US GEOTRACES GP17-OCE and GP17-ANT: Inorganic Carbon Cycling in the South Pacific and Southern Oceans by Direct Measurement

海洋吸收了化石燃料燃烧和其他人类活动产生的大约四分之一的二氧化碳，有助于减缓气候变化。众所周知，太平洋和南大洋吸收和储存了大量的人为二氧化碳，但关于二氧化碳的数量、可变性以及生物地球化学和生态影响的许多问题仍然没有答案。这项研究将通过分析两个GEOTRACES邮轮GP17-OCE和GP17-ANT上的总二氧化碳、总碱度和pH值样本，重点回答太平洋两个地区的一些问题。该项目将支持几名本科生研究人员，并为普通公众和K-12学生创建关于海洋酸化的教育模块。在南太平洋的GP17-OCE探险中，将通过将这次探险收集的数据与1991年、2005年和2014年在该线路上收集的数据进行比较，研究二氧化碳吸收和由此导致的pH值下降(称为海洋酸化)的亚十年尺度变化。一种扩展的多元线性回归技术将被用来区分自然变异性和人类诱导的变化。第二次探险名为GP17-ANT，覆盖了阿蒙森海，该地区之前几乎没有碳测量。该海域常年被几个季节性冰川覆盖(被海冰包围的开阔水域)，并表现出复杂的水循环，使其对全球碳循环的贡献不确定。这次考察收集的数据将检验几个假设，包括碳在该地区如何吸收、混合和再循环，冰川融化、海冰和生物生产力如何影响碳循环，并提供对照未来数据的基线测量，以确定该地区碳循环随时间的变化。这两次探险都将利用大量其他正在测量的参数，特别是铁和锌等微量金属，来研究碳和痕量金属的循环是如何通过PH相互联系的。这一奖项反映了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。

The oceans help to slow climate change by absorbing about a quarter of the carbon dioxide (CO2) produced by burning of fossil fuels and other human activities. The Pacific and Southern Oceans are known to take up and store significant amounts of anthropogenic CO2, but many questions regarding the amount, variability, and biogeochemical and ecological impacts remain unanswered. This research will focus on answering some of those questions in two areas of the Pacific by analyzing samples for total CO2, total alkalinity, and pH on two GEOTRACES cruises, GP17-OCE and GP17-ANT. The project will support several undergraduate student researchers and create educational modules on ocean acidification for general public and K-12 students.On the GP17-OCE expedition in the south Pacific, sub-decadal scale variability in the uptake of CO2 and resulting decrease in pH (termed ocean acidification) will be examined by comparing data collected on this expedition with data from prior occupations of the line in 1991, 2005 and 2014. An extended multilinear regression technique will be used to separate natural variability from human induced changes. The second expedition, GP17-ANT, covers the Amundsen Sea, an area with few prior carbon measurements. This sea is perennially ice-covered with several seasonal polynyas (areas of open water surrounded by sea ice) and exhibits complex water circulation making the contribution to the global carbon cycle uncertain. The data collected from this expedition will examine several hypotheses regarding how carbon is taken up, mixed, and recirculated in the region, how glacial ice melt, sea ice, and biological productivity influence the carbon cycle, and provide baseline measurements against future data to determine changes in the carbon cycle of the region over time. Both expeditions will leverage the myriad of other parameters being measured, particularly trace metals such as iron and zinc, to examine how cycling of carbon and trace metals are interlinked through pH.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.