期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2018
卷号：115
期号：15
页码：3870-3875
DOI：10.1073/pnas.1703445115
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The role of rising atmospheric CO2 in modulating estuarine carbonate system dynamics remains poorly characterized, likely due to myriad processes driving the complex chemistry in these habitats. We reconstructed the full carbonate system of an estuarine seagrass habitat for a summer period of 2.5 months utilizing a combination of time-series observations and mechanistic modeling, and quantified the roles of aerobic metabolism, mixing, and gas exchange in the observed dynamics. The anthropogenic CO2 burden in the habitat was estimated for the years 1765–2100 to quantify changes in observed high-frequency carbonate chemistry dynamics. The addition of anthropogenic CO2 alters the thermodynamic buffer factors (e.g., the Revelle factor) of the carbonate system, decreasing the seagrass habitat’s ability to buffer natural carbonate system fluctuations. As a result, the most harmful carbonate system indices for many estuarine organisms [minimum pHT, minimum Ωarag, and maximum pCO2(s.w.)] change up to 1.8×, 2.3×, and 1.5× more rapidly than the medians for each parameter, respectively. In this system, the relative benefits of the seagrass habitat in locally mitigating ocean acidification increase with the higher atmospheric CO2 levels predicted toward 2100. Presently, however, these mitigating effects are mixed due to intense diel cycling of CO2 driven by aerobic metabolism. This study provides estimates of how high-frequency pHT, Ωarag, and pCO2(s.w.) dynamics are altered by rising atmospheric CO2 in an estuarine habitat, and highlights nonlinear responses of coastal carbonate parameters to ocean acidification relevant for water quality management.
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