Nutrients in freshwater (CSI 020) - Assessment DRAFT created Sep 2013
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- 02 Oct 2012 - Nutrients in freshwater (CSI 020) - Assessment published Oct 2012
- 20 Dec 2010 - Nutrients in freshwater (CSI 020) - Assessment published Dec 2010
- 29 Jan 2009 - Nutrients in freshwater (CSI 020) - Assessment published Jan 2009
- 29 Nov 2005 - Nutrients in freshwater (CSI 020) - Assessment published Nov 2005
- 27 Jul 2004 - Nutrients in rivers
- 09 Feb 2004 - Nitrogen and phosphorus in rivers
- 01 Jun 2001 - Phosphorus concentrations in rivers
Water (Primary topic)
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
- CSI 020
Key policy question: Are concentrations of nutrients in our freshwaters decreasing?
- Average nitrate concentrations in European groundwaters increased from 1992 to 1998, but have declined again since 2005.
- On average, the nitrate concentration in European rivers declined by 0.5 mg N/l over the period 1992 to 2011 (20% relative to the average concentration), reflecting the effect of measures to reduce agricultural inputs of nitrate as well as improvement in wastewater treatment.
- Average orthophosphate concentrations in European rivers have decreased markedly over the last two decades- On average concentrations declined by 0.08 mg P/l between 1992 and 2011 (72% decrease relative to the average concentration). Also average lake phosphorus concentration decreased over the period 1992-2011 (on average by 0.008 mg P/l, or 27% relative to the average concentration). The decrease in phosphorus concentrations reflects both improvement in wastewater treatment and reduction in phosphorus in detergents.
- Overall, reductions in the levels of freshwater nutrients over the last two decades primarily reflect improvements in wastewater treatment. Emissions from agriculture continue to be a significant source.
Nitrate in groundwaters: There was a slight increase in average annual mean nitrate concentration in European groundwaters from 1992 to 1998. Since 2005 the concentrations have declined again, and in 2011 the mean concentration had almost returned to the 1992 level.
Nitrate in rivers: At the European level nitrate concentrations have declined by 0.5 mg N/l on average,or 20% compared to the average concentration over the period.
Agriculture is the largest contributor of nitrogen pollution, and due to the EU Nitrate Directive and national measures the nitrogen pollution from agriculture has been reduced in some regions during 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 1992-2011. In many rivers the reduction started in the 1980s. The decrease is due to the measures introduced by national and European legislation, in particular the Urban Waste Water Treatment Directive , which involves the removal of nutrients. Also the change to use of phosphate-free detergents has contributed to lower phosphorus concentration.
Phosphorus in lakes. During the past few decades there has also been a gradual reduction in phosphorus concentrations in many European lakes. As treatment of urban wastewater has improved, phosphorus in detergents reduced, and many waste water outlets have been diverted away from lakes, phosphorus pollution from point sources is gradually becoming less important. However, diffuse runoff from agricultural land continues to be an important source of phosphorus in many European lakes. Moreover, phosphorus stored in the sediments can keep lake concentrations high and prevent improvement of water quality despite a reduction in inputs.
Specific policy question: Are nitrate concentrations in our groundwater decreasing?
Present concentrations per country
See also WISE interactive maps: Nitrates in groundwater by country
Groundwater nitrate concentrations primarily reflect the relative proportion and intensity of agricultural activity. In 2011, 20 out of 32 countries had groundwater monitoring stations with average concentration above the threshold Groundwater Quality Standard of 50 mg NO3/l as laid down in the Groundwater Directive (2006/118/EC) . Belgium and Spain had the highest proportion (more than 20%) of groundwater stations with average concentration above the standard, but there was also a high proportion (10-20%) of groundwater stations above the standard in Austria, Cyprus, Czech Republic, Denmark, Germany and the Netherlands. Groundwater nitrate concentrations were generally low (most or all groundwater stationsless than 10 mg NO3/l) in Albania, Bosnia and Herzegovina, Croatia, Finland, Iceland, Lithuania, Norway, Serbia and Sweden.
Trends in groundwater nitrate concentration (see also Fig. 1)
Looking at individual groundwater bodies (GWBs) there is wide variation in trends, with 28% of the GWBs showing significantly decreasing nitrate concentrations since 1992 (an additional 3% showed a marginally significant decrease), while 24% of the GWBs showed significantly increasing concentrations (an additional 3% marginally significant). The countries with the highest proportions of GWBs with significant decreasing trends were the Netherlands, Portugal and Slovakia.Along with Slovenia these countries also had the largest absolute (4.6-9.1 mg NO3/l on average) and relative (21-58 % compared to the average concentration) decrease over the period.
