Sammanfattning

The seven biggest rivers cover half of the Baltic Sea catchment area. Nearly 55 million people inhabit their catchment areas, meaning that anthropogenic pressure is high. Anthropogenic pressure is highest in the southern catchments, where population is densest and agricultural activity is intense. Consequently, the nutrient loads are high in the south: For example, in 2017 the area specific total nitrogen load of the River Nemunas was 838 kg km-2, whereas it was 133 kg km-2 for the River Kemijoki (in the north). The variation in the area specific total phosphorus loads was in 2017: The River Göta älv 4.3 kg km-2 and the River Nemunas 26 kg km-2. The seven rivers exported 372,000 t of total nitrogen and 13,500 t of total phosphorus into the Baltic Sea in 2017, which was nearly 40% of the total nitrogen and phosphorus loads of the Baltic Sea. The Neva River contributed over 40% of the total flow into the Baltic Sea Catchment area, but the River Vistula had the highest total nitrogen and total phosphorus loads in 2017 with 30% and 28% respectively. Total phosphorus load showed a statistically significant decrease from 1995 to 2017, with total phosphorus being decreased by 6,000 t (30%), but the trends for individual rivers varied greatly. The decreasing tendency in the total nitrogen load found previously had levelled off. To enable division of nutrient load reductions according to their origin country nutrient input ceilings were established for five of the seven biggest rivers (the 5 biggest transboundary rivers). In 2017 the remaining reduction to fulfill the input ceiling of those five rivers was 71,000 t of total nitrogen and 8600 t of total phosphorus. The proportion of the remaining TN reduction of the five biggest rivers was 56% of the total remaining TN reduction of the whole Baltic Sea and 88% of the remaining TP reduction respectively.

Publicerad i

Baltic Sea Environment Proceedings
2021, nummer: 178
Utgivare: Helsinki Commission

SLU författare

• Sonesten, Lars

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    

Associerade SLU-program

Kust och hav
Sjöar och vattendrag
Övergödning
Använder FOMA data


Globala målen

SDG6 Säkerställa tillgången till och en hållbar förvaltning av vatten och sanitet för alla
SDG14 Bevara och nyttja haven och de marina resurserna på ett hållbart sätt för en hållbar utveckling


UKÄ forskningsämne

Oceanografi, hydrologi, vattenresurser
Geokemi
Ekologi


Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/113939