Enrichment of Geogenic Organoiodine Compounds in Alluvial-Lacustrine Aquifers: Molecular Constraints by Organic Matter,Environmental Science & Technology

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Enrichment of Geogenic Organoiodine Compounds in Alluvial-Lacustrine Aquifers: Molecular Constraints by Organic Matter
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2024-03-19 , DOI: 10.1021/acs.est.3c07314
Jiangkai Xue _{1,

2} , Yamin Deng _{1,

2} , Kunfu Pi _{1,

2} , Qing-Long Fu ₂ , Yao Du _{1,

2} , Yuxiao Xu _{1,

2} , Xiaofang Yuan ₁ , Ruiyu Fan _{1,

2} , Xianjun Xie _{1,

2} , Jianbo Shi _{1,

2} , Yanxin Wang _{1,

2}

Affiliation

Organoiodine compounds (OICs) are the dominant iodine species in groundwater systems. However, molecular mechanisms underlying the geochemical formation of geogenic OICs-contaminated groundwater remain unclear. Based upon multitarget field monitoring in combination with ultrahigh-resolution molecular characterization of organic components for alluvial-lacustrine aquifers, we identified a total of 939 OICs in groundwater under reducing and circumneutral pH conditions. In comparison to those in water-soluble organic matter (WSOM) in sediments, the OICs in dissolved organic matter (DOM) in groundwater typically contain fewer polycyclic aromatics and polyphenol compounds but more highly unsaturated compounds. Consequently, there were two major sources of geogenic OICs in groundwater: the migration of the OICs from aquifer sediments and abiotic reduction of iodate coupled with DOM iodination under reducing conditions. DOM iodination occurs primarily through the incorporation of reactive iodine that is generated by iodate reduction into highly unsaturated compounds, preferably containing hydrophilic functional groups as binding sites. It leads to elevation of the concentration of the OICs up to 183 μg/L in groundwater. This research provides new insights into the constraints of DOM molecular composition on the mobilization and enrichment of OICs in alluvial-lacustrine aquifers and thus improves our understanding of the genesis of geogenic iodine-contaminated groundwater systems.

中文翻译：

冲积湖相含水层中地质有机碘化合物的富集：有机物质的分子约束

有机碘化合物（OIC）是地下水系统中的主要碘物种。然而，地质 OIC 污染地下水的地球化学形成背后的分子机制仍不清楚。基于多目标现场监测，结合冲积湖相含水层有机成分的超高分辨率分子表征，我们在还原性和近中性 pH 条件下，在地下水中总共鉴定出了 939 个 OIC。与沉积物中的水溶性有机物（WSOM）相比，地下水中溶解的有机物（DOM）中的OIC通常含有较少的多环芳烃和多酚化合物，但含有更多的高度不饱和化合物。因此，地下水中地源 OIC 有两个主要来源：OIC 从含水层沉积物中的迁移以及碘酸盐的非生物还原以及还原条件下的 DOM 碘化。 DOM 碘化主要通过将碘酸盐还原产生的反应性碘掺入高度不饱和化合物中发生，优选含有亲水官能团作为结合位点。它导致地下水中 OIC 的浓度升高至 183 μg/L。这项研究为DOM分子组成对冲积湖相含水层中OIC的动员和富集的限制提供了新的见解，从而提高了我们对地质碘污染地下水系统成因的理解。

更新日期：2024-03-19

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