Collaborative Research: GEOTRACES Pacific Section: Mercury Speciation Along a Zonal Section in the Eastern Tropical South Pacific

来自莱特州立大学和伍兹霍尔海洋研究所的科学家将参加2013年前往东热带南太平洋(ETSP)的GEOTRACES邮轮。在从秘鲁到塔希提岛的这一断面上采集的海水样本将分析总汞(Hg)、一甲基汞(CH3)、二甲基汞((CH3)2Hg)和元素汞(Hg0)，以构建高分辨率的垂直和水平剖面。除了过滤后的海水样本，科学家们还将分析悬浮颗粒中的总汞和CH3汞，以及雨水和气溶胶样本中的汞物种，以及半胱氨酸和谷胱甘肽等溶解和颗粒硫醇。邮轮航道从秘鲁附近的上升流区域延伸到广阔的氧气最小区域(OMZ)，然后是东太平洋隆起的热液喷口区域，最后进入塔希提岛附近的高度贫营养化水域。这些不同的海洋学特征将使研究人员能够确定它们对海洋中汞的输入和循环的影响。具体地说，他们计划评估(1)秘鲁近海大陆边缘是否是汞、CH3汞和(CH3)2HG的重要来源；(2)OMZ是海洋中甲基化汞水平最高的地区；(3)热液系统是总汞和甲基化汞的重要来源；(4)沿这一轨道的生产力巨大梯度影响了这种元素的垂直分布、生物有效性和形态形成。就更广泛的影响而言，这项研究可能有助于了解海洋中甲基汞的来源，甲基汞在鱼类中生物积累，对食用海鲜的人构成危害。为了改善科学教育，这位来自莱特州立大学的倡导者和他的研究生计划让代顿地区贝尔布鲁克中学的一个七年级学生通过课堂访问、博客和在邮轮期间与他们互动的方式，参与他们在海上的研究经历。莱特州立大学的一名研究生和一名本科生将作为该项目的一部分得到支持和培训。

Scientists from Wright State University and Woods Hole Oceanographic Institution will participate in the 2013 GEOTRACES cruise to the Eastern Tropical South Pacific (ETSP). Seawater samples collected during this transect from Peru to Tahiti will be analyzed for total mercury (Hg), monomethylmercury (CH3Hg+), dimethylmercury ((CH3)2Hg), and elemental Hg (Hg0) to construct high-resolution vertical and horizontal sections. In addition to filtered seawater samples, the scientists will also analyze suspended particles for total Hg and CH3Hg+, as well as rain and aerosol samples for Hg species and dissolved and particulate thiols, such as cysteine and glutathione. The cruise track extends from the upwelling region off Peru, to an expansive oxygen minimum zone (OMZ), followed by the hydrothermal vent fields of the East Pacific Rise, and finally into the highly oligotrophic waters near Tahiti. These different oceanographic features will allow the researchers to determine their influence on the inputs and cycling of Hg in the ocean. Specifically, they plan to assess whether (1) continental margins off Peru are a significant source of Hg, CH3Hg+, and (CH3)2Hg; (2) the OMZ sustains the highest levels of methylated Hg in the ocean; (3) hydrothermal systems are important sources of total and methylated Hg; and (4) the large gradient in productivity along this track impact the vertical distribution of this element, its bioavailability, and its speciation. In terms of broader impacts, this research may have societal benefits in helping to understand the source of methylmercury in the ocean, which bioaccumulates in fish and poses a hazard to those who eat seafood. In an effort to improve science education, the proponent from Wright State University and his graduate student plan to involve a class of 7th graders at Bellbrook Middle School in the Dayton area in their research experiences at sea via classroom visits, a blog, and interacting with them during the cruise. One graduate student and one undergraduate student from Wright State University would be supported and trained as part of this project.