Modeling the dissolved CO2 system in the redox environment of the Baltic Sea

Moa Edman and Anders Omstedt

Limnol. Oceanogr., 58(1), 2013, 74-92 | DOI: 10.4319/lo.2013.58.1.0074

ABSTRACT: Generation and depletion of total alkalinity (AT) were added to a Baltic Sea numerical model. The vertical distribution of generation and depletion of total alkalinity were described and attributed to different processes in the Eastern Gotland basin at the Gotland deep station (BY15) during the 1995–2004 period. At this site, the mean annual generation (28.2 µmol kg−1 yr−1) and depletion (−25.8 µmol kg−1 yr−1) were almost balanced, though the transient rates were much faster (+125/−340 µmol kg−1 yr−1). The mean volume-integrated AT content increased up to 50 µmol kg−1 when generation and depletion were added to the model. The AT changes were coupled to oxidation–reduction (redox) reactions and the model budget indicates that internal generation and depletions is as important as lateral transports, including riverine input, at this site. Model predictive capability in marine environments with strong biogeochemical gradients was improved by coupling within the dissolved CO2, and the biogeochemical, systems. This enables evaluation of eutrophication, acidification, and climate change simultaneously, and is important specifically in regions with permanent or periodic anoxia.

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