Gledhill Martha, Hollister Adrienne, Seidel Michael, Zhu Kechen, Achterberg Eric P, Dittmar Thorsten, Koschinsky Andrea
GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
Department of Physics and Earth Sciences, Jacobs University Bremen gGmbH, Campus Ring 1, 28759 Bremen, Germany.
Sci Adv. 2022 Aug 5;8(31):eabm2249. doi: 10.1126/sciadv.abm2249.
Dissolved organic matter (DOM) is a distinct component of Earth's hydrosphere and provides a link between the biogeochemical cycles of carbon, nutrients, and trace metals (TMs). Binding of TMs to DOM is thought to result in a TM pool with DOM-like biogeochemistry. Here, we determined elemental stoichiometries of aluminum, iron, copper, nickel, zinc, cobalt, and manganese associated with a fraction of the DOM pool isolated by solid-phase extraction at ambient pH (DOM) from the Amazon plume. We found that the rank order of TM stoichiometry within the DOM fraction was underpinned by the chemical periodicity of the TM. Furthermore, the removal of the TM pool at low salinity was related to the chemical hardness of the TM ion. Thus, the biogeochemistry of TMs bound to the DOM component in the Amazon plume was determined by the chemical nature of the TM and not by that of the DOM.
溶解有机物（DOM）是地球水圈的一个独特组成部分，它在碳、营养物质和痕量金属（TMs）的生物地球化学循环之间提供了一个联系。痕量金属与DOM的结合被认为会形成一个具有类似DOM生物地球化学性质的痕量金属库。在这里，我们测定了铝、铁、铜、镍、锌、钴和锰的元素化学计量比，这些元素与通过固相萃取在环境pH值下从亚马逊羽流中分离出的一部分DOM库相关联。我们发现，DOM组分中痕量金属化学计量比的排序受到痕量金属化学周期性的支撑。此外，低盐度下痕量金属库的去除与痕量金属离子的化学硬度有关。因此，亚马逊羽流中与DOM组分结合的痕量金属的生物地球化学是由痕量金属的化学性质而非DOM的化学性质决定的。
