地下煤火土壤典型重金属分布特征

通过采集乌鲁木齐大泉湖火区土壤样及实验室测定,研究了火区土壤理化性质与重金属Hg,As,Cu,Pb,Cr,Zn,Ni空间分布特征。结果表明:温度正常区土壤温度随采样深度增加的幅度较温度异常区小;温度正常、温度异常区土壤有机质含量随深度的增加均减少,温度正常区I,II,III,IV层土壤有机质含量大于温度异常区相应土层有机质含量;温度异常区土壤层I重金属Cu,Pb,Cr,Zn,Ni含量均小于温度正常区土壤层I相应重金属含量,II层则有增加的趋势并大于温度正常区相应土层重金属含量;温度正常区、温度异常区土壤Hg,As,Cu,Ni重金属含量随深度变化幅度及波动幅度较小,而温度异常区土壤Pb,Cr,Zn重金属含量随深度变化波动幅度较温度正常区大;火区热效应、地形、土壤及气象因子是影响土壤重金属分布的主要原因。土壤典型重金属砷形态分析表明:残留态砷含量最高,水溶态砷含量最低;水溶态砷在火区取样区域内I,II,III,IV土壤层区域富集特征与各层土壤碳酸钙富集特征趋于一致;温度正常区土壤残留态砷、铁形砷含量随深度变化的趋势与土壤碳酸钙含量随深度变化趋势一致;温度异常区残留态砷含量随深度增加波动趋势与土壤有机质含量波动趋势有较强关联性;温度正常区、温度异常区均值水溶态砷含量基本稳定,表明其与温度、土壤特性等无明显相关性。

Characteristics of the distribution of typical heavy metals in the soils of underground coal fire

In the present paper，the authors conducted some experiments on the samples of the soils of Daquanhu coal fire for analyzing the characteristics of the heavy metals distribution in this fire zone，such as the Hg，As，Cu，Pb，Cr and the Zn，which is relevant to the soil properties of the sampling sites.Results show that the temperature increases with the depth increase of the sampling site in both normal and abnormal area，and the variation of temperature increase in the normal area is less than that of the abnormal area.The content of organic matter of soils decreases with the depth increase of the sampling site in both the normal area and the abnormal area.And the layer one，the layer two，the layer three and the layer four of the normal area soil contains more organic matter than that of the abnormal area soils.The contents of some heavy metals in the layer one of normal area soil，such as the Cu，Pb，Cr，Zn and the Ni，are less than that of the layer one of the abnormal soil.In the layer two of the abnormal area soil，the content of these heavy metals shows a trend of increase.In both the normal area and the abnormal area soils，the contents of the Hg，As，Cu and the Ni fluctuate little along the increase of the depth of sampling site.But the contents of the Pb，Cr and the Zn in abnormal area soil fluctuate more than that of the normal area soil.Results also show that the heat effect of the coal fire，the topography of the fire zone，the properties of the soil and the local climate parameters are the main factors to impact the spatial distribution of the heavy metals in the soil of underground coal fires.An analysis of the As speciation shows that the content of the residual As speciation is the highest，and that of the water soluble As speciation is the lowest.Contents contour maps show that the accumulating characteristics of the water soluble As speciation within the soil of the layer one to layer four consequently has the same trend of the accumulation of CaCO3 in this area.In the normal area of the fire zone，the contents of the residual As speciation and the iron As speciation have the same trend of change as the change of CaCO3 following the sampling depth increase.However，in the abnormal area of the fire zone，the content of the residual As fluctuates with a similar trend of the content of the organic matter following the increase of sampling depth.The mean content of the water soluble As in both the normal area and the abnormal area stays stable，which indicates that no close relationship exists between the As content and the soil temperature as well as the soil properties.