Abrupt Ocean Acidification Events

海洋突然酸化事件

• 批准号: NE/H017518/1
• 负责人: Paul Pearson
• 金额: $ 49.79万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH017518%2F1
• 关键词: Abrupt; Ocean; Acidification; Events

Global warming is not the only consequence of rising levels of carbon dioxide in the atmosphere. Because CO2 is an acidic gas, and a high proportion of the human emissions eventually get mixed into the ocean, the oceans are becoming more acidic. As humanity aims to limit emissions by setting targets it is vital to predict what effect such acidification will have on marine life and chemical processes in the ocean. Experimental work suggests that plankton that make their shells out of calcium carbonate ('calcify') may be particularly affected. One way to predict the future is to study similar events in the geological past. Millions of years ago atmospheric carbon dioxide levels were higher than they are at present, causing ocean acidification. The geological record contains a number of abrupt events where acidification increased rapidly in response to natural emissions. These events are of different sizes so can be viewed as a set of 'natural experiments' in ocean acidification on a global scale. So far the amount of acidification during these events has not been measured adequately and details of the way marine life was affected have not been fully investigated. This proposal aims to rectify this. At present we are faced with an apparent paradox. Geological evidence indicates that some of the past acidification events were likely quite severe, especially the biggest of all which defines the boundary between the Paleocene and Eocene epochs. Although there were some extinctions, migrations and other effects, overall there was not a very great response in the plankton. This includes calcifying plankton like coccolithophorids and foraminifera. Hence it may be that these groups are more resilient to pH changes than laboratory experiments suggest. Possibly the rate of change is the most important factor, and the plankton can adapt within limits. Alternatively we may be wrong about the degree of acidification that occurred in the surface waters where these organisms live. These uncertainties must be resolved as a matter of urgency. Acidity changes in the past ocean leave a chemical fingerprint in the shells of one group of calcifying organism, the foraminifera, some of which live as plankton at different depths in the water column and some on the sea floor. This fingerprint is the ratio of isotopes of boron incorporated into the shell. By measuring this we can calculate the acidity of the water in which the foraminifera lived. One potential problem is that the overall ratio of boron isotopes in seawater has changed through time, although there are several ways in which we can constrain this, for instance by examining acidity profiles based on foraminifera that live at different water depth. The proposal will investigate a variety of geological records from the deep sea and the margins of the oceans. Unique among these is a borehole through marine sediments in Tanzania. Preliminary work revealed the presence of a highly expanded (thick) record of the onset of the Paleocene / Eocene event. Crucially the foraminifera are excellently preserved. In 2008 this site was redrilled using superior drilling technology and the excellent cores currently await detailed sampling and study. This record will enable us to define the rate and magnitude of pH change as well as study the effects on the extraordinarily diverse communities of well-preserved plankton at that site. Other sites provide a set of events of various magnitudes. By assessing the degree of acidification and the ecological responses, we can calibrate the effects. The task is not easy however; factors other than acidity were involved, and the 'background' level of acidity before and after these events was different from the modern ocean. Only by integrating the results of this study with ongoing experimental work by other groups can we aim to provide more accurate predictions of what might happen under different emissions scenarios in the future.

全球变暖并不是大气中二氧化碳水平上升的唯一结果。由于二氧化碳是一种酸性气体，并且大部分人类排放最终被混合到海洋中，因此海洋变得越来越酸性。由于人类旨在通过设定目标来限制排放，因此至关重要的是，预测这种酸化对海洋生物和化学过程的影响将是什么影响。实验性工作表明，将其壳从碳酸钙（钙化）中弹出的浮游生物可能受到特别影响。预测未来的一种方法是研究地质过去的类似事件。数百万年前，大气二氧化碳水平高于目前，导致海洋酸化。地质记录包含许多突然的事件，其中酸化因自然排放而迅速增加。这些事件具有不同的大小，因此可以将其视为全球范围内海洋酸化中的一组“自然实验”。到目前为止，在这些事件期间的酸化量尚未得到充分测量，并且尚未对海洋生物的影响细节进行全面研究。该建议旨在纠正这一点。目前，我们面临着明显的悖论。地质证据表明，过去的某些酸化事件可能很严重，尤其是定义古新世和始新世时期边界的所有最大的事件。尽管存在一些灭绝，迁移和其他影响，但总体而言，浮游生物没有很好的反应。这包括钙化浮游生物等浮游生物和有孔虫。因此，这些组可能比实验室实验所建议的更适合pH变化。变化速率可能是最重要的因素，浮游生物可以在限制内适应。另外，我们可能在这些生物所居住的地表水域中发生的酸化程度可能是错误的。这些不确定性必须在紧急情况下解决。过去海洋中的酸度变化在一组钙化生物体的壳中留下了化学指纹，其中一些有孔虫在水柱的不同深度和海底的不同深度处为浮游生物。该指纹是掺入壳中的硼的同位素的比率。通过测量这一点，我们可以计算有孔虫寿命的水的酸度。一个潜在的问题是，随着时间的流逝，海水中的硼同位素的总比率发生了变化，尽管我们可以通过几种方式来限制这一点，例如，基于生活在不同水深的有孔虫基于有孔虫的酸度剖面。该提议将调查来自深海和海洋边缘的各种地质​​记录。其中独有的是坦桑尼亚海洋沉积物的钻孔。初步工作揭示了古新世 /始新世事件发作的高度扩展（厚）记录。至关重要的是，有孔虫得到了很好的保存。 2008年，该站点使用出色的钻井技术重新填充，目前正在等待详细的采样和研究。该记录将使我们能够定义pH变化的速率和幅度，并研究对该地点保存完好的浮游生物群体多样化社区的影响。其他站点提供了一组各种大小的事件。通过评估酸化程度和生态反应，我们可以校准效果。但是，任务并不容易；除了酸度以外，其他因素涉及这些事件之前和之后的酸度水平与现代海洋不同。只有通过将这项研究的结果与其他小组的持续实验工作相结合，我们才能为将来的不同排放情况下可能发生的情况提供更准确的预测。

项目成果

Constraining the evolution of Neogene ocean carbonate chemistry using the boron isotope pH proxy

• DOI: 10.1016/j.epsl.2018.06.017
• 发表时间: 2018-09
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: S. Sosdian;R. Greenop;M. Hain;G. Foster;P. Pearson;C. Lear

Public understanding in Great Britain of ocean acidification

• DOI: 10.1038/nclimate3005
• 发表时间: 2016-08-01
• 期刊: NATURE CLIMATE CHANGE
• 影响因子: 30.7
• 作者: Capstick, Stuart B.;Pidgeon, Nick F.;Pearson, Paul N.
• 通讯作者: Pearson, Paul N.

Layering in the Paleocene/Eocene boundary of the Millville core is drilling disturbance.

Millville 岩心古新世/始新世边界的分层是钻井干扰。

• DOI: 10.1073/pnas.1322077111
• 发表时间: 2014
• 期刊: Proceedings of the National Academy of Sciences of the United States of America
• 影响因子: 11.1
• 作者: Pearson PN

Extreme warming of tropical waters during the Paleocene-Eocene Thermal Maximum

• DOI: 10.1130/g35637.1
• 发表时间: 2014-09-01
• 期刊: GEOLOGY
• 影响因子: 5.8
• 作者: Aze, T.;Pearson, P. N.;Foster, G. L.
• 通讯作者: Foster, G. L.

Effect of diagenetic recrystallization on the strength of planktonic foraminifer tests under compression

• DOI: 10.1144/jmpaleo2013-032
• 发表时间: 2014-12
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: P. Pearson;S. Evans;James Evans