Establishing the current relation between observed oxygen conditions and oxygen proxies in western Norwegian fjords

• Recently, there have been alarming reports regarding the de-oxygenation of Norwegian fjords due to climate change. Warming coastal waters and a suggested decrease in the renewal frequency of the fjords’ deep, stagnant basin water have been linked to the reduced oxygen concentrations. The fjords are economically important to Norway, and the water quality is (of course) of uttermost importance to the local ecosystem. Here I present a new project, FJO2RD, which investigates recent changes in the physical forcing and the renewal frequency while utilising paleo records from sediment archives to provide information on natural variability in fjord oxygenation during the last ca. 400 years. New multi- and gravity cores will be obtained from two fjords, Masfjorden and Lurefjorden, in western Norway. The oxygenation history will be reconstructed based on benthic foraminiferal assemblages and geochemical analyses. The Mn/Ca ratio will be analysed to study the extent of hypoxic conditions and past oxygen dynamics, and the Ba/Ca ratio to study runoff variability and stratification. The stable carbon isotopes will infer remineralisation associated with the change in oxygen. Dissolved oxygen concentrations will further be quantified using a modified Behl dissolved oxygen index, which is a method that calculates changes in oxygen concentrations by using a weighted average for each oxygen category as 0.1 mL/L for dysoxic, 0.5 mL/L for suboxic, and 1.5 mL/L for weakly hypoxic-oxic conditions. The results of these analyses will be used as the basis for my PhD-thesis

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Multidisciplinär geovetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geosciences, Multidisciplinary (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Oceanografi, hydrologi och vattenresurser (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Oceanography, Hydrology and Water Resources (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

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