Formation of Organic Iodine Supplied as Iodide in a Soil-Water System in Chiba, Japan
Formation of Organic Iodine Supplied as Iodide in a Soil-Water System in Chiba, Japan
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DOI：
10.1021/es1032162
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发表时间：
2011-03-15
影响因子：
11.4
通讯作者：
Terada, Yasuko
中科院分区：
文献类型：
--
作者：
Shimamoto, Yoko S.;Takahashi, Yoshio;Terada, Yasuko
研究了土壤水系统中碘的形态，以了解地表环境中碘迁移的机制。对于日本千叶养老地区 0-12 厘米深度采集的样品，分别采用 K-edge XANES 和 HPLC-ICP-MS 测定土壤和孔隙水中的碘形态。 0-6cm深度收集的孔隙水含有50%-60%与溶解有机质结合的有机碘，其余部分为I(-)。在9-12厘米深度，98%的碘以溶解的I(-)形式存在。相比之下，XANES 分析表明，土壤中的碘在所有深度都以有机碘的形式存在。使用微型 XRF 分析获得了土壤颗粒的碘分布图，这也表明碘与有机物结合。漆酶具有将I(-)氧化成12的能力，在土壤水层表面活性较高，表明碘氧化酶可以促进碘有机化。有机碘在土壤水系统中的分配系数比碘化物大10倍以上。无机碘向有机碘的转化在碘固定中起着重要作用，特别是在地表土壤水系统中。
Speciation of iodine in a soil water system was investigated to understand the mechanism of iodine mobility in surface environments. Iodine speciation in soil and pore water was determined by K-edge XANES and HPLC-ICP-MS, respectively, for samples collected at a depth of 0-12 cm in the Yoro area, Chiba, Japan. Pore water collected at a 0-6 cm depth contained 50%-60% of organic iodine bound to dissolved organic matter, with the other portion being I(-). At a 9-12 cm depth, 98% of iodine was in the form of dissolved I(-). In contrast, XANES analysis revealed that iodine in soil exists as organic iodine at all depths. Iodine mapping of soil grains was obtained using micro-XRF analysis, which also indicated that iodine is bound to organic matter. The activity of laccase, which has the ability to oxidize I(-) to 12, was high at the surface of the soil water layer, suggesting that iodide oxidizing enzymes can promote iodine organification. The distribution coefficient of organic iodine in the soil water system was more than 10-fold greater than that of iodide. Transformation of inorganic iodine to organic iodine plays an important role in iodine immobilization, especially in a surface soil water system.