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The Baltic Sea a century ago — a reconstruction from model simulations, verified by observations
Authors:
Source:
Journal of Marine Systems, 74: 485-494, 2008.
Abstract:
“Pre-industrial" trophic conditions in the Baltic Sea were simulated with SANBALTS (Simple As Necessary BAltic Long-Term large Scale) model. External nutrient inputs to the major basins of the Baltic Sea a century ago were reconstructed from various literature and data sources. The reconstructed input of total nitrogen was less than a half and that of total phosphorus was about a third of their contemporary values. The simulated “pre-industrial" conditions are validated by comparison to actual historical data on the water transparency, oxygen concentration, primary production, and net sediment accumulation. The “pre-industrial" trophic state could have been more phosphorus limited than today because simulated basin-wide annual averages of dissolved inorganic phosphorus concentrations of 0.06—0.3 M P are about 40—80% of their present day values, while dissolved inorganic nitrogen concentrations of 2—4 M N are almost the same as today or even slightly higher. Keywords: Nitrogen, Phosphorus, Reference conditions, Coastal point loads, Biogeochemical fluxes, Trophic state, Baltic Sea
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