Nutrients in freshwater in Europe

Indicator Assessment
Prod-ID: IND-8-en
Also known as: CSI 020 , WAT 003
Created 29 Jan 2018 Last modified 07 Feb 2019
27 min read

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Nutrient conditions in European surface waters have improved over recent decades, while there has been no overall decline in nitrate concentrations in groundwater.   Since 2007, average nitrate concentrations in European groundwater have declined and are currently closer to the 1992 level. On average, nitrate concentration in European rivers declined by 0.02 milligrams per liter of nitrogen (mg N/l), or 0.8 %, per year over the period 1992-2015. The decline in nitrate concentration reflects the effect of measures to reduce agricultural inputs of nitrate, as well as improvements in waste water treatment. The average orthophosphate concentration in European rivers has decreased markedly over the last two decades (by 0.002 milligrams per liter of phosphorous (mg P/l), or 1.8 %, per year. The average total phosphorus concentration in lakes also decreased over the period 1992-2015 (0.0004 mg P/l, or 0.9 % per year). The decrease in phosphorus concentration reflects both improvements in waste water treatment and the reduction of phosphorus in detergents.

Key messages

  • Nutrient conditions in European surface waters have improved over recent decades, while there has been no overall decline in nitrate concentrations in groundwater.  
  • Since 2007, average nitrate concentrations in European groundwater have declined and are currently closer to the 1992 level.
  • On average, nitrate concentration in European rivers declined by 0.02 milligrams per liter of nitrogen (mg N/l), or 0.8 %, per year over the period 1992-2015.
  • The decline in nitrate concentration reflects the effect of measures to reduce agricultural inputs of nitrate, as well as improvements in waste water treatment.
  • The average orthophosphate concentration in European rivers has decreased markedly over the last two decades (by 0.002 milligrams per liter of phosphorous (mg P/l), or 1.8 %, per year.
  • The average total phosphorus concentration in lakes also decreased over the period 1992-2015 (0.0004 mg P/l, or 0.9 % per year).
  • The decrease in phosphorus concentration reflects both improvements in waste water treatment and the reduction of phosphorus in detergents.

Are nutrient concentrations in Europe's freshwaters decreasing?

Nutrient trends in European water bodies

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Groundwater - nitrate
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Rivers - nitrate
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Rivers - phosphate
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Lakes - phosphorus
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Nitrate in groundwater: There was a slight increase in average annual mean nitrate concentrations in European groundwater between 1992 and 1997. Until 2002, the concentrations declined somewhat before increasing again towards 2007. Since then the average concentrations have declined and in 2015 they were at a level closer to the 1992 level. To be able to include more monitoring stations, and thus increase representativeness, aggregated time series have been calculated for 2000-2015 (the shorter time series) in addition to 1992-2015 (the longer time series). Here the shorter time series follows the longer time series closely and the concentrations in 2015 were slightly lower than at the start of the time series in 2000.

Nitrate in rivers: At European level, river nitrate concentrations have declined steadily over the period 1992-2015. The trend is the same for the time period 2000-2015, but the concentration level is lower. As the shorter time series includes more monitoring stations, this lower level is more representative of the nitrate conditions in European rivers. Agriculture is the largest contributor of nitrogen pollution and, thanks to the EU Nitrates Directive [1] and national measures, nitrogen pollution from agriculture has been reduced in some regions over the last 10-15 years. This reduced pressure is reflected in lower river nitrate concentrations.

Phosphorus in rivers. The average concentrations of orthophosphate in European rivers more than halved over the period 1992-2015. In many rivers the reduction started in the 1980s. The marked decline is also evident for the time period 2000-2015, but contrary to the nitrate results, the average concentration is somewhat higher when using this larger, more representative set of river stations. The decrease in river orthophosphate is thanks to the measures introduced by national and European legislation, in particular the Urban Waste Water Treatment Directive [2], which involves the removal of nutrients. Also, the switch to phosphate-free detergents has contributed to lower phosphorus concentrations.

Phosphorus in lakes. Over recent decades, there has been a gradual reduction in total phosphorus concentrations in many European lakes, although it has not been not as sharp the reduction of orthophosphate in rivers. Again, the concentration level is higher for the shorter, more representative time series. As the treatment of urban waste water has improved, the amount of phosphorus in detergents has been reduced, many waste water outlets have been diverted away from lakes and phosphorus pollution from point sources has gradually become less significant, the total phosphorus concentration in lakes has declined. However, diffuse runoff from agricultural land continues to be a major source of phosphorus in many European lakes. Moreover, phosphorus stored in sediment can keep lake concentrations high and prevent the improvement of water quality despite a reduction in inputs.


Are nitrate concentrations in Europe's groundwater decreasing?

Nitrate in groundwater in Europe

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Current concentrations per country

Groundwater nitrate concentrations primarily reflect the relative proportion and intensity of agricultural activity (see Nitrates in groundwater by countries and groundwater bodies). Between 2013 and 15, 12 out of 22 countries had groundwater bodies (GWBs) with an average nitrate concentration above the EU Groundwater Quality Standard of 50 milligrams of nitrate per litre (mg NO3/l), as laid down in the Groundwater Directive [3]. Belgium, Bulgaria and Cyprus (with few GWBs) had the highest proportion (more than 10 %) of GWBs with an average concentration above the standard, but there were also GWBs above the standard in Austria, Croatia, Czechia, Denmark, Finland, France, Portugal and Slovakia. Groundwater nitrate concentrations were generally low (more than 80 % of GWBs having less than 10 mg NO3/l) in Albania, Estonia, Finland, Iceland, Latvia, Lithuania and Sweden. Groundwater nitrate data were not available for all countries for 2013-15.

Trends in groundwater nitrate concentration (see Fig. 2)

There was a slight increase in average annual mean nitrate concentrations in European groundwater between 1992 and 1997. Until 2002, the concentrations declined somewhat before increasing again towards 2007. Since then the average concentrations have declined, and in 2015 they were at a level closer to the 1992 level. Using the filter in figure 2, the groundwater nitrate time series for individual countries can be illustrated.

The apparent lack of an overall trend in nitrate concentrations in European groundwater is because of  opposing trends for individual GWBs (see Groundwater - nitrate - statistical analysis). A total of 31 % of GWBs have shown decreasing nitrate concentrations since 1992, while 32 % of the GWBs have shown increasing concentrations. For the shorter time series starting in 2000, there were slightly more negative (29 %) than positive trends (25 %), but the proportion of GWBs with no trend was somewhat higher (46 %). The countries with the highest proportions (30-60 %) of GWBs with significant decreasing trends since 1992 were Austria, Finland, Ireland,  Portugal and Slovakia. The former four countries also had the largest average annual relative decrease in concentrations. From the larger selection of countries with time series from 2000, Spain and Switzerland also had a high proportion of decreasing trends, while the larger number of time series for Slovakia gave a higher proportion of increasing than decreasing trends for this time period.


Are nutrient concentrations in Europe's surface waters decreasing?

Nitrate in rivers in Europe

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