State Environmental Protection Key Laboratory of Costal Ecosystem, National Marine Environmental Monitoring Center, Linghe Street 42, Shahekou District, Dalian, 116023, Liaoning Province, China.
State Environmental Protection Key Laboratory of Costal Ecosystem, National Marine Environmental Monitoring Center, Linghe Street 42, Shahekou District, Dalian, 116023, Liaoning Province, China.
Mar Environ Res. 2024 Oct;201:106688. doi: 10.1016/j.marenvres.2024.106688. Epub 2024 Aug 14.
Seawater calcium ion (Ca) concentration was investigated based on the potentiometric titration method during the summer of 2018 in the Bohai Sea, China. The measured Ca concentration ranged from 7760 to 9739 μmol kg and deviated from the theoretical Ca values, which were estimated from the calcium/salinity ratio. The excess calcium (Ca) ranged from 186 to 1229 μmol kg, showing a decreasing trend from the estuary to the nearshore, and then the offshore areas. Riverine input was an important source of seawater Ca in the Bohai Sea. Biological activity was another factor in regulating seawater Ca by precipitation in the Yellow River estuary and dissolution in other area of the Bohai Sea. Furthermore, the aragonite saturation state (Ω) values calculated from the measured Ca concentrations showed a significant deviation from the values calculated from the theoretical Ca concentrations, especially in the estuarine area with a maximum difference of 18.5%. Therefore, the disregard of the calcium addition would lead to an underestimation of the calcium carbonate saturation state and a deviation in the assessment of ocean acidification in marginal seas.
基于 2018 年夏季在中国渤海的电位滴定法，对海水中钙离子（Ca）浓度进行了研究。测量的 Ca 浓度范围为 7760 至 9739 μmol kg，与根据钙/盐度比值估算的理论 Ca 值存在偏差。过剩 Ca（Ca）浓度范围为 186 至 1229 μmol kg，从河口到近岸，然后到近海地区呈下降趋势。河流输入是渤海海水 Ca 的重要来源。生物活动是通过在黄河河口沉淀和在渤海其他地区溶解来调节海水中 Ca 的另一个因素。此外，根据实测 Ca 浓度计算得出的文石饱和度（Ω）值与根据理论 Ca 浓度计算得出的值存在显著偏差，特别是在河口地区，最大偏差为 18.5%。因此，忽视钙的添加会导致对碳酸钙饱和度的低估以及对边缘海酸化评估的偏差。
