Ocean Acidification: Effect on the Availability of Divalent Trace Metals to Phytoplankton

海洋酸化：对浮游植物二价微量金属有效性的影响

• 批准号: 1315200
• 负责人: Francois Morel
• 金额: $ 49.44万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1315200&HistoricalAwards=false
• 关键词: Ocean; Acidification; Effect; Availability; Divalent

The ongoing changes in seawater chemistry caused by the dissolution of anthropogenic CO2 into surface seawater will affect the growth of phytoplankton and, hence, the functioning of marine food webs. One effect of the acidification (lowering of pH) caused by the increasing CO2 is a change in the chemical speciation and bioavailability of essential trace metals. Recent work with natural seawater samples has shown an unexpected result: a decrease at low pH in the bioavailability of zinc (Zn), a metal that plays key enzymatic roles in phytoplankton. Zinc, like other essential metals, is known to be bound to organic complexing agents in surface seawater. Acidification is expected to decrease the extent of Zn complexation and thus augment its availability to phytoplankton. Such increase in Zn biovailability is indeed seen upon acidification of laboratory media in which Zn is bound to a known complexing agent.In this project, a research team at Princeton University will test whether the paradoxical decrease in Zn biovailabilty seen in acidified samples of natural seawater is explained by a shift of Zn from weak and bioavailable organic complexes to strong unavailable complexes. Proof of principle for such a "two-ligand mechanism" has been obtained in laboratory systems and is generalizable in principle to other bio-useful trace metals such as manganese, cobalt, nickel copper and cadmium. The experiments will involve parallel chemical and biological experiments with natural surface seawater samples at different pHs: (i) electrochemical measurements of Zn and Cd complexation by weak and strong ligands, and ( ii) Zn and Cd uptake experiments with model phytoplankton species and natural populations. Broader impacts: This project is directly relevant to an issue of great concern to society and will further our understanding of the possible ecological effects of global ocean acidification, an ineluctable consequence of the ongoing increase in atmospheric CO2. It will also augment our understanding of the processes that control the bioavailability of essential trace metals to marine phytoplankton. The results of the research are thus expected to generate wide interest and some will likely be published in journals with broad dissemination and high impact. They will be also incorporated into two of the courses taught by the Principal Investigator at the undergraduate and graduate levels and in a "Science day" event at a local elementary school.

人为CO2溶解到表层海水中所引起的海水化学的持续变化将影响浮游植物的生长，从而影响海洋食物网的功能。 二氧化碳增加引起的酸化（pH值降低）的一个影响是基本微量金属的化学形态和生物利用度的变化。 最近对天然海水样品的研究显示了一个意想不到的结果：在低pH值下锌（Zn）的生物利用度降低，锌是一种在浮游植物中发挥关键酶作用的金属。 锌与其他必需金属一样，已知在表层海水中与有机络合剂结合。 酸化预计将减少锌络合的程度，从而增加其对浮游植物的可用性。 在实验室介质中，Zn与一种已知的络合剂结合，酸化后确实可以看到Zn生物有效性的增加。在该项目中，普林斯顿大学的一个研究小组将测试天然海水酸化样品中Zn生物有效性的反常下降是否可以解释为Zn从弱的和生物可利用的有机络合物转移到强的不可利用的络合物。 这种“双配体机制”的原理证明已经在实验室系统中获得，并且原则上可推广到其他生物有用的痕量金属，如锰、钴、镍、铜和镉。 这些实验将涉及在不同pH值下对天然表层海水样品进行平行的化学和生物实验：（一）通过弱配体和强配体对锌和镉络合作用进行电化学测量，（二）对模式浮游植物物种和自然种群进行锌和镉吸收实验。更广泛的影响：该项目直接关系到社会极为关切的一个问题，并将增进我们对全球海洋酸化可能产生的生态影响的理解，这是大气二氧化碳持续增加的一个不可避免的后果。 它还将增加我们对控制海洋浮游植物必需微量金属生物利用度的过程的理解。 因此，预计研究结果将引起广泛的兴趣，其中一些可能会发表在传播广泛和影响深远的期刊上。它们还将被纳入主要研究员在本科生和研究生一级教授的两门课程以及当地一所小学的“科学日”活动。