污灌区土壤团聚体重金属含量分布特征研究

Distribution Characteristics of Heavy Metals Contents in Soil Aggregates of Sewage Irrigation Area

    摘要
  • 摘要:
      目的  研究污灌区农田土壤团聚体重金属负载和分布特征，为受污染耕地风险评估和安全利用提供科学指导。
      方法  以河南省新乡县某污灌冬小麦种植农田土壤为研究对象，通过干筛法对不同土壤团聚体进行筛分，采用重金属分布因子和质量负载因子法，分析了不同粒径土壤团聚体中重金属Cr、Ni、Cu、Zn、Cd、Pb全量及有效态含量特征。
      结果  研究区土壤pH值、有机质、阳离子交换量和电导率分别为7.38 ~ 9.07、11.04 ~ 42.99 g kg−1、5.80 ~ 14.81 cmol kg−1和124.77 ~ 394.70 μS cm−1。pH变异系数为3%，属于弱变异性，而有机质、阳离子交换量和电导率的变异系数分别达到17%、15%和24%，为低变异性。Cr在1 ~ 0.50 mm粒径土壤团聚体中含量最高，达到253.98 mg kg−1，而Ni、Cu、Zn、Cd和Pb含量在0.50 ~ 0.25 mm粒级团聚体最高，分别为22.49、6.59、18.99、1.12和22.88 mg kg−1。不同粒径团聚体中Cr、Ni、Zn和Pb分布因子均小于1，Cu分布因子仅在0.5 ~ 0.25 mm粒径的团聚体大于1，而Cd在不同粒径团聚体上的分布因子均大于1，不同粒径中重金属质量负载因子表现为5 ~ 2 mm > 8 ~ 5 mm > 2 ~ 1 mm > （ < 0.25 mm） > 1 ~ 0.50 mm > 0.50 ~ 0.25 mm。Cr、Zn有效态含量在< 0.25 mm粒径团聚体中含量最高，而Ni、Cu、Cd和Pb有效态含量在0.50 ~ 0.25 mm粒径团聚体中含量最高，团聚体各粒级重金属全量与有效态含量显著正相关（P < 0.05）。
      结论  小粒径团聚体重金属总量和有效态含量较高，且两者呈显著正相关关系，而大粒径团聚体负载因子较高；所有重金属中Cd分布因子最高。

     

    Abstract:
      Objective  In order to provide the scientific guidance for risk assessment and safety utilization of polluted field in irrigation areas, the distribution of heavy metals in soil aggregates of the sewage irrigation area was studied.
      Method  Winter wheat planting farmland in Xinxiang County, Henan Province, was taken as the research object. Dry screening method was used to obtain different sizes of soil aggregates, and the distribution characteristics of total and available contents of heavy metals (Cr, Ni, Cu, Zn, Cd and Pb) in soil aggregates were analyzed using mass loading factor and distribution factor.
      Result  The results showed that pH, organic matter, cation exchange capacity, and conductivity ranged from 7.38 to 9.07, 11.04 to 42.99 g kg−1, 5.80 to 14.81 cmol kg−1, 124.77 to 394.70 μS cm−1, respectively. The variation coefficient of pH was 3%, belonging to weak variation. And the variation coefficients of soil organic matter, cation exchange capacity and electrical conductivity were 17%, 15% and 24%, respectively, being low variation. The content of Cr in 1-0.5 mm aggregate was the highest, which was 253.98 mg kg−1. The contents of Ni, Cu, Zn, Cd and Pb in 0.5-0.25 mm aggregate were higher, with 22.49 mg kg−1, 6.59 mg kg−1, 18.99 mg kg−1, 1.12 mg kg−1 and 22.88 mg kg−1, respectively. The distribution factors of Cr, Ni, Zn and Pb in all aggregates were less than 1, the distribution factor of Cu in 0.5-0.25 mm aggregates was greater than 1, and while the distribution factor of Cd in 8-5 mm, 5-2 mm, 2-1 mm, 1-0.5 mm, 0.5-0.25 mm and ( < 0.25 mm) aggregates was greater than 1. The mass loading factors of heavy metals in different particle sizes were 5-2 mm > 8-5 mm > 2-1 mm > ( < 0.25 mm) > 1-0.5 mm > 0.5-0.25 mm. The contents of Cr and Zn were the highest in the aggregates with particle size < 0.25 mm, and while Ni, Cu, Cd and Pb was the highest in 0.5-0.25 mm aggregates. The total contents of heavy metals in each particle size was significantly positively correlated with its available content (P < 0.05).
      Conclusion  Total and available contents of heavy metals were more distributed in small size of soil aggregates, and they exhibited significantly correlation with each other, while the values mass loading factor were higher in larger size of soil aggregates. The number of distribution factor of Cd was the highest than other heavy metals.

     

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