Towards a mechanistic understanding of carbon stabilization in manganese oxides.
Towards a mechanistic understanding of carbon stabilization in manganese oxides.
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DOI：
10.1038/ncomms8628
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发表时间：
2015-07-21
影响因子：
16.6
通讯作者：
Greenwell C
中科院分区：
文献类型：
--
作者：
Johnson K;Purvis G;Lopez-Capel E;Peacock C;Gray N;Wagner T;März C;Bowen L;Ojeda J;Finlay N;Robertson S;Worrall F;Greenwell C
矿物稳定沉积物中的有机碳(OC)，从而在多个尺度上直接影响全球气候，但它们如何做到这一点还远未被了解。在这里，我们展示了在水处理厂中的氧化锰(氧化锰)过滤器床捕获溶解的有机碳，因为涂层在清洁砂粒周围形成一层，质量分数为3w/wc。利用光谱和热重分析方法，我们确定了两个主要的有机碳组分。一种是耐热的(>；550 °C)，另一种是更不稳定的(<；550 °C)。我们推测，被捕获的有机碳的热稳定性是由于它内部的羧酸基结合到氧化锰表面，再加上层内的物理捕获。我们发现表面结合的有机碳和整体有机碳的性质有显著的不同。我们推测，聚合反应可能发生在层内的深处。我们还建议在未来对自然系统中有机化合物的研究中必须考虑这些过程。众所周知，矿物可以稳定沉积物中的有机碳，影响生物地球化学循环和全球气候，但其机制尚不清楚。在这里，作者们认为，锰氧化物可以捕获有机碳，并可能起到‘矿物泵’的作用，将碳在不稳定形式和难处理形式之间转化。
Minerals stabilize organic carbon (OC) in sediments, thereby directly affecting global climate at multiple scales, but how they do it is far from understood. Here we show that manganese oxide (Mn oxide) in a water treatment works filter bed traps dissolved OC as coatings build up in layers around clean sand grains at 3%w/wC. Using spectroscopic and thermogravimetric methods, we identify two main OC fractions. One is thermally refractory (>550 °C) and the other is thermally more labile (<550 °C). We postulate that the thermal stability of the trapped OC is due to carboxylate groups within it bonding to Mn oxide surfaces coupled with physical entrapment within the layers. We identify a significant difference in the nature of the surface-bound OC and bulk OC . We speculate that polymerization reactions may be occurring at depth within the layers. We also propose that these processes must be considered in future studies of OC in natural systems. Minerals are known to stabilize organic carbon in sediments, affecting biogeochemical cycles and global climate, but the mechanism is not understood. Here, the authors suggest that manganese oxides can trap organic carbon and may act as a ‘mineral pump', transforming carbon between labile and refractory forms.