Cd的部分样点的单因子生态风险指数Eri值存在生态风险,其中Hg的个别特征点已经达到Ⅲ级(中等风险)水平;潜在生态风险指数表明,研究区80%的样点无潜在生态风险,20%样点处于一般生态风险水平。

 

关键词: 潮汐, 植被带, 河口湿地, 活性硅酸盐, 生物硅

Abstract: Soil heavy metal pollution is a potential hazardous factor to forest health. However, few studies have conducted on heavy metal contents, spatial variability and pollution status of natural forest soils in Daxing’an Mountains. In the study, the contents of Cd, Cr, Pb, Cu, Zn, Ni, Hg and As in forest soils of Daxing’an Mountains were analyzed. The spatial variability of these heavy metal elements mentioned above and their pollution potential in the region were evaluated by using GIS spatial analysis combined with classic heavy metal pollution assessment methods. The results showed that: (1) The spatial distributions of heavy metal contents exhibited moderate spatial heterogeneity, with variation coefficients from 16.67% to 35.39%. C0/(C0+C) values of Cd, Cr, Pb, Zn, Hg and As were less than 25%, suggesting that the spatial variability of their contents was mainly determined by structural factors, such as soil parent material and topography. C0/(C0+C) values of Cu and Ni varied in the range of 25%-75%, which means that these metals were mainly affected by non-structural factors and human activities.  The distribution patterns of heavy metal contents in the region presented as patchy, banded and island modes. (2) The contents of the eight heavy metals in the region showed a trend of accumulation. However, the average and maximum contents of the eight heavy metals were below the soil threshold levels of the Second Grade Criteria of the China’s Environmental Quality Standard (GB 15618-1995). The maximum contents of Cu, Zn and As exceeded the soil threshold levels of the First Grade Criteria, and the maximum contents of the other five elements were below the soil threshold levels of the First Grade Criteria. (3) As showed by the Geo-accumulation index, there was no pollution risk of Cr, Pb and Ni in the region, while the pollution risk of the other five elements was low. The Nemerow pollution index showed that slight pollution of heavy metals existed for overall soil quality in the region. Single factor ecological risk index showed that no potential risk was detected for Cu, Ni, Pb, Cr, Zn and As contents; however, the contents of Hg and Cd from some sites showed pollution risk. The content of Hg from some sites even reached the Third Pollution Level (moderate risk). The total potential ecological risk index  of 80% samples in the study area was at the riskfree level, and that of 20% of the samples was at the general level of risk.

Key words: tide, biogenic silica, dissolved silicate, vegetation zone, estuarine wetland