Collaborative Research: Vegetation assimilation as a source of mercury in a salt marsh ecosystem and implications for soil and tidal water exposures

合作研究：植被同化作为盐沼生态系统中汞的来源以及对土壤和潮汐水暴露的影响

• 批准号: 2329941
• 负责人: Inke Forbrich
• 金额: $ 8.77万
• 依托单位: University of Toledo
• 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: 2023-01-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2329941&HistoricalAwards=false
• 关键词: Collaborative; Research; Vegetation; assimilation; source

The goal of this award is to determine the origin and fate of mercury in a salt marsh ecosystem in the Plum Island Sound of Massachusetts and potential export to near shore coastal oceans. Mercury is a potent neurotoxin and leading cause for fish consumption advisories in the U.S and across the world. Along the U.S. East Coast, salt marsh sparrows have shown harmful exposures to mercury with elevated blood levels posing risks for reproductive outputs. The origin of mercury in these salt marshes is largely unknown. Possible reasons for high mercury exposure are contributions from runoff from adjacent watersheds or atmospheric inputs from legacy industrial impacts. This award will study the role of direct plant uptake of atmospheric mercury by salt marsh plants as the mercury source for these salt marsh ecosystems. In this tidal system, an additional focus lies on the transfer of mercury to soils by the plants and with death of the plants its export to the coastal ocean. The award will train and involve graduate and undergraduate students in the research.This award aims to quantify mercury sinks and sources and their relationships to plant primary productivity, tissue turnover rates, and soil dynamics, in a salt marsh ecosystem where some of the highest biological mercury exposures have been reported. The first hypothesis is that that plant mercury assimilation is the dominant source of mercury in this estuary where salt marshes dominate in areal extent (50 to 90% of surface area). The second hypothesis is that vegetation assimilation of mercury is incorporated into soils upon plant senesce leading to high mercury accumulation in soils, which ultimately is mobilized to tidal water leading to net export of mercury from salt marshes to tidal water. This is analogue to the “outwelling” hypothesis for carbon that proposes that salt marshes produce an excess of autochthonous carbon over what is degraded and stored resulting in net export to the coastal ocean where it stimulates ocean net primary production. Proposed measurements include quantification of atmospheric mercury deposition inputs via deployment of a micrometeorological flux-gradient system that allows to measure ecosystem-level gaseous atmospheric mercury fluxes including plant mercury assimilation, along with detailed vegetation mercury dynamics and other deposition processes. Spatial transect sampling of tidal water from the ocean through the tidal water up to the freshwater headwater will be conducted and analyzed for mercury species (dissolved, particulate, methyl-mercury and mercury bound contained in wrack detritus) in order to assess lateral exchanges between salt marsh and tidal water. Finally, distribution patterns of total mercury and methylated mercury in salt marsh soils will be characterized to constrain processes — both natural and anthropogenic — that lead to mercury accumulation in these 2,500-to-3,500 year old soils.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.

该奖项的目的是确定马萨诸塞州梅子岛的盐沼泽生态系统中汞的起源和命运，并潜在出口到近海岸沿海海洋。汞是美国和世界各地鱼类消费咨询的潜在神经毒素和主要原因。沿着美国东海岸，盐玛Sh麻雀显示出有害的汞暴露，血液水平升高，构成了生殖产量的风险。这些盐沼中的汞的起源在很大程度上是未知的。高汞接触的可能原因是来自相邻流域或传统工业影响的大气投入的径流的贡献。该奖项将研究盐沼泽植物对大气汞的直接摄入作为这些盐沼泽生态系统的汞来源的作用。在这个潮汐系统中，另一个重点在于将汞转移到植物和植物死亡的土壤中。它出口到沿海海洋。该奖项将培训并涉及研究生和本科生参加研究。该奖项旨在量化盐沼泽生态系统中的汞汇集和来源及其关系，以培养汞汇集，组织周转率和土壤动力学，在盐沼泽生态系统中报道了一些最高的生物学暴露。第一个假设是，植物汞同化是盐沼在面积占主导地位的河口（占表面积的50％至90％）中的主要汞来源。第二个假设是，汞的植被同化在导致土壤中高汞积聚的植物传感器上掺入土壤中，最终动员到潮汐水，导致汞净出口从盐沼到潮汐水。这类似于碳的“外出”假设，该假设提议盐沼泽产生过量的自动碳，而不是降解和存储的碳，从而导致净出口到沿海海洋刺激海洋净产量产量。建议的测量包括通过部署微量学通量梯度系统来定量大气汞沉积输入，该系统允许测量生态系统级气态气态大气汞通量，包括植物汞同化，以及详细的植被汞动态和其他沉积过程。将对从海洋到潮汐水到淡水源头进行潮汐水的空间样品对汞物种进行并进行分析（溶解，尤其是包装中包含在包装中的甲基汞和汞），以评估盐沼和潮汐水之间的横向交换。最后，盐沼土壤中总汞和甲基化汞的分布模式将以约束过程（无论是自然和人为的）而导致在这2500至3,500年的土壤中积累的汞积累。这奖反映了NSF的法规任务，并通过使用基础的智力效果和广阔的范围来评估了NSF的法定任务，并被认为是诚实的。