大同盆地高砷地下水系统沉积物环境磁学特征  

Environmental Magnetic Properties of Sediments of High Arsenic Groundwater System,Datong Basin

作　　者：谢先军[1] 王焰新[1] 苏春利[1] 刘怀庆[1] 段萌语[1] 张宏达[1] 

机构地区：[1]中国地质大学环境学院及教育部生物地质与环境地质重点实验室,湖北武汉430074

出　　处：《地球科学（中国地质大学学报）》2008年第1期117-123,共7页Earth Science-Journal of China University of Geosciences

基　　金：国家杰出青年科学基金项目(No.40425001);教育部重点科研项目(No.105033)

摘　　要：为了研究高砷含水层沉积物中砷与磁性矿物的关系,对大同盆地高砷地区含水层钻孔样品进行了环境磁学和地球化学分析,结果表明亚铁磁性矿物是决定含水层沉积物磁性特征的主要磁性矿物.通过对比砷和磁性参数在垂向上的变化趋势发现,高砷含量往往对应着低的饱和等温剩磁(SIRM)值,揭示出砷和顺磁性矿物之间也存在联系.沉积物砷含量与磁性参数的相关系数均小于0.5(α=0.05),表明砷和亚铁磁性矿物及不完整反铁磁性矿物之间不存在明显的联系.在所有磁性参数中磁化率(χ)和砷含量之间相关性最显著,相关系数均在0.4(α=0.05)左右,低的相关系数与亚铁磁性矿物和不完整反铁磁性矿物对顺铁磁性矿物的稀释有关.该地区高砷地下水的形成可能与水铁矿及纤铁矿等砷的赋存矿物在还原条件下的还原溶解有关.The purpose of the study is to test the possible relationship between magnetic parameters and arsenic in high arsenic aquifer sediment. Magnetic and geochemical study on core sediments from Datong basin suggests that the dominant magnetic mineral is ferrimagnetic. Magnetic measurements and arsenic concentration analysis were carried out to understand the distribution characteristics of magnetic parameters and arsenic in sediments. All core samples with high arsenic content have low saturation isothermal remnant magnetism （SIRM） values, indicating the correlation between arsenic and paramagnetic mineral. The correlation factors between arsenic content and magnetic parameters are very low （R^2〈0. 5, α= 0. 05）, but the magnetic susceptibility （χ） is better correlated than the other magnetic parameters With correlation factor of about 0. 4 （α= 0. 05）. The low correlation between magnetic proxies and arsenic content is attributed to the dilution of paramagnetic minerals by the ferrimagnetic and anti-ferromagnetic minerals. The occurrence of As-rich groundwater in this region may be due to dissolution of As-bearing Fe mineral （e. g. γFeOOH, 5Fe2O3·9H2O） and subsequent arsenic release.

关 键 词：大同盆地 砷 地下水系统 沉积物 环境磁学. 

分 类 号：X143[环境科学与工程—环境科学] P33[天文地球—水文科学]