Recent experimental studies have demonstrated that clay minerals (e.g., kaolinite, illite, and montmorillonite) have higher affinities for some trace elements under acidic versus alkaline conditions. This suggests that clays might be important vectors in the transport of trace elements from sites of acidic chemical weathering on land to marine depositional environments. To determine if clays behave similarly in nature, we collected water and mud (consisting of 38.5%–61.1% of kaolinite and montmorillonite) samples from boiling, low‐pH, mud pools venting at the El Tatio Geyser Field (ETGF) in Chile. Based on elemental abundances in the aqueous/solid phases, we observed that mud samples collected from lower pH pools (e.g., pH = 2.42 and 3.55) have high concentration factors for anionic elements (e.g., P and As) but low concentration factors for cationic elements (e.g., Ca, Mn, and Sr), while mud samples from higher pH pools (e.g., pH = 4.87 and 5.84) display the opposite trend. Acid‐base leaching experiments further reveal that increasing solution pH (to reflect downstream transport) led to the release of As and P from the mud surfaces due to increasingly negative surface charge, while decreasing pH (to determine the effects of re‐acidification) released Li, Ca, Co, Sr, Mo, and Cd. Our study confirms previous experimental findings that demonstrate clay minerals can assemble a diverse inventory of trace elements during acid weathering (e.g., As) but then liberate them back into the aqueous phase as aqueous pH increases. Importantly, these observations provide a mechanism to account for the previous observations of regional As contamination in rivers downstream of the ETGF.

中文翻译：

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智利El Tatio Geyser油田热液泥浆中粘土的痕量元素分配

最近的实验研究表明，粘土矿物（例如高岭石，伊利石和蒙脱石）在酸性和碱性条件下对某些微量元素具有更高的亲和力。这表明粘土可能是微量元素从陆地上的酸性化学风化作用地点到海洋沉积环境的重要载体。为了确定粘土在自然界中的行为是否相似，我们从智利El Tatio间歇泉油田（ETGF）的沸腾，低pH值泥浆池中收集了水和泥浆（占38.5％–61.1％的高岭石和蒙脱土）样品。基于水/固相中元素的丰度，我们观察到从较低pH池（例如pH = 2.42和3.55）收集的泥浆样品对阴离子元素（例如 P和As），但阳离子元素（例如Ca，Mn和Sr）的低浓度因子，而来自较高pH池（例如pH = 4.87和5.84）的泥浆样品则显示出相反的趋势。酸碱浸出实验进一步揭示，由于表面负电荷的增加，溶液pH值的增加（以反映下游迁移）导致泥浆表面的As和P释放，而pH值的下降（确定重新酸化的影响）则降低了。 Li，Ca，Co，Sr，Mo和Cd。我们的研究证实了先前的实验结果，这些结果表明粘土矿物可以在酸性风化过程中（例如As）聚集各种微量元素，但随着水溶液pH值的增加，它们可以释放回到水相中。重要的，