Interannual variability of oceanic pH in a highly human-perturbed bay in China

, which is 3.6 times faster than that observed in the open ocean, indicating significant anthropogenic impacts on pH variations in Jiaozhou Bay. The long-term pH changes showed strong correlations with coastal environmental pollution status, characterized by three distinct phases: a decline from 1980 to 1986, followed by an increase during 1991 to 2004, and subsequently another decreasing trend from 2004 to 2016. Terrestrial (including wastewater) inputs were identified as predominant anthropogenic factors influencing these pH variations. Furthermore, this study highlights that while future management should focus on reducing organic matter and nutrient inputs, particular attention should be paid to the direct impacts of dissolved inorganic carbon (DIC) from treated wastewater discharge on pH reduction.