Institute of Marine Science and Technology, Shandong University, Qingdao 266237, China.
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Function Laboratory for Ocean Dynamics and Climate, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China.
Sci Total Environ. 2022 Apr 1;815:152935. doi: 10.1016/j.scitotenv.2022.152935. Epub 2022 Jan 8.
The North Yellow Sea (NYS) is a productive marginal sea of the western North Pacific. In summer and autumn, CaCO saturation states beneath the seasonal thermocline in the NYS have frequently fallen below critical levels, indicating that marine calcifying organisms are under threat. To explore the long-term evolution of the acidification of the NYS, we reconstructed seasonal variations in subsurface aragonite saturation state (Ω) and pH during 1976-2017, using wintertime and summertime temperature, salinity, dissolved oxygen and pH data mainly from a quality-controlled oceanographic database. Over the past 40 years, the wintertime warming rate in the NYS was twice the rate of global ocean surface warming. Warming-induced decrease in CO solubility canceled out a part of the wintertime Ω decrease caused by atmospheric CO increase, and also had minor effect on pH changes in winter. Although the NYS is a semi-enclosed marginal sea, its interannual variations of wintertime temperature, salinity, pH and Ω were correlated to Pacific Decadal Oscillation with a lag of 2-3 years. Due to the eutrophication-induced enhancement of net community respiration beneath the seasonal thermocline, long-term declines of bottom-water Ω and pH in summer were substantially faster than the declines of assumed air-equilibrated Ω and pH in spring. Over the past 40 years, the amplitudes of seasonal variations of bottom-water Ω and pH from spring to summer/autumn have increased by 4-7 times. This amplification has pushed the NYS towards the critical threshold of net community CaCO dissolution at a pace faster than that forecast under scenarios of atmospheric CO increase. In summary, our results provide insights into the combined effects of ocean warming, eutrophication, atmospheric CO rise and climate variability on coastal hydrochemistry, explaining how the environmental stresses on local marine calcifying organisms and the benthic ecosystem increased over the past 40 years.
北黄海（NYS）是西北太平洋一个生产力较高的边缘海。在夏季和秋季，北黄海季节性温跃层以下的碳酸钙饱和度状态经常低于临界水平，这表明海洋钙化生物受到威胁。为了探索北黄海酸化的长期演变，我们利用冬季和夏季的温度、盐度、溶解氧和 pH 数据，主要来自一个经过质量控制的海洋学数据库，重建了 1976-2017 年期间的次表层霰石饱和度状态（Ω）和 pH 的季节性变化。在过去的 40 年里，北黄海的冬季变暖速度是全球海洋表面变暖速度的两倍。变暖引起的 CO2溶解度降低抵消了部分由大气 CO2增加引起的冬季 Ω 降低，对冬季 pH 变化的影响也较小。尽管北黄海是一个半封闭的边缘海，但它的冬季温度、盐度、pH 和 Ω 的年际变化与太平洋十年涛动相关，滞后 2-3 年。由于营养盐引发的季节性温跃层下净群落呼吸增强，夏季底层水 Ω 和 pH 的长期下降速度远远快于春季假定的空气平衡 Ω 和 pH 的下降速度。在过去的 40 年里，从春季到夏季/秋季的底层水 Ω 和 pH 的季节性变化幅度增加了 4-7 倍。这种放大作用使北黄海朝着净群落 CaCO3溶解的临界阈值发展的速度比在大气 CO2增加情景下的预测速度更快。总之，我们的研究结果提供了对海洋变暖、富营养化、大气 CO2上升和气候变化对沿海水化学的综合影响的深入了解，解释了过去 40 年来，当地海洋钙化生物和海底生态系统面临的环境压力是如何增加的。
