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首页> 外文期刊>Geochimica et Cosmochimica Acta: Journal of the Geochemical Society and the Meteoritical Society >Molecular isotopic insights into hydrodynamic controls on fluvial suspended particulate organic matter transport
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Molecular isotopic insights into hydrodynamic controls on fluvial suspended particulate organic matter transport

机译：氟尿悬浮颗粒有机物质运输中的分子同位素见解探讨流体动力学对照

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Hydrodynamic sorting has been shown to strongly influence the composition and age of organic carbon (OC) during sediment transport and burial in the marine environment, yet sorting effects on terrestrial OC (OCterr) in fluvial systems remain poorly understood. We conducted size fractionation of suspended particle samples from the lower Yellow River, China, and examined variations in mass distribution and carbon isotopic (delta C-13 and Delta C-14) composition of bulk OC and specific biomarkers among grain size fractions in order to investigate the influence of hydrodynamic sorting and selective transport on organic matter export. In general, the 16-32 mu m and 32-63 mu m fractions contributed the most of sediment mass while the majority of the OC resided in the 16-32 mu m fraction. Over 80% of OC and n-fatty acids (FAs) were concentrated in <32 mu m fractions. Significant differences in OC%, surface area (SA), Delta C-14(OC), n-FAs contents, and compound-specific C-13 and C-14 compositions were found among size fractions. Of particular note was a progressive decrease of Delta C-14 values (i.e., increase in C-14 age) of long-chain (C26+28+30) FAs with decreasing grain size. Taken together, the bulk and molecular characteristics imply two distinct types of selective OCterr transport in the Yellow River. Coarser particles (>32 mu m), characterized by relatively low SA, OC%, and Delta C-14(OC) values, but higher Delta C-14 values of C26+28+30 FAs, are inferred to reflect a combination of bedrock-derived detrital sediment and fresh vascular-plant material (e.g., plant fragments). In contrast, finer particles (<32 mu m), exhibiting higher SA, OC%, and lower Delta C-14(26+28+30FAs) values, reflect preferential transport of pre-aged, mineral soil-derived OC that is susceptible to repeated mobilization, as well as widespread dispersal in marginal seas. The latter, once buried in marine sediments, could account for the high burial efficiency of OCterr in the adjacent Bohai Se
机译：已经证明了流体动力学分类强烈影响沉积物运输期间有机碳（OC）的组成和年龄，在海洋环境中埋葬，但河流系统中的陆生物癌症的分类效果仍然很清楚。我们进行了来自下黄河，中国的悬浮颗粒样品的大小分馏，并在粒度分数中检查了粒度ob和特定生物标志物的块状分布和碳同位素（Delta c-13和delta c-14）组成的变化，以便探讨流体动力分类和选择性运输对有机质出口的影响。一般来说，16-32亩m和32-63亩m级分数促使大多数沉积物质量，同时大多数oc仍在16-32μm馏分中。超过80％的OC和N-脂肪酸（FAS）浓缩在<32μm的级分中。在尺寸级分之间发现了OC％，表面积（SA），δC-14（OC），N-Fas含量和化合物特异性C-13和C-14组合物的显着差异。特别值得注意的是长链（C-14）的δC-14值（即C-14年龄的增加）的逐渐减少（C-14），其粒径降低。一起携带，散装和分子特性意味着黄河中有两种不同类型的选择性八交通。较粗糙的颗粒（>32μm），其特征在于相对低的SA，OC％和DELTA C-14（OC）值，但是推断出C26 + 28 + 30 Fas的ΔC-14值，以反映组合基岩衍生的滴乳沉积物和新鲜血管 - 植物材料（例如，植物碎片）。相反，粒料颗粒（<32μm），表现出更高的SA，OC％和下δC-14（26 + 28 + 30Fas）值，反映预先变老的矿物土壤衍生的OC的优先运输重复动员，以及在边缘海洋中的广泛分散。后者曾经埋在海洋沉积物中，可以考虑邻近渤海SE的OcterR的高埋藏效率

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