煤矸石堆积区土壤重金属形态组成与生物有效性的空间变化特征以峰峰矿区为例

Spatial variation characteristics of soil heavy metal speciation and bioavailability in coal gangue accumulation area—Taking Fengfeng mining area as an example

  • 摘要: 煤矸石地表堆积是我国东部煤矿区生态环境破坏的典型形式,造成堆积区土壤重金属污染的防控已成为当前研究热点。以河北峰峰矿区某在用煤矸石山周边(方圆300 m以内)浅层土壤(垂直深度40 cm以浅)为研究对象,采用Tessier连续提取法和电感耦合等离子体发射光谱仪,测定Cu、Cr、As、Pb这4种土壤重金属的有效态、铁(锰)氧化物结合态、有机结合态和残渣态含量,基于生物活性系数(MF)和生态风险评价编码法(RAC)计算与评价4种土壤重金属生物有效性及生态风险,剖析4种土壤重金属形态组成与生物有效性的空间变化特征。结果表明:(1) 煤矸石的堆存具有提高周围土壤中Cu、Cr、As、Pb有效态质量分数和降低残渣态质量分数的效应,且与距煤矸石山的水平距离成反比,当水平距离达到或接近300 m时,该效应基本消失。(2) 土壤总有机碳(TOC)质量分数与4种重金属有效态质量分数的相关系数均超过0.6,达到显著正相关水平(p<0.05),是影响研究区土壤重金属有效态含量空间变化特征的主要因素。(3) 4种土壤重金属生物有效性的空间变化特征可分为2个类型,Ⅰ类为“MF值一般大于3,且具有显著的空间异质性”;如 Cu、Cr,Ⅱ类为“MF值一般小于3,且具有显著的空间同质性” ,如As、Pb。(4) 当距煤矸石山水平距离分别小于80和40 m时,土壤重金属Cu、Cr的 MF平均值超过中等风险水平阈值的60%,应予以重视。建议综合考虑煤矸石山存续状态、土壤重金属累积效应及生物有效性空间变化特征等因素,制定煤矸石堆积区土壤重金属污染精准防控及安全利用策略。

     

    Abstract: The surface accumulation of coal gangue is a typical form of ecological environment destruction in the eastern coal mining area of China, and the prevention and control of heavy metal pollution in the soil in the accumulation area has become a hot spot in the current research. Taking the shallow soil (with a vertical depth of 40 cm and below) around a coal gangue mountain (within a radius of 300 m) in use in the Fengfeng mining area of Hebei as the research object, the active state, iron manganese oxidation state, organic state and residue state of four kinds of soil heavy metals, including Cu, Cr, As and Pb, were determined by Tessier continuous extraction method and inductively coupled plasma emission spectrometer. Based on Bioactivity Factor (MF) and Ecological Risk Assessment Coding (RAC) method, the bioavailability and ecological risk of the four soil heavy metals were calculated and evaluated, and the spatial variation characteristics of the morphological composition and bioavailability of the four soil heavy metals were analyzed.The results show that: (1) The storage of coal gangue has the effect of increasing the proportion of Cu, Cr, As and Pb active state content in the surrounding soil and reducing the proportion of residue state content, and is inversely proportional to the horizontal distance from the coal gangue mountain. When the horizontal distance reaches or approaches 300 m, the effect basically disappears. (2) The correlation coefficients between the mass fraction of soil Total Organic Carbon (TOC) and the available mass fractions of the four heavy metals all exceeded 0.6, reaching a significant positive correlation level (p<0.05), which was the main factor affecting the spatial variation characteristics of the soil heavy metal availability content in the study area. (3) The spatial variation characteristics of the bioavailability of the four soil heavy metals can be divided into two types. Type I is “MF value is generally greater than 3 and has significant spatial heterogeneity”, such as Cu, Cr. Type Ⅱ is “MF value is generally less than 3 and has significant spatial homogeneity”, such as As, Pb. (4) When the horizontal distance from the coal gangue mountain is less than 80 m and 40 m, respectively, the average MF of soil heavy metals Cu and Cr exceeds 60% of the medium risk level threshold, which should be taken seriously. It is recommended to comprehensively consider factors such as the existence status of coal gangue mountains, the cumulative effect of heavy metals in the soil and the spatial variation characteristics of bioavailability. Formulate a precise prevention and control and safe utilization strategy for soil heavy metal pollution in coal gangue accumulation areas.

     

/

返回文章
返回