黔西南铊污染区铊的水环境地球化学研究

黔西南滥木厂地区由于铊的硫化物矿化,导致铊在地下水和地表水中十分富集,其富集程度从高到低依次为矿坑深层地下水、地表溪流水和浅层地下水。地下水中铊的含量在矿化区最高,随着远离矿化区而逐渐降低。在地表溪流水中,铊的含量表现出下游河段远远高出上游和中游河段的分布特征;下游溪流水中铊的较高含量可能与来自矿化区地下水在下游河床溢出的贡献有关。滥木厂研究区水体中铊的富集具有潜在的环境危害。饮用水中铊的含量低于美国的安全标准,尚未构成明显的健康危害,但应该加强对饮用水中铊含量的定期监测。富铊的溪流水通过农业灌溉途径会造成铊的进一步扩散,从而导致农业土壤的铊污染,值得高度关注。

AQUEOUS ENVIRONMENTAL GEOCHEMISTRY OF THALLIUM IN A THALLIUM CONTAMINATED AREA OF SOUTHWEST GUIZHOU

In the Lanmuchang area in Southwest Guizhou thallium is highly concentrated in groundwater and surface water resulting from thallium-rich sulfide mineralization. The enrichment extent follows a descending order from deep mine groundwater to stream water to shallow groundwater. Thallium shows the highest concentrations in groundwater within the thallium-mineralized area, with decreasing trend away from this area to the background level. In surface stream water, thallium shows higher concentrations in downstream waters than in up-and mid-stream waters. The markedly high levels of thallium in the downstream waters are likely contributed by unidentified discharge of deep groundwater through fracture zones at the southern margin of the thallium-mineralized area. The enrichment of thallium in the aqueous system of the Lanmuchang area imposes potential environmental risk. Thallium levels in the currently supplied drinking water are lower than in the USEPA regulated safe limit for thallium, and do not impose obvious health hazard at present, but a long-term monitoring on thallium in the drinking water should be taken into consideration. The thallium-rich stream waters may further disperse through agricultural irrigation and consequently cause thallium contamination in arable soils, which should not be overlooked.