Importance of Riverine Discharge on the Benthic Flux of Alkalinity to Continental Margins

河流排放对大陆边缘底栖碱度通量的重要性

• 批准号: 1948914
• 负责人: Martial Taillefert
• 金额: $ 62.35万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1948914&HistoricalAwards=false
• 关键词: Importance; Riverine; Discharge; Benthic; Flux

Importance of Riverine Discharge on the Benthic Flux of Alkalinity to Continental MarginsOcean acidification is the process that lowers the pH of the ocean over time due to uptake of atmospheric carbon dioxide. This project investigates how chemical reactions in marine sediments exposed to high riverine sediment loads influence ocean acidification in coastal waters. Although we know that ocean acidification affects marine life and commercial fisheries in coastal waters, little is known about how acidification processes in the water column are influenced by reactions occurring in sediments on the sea floor. The role of large sediment deposits from rivers in these processes has also never been investigated. This study will be conducted in the Mississippi River and Gulf of Mexico. The Mississippi River transports a high sediment load to the continental shelf in the Gulf of Mexico and plays an important role in the economy of the southern coast of the United States. Results from this study will be useful to the oceanographic community for increasing understanding of ocean acidification processes in delta and shelf environments. It will also benefit decision makers interested in predicting the role of sediments on the nutrient -rich Louisiana shelf for discharge control purposes. This project also has an important educational component by training undergraduate, graduate, and postdoctoral students, providing experiences at sea for undergraduates, and conducting outreach activities with K-12 students.The geochemical and microbiological processes responsible for the transformation of particles deposited on the seafloor will be characterized near the Mississippi River mouth and along the nearby continental slope. The release of acids (CO2) and bases (alkalinity) from the sediment will be quantified using autonomous instruments deployed on the seafloor to determine whether sediments contribute to the acidity of the surrounding water column or instead provide bases to buffer the water column from atmospheric CO2 inputs. As the Mississippi River discharge during the later Winter and Spring provides much more sediment to the coastal zone compared to the rest of the year, research cruises will be taken twice a year to determine how seasonal variations in riverine discharge affect the release of acids and bases into the water column. Mathematical models will then be used to predict the effect of seasonal variations on acids or bases release to the water column. This study will therefore provide a quantitative understanding of the role of large sediment depositions to the seafloor on sediment geochemical and microbiological processes and their feedback to the overlying waters. Simultaneously, a large data set will be generated and used to calibrate mathematical models and better characterize benthic-pelagic interactions. Such efforts are needed to predict how continental margins respond to constantly increasing stress from anthropogenic activities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

河流排放对大陆边缘底栖碱度通量的重要性海洋酸化是由于吸收大气二氧化碳而随着时间的推移降低海洋 pH 值的过程。该项目研究暴露于高河流沉积物负荷的海洋沉积物中的化学反应如何影响沿海水域的海洋酸化。尽管我们知道海洋酸化会影响沿海水域的海洋生物和商业渔业，但人们对海底沉积物中发生的反应如何影响水体酸化过程却知之甚少。河流中大量沉积物在这些过程中的作用也从未被研究过。这项研究将在密西西比河和墨西哥湾进行。密西西比河将大量泥沙输送至墨西哥湾大陆架，在美国南部海岸的经济中发挥着重要作用。这项研究的结果将有助于海洋学界增进对三角洲和陆架环境中海洋酸化过程的了解。它还将使有兴趣预测沉积物在营养丰富的路易斯安那大陆架上的作用以控制排放的决策者受益。该项目还具有重要的教育组成部分，包括培训本科生、研究生和博士后，为本科生提供海上经验，以及与 K-12 学生开展外展活动。负责沉积在海底的颗粒转化的地球化学和微生物过程将在密西西比河口附近和附近的大陆坡上进行表征。沉积物中酸（CO2）和碱（碱度）的释放将使用部署在海底的自主仪器进行量化，以确定沉积物是否会导致周围水体的酸度，或者是否提供碱来缓冲水体免受大气二氧化碳输入的影响。由于与一年中其他时间相比，密西西比河在冬季末和春季期间的排放量为沿海地区提供了更多的沉积物，因此每年将进行两次研究巡航，以确定河流排放量的季节性变化如何影响酸和碱向水体中的释放。然后，数学模型将用于预测季节变化对向水体释放酸或碱的影响。因此，这项研究将定量了解海底大型沉积物沉积对沉积物地球化学和微生物过程的作用及其对上覆水域的反馈。同时，将生成大量数据集并用于校准数学模型并更好地表征底栖-中上层相互作用。需要做出这样的努力来预测大陆边缘如何应对人类活动不断增加的压力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。