Estimation of the nutrient load on the Gulf of Finland from the Russian part of its catchment

The nutrient load on the Gulf of Finland, the Baltic Sea, is estimated taking into account the export of nutrients from Lake Ladoga with Neva runoff, from the Chudsko-Pskovskoe Lake with Narva runoff, from a partial watershed of the Gulf of Finland, and wastewater discharges from St. Petersburg. The data used include the materials of state monitoring of water bodies and state statistical reports on northwestern Russia, materials of GUP Vodokanal Sankt Peterburga, the results of earlier researches of water quality formation in Lake Ladoga, the Gulf of Finland, and on their catchment, and the results of calculation of nutrient load on the gulf with the use of a model developed in the Institute of Limnology, RAS. Currently, the annual nutrient load on the Gulf of Finland is ∼5200 t P_tot and 70800 t N_tot. The phosphorus load exceeds the admissible levels recommended by the Helsinki Commission, thus suggesting the need to search for real ways to reduce the load in the future.