In the Argentina Puna region, there are several metal sulfide mines that ceased their activity twenty years ago without a proper closure plan. The exposure of the waste rocks and tailing impoundments to weathering led to sulfide oxidation and generation of highly acid solutions rich in metal(oid)s, that react with the unaltered waste rocks, partitioning into different solid phases. The As speciation along a 82 cm depth oxidation profile described in the Pan de Azucar mine tailings was studied by standardized . sequential extraction procedures. Results show that the highest As concentration remain in the bottom unaltered layer mainly associated with primary and secondary sulfides. In the upper layers, the total As concentrations are ～40 to 70% lower than that of the bottom layer, and most As is associated with amorphous and crystalline oxides. The most bioavailable forms of As (exchangeable and soluble) account for less than 1.5% of the total As concentration.
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机译：在阿根廷普陀地区，有几种金属硫化物矿山在二十年前停止了他们的活动，没有适当的封闭计划。废岩和拖尾蓄水阻挡的曝光导致硫化物氧化和富含金属（OID）S的高酸溶液的产生，其与未嵌入的废岩反应，分配成不同的固相。通过标准化研究了沿PAN de Azucar矿井尾矿中描述的82cm深度氧化曲线的沿着82cm深度氧化曲线的形状。顺序提取程序。结果表明，浓度最高的浓度在底部未改变层中留在主要与初级和仲硫化物相关。在上层中，作为浓度的总量低于底层的40％至70％，大多数与无定形和结晶氧化物相关。作为（可交换和可溶性）的最具生物可利用形式的形式占总浓度的总量的1.5％。
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