Danielsson, Å. Linköping University, asada@tema.liu.se

During the last decades, the silica concentrations have decreased in the Balitc Sea. This is probably an effect of an increased nutrient load and an increased primary production. Further, a decrease in silica concentration, combined with increasing nitrogen and phosphorus loads, may qualitatively change the entire ecosystem. Nitrogen is assumed to be limiting the primary production. However, recent changes in DSi/N ratio, before the diatom spring bloom, indicate that dissolved silica may become the limiting nutrient instead. This may lead to a favouring of non-silica dependent plankton species. Non-parametric time series analysis and modelling have already been used to quantify these changes in the water mass, while the situation in sediments is neglected. By dating sediment cores the sedimentation rate is calculated. Cokriging, with silica as primary variable and sediment characteristics and other important variables as covariables, will be used to estimate the spatial distribution. Using the distribution together with sediment rates, an estimate of the total amount accumulated in the different layers in the sediment is received. This estimate will be compared with previous ones, drawn from budget models in the water mass, where the accumulation has been calculated as the difference between the outflowing and inflowing amounts.
Day: Friday, Feb. 5
Time: 04:00 - 04:15pm
Location: Sweeney Center
Code: SS13FR0400S