Input of DOC to the Baltic Sea
Altered surface water residence times (SWRTs), e.g. due to changed precipitation, is a current aspect of global change. Freshwater systems receive large amounts of organic material from land, mainly as dissolved organic carbon (DOC), and the SWRT is dictating the time available for degradation of this DOC, before it is further exported to marine systems. Reactive DOC can be degraded into CO2 by O2-consuming photochemical and microbial processes, at rates that are significant for the dissolved O2 concentrations of poorly mixed waters and for the water-atmosphere exchange of greenhouse gases. Thus, in the sensitive environment of the Baltic Sea, the fate of DOC has important consequences.
By a combination of field surveys and experiments, we study key aspects of how SWRT and environmental drivers regulate DOC reactivity. The objectives are to: (I) Determine the degree to which SWRT exerts first-order (direct) control of DOC age, quality and reactivity. (II) Investigate interaction effects between SWRT and environmental factors in the regulation of DOC photo- and bio-reactivity. (III) Quantify the effects of contrasting nutrient concentrations, pH and salinity in freshwater and estuarine systems, on short- and long-term biological and photo-chemical DOC reactivity. The project will improve basic understanding of how one of the most important O2consuming processes in the Baltic Sea, i.e. the degradation of DOC, will respond to a changing environment and altered SWRTs.
Co-funded by CEC (2013-2016) and the Formas strong research environment "Managing multiple stressors in the Baltic Sea" (2013-2015).
We recently participated the ASLO Ocean Sciences Meeting 2014 in Honolulu, Hawaii, with the following abstract titles (presenter):
Alves Soares AR, Marchlewska J, Islam S, and Berggren M.: River export of bioavailable nutrients and labile organic carbon: effects on estuarine nutrient stoichiometry and bacterioplankton nutrient limitation
Alves Soares AR, Kritzberg ES, Persson DA, and Berggren M.: Labile organic carbon in river runoff: the importance of carbon sources and water residence times
We have published the following paper in Journal of Plankton Research:
Berggren M, Sponseller RA, Alves Soares AR and Bergström A-K. 2015. Toward an ecologically meaningful view of resource stoichiometry in DOM-dominated aquatic systems. Journal of Plankton Research, advance online access.