以内蒙古河套平原西北部的高砷地下水分布区为研究区,通过对区内22组地下水和2组地表水中碘含量的测试和分析可知,研究区地下水中碘含量在27.30—1638.00μg/L,其中,约50%的地下水样品中碘含量超过我国饮用水的标准限定值150μg/L,约84.6%的高碘地下水为高砷地下水。高碘地下水主要分布于研究区北部地下水水流相对滞缓的平原中心地带,以Cl-Na、Cl·HCO3-Na和HCO3·Cl-Na型水为主。研究区地下水中碘的富集有两种机制:浅层地下水的蒸发作用和深部富含有机质的、偏还原的地下水环境中的微生物作用。两种机制相比,后者对地下水中碘的贡献更大些,但前者更普遍些。
Twenty groundwater samples and two surface water samples were collected to analyze the occurrence and distribution of iodine in groundwater in the area of Hangjinhouqi in the Hetao Plain, Inner Mongolia. The results show that concentrations of iodine in the groundwater vary between 27.30 and 1,638.00 μg/L. The concentrations of iodine in more than 50% of the groundwater samples exceed the national standard for drinking water (150 μg/L) , and about 84.6% of the samples were located in high As areas. High iodine groundwater mainly occurs in the central part with slow groundwater flow and strong evaporation in the north of the study area. Furthermore, most of the high iodine groundwater is of CI-Na, CI-HCO3-Na and HCO3-C1-Na types. Two mechanisms are thought to contribute to the enrichment of iodine in groundwater in this region. One is the evaporation of shallow groundwater; the other is the microorganisms in the reducing and organic matter-rich deep groundwater. Comparison of these two mechanisms show that the latter is more important, however, the former is more common.