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首页> 外文OA文献 >Linking lithology and land use to sources of dissolved and particulate organic matter in headwaters of a temperate, passive-margin river system
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Linking lithology and land use to sources of dissolved and particulate organic matter in headwaters of a temperate, passive-margin river system

机译：将岩性和土地利用与温带被动边缘河流系统的源头中溶解和颗粒有机物的来源联系起来

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A number of rivers have been found to transport highly aged organic matter [OM]; however, the sources of this aged material remain a matter of debate. One potential source may be erosion and weathering of headwater lithologies rich in ancient sedimentary OM. In this study, waters, suspended particulates, streambed sediments, rocks and soils from fourteen small headwater watersheds of a mid-size, temperate, passive margin river were sampled and characterized by Δ14C, δ13C, and POC/TPN ratios to identify sources of particulate and dissolved OM delivered to the river mainstem. These headwater sites encompass a range in lithology (OM-rich shales, OM-lean carbonate/mudstone facies, and OM-free crystalline rocks) and land use types (forested and agricultural), and allow investigation of the influence of agriculture and bedrock types on stream OM characteristics. Streams draining large areas of both agricultural land use and OM-rich lithology contain particulate OM [POM] that is more 14C-depleted than streams draining forested, shale-free watersheds. However, this is not sufficient to account for the significantly lower Δ14C-POC measured in the river mainstem. Dissolved OM [DOM] Δ14C are in all cases enriched compared to POM from the same stream, but are otherwise highly variable and unrelated to either land use or lithology. POC/TPN ratios were likewise highly variable. POC and DOC δ13C signatures were similar across all watersheds. Based on isotope mass balance, 14C-free fossil OM sources contribute 0–12% of total stream POM. Although these results do not unequivocally separate the influences of land use and lithology, watershed coverage by shale and agriculture are both important controls on stream Δ14C-POC. Thus export of aged, particle-associated OM may be a feature of river systems along both passive and active continental margins.
机译：已经发现许多河流运输着高度老化的有机物[OM]。但是，这种陈旧材料的来源仍存在争议。一种潜在的来源可能是富含古代沉积有机质的源头岩性的侵蚀和风化。在这项研究中，对中温带被动边缘河的14个小上游水域的水，悬浮颗粒，河床沉积物，岩石和土壤进行了采样，并用Δ14C，δ13C和POC / TPN比进行了表征，以识别颗粒物来源。溶解的OM输送到河流干线。这些上游源头涵盖了一系列的岩性（富含OM的页岩，富含OM的碳酸盐/泥岩相和不含OM的结晶岩）和土地利用类型（森林和农业），并可以研究农业和基岩类型的影响流OM特性。排放大面积农业土地利用和富含OM的岩性的河流所含的OM [POM]颗粒比排放有森林，无页岩流域的河流要多消耗14C。然而，这不足以说明在河流主干中测得的Δ14C-POC明显较低。与来自同一溪流的POM相比，溶解的OM [DOM]Δ14C在所有情况下都富集，但其他方面变化很大，并且与土地利用或岩性无关。 POC / TPN比率同样变化很大。在所有流域中，POC和DOCδ13C签名均相似。根据同位素质量平衡，无14C的化石OM源占总物流POM的0–12％。尽管这些结果并没有明确区分土地利用和岩性的影响，但页岩和农业的流域覆盖都是对水流Δ14C-POC的重要控制。因此，老化的，与颗粒相关的有机质的出口可能是被动大陆边缘和主动大陆边缘的河流系统的特征。

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