Clay minerals as a source of cadmium to estuaries
Clay minerals as a source of cadmium to estuaries
复制标题
粘土矿物作为河口镉的来源
DOI：
10.1038/s41598-020-67279-w
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发表时间：
2020-06-26
影响因子：
4.6
通讯作者：
Konhauser, Kurt O.
中科院分区：
文献类型：
--
作者：
Hao, Weiduo;Kashiwabara, Teruhiko;Konhauser, Kurt O.
鉴于粘土矿物的高表面反应性，推测絮凝将导致边缘海洋环境中的金属积累。然而，粘土对金属的吸附程度受到溶液pH值和离子强度的影响，并且当河流粘土遇到pH值和离子强度显着增加的海水时，是否确实充当金属汇仍不清楚。在这里，我们对三种常见的粘土矿物——高岭石、伊利石和蒙脱石进行了镉（Cd）吸附实验。我们发现，当 pH 值和离子强度条件从淡水过渡到海水时，伊利石和蒙脱石表面的 20-30% 的镉被解吸，而高岭石则没有表现出明显的差异。同步加速器 X 射线吸收光谱证实，当粘土遇到海水 pH 值和离子强度条件时，Cd 的释放对应于从外层到内层复合物的键合变化。如果吸附在河流粘土矿物上的其他微量营养素（例如铜、锌、钴）的行为与镉类似，我们推测它们在边缘海洋环境中的解吸应该对生物圈的生产力产生重大影响。
Given the high surface reactivity of clay minerals, it is assumed that flocculation will lead to metal accumulation in marginal marine settings. However, the degree of metal sorption to clays is impacted by solution pH and ionic strength, and it remains unknown whether riverine clays indeed serve as a metal sink once they encounter seawater where pH and ionic strength markedly increase. Here, we conducted cadmium (Cd) adsorption experiments to three types of common clay minerals - kaolinite, illite and montmorillonite. We found that 20-30% of Cd from illite and montmorillonite surfaces were desorbed when transitioning from freshwater to seawater pH and ionic strength conditions, while kaolinite showed no discernible differences. Synchrotron X-ray adsorption spectroscopy confirmed that Cd release corresponded to a change in bonding from outer- to inner-sphere complexes when clays encountered seawater pH and ionic strength conditions. If other trace nutrients (such as Cu, Zn, Co) adsorbed onto riverine clay minerals behave in a similar manner to Cd, we speculate that their desorption in marginal marine settings should exert a significant impact on the productivity of the biosphere.