| 大同盆地地下水中碳硫同位素组成特征及其对碘迁移富集的指示 |
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| 引用本文： | 朱沉静,李俊霞,谢先军.大同盆地地下水中碳硫同位素组成特征及其对碘迁移富集的指示[J].地球科学,2021,46(12):4480-4491. |
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| 作者姓名： | 朱沉静 李俊霞 谢先军 |
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| 作者单位： | 中国地质大学环境学院,湖北武汉 430078;中国地质大学环境学院,湖北武汉 430078;中国地质大学生物地质与环境地质国家重点实验室,湖北武汉 430078 |
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| 基金项目： | 国家自然科学基金项目42020104005国家自然科学基金项目41502230 |
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| 摘 要： | 为深入探究地下水系统中影响碘迁移转化的主控水文生物地球化学过程，对大同盆地典型高碘地下水区完成样品采集，分析地下水样品基础理化性质及碳硫同位素组成特征.结果表明，大同盆地地下水碘含量变化范围为14.40~1 030.00 μg/L，高碘地下水（I>100 μg/L）主要分布在盆地中心排泄区.地下水中溶解性无机碳的δ13CDIC值变化范围为-12.11‰~-9.79‰，硫酸盐δ34SSO4值介于4.04‰~16.63‰.δ13CDIC和DOC之间存在较明显的正相关关系，表明有机质的微生物降解过程是区域地下水无机碳的重要来源之一.同时，δ13CDIC与δ34SSO4一定的负相关关系表明硫酸盐是有机质微生物降解过程中潜在电子受体之一，且地下水水环境以偏还原环境为主.高碘地下水表现出低δ13CDIC、高δ34SSO4的同位素特征，表明有机质的微生物降解过程是控制地下水中碘迁移释放的主要过程之一，与该过程相伴而生的碘形态转化进一步促使碘以碘离子的形式在偏还原的地下水环境中发生富集.
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| 关 键 词： | 碘 地下水 大同盆地 碳硫同位素 迁移释放 水文地质学 |
| 收稿时间： | 2021-04-08 |
Carbon and Sulfur Isotopic Features and Its Implications for Iodine Mobilization in Groundwater System at Datong Basin,Northern China |
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| Abstract: | In order to understand the dominant hydro-biogeochemical processes affecting the migration and transformation of iodine in groundwater system, in this study it analyzed the chemistry and carbon/sulfur isotope signatures of groundwater samples from typical high iodine area in Datong basin. Results show that the iodine concentrations of groundwater range from 14.40 to 1 030.00 μg/L and high iodine groundwater (I>100 μg/L) is mainly distributed in the discharge area near the center of the basin. The δ34SSO4 and δ13CDIC signatures of groundwater have the ranges of (-12.11‰)-(-9.79‰) and 4.04‰-16.63‰, respectively. The positive correlation between the δ13CDIC values and DOC concentrations in groundwater suggests that microbial degradation of organic matter is one of the important sources of DIC in the Datong basin. The correlation between the low δ13CDIC values and the high δ34SSO4 values indicates that groundwater SO42- serves as one of the electron accepters during the biodegradation of organic matter, and groundwater environment was dominant by the weak reducing conditions. High iodine groundwater is characterized by lower δ13CDIC and higher δ34SSO4, indicating that microbial degradation of organic matter, which acts as a dominate host of sediment iodine, promotes the release of iodine into groundwater. Moreover, the transformation among iodine species, for instance, from organic iodine/iodate to iodide, also favors the enrichment of groundwater iodine under the reducing conditions. |
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