三峡库区梅溪河消落带土壤重金属污染特征及其影响因素

Pollution Characteristics and Influencing Factors of Soil Heavy Metals in the Riparian Zone of Meixi River of the Three Gorges Reservoir Area

    摘要
  • 摘要:
    目的 探究三峡库区梅溪河消落带土壤重金属污染特征，明晰其主要影响因素，为三峡库区消落带土壤重金属污染防治、生态环境保护和土地资源合理利用与管理提供科学依据。
    方法 以库岸带为对照，采用原位调查监测方法，并运用地质累积指数法对消落带土壤砷（As）、镉（Cd）、铬（Cr）、汞（Hg）、镍（Ni）、铅（Pb）、锌（Zn）、铜（Cu）、锰（Mn）、铁（Fe）等10种重金属元素污染特征及其影响因素进行系统研究。
    结果 三峡库区梅溪河消落带及库岸带土壤中各重金属元素总体处于轻污染水平（0 < Igeo ≤ 1），其中As和Cd为土壤主要重金属污染元素；消落带各土层的土壤重金属地质累积指数变化在0.038 ~ 0.422之间，与库岸带相比总体上均增大，其中大多数土壤重金属在160 ~ 170 m消落带富集最为明显；土地利用方式对消落带土壤重金属污染程度影响显著（P < 0.05），其地质累积指数大小排序为自然恢复草地（0.184） > 农耕地（0.179） > 人工营造林地（0.178）；2019年消落带土壤As、Cu、Hg、Ni的地质累积指数分别为0.357、0.121、0.148、0.097，与2018年相比均显著减小，其他土壤重金属变化则不明显（P > 0.05）；消落带高程梯度是影响各土层土壤重金属污染的主要因素，且土地利用方式与高程梯度存在协同作用。
    结论 梅溪河消落带土壤重金属污染总体较轻，其受到消落带周期性水位涨落、土地利用方式、土层深度及时间等因素的综合影响。

     

    Abstract:
    Objective The aim was to understand the pollution characteristics of soil heavy metal in the riparian zone of Meixi River and clarify the main influencing factors, in order to provide a scientific basis for the prevention and control of soli heavy metal pollution, ecological environment protection and sustainable land-use management in the Three Gorges Reservoir area.
    Method Taking the reservoir bank as the control, the pollution characteristics and influencing factors of ten heavy metals (As, Cd, Cr, Hg, Ni, Pb, Zn, Cu, Mn, Fe) were systematically studied by the method of in-situ survey and monitoring, with using the geo-accumulation index (Igeo).
    Result Soil heavy metals in the riparian zone and the reservoir bank of Meixi River of the Three Gorges Reservoir Area were basically at a slight pollution level (0 < Igeo ≤ 1), among which As and Cd were the main heavy metal pollutants in the soil. Compared with the reservoir bank, geo-accumulation index of soil heavy metals which were generally higher in the riparian zone varied from 0.038 to 0.422. Most of soil heavy metals were most significantly enriched in the riparian zone of 160 ~ 170 m. Land use types significantly affected the pollution degree of soil heavy metal in the riparian zone (P < 0.05), and the order of Igeo was naturally restored grassland (0.184) > farmland (0.179) > artificially constructed forest land (0.178). In 2019, Igeo values of As, Cu, Hg and Ni in the riparian zone were 0.357, 0.121, 0.148 and 0.097, respectively, which were all significantly lower than those in 2018 (P < 0.05), while the changes of other soil heavy metals were no significant (P > 0.05). The elevation gradient was the predominant factor affecting heavy metal pollution in all soil layers and showed a synergistic effect with land use type.
    Conclusion Soil heavy metal pollutions in the riparian zone of Meixi River of the Three Gorges Reservoir Area are generally slight and influenced by a combination of factors such as periodic water-level fluctuations, land use type, soil depth and time.

     

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