内蒙古高砷含水层沉积物有机质特征研究
发布时间:2018-07-10 00:49
本文选题:高砷地下水 + 有机质 ; 参考:《中国地质大学(北京)》2015年硕士论文
【摘要】:本文以内蒙古河套平原高砷地下水地区为研究区,钻取两个钻孔,并采集沉积物样品。通过资料整理、实地考察、野外取样及室内分析测试等过程,对研究区沉积物有机质类型、起源及生物地球化学意义进行研究。得到以下认识:1、通过对样品的无机组分测试分析,揭示了沉积物砷含量及影响因素。沉积物中砷的含量为4.44-28.89μg/g,均值为12.07μg/g;Fe2O3的含量在1.43-6.86%之间,均值为3.56%;Mn O的含量在0.03-0.135%之间,均值为0.06%。沉积物中砷的含量与铁和锰的关系密切,存在明显的正相关关系,相关系数分别为0.88、0.83。推测铁和锰的氧化物吸附砷是沉积物富砷的主要原因。2、通过对样品的总有机碳及有机碳同位素的测试分析,初步了解沉积物有机质总体特征。研究区沉积物总有机碳含量较低,TOC含量在0.03-1.65%之间。砷与TOC含量也呈正相关关系,相关系数为0.56。样品的δ13C取值在-24.24‰到-32.3‰之间,更接近于陆地植物的δ13C值,说明研究区沉积物中的有机质主要来源于陆源植物。TOC与δ13C的分布与岩性关系密切,粘性样品有机质含量比砂质样品丰富。3、通过对沉积物标志性有机质的测试分析,揭示了有机质起源特征及生物地球化学意义。沉积物有机质中长链正构烷烃含量丰富,且奇偶优势明显。有机物主要来源于草本高等植物,少量来源于木本植物。部分样品奇偶优势不明显,且存在UCM,说明有成熟石油有机质的侵入。藿烷类化合物和甾烷类化合物的构型特征也说明有些样品已达到成熟。研究表明,微生物首先利用石油起源的正构烷烃,促进吸附砷的铁锰氧化物还原,从而导致砷的释放。砂质沉积物的有机质含量较低,但含有石油起源的有机质,便于微生物的选择性利用,使砷发生活化。
[Abstract]:In this paper, two boreholes were drilled from the high arsenic groundwater area of Hetao Plain, Inner Mongolia, and sediment samples were collected. The types, origins and biogeochemical significance of sediment organic matter in the study area were studied by means of data collation, field investigation, field sampling and laboratory analysis. The content of arsenic in sediment and its influencing factors were revealed by analyzing the inorganic components of the samples. The content of arsenic in sediment is 4.44-28.89 渭 g / g, the mean value is 12.07 渭 g / g, the content of Fe _ 2O _ 3 is between 1.43-6.86%, the mean value is between 0.03-0.135% and the average is 0.06%. The content of arsenic in sediment is closely related to iron and manganese, and there is a significant positive correlation between arsenic and manganese. The correlation coefficient is 0.888 ~ 0.83, respectively. It is inferred that the adsorption of arsenic by oxides of iron and manganese is the main cause of arsenic enrichment in sediments. The total organic carbon and organic carbon isotopes of the samples are measured and analyzed to preliminarily understand the overall characteristics of organic matter in sediments. The total organic carbon content of sediments in the study area is lower than that of TOC in the range of 0.03-1.65%. There was also a positive correlation between arsenic and TOC content, the correlation coefficient was 0.56. The 未 ~ (13) C values of the samples range from -24.24 鈥,
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