Soluble Mn(III)-L complexes are abundant in oxygenated waters and stabilized by humic ligands
Soluble Mn(III)-L complexes are abundant in oxygenated waters and stabilized by humic ligands
复制标题
DOI：
10.1016/j.gca.2016.11.043
复制
发表时间：
2017-02-15
影响因子：
5
通讯作者：
Luther, George W., III
中科院分区：
文献类型：
--
作者：
Oldham, Veronique E.;Mucci, Alfonso;Luther, George W., III
溶解的Mn（DMN（t））被认为是在氧气存在下由亚稳态的Mn（II）主导的，因为稳定形式是不溶性的Mn（IV）。我们首次表明，当通过有机配体稳定为Mn（iii）-L复合物时，Mn（III）在含氧水柱中也是可溶性物种稳定。我们测量了沿海峡湾的氧水域和半质系系统中的Mn（III）-L复合物，在那里它们占DMN（T）的86％（T）。尽管Mn（III）形成与Fe（III）相似的复合物，但与大多数类似的Fe（III）-L复合物不同，MN（III）-L复合物并非胶体，因为它们都通过0.20 MU M和0.02 MU M滤波器。根据MN（III）复合物的动力学稳定性和给定系统的微生物群落，这些MN（III）-L复合物能够捐赠或接受电子，因此可以用作还原剂或氧化剂，因此可以在生物学上可用，因此可以参与多种氧化还原反应和生物地球化学过程。此外，样品酸化实验表明，Mn（III）与腐殖质配体的结合负责多达100％的络合率，这可能会影响包括Fe（III）在内的其他金属配合物的形成，从而影响养分的可用性和吸收。因此，腐殖质配体在从沿海地区到海洋的溶解的MN运输中起着比以前想象的更大的作用。 （c）2016 Elsevier Ltd.保留所有权利。
Dissolved Mn (dMn(T)) is thought to be dominated by metastable Mn(II) in the presence of oxygen, as the stable form is insoluble Mn(IV). We show, for the first time, that Mn(III) is also stable as a soluble species in the oxygenated water column, when stabilized by organic ligands as Mn(III)-L complexes. We measured Mn(III)-L complexes in the oxygenated waters of a coastal fjord and a hemipelagic system where they make up to 86% of the dMn(T). Although Mn(III) forms similar complexes to Fe(III), unlike most of the analogous Fe(III)-L complexes, the Mn(III)-L complexes are not colloidal, as they pass through both 0.20 mu m and 0.02 mu m filters. Depending on the kinetic stability of the Mn(III) complexes and the microbial community of a given system, these Mn(III)-L complexes are capable of donating or accepting electrons and may therefore serve as both reductants or oxidants, can be biologically available, and can thus participate in a multitude of redox reactions and biogeochemical processes. Furthermore, sample acidification experiments revealed that Mn(III) binding to humic ligands is responsible for up to 100% of this complexation, which can influence the formation of other metal complexes including Fe(III) and thus impact nutrient availability and uptake. Hence, humic ligands may play a greater role in dissolved Mn transport from coastal areas to the ocean than previously thought. (C) 2016 Elsevier Ltd. All rights reserved.