Constraining the air-sea exchange of inorganic and methylated mercury with high resolution spatial and temporal measurements in the Sargasso Sea

通过马尾藻海的高分辨率空间和时间测量限制无机汞和甲基化汞的海气交换

• 批准号: 2319385
• 负责人: Robert Mason
• 金额: $ 68.07万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2319385&HistoricalAwards=false
• 关键词: Constraining; air; sea; exchange; inorganic

Mercury (Hg), a global pollutant, is released to the biosphere predominantly by human activity, through intentional use or as a trace element in coal, ores, and other products. These releases are exacerbated by climate change. Atmospheric Hg is predominantly elemental Hg (Hg0) - a gas with a relatively long residence time that can be transported globally to remote regions. After its transformation by atmospheric chemical reactions to ionic Hg, it is deposited to the ocean through precipitation, aerosol, and gaseous Hg deposition. In surface waters, ionic Hg is biologically and abiotically transformed into Hg0, which is then returned to the atmosphere via gas exchange. Overall, atmospheric deposition is the primary source, and Hg0 gas evasion is the primary loss mechanism for ocean Hg. The extent of air-sea exchange therefore alters the ocean Hg burden and impacts the global mercury cycle. Furthermore, the oceanic ionic Hg can be transformed into the more toxic and bioaccumulative methylmercury (MeHg), which concentrates in seafood sufficiently to be a global human health concern and impact wildlife. Understanding the factors that mediate the air-sea exchange of Hg is of vital importance for assessing the impact of humans and climate change on MeHg levels in seafood, and human health.The project, co-funded by the Chemical Oceanography Program and the Atmospheric Chemistry Program, will evaluate the concentrations of Hg in the surface ocean and atmosphere to examine the factors controlling their concentration and chemistry, and the magnitude of the Hg sources and sinks. There is limited data examining the seasonal and temporal variability of Hg speciation in the surface ocean at a specific location, and its air-sea exchange, and this is the study’s primary focus. Measurements will be made in the North Atlantic Ocean near Bermuda, during both monthly and specific Hg-focused cruises. Atmospheric samples will be collected as well at the atmospheric sampling station in Bermuda. During cruises, high resolution Hg speciation data in the atmosphere (gaseous and aerosol) and surface waters (gaseous elemental Hg, dissolved and particulate ionic Hg, MeHg and dimethylmercury) will be gathered to examine the sources of Hg and its transformations, and how this impacts the formation of MeHg. Additionally, measurements of Hg stable isotopes in atmospheric and water samples will be used to identify sources (e.g., geogenic or anthropogenic inputs) and delivery mechanisms of Hg to this region. This proposed research will further assess the importance of natural variability, human activity, and climate change on altering Hg and MeHg levels in the ocean, and in marine organisms consumed by humans.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.

汞 (Hg) 是一种全球污染物，主要通过人类活动、有意使用或作为煤炭、矿石和其他产品中的微量元素释放到生物圈中。大气中的汞主要是元素汞。 (Hg0) - 一种停留时间相对较长的气体，可在全球范围内输送到偏远地区，通过大气化学反应转化为离子汞后，通过降水、气溶胶和气态汞沉积到海洋中。在地表水中，离子态汞通过生物和非生物转化为Hg0，然后通过气体交换返回大气。总体而言，大气沉降是主要来源，而Hg0气体逃逸是海洋汞损失的主要机制。因此，海气交换改变了海洋汞负荷并影响全球汞循环。此外，海洋离子汞可以转化为毒性更强、生物累积性更强的甲基汞。 （甲基汞）在海鲜中的含量足以成为全球人类健康问题并影响野生动物，了解介导汞气海交换的因素对于评估人类和气候变化对海鲜中甲基汞水平的影响至关重要。该项目由化学海洋学计划和大气化学计划共同资助，将评估表层海洋和大气中的汞浓度，以研究控制其浓度和化学性质的因素，以及汞的大小来源和研究特定地点表层海洋中汞形态及其海气交换的数据有限，这是该研究的主要重点，将在百慕大附近的北大西洋进行测量。 ，在每月和特定的汞巡航期间，还将在百慕大的大气采样站收集大气（气态和气溶胶）和地表水中的高分辨率汞形态数据。将收集汞（气态元素汞、溶解的和颗粒离子汞、甲基汞和二甲基汞）来研究汞的来源及其转化，以及这如何影响甲基汞的形成。此外，还将测量大气和水样中的汞稳定同位素。用于确定该地区汞的来源（例如，地理或人为输入）和输送机制。这项拟议的研究将进一步评估自然变异、人类活动和气候变化的重要性。该奖项反映了 NSF 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。