天津东部地区水土环境碘地球化学特征及其成因分析

碘是人体必需的微量元素之一,高碘或低碘均能引起人类或动物的各种疾病。对天津东部地区水土环境中碘地球化学特征及成因进行了研究,结果表明,研究区表层土壤碘含量变化范围是0.89～17.09 mg/kg,平均为5.11 mg/kg,是天津市背景值的1.92倍,是全国背景值的1.36倍。深层土壤碘含量在0.64～34.55 mg/kg之间,平均为10.73 mg/kg,是天津市深层土壤基准值的3.93倍,是研究区表层土壤的2.1倍,研究区表层和深层土壤碘均处于富集状态。表层土壤碘高背景区分布面积较大,主要集中分布在东丽区、宁河区南部、滨海新区北部。浅层地下水碘含量范围在0.03～4.00 mg/L之间,平均为0.56mg/L,高碘地下水分布面积较大,主要分布在东丽区、津南区、宁河区南部、滨海新区(除去西南部)。研究区历史上海陆交互作用强烈,海水提供的大量碘物质在此残留富集,可能是造成水土环境中碘元素整体偏高的自然原因。

Geochemical Characteristics and Genesis of Iodine in Soil and Water Environments of Eastern Tianjin

Iodine is one of the essential trace elements of human, but too high or too low content of iodine in the human body may cause various diseases. The paper studied geochemical characteristics and causes of iodine in soil and water environments of eastern Tianjin. The results showed that the iodine content in surface soil was between 0.89 mg/kg and 17.09 mg/kg, with an average of 5.11 mg/kg, which was 1.92 times of its background value of Tianjin or 1.36 times of the national background value. The iodine content in deep soil ranged from 0.64 mg/kg to 34.55 mg/kg, with an average of 10.73 mg/kg, which was 3.93 times of the benchmark value of deep soil or 2.1 times of the value of surface soil in the study area. The surface and deep soils of the study area showed enrichments of iodine. The area of surface soil with high iodine background is large, distributed mainly in Dongli district, southern Ninghe district and northern Binhai new district. The iodine content of shallow groundwater ranged from 0.03 mg/L to 4.00 mg/L, with an average of 0.56 mg/L. The area of groundwater with high iodine content is also large, distributed mainly in Dongli district, Jinnan district, southern Ninghe district and Binhai new district (except of the southwest region). Historically, the study area was a strong land-sea interaction zone and enriched a large amount of iodine supplied by seawater, which could result in the overall high iodine contents in soil and water environments of the study area.