Collaborative Research: Constraining the sources, ages and alteration of dissolved and particulate lipids in estuarine and coastal organic matter

碳14对溶解有机碳(DOC)和颗粒有机碳(POC)生化类别的研究结果表明，碳水化合物和蛋白质来自最近固定在有机物中的二氧化碳(即现代)，而脂肪部分是DOC和POC中最老的(约103-104年BP)成分。脂组分年龄较大被认为是由于有机物质来源、停留时间和/或反应性的差异。然而，需要更多的研究来了解脂肪组分的年龄及其对大洋DOC和POC平均年龄的贡献。为此，威廉和玛丽·弗吉尼亚海洋科学学院的一位科学家和她来自俄亥俄州立大学的合作者计划研究跨越特拉华湾及其邻近沿海水域陆地-海洋边界的亲脂有机物的来源(即陆源、海洋、自然、人为)、转化和命运。为了达到他们的目标，研究人员将对不同有机成分(即大量DOC和POC及其脂类成分)及其同位素(delta14C和del13C)特征随盐度的变化进行保守和非保守行为的地球化学评估。这将提供关于整个河口尺度上每个组成部分的总体平均输入和汇的信息。此外，DOC、POC和脂类成分的光化学反应和微生物活性将在与河口混合和停留时间相关的时间尺度上的受控孵化实验中进行评估。预计这项研究将为亲脂有机物如何影响河口和沿海水域DOC和POC的年龄、反应性和循环提供新的见解。就更广泛的影响而言，威廉和玛丽·弗吉尼亚海洋科学学院的科学家计划让里约热内卢埃斯特多大学的研究生参与该研究项目，从而建立美国和巴西科学家之间的合作。作为该项目的一部分，威廉和玛丽学院弗吉尼亚海洋科学研究所的一名研究生和俄亥俄州立大学的一名研究生将得到支持和培训。

Results from carbon-14 studies of biochemical classes of dissolved organic carbon (DOC) and particulate organic carbon (POC) have shown that carbohydrate and protein derive from carbon dioxide that has been recently fixed into organic matter (i.e., modern in age), whereas the lipid fraction is the most highly aged (~103-104 yrs BP) component of both DOC and POC. The older age of the lipid fraction is believed to be due to differences in organic matter sources, residence times, and/or reactivity. However, more studies are needed to understand the age of the lipid fraction and its contribution to the average age of oceanic DOC and POC. For this reason, a scientist from the College of William and Mary Virginia Institute of Marine Science and her collaborator from Ohio State University plan to examine the sources (i.e., terrigenous, marine, natural, anthropogenic), transformations, and fate of lipophilic organic matter across the land-ocean boundary of Delaware Bay and its adjacent coastal waters. To attain their goal, the researcher will carry out a geochemical evaluation of the conservative vs. non-conservative behavior of different organic constituents (i.e., bulk DOC and POC and their lipid components) and their isotopic (delta14C and del13C) signatures as a function of salinity. This will provide information on the overall mean inputs and sinks of each constituent on the scale of the entire estuary. In addition, the photochemical and microbial reactivity of DOC, POC and lipid components will be evaluated in controlled incubation experiments on timescales relevant to estuarine mixing and residence times.It is anticipated that this study will provide new insights on how the lipophilic organic matter contributes to the age, reactivity, and cycling of DOC and POC in estuarine and coastal waters.In terms of the broader impacts, at no cost to the project, the scientist from the College of William and Mary Virginia Institute of Marine Science plans to involve graduate students from the Universidade do Estado do Rio de Janeiro in the research project, thereby building a collaboration between U.S. and Brazilian scientists. One graduate student from the College of William and Mary Virginia Institute of Marine Science and one graduate student from Ohio State University would be supported and trained as part of this project.