Geographical region time series and trends (Fig. 2)
There is marked variation in groundwater nitrate concentrations between different geographical regions of Europe. In Western Europe the concentrations are high, and the levels have been fairly stable over the whole period, with similar proportions of decreasing and increasing trends, and about half the GWBs with no significant trend. The other regions are represented by far fewer GWBs. The results show that Northern Europe is at the other end of the scale compared to Western Europe, with low concentrations. But as for Western Europe the levels have been fairly stable over time. In Eastern Europe the average concentrations started declining after 1996, but increased again after 2003. However, after a marked decline between 2010 and 2011, the levels are currently (2011) at about the same level as the start of the time series, and about 10 mg NO3/l lower than in Western and Southeastern Europe. In Southeastern Europe (only represented by Bulgaria) the concentration levels were high in the period 1997-2000. Disregarding this peak, there is still an overall increasing trend, with levels now slightly higher than in Western Europe. However, as for the other regions, the proportions of significantly increasing and decreasing trends were similar.
Specific policy question: Are concentrations of nutrients in our surface waters decreasing?
Present concentrations per country
See WISE interactive maps: Mean annual Nitrates in rivers
Rivers draining land with intense agriculture or high population density generally have the highest nitrate concentrations. Rivers with nitrate concentrations exceeding 5.6 mg N/l are found predominantly in northwest France and southeast UK and northern Spain. However, a high proportion (more than 20%) of rivers with concentrations exceeding 3.6 mg N/l are found in many other countries, particularly in Belgium, the Czech Republic, Denmark, Germany and Luxembourg. Rivers in the more sparsely populated Northern Europe and mountainous regions generally have average concentrations less than 0.8 mg N/l.
Trends in nitrate concentration (see also Fig. 1)
Overall there has been a significant decrease in river nitrate concentrations at 38% of the stations (an additional 5% marginally significant), while there has been a significant increase at 10% of the stations (an additional 42% marginally significant). The countries with the highest proportions of river stations with significant decreasing trends are the Czech Republic, Denmark, Germany and Slovakia. Across Europe as a whole, the rate of improvement is still slow, reflecting the continued significance of agricultural nitrogen emissions. The Czech Republic, Denmark, Germany had the largest average decrease over the period (1.1-3.4 mg N/l, or 33-69% compared to the average concentration), while Bulgaria and Sweden also had large relative decrease (41 and 40 %, respectively).
Geographical region time series and trends (Fig. 3)
There is marked variation in river nitrate concentrations between regions, with Western Europe rivers having 2-3 mg N/l higher concentrations than Northern Europe, on average, and the remaining regions being somewhere in between. Except for the increasing trend in Southern Europe (0.6 mg N/l over the period on average), nitrate concentrations are generally decreasing (by on average 0.1, 0.3, 0.7 and 0.7 mg N/l over the period for North, East, Southeast and West, respectively)).
Sea region time series and trends (Fig. 4)
Nitrate concentrations in rivers vary markedly between the sea regions of Europe. The average nitrate concentration in rivers draining to the Greater North Sea is currently around 1-2 mg N/l higher than that in rivers feeding the the Black Sea, the Celtic Seas, Bay of Biscay and the Iberian Coast, 2-3 mg N/l higher than the rivers feeding the Baltic Sea and the Mediterranean Sea and around 3.5 mg N/l higher than that of rivers draining to the Arctic Ocean. The difference compared to the other sea regions was even larger at the beginning of the time series.
The Greater North Sea is the only sea region where there is a marked decreasing trend (1.0 mg N/l decrease over the period on average and 60% significantly declining trends). However, both for the Arctic Ocean, the Baltic Sea, the Black Sea and the Mediterranean Sea regions there are markedly more significant decreasing than increasing trends, but here the number of not significant trends is larger. For the Celtic Sea, Bay of Biscay and the Iberian Coast region there is virtually no trend, with equally many significantly increasing and decreasing trends, and a majority of the stations (64%) having no significant trend.
