10.18453/rosdok_id00002303 Müller, Jens Daniel Jens Daniel Müller http://d-nb.info/gnd/1168826969 https://orcid.org/0000-0003-3137-0883 Universität Rostock 2018 333.7 Natural resources, energy and environment 540 Chemistry & allied sciences 624 Structural and Environmental Engineering 2018 en http://purl.uni-rostock.de/rosdok/id00002303 urn:nbn:de:gbv:28-diss2018-0135-7 Globally, ocean acidification presents a threat to marine ecosystems. In the Baltic Sea, this process could so far not be quantified, partly due to a lack of appropriate pH observations. This study unravels a positive alkalinity trend in the Baltic Sea over the past two decades that counteracted acidification. Further, state-of-the-art spectrophotometric pH measurements in brackish waters are enabled by characterizing pH buffer solutions and the indicator dye m-Cresol purple at low salinities. Finally, pH fluctuations and their implications for benthic ecosystems are examined.