Freshwater - Drivers and pressures (Finland)

Water quality is also affected by weather conditions and variations in runoff[1]. During 2000–2003, there were periods where the water quality clearly deteriorated. In 2002 most of the country suffered from the worst drought in several decades, which caused water levels to drop in many water bodies. During the winter of 2002–2003, extremely poor oxygen conditions were observed in about 450 small and shallow lakes, especially in southern and western Finland, and mass die-offs of fish occurred in many of these lakes. The main reasons for the severe oxygen problems were an early ice cover and the low water levels. Low water levels also contributed to the degradation of rivers, especially in south-western Finland.

The nutrient load and natural leaching[2]

Nutrients from diffuse and point sources cause the water quality to deteriorate. The share of the diffuse sources of the total anthropogenic load for phosphorus is about 80 % and for nitrogen about 60 %. The anthropogenic load is higher than the natural leaching for both nutrients. The deposition affects the water quality, too. The input of nutrients due to deposition and natural leaching was estimated to enable the comparison with the amount of nutrient inputs from different anthropogenic sources in 2008.

Table 2: The phosphorus and nitrogen loads from different sources and the estimates of deposition and natural leaching in Finland in 2008

The comparison between the situation in 2008 and 2004 shows no significant changes. Many of the point source categories as well as the deposition show a slight decrease in the nutrient load. Agriculture is the largest source both in 2004 and in 2008 and the share of agriculture of the total load has slightly increased.

Table 3: Anthropogenic loads of nutrients in 2004 by source[3]

Figure 3: The shares of anthropogenic loads of nutrients in 2004 by source[4]

Even if the changes in the nutrient inputs have recently been small, some cases show significant decreases over a longer period of time. Especially emissions of phosphorus from industry and municipalities have had a clear decrease after 1980.

Figure 4: Development of nutrient emissions from point sources into water 1980 - 2007[5]

Nutrient balances in agriculture

The use of phosphorus in agriculture has decreased considerably during the last two decades[6]. In the late 1980s, the phosphorus balance was around 30 kg/ha and has decreased smoothly since then to the 5 kg/ha of today. There is a decrease of almost 70 % in the use of phosphorus fertilisers and the phosphorus content in manure has fallen by 15 %. However, no clear signs have been observed in the water bodies despite the decrease in the phosphorus balance. This is basically due to the earlier accumulation of phosphorus in the soil.

In Europe the highest values of phosphorus balance are 15-20 kg/ha (Belgium, the Netherlands). The balance in Finland is slightly lower than in Denmark and Norway but higher than in Sweden (1 kg/ha) and Ireland (7 kg/ha).

The nitrogen balance has had a similar development; from values slightly above 100 kg/ha to below 50 kg/ha which is the average European level[7]. The nitrogen content in the fertilizers has decreased by 20 % and the content in manure by 25 %. This decrease has not yet been visible in the water quality.

Urban wastewater treatment[8]

There were over 200 municipal wastewater treatment facilities in 2004. With a very few exceptions, the treatment facilities use the biological-chemical (i.e. tertiary) process. The total incoming loads of BOD₇, phosphorus and nitrogen have steadily increased but the effect of the reduction processes has increased even more. The percentage of reduction, calculated as the ratio between the amount of reduction and the load of the influent, is about 95-96 % for BOD₇ and phosphorus. For nitrogen, the improvement of the reduction process has been as clear but the percentage of reduction remains slightly below 50 %

Table 4: The incoming and remaining loads of (tonnes/year) and the percentage of reduction in the Finnish municipal wastewater treatment facilities 1971–2004

Table 5: The incoming and remaining loads of phosphorus (tonnes/year) and the percentage of reduction in the Finnish municipal wastewater treatment facilities 1971–2004

Table 6: The incoming and remaining loads of nitrogen (tonnes/year) and the percentage of reduction in the Finnish municipal wastewater treatment facilities 1971–2004

 Wastewater treatment in rural areas[9]

The treatment of wastewater in rural areas with no centralised sewerage system will be improved greatly over the coming years, thanks to legislation in the Onsite Wastewater System Decree (542/2003), which came into force on 1 January 2004. The Decree sets minimum standards for wastewater treatment and the planning, construction, use and maintenance of treatment systems. The treatment facilities should in most cases meet the new requirements by 2014.