Collaborative Research: The effects of terrestrial organic matter inputs on coastal mercury cycling, methylmercury production and bioaccumulation

合作研究：陆地有机物质输入对沿海汞循环、甲基汞产生和生物累积的影响

• 批准号: 2148407
• 负责人: Robert Mason
• 金额: $ 39.8万
• 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: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2148407&HistoricalAwards=false
• 关键词: Collaborative; Research; effects; terrestrial; organic

Climate change will influence the delivery of contaminants, organic matter, and nutrients from land to the coastal ocean. This is because higher rainfall and warming increase runoff from land to coastal waters. Runoff also influences coastal algal blooms. These changes are expected to alter the distribution of mercury in the water and impact its availability for biological uptake. Mercury is a potent toxin. Its uptake into the food web contaminates fish and seafood and affects human health. This project will study how organic matter delivered from land to coastal waters affects mercury concentrations in seawater and in the food webs of the Gulf of Maine. The Gulf of Maine is one of the largest and most important coastal fishing grounds in the United States. This project will measure the concentration and isotopes of mercury on samples collected from research cruises under different algal bloom conditions and river flows. Lab experiments will be used to study how land-derived organic matter affects mercury accumulation in plankton. The project will provide research experiences for four undergraduate students in a STEM field. Training will be provided to a PhD student and a postdoctoral fellow. Findings from the project will provide critical information about the effect of climate change on mercury levels in marine waters and food webs. This information is needed for achieving the goals of the Minamata Convention, a global treaty for reducing mercury emissions to the environment.This project will examine the effects of climate change on terrestrial organic matter and mercury concentrations in Gulf of Maine waters. Specifically, the scientists will study the complex and often competing processes that influence: 1) mercury cycling and distribution; 2) the formation of methylmercury; and 3) methylmercury uptake to microplankton. Terrestrial organic matter plays an important role in transferring mercury from watersheds to coastal and offshore waters. It also controls the formation of methylmercury in water by providing a microenvironment that promotes the methylation of mercury by microbes, which represents the first step for uptake of methylmercury into seafood. However, some plankton can directly use organic matter as a food source (so-called “mixotrophs”) and can bioaccumulate methylmercury during feeding. Mixotrophs can dominate microplankton assemblages in coastal waters at some times of the year, and previous studies have not explored the impact of this feeding mode on methylmercury uptake at the base of the food web. This project will study the effects of organic matter dynamics on mercury and methylmercury cycling and bioaccumulation through 1) field surveys and shipboard experiments in the Gulf of Maine, where delivery of terrestrial organic matter is increasing, and 2) through laboratory microcosm experiments using autotrophic and mixotrophic microplankton taxa under contrasting carbon acquisition modes and organic matter characteristics and concentrations. This work will also apply novel mercury and methylmercury-specific isotope analyses and measures of organic matter quality to increase understanding of mercury cycling in coastal environments. This research will fill important gaps in predicting the effects of environmental changes on marine methylmercury levels, providing critical information to mitigating mercury emissions and methylmercury exposures, and for predicting changes in mercury levels in seafood in the future.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.

气候变化将影响污染物、有机物和养分从陆地到沿海海洋的输送，因为降雨量增加和变暖增加从陆地到沿海水域的径流也会影响沿海藻华。汞在水中的分布及其对生物吸收的影响 汞是一种强效毒素，它被食物网吸收后会污染鱼类和海鲜，并影响人类健康。缅因湾海水和食物网中的汞浓度 缅因湾是美国最大和最重要的沿海渔场之一，该项目将测量研究中收集的样品中的汞浓度和同位素。实验室实验将用于研究陆地有机物如何影响浮游生物中的汞积累，该项目将为 STEM 领域的四名本科生提供研究经验。该项目的研究结果将提供有关气候变化对海洋水域和食物网中汞含量的影响的重要信息，这些信息是实现《水俣公约》这一全球减排条约的目标所必需的。该项目将研究气候变化对缅因湾水域陆地有机物和汞浓度的影响，具体而言，科学家将研究影响以下因素的复杂且经常相互竞争的过程：1)汞的循环和分布；2) 甲基汞的形成；以及 3) 微型浮游生物对甲基汞的吸收在汞从流域转移到沿海和近海水域方面发挥着重要作用。促进微生物对汞进行甲基化的微环境，这是海鲜吸收甲基汞的第一步。一些浮游生物可以直接利用有机物作为食物来源（所谓的“混合营养生物”），并且可以在摄食过程中生物富集甲基汞，混合营养生物可以在一年中的某些时候主导沿海水域的微型浮游生物群落，之前的研究尚未探讨其影响。这种进食模式对食物网底部甲基汞吸收的影响 该项目将研究有机物动态对汞和甲基汞循环的影响。通过以下方式进行生物富集：1）在缅因湾进行实地调查和船上实验，其中陆地有机物的输送量正在增加；2）通过在对比碳获取模式和有机物特征和浓度下使用自养和混合营养微型浮游生物类群进行实验室微观实验。该工作还将应用新型汞和甲基汞特定同位素分析和有机物质量测量，以增进对沿海环境中汞循环的了解。在预测环境变化对海洋甲基汞水平的影响、为减轻汞排放和甲基汞暴露以及预测未来海鲜中汞水平的变化提供关键信息方面填补了重要空白。该奖项反映了 NSF 的法定使命，并被认为是值得的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来获得支持。