River water quality in the Finnish Eurowaternet

The Finnish Eurowaternet monitoring network includes about 200 river sites that are among the northernmost in the European Eurowaternet monitoring network.Their water quality was investigated using the medians of physico-chemical parameters (total phosphorus, total nitrogen, dissolved oxygen saturation percentage, pH, alkalinity, chemical oxygen demand, colour, electrical conductivity, total suspended solids, turbidity), hygienic indicator bacteria and trace metals (iron, zinc, nickel, chromium, copper, cadmium, arsenic, lead and mercury) calculated for the period 1998-2002.The river water quality was poorest in the south, improved towards the north and was best above the Arctic Circle.In addition it varied in the east-west direction being poorest in the west and best in the east.In the south population density is higher, there is more industry, arable land, agriculture and animal husbandry, which explain water quality differences.On a European scale the majority of the Finnish rivers, particularly those in the north, are rather unpolluted.