Present concentration per country
Relatively low concentrations of phosphorus in rivers and lakes are found in e.g. Northern Europe (Norway, Sweden, and Finland), the Alps, and the Pyrenees and Scotland, predominantly reflecting regions of low population density and/or high levels of wastewater collection and treatment. In contrast, relatively high concentrations (greater than 0.1 mg P/l P) are found in several regions with high population densities and intensive agriculture, including: Western Europe (southeast UK, the Netherlands, Belgium, western Germany, northernFrance), Southern Europe (southern Italy, central Spain and mid-Portugal), Eastern Europe (Hungary, Slovakia, Czech Republic, Poland), and South-Eastern Europe (Bulgaria, Former Yugoslav Republic of Macedonia, Serbia, Kosovo under UNSC Resolution 1244/99, Romania, Serbia, Turkey). Given that phosphorus concentrations greater than 0.1-0.2 mg P/l P are generally perceived to be sufficiently high to result in freshwater eutrophication, the observed high values in some regions of Europe are of particular concern.
Trends in phosphorus concentration (see also Fig. 1)
Average concentrations of orthophosphate in European rivers have decreased markedly since 1992. At 48% of the river stations there has been a significant decline in orthophosphate concentration since 1992 (an additional 6% marginally significant), while there has been a significant increase at only 7% of the stations (an additional 2% marginally significant). For lakes there has been a significant decline in total phosphorus concentrations since 1992 at 31% of the stations (an additional 7% marginally significant), while there has been a significant increase at 11% of the stations (an additional 2% marginally significant). This decrease reflects the success of legislative measures to reduce emissions of phosphorus such as those required by the Urban Waste Water Treatment Directive  (UWWTD).The countries showing the strongest decreasing trend (in terms of % significant decreasing trends, relative and/or absolute decrease over the period) were Austria (rivers only), Belgium (no consistent lake series), the Czech Republic (no consistent lake series), Denmark (lakes only), France (no consistent lake series), Germany (lakes only), the Netherlands (no consistent river series), Switzerland and the UK (rivers only).These are all countries with a large proportion of the population (more than 80%) connected to wastewater treatment (to a large extent tertiary), andexcept the Czech Republic and Switzerland all these countries were supposed to comply with the UWWTD by 2005 . There are also other countries with high treatment levels (all also with compliance deadline in 2005), but where this has been the situation for some time, thus expecting less trend in phosphorus concentrations (Finland, Sweden) or where there are no consistent river or lake phosphorus dataseries (Greece, Italy, Spain).
Sea region time series and trends (Fig. 6)
Orthophosphate concentrations are generally lowest for rivers draining to the Baltic Sea and in particular the Arctic Ocean. For the other sea regions the concentration levels are currently fairly similar, but at the start of the time series, concentrations were highest for rivers draining to the Greater North Sea and the Celtic Seas, Bay of Biscay and the Iberian Coast. There are more significant decreasing than increasing trends in all regions, but the strongest decreasing trends are found in the Greater North Sea (54% significant decreasing trends, 0.13 mg P/l decline over the period on average) and the Celtic Seas, Bay of Biscay and the Iberian Coast regions (68% significant decreasing trends, 0.12 mg P/l decline over the period on average).
Geographical region time series and trends (Fig. 5 and Fig.7)
Northern Europe has markedly lower river orthophosphate concentrations than in the other regions of Europe. The same pattern is seen for lake total phosphorus concentrations. River orthophosphate concentrations have decreased in Eastern (54% significant decreasing trends, 0.06 mg P/l decline over the period on average) and Western Europe (64% significant decreasing trends, 0.12 mg P/l decline over the period on average). In Northern Europe there has hardly been any changes, while in Southeastern Europe the concentrations are highly variable, giving no clear trend overall.
Lake total phosphorus (Fig. 7) shows a similar strong decrease for Western Europe (53% significant decreasing trends, 0.04 mg P/l decline over the period on average), but the trend may be leveling out from 2005. There is virtually no trend in lake total phosphorus in Northern and Eastern Europe.
The difference between lake and river data for Eastern Europe is partly caused by the inclusion of a number of Czech and Slovak stations in the rivers dataset, with predominantly negative trends. Overall, the trend statistics for Eastern Europe lake total phosphorus indicates mainly decreasing trends (58% significant), but this decrease is hardly visible from the mean concentration time series (0.003 mg P/l decline over the period on average).
 The (UWWD): Council Directive 91/271/EEC concerning urban waste-water treatment.
Waterbase - Rivers
provided by European Environment Agency (EEA)
Waterbase - Lakes
provided by European Environment Agency (EEA)
Waterbase - Groundwater
provided by European Environment Agency (EEA)
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