MCA: Developing a Paleorecord of Hg in Long-Lived Mollusks from the Gulf of Maine

汞(Hg)污染是一个严重的环境问题，影响生态系统和人类健康，人类接触的大部分来自海鱼消费。气候变化和自然气候变异性对海洋生态系统中汞的迁移和生物积累的影响还没有完全了解。这种了解对于制定目标和评估限制海洋生态系统汞污染和人类暴露的政策努力的进展情况至关重要。这项研究试图建立一个大约1000年来保存在从缅因湾收集的蛤壳中的汞的记录，缅因湾是世界上变暖最快的地区之一。与树木年轮一样，蛤壳具有可以精确确定年代的层，并有可能保存高分辨率的信号，这些信号反映了汞浓度过去的变化和生物群的积累。重要的是，这一汞记录可以与保存在蛤壳中的其他类型的气候代理信息配对，提供关于这种生物中的海洋汞如何随着气候变化而变化的详细信息。这一记录将为校准和改进预测政策和气候变化对海洋生态系统从几个世纪以来的汞污染中恢复的影响的模型提供特别有用的数据集。其他更广泛的影响包括在以本科生为主的机构(格林内尔学院)和大型公立研究型大学(爱荷华州立大学)的研究人员之间建立新的区域科学伙伴关系，以及本科生研究的新机会。将从缅因湾沿海地区收集北极软体动物样本，并将贝壳汞浓度与水、沉积物和生物群总汞和甲基汞(MeHg)浓度进行比较。这些比较将使研究人员能够评估贝壳汞是否是环境汞和甲基汞生物积累的可靠替代品，并评估同时代贝壳样品的重现性。然后，将根据高分辨率测量贝壳汞的基础上，建立缅因湾汞的总年表，该贝壳档案跨越上个千年，这一时期跨越了气候和海洋环流的重大变化以及当地和全球来源汞排放的大幅增加。这一记录可以直接与现有的和新的古气候替代记录进行比较，包括现有的氧稳定同位素记录和新测量的微量元素记录(巴和锰)。这项工作的结果应该能够确定汞生物积累对自然气候变异性的敏感性，并评估用于预测不同气候变化情景下海洋生物群未来汞轨迹的生物地球化学-气候耦合模型。该项目由地球科学地球生物学和低温地球化学项目部、海洋科学海洋地质和地球物理项目部和既定的激励竞争研究计划(EPSCoR)共同资助。该奖项反映了NSF的法定使命，并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，被认为值得支持。

Mercury (Hg) contamination is a serious environmental problem that affects ecosystems and human health, with most of human exposure coming from marine fish consumption. The impact of climate change and natural climate variability on the movement and bioaccumulation of Hg in marine ecosystems is not fully understood. Such understanding is vital to setting targets and assessing the progress of policy efforts to limit Hg contamination of marine ecosystems and human exposure. This research seeks to develop an approximately 1000-year record of Hg preserved in clam shells collected from the Gulf of Maine, one of the most rapidly warming regions of the world’s oceans. Like tree rings, clam shells possess layers that can be precisely dated and have potential to preserve highly resolved signals of past variation in Hg concentrations and accumulation by biota. Importantly, this Hg record can be paired with other kinds of climate proxy information preserved in the clam shells, giving detailed information about how marine Hg in this organism changes in response to a changing climate. This record will provide an especially useful dataset for calibrating and improving models for predicting the effects of policy and climate change on the recovery of marine ecosystems from centuries of Hg pollution. Other broader impacts include development of a new regional scientific partnership between researchers at a predominantly undergraduate institution (Grinnell College) and a large public research university (Iowa State University) and new opportunities for undergraduate research.Samples of the mollusk Arctica islandica will be collected from coastal locations in the Gulf of Maine and shell Hg concentrations compared to water, sediment, and biota concentrations of total Hg and methylmercury (MeHg). These comparisons will permit the researchers to evaluate whether shell Hg is a robust proxy of environmental Hg and MeHg bioaccumulation and to assess reproducibility of coeval shell samples. A master chronology of Hg in Gulf of Maine will then be constructed based on measuring shell Hg at high-resolution for an existing cross-dated A. islandica shell archive spanning the last millennium, a period which spans significant climatic and ocean circulation changes and large increases in Hg emissions from local and global sources. This record can be directly compared to existing and novel paleoclimate proxy records, including existing oxygen stable isotope records and newly measured trace-element records (Ba and Mn). Results of this work should permit determination of the sensitivity of Hg bioaccumulation to natural climate variability and evaluation of coupled biogeochemical-climate models used for predicting trajectory of future Hg in marine biota under various climate change scenarios. This project is jointly funded by the Division of Earth Sciences Geobiology and Low-Temperature Geochemistry Program, the Division of Ocean Sciences Marine Geology and Geophysics Program and the Established Program to Stimulate Competitive Research (EPSCoR).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.