The North Yellow Sea is a semi-enclosed shallow-water marginal sea of the western North Pacific. Below the seasonal thermocline, subsurface aragonite saturation state (Ω_arag) values of 1.0–1.5 have frequently been observed in summer and autumn, indicating that marine calcifying organisms in the area are under threat. In this study, we developed mechanism-based models relating summertime and autumnal subsurface Ω_arag to seawater temperature, practical salinity (S_P), dissolved oxygen and atmospheric CO₂ concentration, taking into consideration the combined effects of atmospheric CO₂ intrusion, metabolic CO₂ increase, and region-specific water mixing modes. For the central offshore areas of the North Yellow Sea, we found that cold water mass Ω_arag = 0.00885 × [(61.745 × S_P + 320 – 17/138 × AOU) − (DIC^Winter + 106/138 × AOU)] + 0.46, where DIC^Winter is the air-equilibrated bottom-water dissolved inorganic carbon concentration at the beginning of the year, and AOU is the apparent oxygen utilization. In the southern area that was likely influenced by the adjacent Bohai Sea water, we found that nearshore subsurface Ω_arag = 0.00939 × [(73.245 × S_P − 17/138 × AOU) − (DIC^Winter + 106/138 × AOU)] + 0.53. Subsurface Ω_arag values reconstructed from the two formulae are in general agreement with Ω_arag values calculated from observed dissolved inorganic carbon and total alkalinity values, with a standard deviation of 0.15 (n = 333). This is a successful attempt to reconstruct coastal subsurface Ω_arag values from common hydrochemical data using mechanism-based models, and the approach may have applicability in similar coastal systems.

北黄海是北太平洋西部的半封闭浅水边缘海。在季节性温跃层以下，在夏季和秋季经常观察到1.0–1.5的地下文石饱和状态（_Ωarag）值，表明该地区的海洋钙化生物受到威胁。在这项研究中，我们考虑到大气CO ₂入侵，新陈代谢CO的综合影响，建立了基于机制的模型，将夏季和秋季的地下Ω_耕作与海水温度，实际盐度（S _P），溶解氧和大气CO ₂浓度相关联_2个增加和特定地区的水混合模式。对于北黄海的中部近海地区，我们发现冷水质量_Ωarag  = 0.00885×[（（61.745×  S _P  + 320 – 17/138×AOU）−（DIC ^Winter  + 106/138×AOU）] + 0.46，其中DIC ^Winter是年初空气平衡的底水中溶解的无机碳浓度，而AOU是表观氧气利用率。在可能受到邻近渤海水影响的南部地区，我们发现近岸地下_Ωarag  = 0.00939×[（73.245×  S _P − 17/138×AOU）−（DIC ^Winter  + 106/138×AOU）] + 0.53。地下Ω_阿拉格从这两个公式重建得到的值通常与根据观察到的溶解的无机碳和总碱度值计算出的_Ωarag值一致，标准偏差为0.15（n  = 333）。这是使用基于机理的模型从常见的水化学数据重建沿海地下_Ωarag值的成功尝试，并且该方法可能在类似的沿海系统中具有适用性。