Rivers and wetlands are a major source of terrestrial derived carbon for coastal ocean margins. This results in a net loss of terrestrial carbon into the shelf water and their subsequent transport to interior ocean basin. This study investigates the transport of dissolved inorganic carbon (DIC) in the surface‐mixed layer of Louisiana Shelf in northern Gulf of Mexico (nGOM) adjacent to the Wax Lake Delta (WLD) and Barataria Bay (BB), which represent contrasting net land gain and net land loss areas in this region. DIC samples were collected, in conjunction with short‐lived radium isotopes ²²⁴Ra (t_1/2 = 3.66 days) and ²²³Ra (t_1/2 = 11.43 days) samples during June and September 2019, to quantify shelf transport of DIC in the surface‐mixed layer during period of high and low river flow, respectively. Radium distribution implied shelf mixing rates of 140–6,759 and 63–2,724 m² s⁻¹ for WLD and BB regions, respectively, with more than tenfold decrease in rates between the two seasons. Net shelf transport of DIC was found to be highest for the WLD region in June, highlighting the importance of freshwater discharge in exporting DIC. An upscaling of our study for the entire Louisiana Shelf indicates that 1.54–20.19 × 10⁹ mol C d⁻¹ transported in June 2019 and 0.34–8.12 × 10⁹ mol C d⁻¹ in the form of DIC was exported across the shallow region of the shelf during high and low river flow seasons, representing an important source of DIC to the NGOM.

中文翻译：

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墨西哥北部海湾路易斯安那州陆架表层混合层中的溶解无机碳迁移

河流和湿地是沿海海洋边缘陆地衍生碳的主要来源。这导致陆地碳净损失到架子水中，并随后被运输到内部海洋盆地。这项研究调查了墨西哥湾北部（nGOM）路易斯安那州陆架的表层混合层中与蜡质三角洲（Wax Lake Delta）和巴拉塔里亚湾（Barataria Bay）（BB）相邻的溶解性无机碳（DIC）的运输情况该地区的土地获取和净土地流失面积。收集了DIC样品以及短命镭同位素²²⁴ Ra（t _1/2  = 3.66天）和²²³ Ra（t _1/2 = 11.43天）在2019年6月和9月期间进行采样，以分别量化在河流高流量和低流量期间DIC在表面混合层中的架子运输。镭的分布意味着WLD和BB地区的架子混合速率分别为140–6,759和63–2,724 m ²  s ^-1，两个季节之间的混合速率降低了十倍以上。发现6月份WLD地区DIC的净架子运输量最高，这突出了淡水排放在DIC出口中的重要性。我们的整个路易斯安那货架研究的升尺度表示1.54-20.19×10 ⁹ 摩尔C ^ d ^-1输送在2019年6月和0.34-8.12×10 ⁹ 摩尔C ^ d ^-1 DIC形式的DIC在高河流量和低河流量季节出口到架子的浅水区，代表了NGOM的DIC的重要来源。