Change search
ReferencesLink to record
Permanent link

Direct link
Past, present and future state of the biogeochemical Si cycle in the Baltic Sea.
GeoBiosphere Science Centre, Department of Geology, Lund University, Sweden.
Stockholm University, Stockholm Resilience Centre.
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
Department of Water and Environmental Studies, Linköping University, Sweden.
Show others and affiliations
2008 (English)In: Journal of Marine Systems, Vol. 73, 338-346 p.Article in journal (Refereed) Published
Abstract [en]

The Baltic Sea is one of many aquatic ecosystems that show long-term declines in dissolved silicate (DSi) concentrations due to anthropogenic alteration of the biogeochemical Si cycle. Reductions in DSi in aquatic ecosystems have been coupled to hydrological regulation reducing inputs, but also with eutrophication, although the relative significance of both processes remains unknown for the observed reductions in DSi concentrations. Here we combine present and historical data on water column DSi concentrations, together with estimates of present river DSi loads to the Baltic, the load prior to damming together with estimates of the long-term accumulation of BSi in sediments. In addition, a model has been used to evaluate the past, present and future state of the biogeochemical Si cycle in the Baltic Sea. The present day DSi load to the Baltic Sea is 855 ktons y− 1. Hydrological regulation and eutrophication of inland waters can account for a reduction of 420 ktons y− 1 less riverine DSi entering the Baltic Sea today. Using published data on basin-wide accumulation rates we estimate that 1074 ktons y− 1 of biogenic silica (BSi) is accumulating in the sediments, which is 36% higher than earlier estimates from the literature (791 ktons y− 1). The difference is largely due to the high reported sedimentation rates in the Bothnian Sea and the Bothnian Bay. Using river DSi loads and estimated BSi accumulation, our model was not able to estimate water column DSi concentrations as burial estimates exceeded DSi inputs. The model was then used to estimate the BSi burial from measured DSi concentrations and DSi load. The model estimate for the total burial of BSi in all three basins was 620 ktons y− 1, 74% less than estimated from sedimentation rates and sediment BSi concentrations. The model predicted 20% less BSi accumulation in the Baltic Proper and 10% less in the Bothnian Bay than estimated, but with significantly less BSi accumulation in the Bothnian Sea by a factor of 3. The model suggests there is an overestimation of basin-wide sedimentation rates in the Bothnian Bay and the Bothnian Sea. In the Baltic Proper, modelling shows that historical DSi concentrations were 2.6 times higher at the turn of the last century (ca. 1900) than at present. Although the DSi decrease has leveled out and at present there are only restricted areas of the Baltic Sea with limiting DSi concentrations, further declines in DSi concentrations will lead to widespread DSi limitation of diatoms with severe implications for the food web.

Place, publisher, year, edition, pages
2008. Vol. 73, 338-346 p.
National Category
Environmental Sciences
URN: urn:nbn:se:su:diva-17767DOI: 10.1016/j.jmarsys.2007.10.016ISI: 000260563300009OAI: diva2:184288
Available from: 2009-01-20 Created: 2009-01-20 Last updated: 2012-03-26Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Humborg, ChristophSmedberg, ErikMörth, Carl-Magnus
By organisation
Stockholm Resilience CentreDepartment of Applied Environmental Science (ITM)
Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 114 hits
ReferencesLink to record
Permanent link

Direct link