Sources of organic matter in two contrasting tropical coastal environments: The Caribbean Sea and the eastern Pacific
Sources of organic matter in two contrasting tropical coastal environments: The Caribbean Sea and the eastern Pacific
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DOI：
10.1016/j.jsames.2019.102349
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发表时间：
2019-12
影响因子：
1.8
通讯作者：
C. Huguet;J.‐H. Kim;C. González‐Arango;V. Ramírez-Valencia;S. Kang;J. Gal;K. Shin
中科院分区：
文献类型：
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作者：
C. Huguet;J.‐H. Kim;C. González‐Arango;V. Ramírez-Valencia;S. Kang;J. Gal;K. Shin
在这项研究中，我们使用甘油二烷基甘油四醚(GDGTS)和正构烷烃类脂生物标志物的组合来评估哥伦比亚两个不同热带沿海环境中的有机质(OM)来源。在生产力较低的加勒比海和生产力较高的东太平洋之间存在着明显的差异，东太平洋的陆地贡献率较高，与河流输入密切相关。尽管较高的陆地植物衍生的正构烷烃可以作为风尘输送，但我们的结果表明，我们的样品主要来自河流。当观察GDGT的分支组成时，可以在大多数加勒比站和太平洋一些较沿海的站点发现原地生产，其#ringstetraindex值高于0.7。东太平洋的其余站点显示了与河流排放有关的土壤侵蚀的GDGTS输入，并沉积在海岸附近。以短链烷烃和裂解酚衡量的海洋产量在东太平洋也较高。看来，陆地输入将带来营养物质，以及OM，从而为自养和异养生物提供燃料，使东太平洋总体上更具生产力。我们还观察到来自岩石成因的有机质，尽管数量很少，特别是在位于主要港口附近的加勒比海沿岸地点。这项研究有助于提高对进入哥伦比亚沿海地区的OM输入、来源和运输机制的复杂混合的理解。目前的工作强调需要将气候、地质环境和水文学结合起来，以充分了解区域范围内的碳循环。
In this study, we evaluate sources of organic matter (OM) in two contrasting tropical coastal environments in Colombia, using a combination of glycerol dialkyl glycerol tetraethers (GDGTs) andn-alkane lipid biomarkers. A clear difference between the less productive Caribbean Sea and the more productive eastern Pacific is observed, with higher terrestrial contributions into the eastern Pacific strongly associated with riverine inputs. Although higher land plant-derivedn-alkanes can be transported as eolian dust, our results suggest mainly riverine sources for our samples. When looking at the branched GDGT compositions, in situ production could be identified in most Caribbean stations and some of the more coastal sites in the Pacific with #ringstetraindex values of above 0.7. The remaining stations in the eastern Pacific display soil-eroded GDGTs inputs associated with river discharges and deposited in the proximity of the coast. Marine production as measured by short chainn-alkanes and crenarchaeol are also higher in the eastern Pacific. It appears that the terrestrial inputs would bring nutrients as well as OM fueling both auto- and heterotrophs making the eastern Pacific overall more productive. We also observe OM of petrogenic origin, albeit in a low amount, especially in coastal Caribbean sites located near main harbors. This study helps improve the understanding of the complex mixture of OM inputs, origins and transport mechanisms into Colombian coastal areas. The present work emphasizes the need to integrate climate, geological setting and hydrology to fully understand the carbon cycle at a regional scale.