Woszczyk Michał

Tytuł

Transport and transformation of total alkalinity from continental rivers – the missing components for understanding pH variation in the Baltic Sea (Transport i transformacja alkaliczności całkowitej z rzek kontynentalnych – brakujące elementy do zrozumienia zmienności pH w Morzu Bałtyckim).
Akronim projektu: ALKALIS

Źródło finansowania

Narodowe Centrum Nauki 2023/49/B/ST10/02690

Czas trwania

2024-2027

Zespół badawczy

Jest to projekt konsorcjalny realizowany przez Instytut Oceanologii PAN w Sopocie (lider) oraz IMGW i UAM. Ja pełnię rolę konsorcjanta.

Fundusze

Kwota dla UAM: 948 550 PLN

Streszczenie

Increasing atmospheric CO2 concentrations cause an overall increase of CO2 concentrations in surface seawater and, consequently, a pH decrease (CO2 is a weak acid). This mechanism, called Ocean Acidification (OA), has been recognized by both the scientific community and policy makers as one of the greatest threats to marine ecosystems but also to the well-being of society, through impacts on fisheries, aquaculture and tourism.
The mechanism of OA is already fairly well understood and traceable in the open ocean waters, where large-scale projects and actions supply an enormous amount of observations and experimental data and where the magnitude of OA is to a large extent thermodynamically consistent with the increase in atmospheric pCO2. On the other hand, in the coastal and shelf seas, OA is still considerably understudied despite their high socio-economic importance and potentially great vulnerability to acidification due to often lower salinity and corresponding lower buffer capacity of waters as compared to open ocean. The Baltic Sea through its specific topography and the hydrological setting is one of the largest brackish water bodies on Earth. The brackishness of the basin creates a unique ecological structure but is also a root cause for a generally low buffer capacity of waters (expressed as total alkalinity, AT) to mitigate OA. The mean surface salinity of about 7 in the central Baltic Sea clearly shows the predominant role of the freshwater component in shaping the chemical composition and properties of the Baltic surface water. However, the knowledge about the role of freshwater input in shaping the AT fields and thus also pCO2 and pH variability in the Baltic Sea remains still insufficient. This is especially the case for the highly understudied southern and south-eastern parts of the Baltic and the large continental rivers flowing there, which drain limestone-rich catchment vulnerable to CO2-induced weathering. In consequence, this knowledge gap still hampers closing the AT mass balance for the entire Baltic and proper setting up biogeochemical models, which are the only tools to study the large-scale variability of pH and pCO2 changes and to forecast the development of OA in the future high-CO2 world. The main hypothesis in the project assumes that total alkalinity loads from continental rivers are increasing which substantially influences the alkalinity budget and pH and pCO2 variability in the Baltic Sea. To verify this hypothesis the following objectives have been set: 1) to identify long-term trends and seasonal variability of total alkalinity concentrations and loads from continental rivers to the Baltic Sea. 2) to identify long-term trends, seasonal variability (and corresponding drivers) of total alkalinity concentrations, pH and pCO2 in the coastal regions of the southern Baltic Sea 3) to assess the role of calcium carbonate formation and dissolution in the transport of riverine alkalinity to the Baltic Sea 4) to quantify the net air/sea CO2 exchange in the lower sections of the continental rivers and coastal zone affected by the riverine total alkalinity supply. The work planned in the project has been distributed into 5 work packages and 11 tasks. It includes experimental observations extending from river mouths to the open sea, laboratory-based microcosm experiments and analysis of the historical, monitoring data. Furthermore, the project results will also be immediately transferred into the ERGOM biogeochemical model to improve its accuracy in simulating CO2 system variability in the Baltic Sea and to assess the large-scale transport of alkalinity from land and its influence on pH and pCO2 fields in the Baltic