太原盆地孔隙水中碘的迁移富集规律

Mobilization and Enrichment Process of Iodine in Pore Water of Taiyuan Basin

水源性高碘地下水是典型的原生劣质水,其对饮用水安全造成严重威胁。以太原盆地中部孔隙水为研究对象,通过采集研究区内57组地下水样品,综合利用Piper三线图、相关分析、元素比值等方法分析了研究区高碘地下水特征,并探讨了其富集过程。结果表明:地下水碘含量超标主要发生在冲积平原孔隙水中,I^(-)质量浓度最大值为1128.0μg/L;高碘地下水水平分带明显,沿地下水流向I^(-)质量浓度逐渐增大;垂向分布特征表现为随含水岩组埋藏深度的增加,I^(-)平均质量浓度逐渐减小;高碘地下水的水化学类型以HCO_(3)^(-)Na型为主,与I^(-)相关的地下水组分为Na^(+)、TDS、Cl^(-)、TOC、HCO^(-)^(3)、pH值和ORP;偏碱性弱还原沉积环境、岩石风化、地下水径流强度、有机质降解、竞争性吸附是太原盆地孔隙水碘富集的自然因素,地表灌溉、人为诱导的越流补给和串层开采是太原盆地孔隙水碘富集的重要外因。

Water⁃born iodine⁃excess is one of the typical primary inferior groundwaterissues,which threatens the security of drinking water severely.Taking the groundwater in central area of Taiyuan Basin as an object,the iodine⁃excess distribution characteristic and enrichment process were analyzed by collecting and testing 57 water samples and the combination using of methods such as Piper diagram,correlate ion analysis and ion ratio.The results show that iodine⁃excess in groundwater mainly appears in pore aquifer of the alluvial plain,and the maxi⁃mum iodine concentration is 1128.0μg/L in the water samples.The horizontal zonation of high iodine groundwater is obvious and the iodine concentration gradually increases along the groundwater flow direction.Besides,of which the vertical distribution is that iodine content de⁃creases with the increase of aquifer group burial depth.The groundwater hydrochemical type is dominated by HCO_(3)^(-)Na,and the main groundwater components are Na^(+),TDS,Cl^(-),TOC,HCO^(-)_(3),pH and ORP,which are correlated with iodine concentration significantly.Sedi⁃mentary environment of weakly⁃alkaline and reduction,rock weathering,runoff,organic matter degradation and competitive adsorption are natural factors of iodine enrichment in the study area.Furthermore,surface irrigation,artificial groundwater leakage recharge and mixing ex⁃ploitation are important external causes of iodine enrichment in Taiyuan Basin.