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。这是因为降雨量增加和变暖增加了从陆地到沿海水域的径流。径流也会影响沿海藻类的繁殖。这些变化预计将改变水中汞的分布，并影响其生物吸收的可用性。汞是一种强效毒素。它进入食物网会污染鱼类和海鲜并影响人类健康。该项目将研究从陆地输送到沿海水域的有机物如何影响海水和缅因湾食物网中的汞浓度。缅因湾是美国最大、最重要的沿海渔场之一。该项目将测量在不同藻华条件和河流流量下从研究巡航中收集的样品中汞的浓度和同位素。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。该项目将为四名本科生提供 STEM 领域的研究经验。将为博士生和博士后提供培训。该项目的研究结果将提供有关气候变化对海水和食物网中汞含量影响的重要信息。这些信息对于实现《水俣公约》的目标是必要的，水俣公约是一项减少环境汞排放的全球条约。该项目将研究气候变化对陆地有机物和缅因湾水域汞浓度的影响。具体来说，科学家们将研究影响以下因素的复杂且经常相互竞争的过程：1）汞循环和分布； 2）甲基汞的形成； 3) 微型浮游生物对甲基汞的吸收。陆地有机质在汞从流域转移到沿海和近海水域方面发挥着重要作用。它还通过提供促进微生物甲基化汞的微环境来控制水中甲基汞的形成，这是海鲜吸收甲基汞的第一步。然而，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。混合营养生物在一年中的某些时候可以主导沿海水域的微型浮游生物群落，之前的研究尚未探讨这种摄食模式对食物网底部甲基汞吸收的影响。该项目将通过以下方式研究有机物动力学对汞和甲基汞循环和生物富集的影响：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。 浓度。这项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。这项研究将填补预测环境变化对海洋甲基汞水平影响的重要空白，为减轻汞排放和甲基汞暴露提供关键信息，并预测未来海鲜中汞水平的变化。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。