Current calcite (CaCO3) dissolution at the seafloor caused by anthropogenic CO2 (NCEI Accession 0176672)

This dataset consists of current CaCO3 dissolution at the seafloor caused by anthropogenic CO2 in the World Oceans. This dataset contains the main results from Sulpis et al. (PNAS, 2018). All the variables have a 1x1 degree resolution. It can be used to compute calcite dissolution at the seafloor for changing bottom-water chemistry, calcite rain rates or current speeds, for instance. Oceanic uptake of anthropogenic CO2 leads to decreased pH, carbonate ion concentration, and saturation state with respect to CaCO3 minerals, causing increased dissolution of these minerals at the deep seafloor. This additional dissolution will figure prominently in the neutralization of man-made CO2. Yet, there has been no concerted assessment of the current extent of anthropogenic CaCO3 dissolution at the deep seafloor. Here, recent databases of bottom-water chemistry, benthic currents, and CaCO3 content of deep-sea sediments are combined with a new rate model to derive the global distribution of benthic calcite dissolution rates and obtain primary confirmation of an anthropogenic component. By comparing pre-industrial with present-day rates, we determine that significant anthropogenic dissolution now occurs in the western North Atlantic, amounting to 40-100% of the total seafloor dissolution at its most intense locations. At these locations, the calcite compensation depth has risen ~300 m. Increased benthic dissolution was also revealed at various hot spots in the southern extent of the Atlantic, Indian and Pacific Oceans. Our findings place constraints on future predictions of ocean acidification, are consequential to the fate of benthic calcifiers, and indicate that a by-product of human activities is currently altering the geological record of the deep sea.

本数据集收录了全球海洋中由人为源二氧化碳（anthropogenic CO2）引发的当前海底碳酸钙（CaCO3）溶解现状，其核心研究结果源自Sulpis等人2018年发表于《美国国家科学院院刊》（PNAS）的工作。数据集内所有变量的空间分辨率均为1×1度，可用于计算不同底水化学条件、方解石（calcite）沉降速率或海流速度下的海底方解石溶解情况，例如各类相关场景。海洋吸收人为源二氧化碳会导致海水pH值、碳酸根离子浓度降低，以及碳酸钙（CaCO3）矿物的饱和状态下降，进而加剧深海海底此类矿物的溶解过程。这类额外的溶解过程在人为二氧化碳的中和过程中发挥着关键作用。然而，目前尚无针对深海海底人为源碳酸钙溶解范围的系统性评估研究。本研究结合最新的底水化学、底栖海流（benthic currents）以及深海沉积物碳酸钙含量数据库，辅以全新的速率模型，推导得到了全球底栖方解石溶解速率的分布特征，并首次证实了溶解过程中的人为影响组分。通过对比前工业化时期与当前的溶解速率，本研究发现西北大西洋海域已出现显著的人为源溶解现象，在溶解最为强烈的区域，人为溶解贡献占总海底溶解量的40%至100%。在这些区域，方解石补偿深度（calcite compensation depth）已抬升约300米。研究同时在大西洋、印度洋与太平洋南部的多个热点区域发现了底栖溶解作用增强的现象。本研究结果为海洋酸化的未来预测提供了约束条件，对底栖钙化生物的生存命运具有重要影响，并表明人类活动的一项副产物正在改变深海的地质记录。