Nutrient losses from small drainage basins were compared to the nutrient fluxes in small coastal rivers in order to study the representativeness of the Finnish monitoring network of small basins, especially as regards agricultural loading to the Baltic Sea. Additionally flux estimates from the period 1986-1990 were compared to those of the period 1981-1985 in order detect possible trends. The results suggest that in coastal regions with high proportions of agricultural land and with low lake percentage, the nutrient losses from agricultural areas mostly enter coastal waters with negligible retention in river channels. The net effect of the various processes in the rivers is small because most of the nutrient losses occur in spring, fall or early winter in connection with high water flows and current velocities, short residence times of water and low intensities of biogeochemical processes. Nitrogen losses from agriculture has probably increased during the 1980s due to increased winter flows and increased use of nitrogen fertilizers. The results indicate that nitrogen loading of the southern and south-western coastal waters of Finland has increased as well.
Nitrogen and Phosphorus Fluxes from Finnish Agricultural Areas to the Baltic Sea
Seppo Rekolainen, Heikki Pitkänen, Albert Bleeker, Sietske Felix; Nitrogen and Phosphorus Fluxes from Finnish Agricultural Areas to the Baltic Sea. Hydrology Research 1 February 1995; 26 (1): 55–72. doi: https://doi.org/10.2166/nh.1995.0004
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