Collaborative Research: How temporal changes in river discharge and storms affect the source and age distribution of sedimentary organic carbon across a river-dominated margin

大陆边缘是动态的区域，接受来自陆地和海洋来源的有机碳输入。一旦被密西西比河引入或固定在路易斯安那州的大陆架上，POC就会沿着大陆架被携带、分解、掩埋或运输到墨西哥湾更深的区域。根据沿海初级生产力估计和河流输入，密西西比河沿岸水域中只有20%-50%的有机碳实际上埋藏在路易斯安那州陆架沉积物中，其中40%来自陆地。因此，密西西比河交付的无法在陆架沉积物中计算的50-80%的碳的命运仍然是制定北美碳收支的关键问题。在这笔资金的资助下，PI提出了一种化合物特有的稳定和放射性碳同位素技术与生物标志物分布相结合的方法，以评估密西西比河三角洲陆架和斜坡中有机碳的命运和运输。这项研究的工作假设是，路易斯安那州陆架/斜坡上SOC的组成和年龄的季节性变化在很大程度上由陆源和海源有机碳的脉冲决定，这些脉冲发生在不同的时间段，受密西西比河流量和风暴能量的变化控制。

Continental margins are dynamic regions that receive inputs of organic carbon derived from both terrestrial and marine sources. Once introduced by the Mississippi or fixed on the Louisiana shelf, POC is carried along the shelf, decomposed, buried, or transported to deeper regions in the Gulf of Mexico. Based on coastal primary production estimates and riverine inputs, only 20-50% of the organic carbon in coastal waters off the Mississippi is actually buried in Louisiana shelf sediments, and 40% of that buried carbon is of terrestrial origin. Thus, the fate of 50-80% of the carbon fraction delivered by the Mississippi that cannot be accounted for in shelf sediments remains a key question in developing a North American carbon budget. Under this funding, the PIs propose a combined approach of compound-specific stable and radiocarbon isotopic techniques and biomarker distributions to evaluate fates and transport of organic carbon in the Mississippi River delta shelf and slope. The working hypothesis of this study is that seasonal changes in the composition and age of SOC across the Louisiana shelf/slope are largely determined by pulses in terrestrially- and marine-derived organic carbon which occur at distinct time periods controlled by changes in Mississippi River discharge and storm energy.