Arctic Ocean redox history and Hg cycling using redox-sensitive trace metals and Hg isotopes: the influence of sea ice

该奖项由2009年《美国复苏和再投资法案》(公法111-5)资助。调查人员将测量以前采集的北极沉积物岩心中的汞(Hg)浓度、汞同位素和一系列痕量金属，以增加对北冰洋古海洋学条件的了解，并全面了解汞循环，特别是在人类干扰汞循环之前。北极沉积物中汞的丰度和同位素组成可能对海冰覆盖、生物生产力和汞来源变化等过程敏感(并因此记录变化)。在研究过程中可以解决的问题包括：1)更新世-全新世北冰洋的汞同位素组成是什么？2)汞同位素能否用于推断北冰洋的不同汞来源？3)汞同位素能否用于量化更新世-全新世北冰洋海冰的消长程度？也就是说，汞同位素能否被用作海冰的替代物？4)汞同位素系统对北极气候和冰量变化过程中有机生产力的变化敏感吗？5)对古代记录的汞同位素研究能否帮助预测未来无冰(夏季)北极环境中汞循环的变化？6)通过研究北极独特环境中的汞同位素所获得的知识能否应用于全球海洋生产力和环流研究？这项工作对理解汞的地球化学循环具有潜在的影响。汞是一种重要的神经毒素。它还有望提高我们破译北极古气候的能力。一名研究生和三名本科生研究实习生将得到拟议研究的支持。

This award is funded under the American Recovery and Reinvestment Act of 2009(Public Law 111-5).The investigators will measure mercury (Hg) concentrations, mercury isotopes, and a suite of trace metals in previously-collected Arctic sediment cores in order to increase understanding of paleoceanographic conditions in the Arctic Ocean as well as overall understanding of mercury cycling, particularly prior to the interference of humans with the mercury cycle. The abundance and isotopic composition of mercury in Arctic sediments may be sensitive to (and thus record changes in) such processes as sea ice cover, biological productivity, and changing sources of mercury. Questions that can be addressed over the course of this research include:1)What is the Hg isotopic composition of the Pleistocene-Holocene Arctic Ocean?2)Can Hg isotopes be used to infer different Hg sources to the Arctic Ocean?3)Can Hg isotopes be used to quantify extent of sea ice growth and retreat in the Pleistocene-Holocene Arctic? That is, can Hg isotopes by used as a proxy for sea ice?4)Is the Hg isotopic system sensitive to changes in organic productivity during shifts in Arctic climate and ice volume?5)Can Hg isotopic investigations of the ancient record help predict changes in the Hg cycle during an ice-free (summer) Arctic environment of the future?6)Can knowledge gained by studying Hg isotopes in the unique environment of the Arctic be applied globally to ocean productivity and circulation studies?This work has potential impacts in understanding the geochemical cycling of mercury, an important neurotoxin. It also promises to improve our ability to decipher Arctic paleoclimate. One graduate student and three undergraduate research interns would be supported by the proposed research.