Surface ocean acidification with increasing atmospheric carbon dioxide and its effects on coral calcification

大气二氧化碳增加导致的表层海洋酸化及其对珊瑚钙化的影响

基本信息

批准号：
20510027
负责人：
OHDE Shigeru
金额：
$ 2.83万
依托单位：
University of the Ryukyus
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-20510027/
关键词：
二酸化炭素海洋酸性化サンゴ石灰化 pH アラゴナイト飽和度海水酸性化

项目摘要

Global warming related with excess emission of carbon dioxide is a burning issue for the world's environments nowadays. Due to fossil fuel burning, atmospheric carbon dioxide is predicted to be double (560 ppm) of pre-industrial period in 2065 and 700 ppm in 2100. Such an increase is reducing surface oceanic pH and carbonate ion concentrations, and thus the degree of calcium carbonate (aragonite crystal) saturation (Ω=[Ca^<2+>][CO_3^<2->]/K), where K is the stoichiometric solubility product for aragonite. Since [Ca^<2+>] is constant in seawater, changes in seawater [CO_3^<2->] could proportionally make changes in seawater Ω. Corals use CO_3^<2-> from seawater to precipitate CaCO_3 (calcification) in their skeletons as the reaction, Ca^<2+>+2HCO_3^-=CaCO_3+H_2O+CO_2. Changes in seawater [CO_3^<2->] possibly affects coral calcification rate. We evaluate the effects of seawater Ω on coral calcification associated with elevated atmospheric carbon dioxide. From the culture experiment data, … More we could conclude that coral calcification is possibly controlled by an inorganic precipitation law (R=k(Ω-1)^n), where R is the precipitation rate, k is the rate constant and n is the empirical-reaction order. In order to figure out the changes in calcification rate with increasing carbon dioxide in future, the rates are normalized (G in %) to the rate at Ω of 4.6, the value for Ω during the pre-industrial period (CO_2=280 ppm). When we use the first-order model (n=1), the model gives a relationship as follows : G=(Ω-1)100/(4.6-1)=27.8(Ω-1), for coral calcification. If atmospheric CO_2 increases from ～280 ppm in 1800 to ～560 ppm in 2065 and to ～700 ppm in 2100, seawater Ω is predicted to decrease from 4.6 to 2.9 and 2.5, respectively. Using the model equation, coral calcification is predicted to decline ～47% and ～58% by 2065 and 2100, respectively. We suggest that coral calcification is closely coupled to CO_2 in seawater and seawater Ω, and declined coral calcification is predicted near future when atmospheric CO_2 further increases. Less

与二氧化碳过量排放相关的全球变暖是当今世界环境面临的一个紧迫问题。由于化石燃料的燃烧，大气中的二氧化碳预计到 2065 年将是工业化前时期的两倍（560 ppm），到 2100 年将达到 700 ppm。这种增加正在降低海洋表面 pH 值和碳酸根离子浓度，从而降低碳酸钙（文石晶体）的饱和度(Ω=[Ca^<2+>][CO_3^<2->]/K)，其中K是文石的化学计量溶解度积，由于[Ca^<2+>]在海水中是恒定的，因此海水会发生变化。 [CO_3^<2->]可以按比例改变海水Ω。珊瑚利用海水中的CO_3^<2->在其骨骼中沉淀CaCO_3（钙化）作为反应， Ca^<2+>+2HCO_3^-=CaCO_3+H_2O+CO_2。海水[CO_3^<2->]的变化可能影响珊瑚钙化速率。我们评估了海水Ω对与大气二氧化碳升高相关的珊瑚钙化的影响。从培养实验数据中，我们可以得出结论，珊瑚钙化可能受无机沉淀规律（R=k(Ω-1)^n）控制，其中R是沉淀速率，k 是速率常数，n 是经验反应级数。为了计算未来随着二氧化碳增加钙化速率的变化，速率被归一化（G 以 % 表示）为 Ω 为 4.6 时的速率，前工业化时期 (CO_2=280 ppm) 的 Ω 值当我们使用一阶模型 (n=1) 时，模型给出的关系如下： G=(Ω-1)100/(4.6-1)=27.8(Ω-1)，如果大气中CO_2从1800年的~280 ppm增加到2065年的~560 ppm，再到2100年的~700 ppm，根据模型方程，海水 Ω 预计将从 4.6 分别降至 2.9 和 2.5。预计到 2065 年和 2100 年，珊瑚钙化作用将分别下降约 47% 和约 58%。我们认为，珊瑚钙化作用与海水中的 CO_2 和海水 Ω 密切相关，并且预计在不久的将来，当大气 CO_2 进一步增加时，珊瑚钙化作用会下降。