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You are here: Home / Data and maps / Indicators / Oxygen consuming substances in rivers / Oxygen consuming substances in rivers (CSI 019) - Assessment published Dec 2010

Oxygen consuming substances in rivers (CSI 019) - Assessment published Dec 2010

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Generic metadata

Topics:

Water Water (Primary topic)

Tags:
soer2010 | freshwater | csi | freshwater quality | bod5 | ammonium | water | thematic assessments | rivers
DPSIR: State
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CSI 019
Dynamic
Temporal coverage:
1992-2008
Geographic coverage:
Albania Austria Belgium Bulgaria Cyprus Czech Republic Denmark Estonia Finland France Germany Greece Hungary Iceland Ireland Italy Latvia Liechtenstein Lithuania Luxembourg Macedonia (FYR) Malta Netherlands Norway Poland Portugal Romania Slovakia Slovenia Spain Sweden Switzerland Turkey United Kingdom
 
Contents
 

Key policy question: Is organic matter and ammonium pollution of rivers decreasing?

Key messages

Concentrations of BOD and total ammonium have decreased in European rivers in the period 1992 to 2009 (Fig. 1), mainly due to general improvement in wastewater treatment.

See also WISE interactive maps:

 Mean annual BOD in rivers and Mean annual Total Ammonium in rivers




Biochemical Oxygen Demand (BOD5) and total ammonium concentrations in rivers between 1992 and 2008

Note: Concentrations are expressed as the average of annual mean concentrations. Up to 3-year gaps of missing values have been interpolated or extrapolated. Only complete series with no missing values after this interpolation/extrapolation are included. Number of river monitoring stations included in analysis per country is noted in brackets. BOD7 data has been recalculated into BOD5 data.

Data source:
Downloads and more info

BOD5 concentrations in rivers between 1992 and 2008 in different geographic regions of Europe

Note: Concentrations are expressed as the average of annual mean concentrations. Up to 3-year gaps of missing values have been interpolated or extrapolated. Only complete series with no missing values after this interpolation/extrapolation are included. The number of river monitoring stations included in the analysis per geographic region is noted in brackets. BOD7 data (Estonia, Finland, Lithuania (1996-2008), Latvia (1996-2001)) has been recalculated into BOD5 data.

Data source:

Waterbase - Rivers (version 10)

http://www.eea.europa.eu/data-and-maps/data/waterbase-rivers-6

Downloads and more info

Total ammonium concentrations in rivers between 1992 and 2008 in different geographic regions of Europe

Note: Concentrations are expressed as the average of annual mean concentrations. Up to 3-year gaps of missing values have been interpolated or extrapolated. Only complete series with no missing values after this interpolation/extrapolation are included. Number of river monitoring stations included in analysis per country and region is noted in brackets.

Data source:
Downloads and more info

BOD5 concentrations in rivers between 1992 and 2008 in different sea regions of Europe

Note: Geographical coverage: Atlantic Ocean, Baltic Sea, Black Sea, Mediterranean Sea and the North Sea.

Data source:
Downloads and more info

Total ammonium concentrations in rivers between 1992 and 2008 in different sea regions of Europe

Note: Geographical coverage: Atlantic Ocean, Baltic Sea, Black Sea, Mediterranean Sea and the North Sea.

Data source:
Downloads and more info

Key assessment

Introduction
Organic matter, measured as Biochemical Oxygen Demand (BOD) and ammonium, are key indicators of the oxygen content of water bodies. Concentrations of these parameters normally increase as a result of organic pollution caused by discharges from waste water treatment plants, industrial effluents and agricultural run-off. Severe organic pollution may lead to rapid de-oxygenation of river water, a high concentration of ammonia and the disappearance of fish and aquatic invertebrates.

The most important sources of organic waste load are: household wastewater; industries such as paper industries or food processing industries; and silage effluents and manure from agriculture. Increased industrial and agricultural production, coupled with a greater percentage of the population being connected to sewerage systems, initially resulted in increases in the discharge of organic waste into surface water in most European countries after the 1940s. Over the past 15 to 30 years, however, the biological treatment (secondary treatment) of waste water has increased, and organic discharges have consequently decreased throughout Europe. See also CSI 024: Urban waste water treatment.


Overall trend in BOD and total ammonium (Fig. 1)
In European rivers, the oxygen demanding substances measured as BOD and total ammonium have decreased by 50 % (from 4.7 mg/l to 2.4 mg O2/l) and 66 %  (from 800 to 275µg N/l),respectively, from 1992 to 2009 (Fig. 1). The decrease is due mainly to improved sewage treatment resulting from the implementation of the Urban Wastewater Treatment Directive. The economic downturn of the 1990s in central and eastern European countries also contributed to this fall, as there was a decline in heavily polluting manufacturing industries. In recent years, however, the downward trends in BOD across Europe have generally levelled. This suggests that either further improvement in wastewater treatment is required or that other sources of organic pollution, for example from agriculture, require greater attention, or both.

Overall there has been a significant decrease in BOD concentrations at 55.8% of the stations (an additional 6.1 % marginally significant) on the European rivers between 1992 and 2009, while there has been a significant increase at only 2.9 % of the stations (an additional 0.8% marginally significant). Similarly, there has been a significant decrease in total ammonium concentrations at 54.4 % of the stations (an additional 5.2 % marginally significant), while there has been a significant increase at only 3.7 % of the stations (an additional 1.1 % marginally significant).

BOD and total ammonium time series and trends per geographic regions (Fig. 2 and Fig. 3)

The largest decrease of BOD from 1992 to 2009 has occurred in the southern European rivers (63 %), represented by the Spanish rivers only (Figure 2). However, their concentrations are still higher than concentrations in other regions except for the southeastern Europen rivers with the highest concentrations in Europe (above 4 mg O2/l). The second largest decrease has occurred in the western European rivers (48 %) with the lowest concentrations since 2001 (below 2 mg O2/l). The decrease is similar in the southeastern (42 %) and the eastern European rivers (43 %). The northern European rivers have the lowest decrease (24 %). Their concentrations are represented by the Finnish rivers with low concentrations since 1992 (around 2 mg O2/l).

The largest proportion of monitoring stations with significant or marginally significant negative trend in BOD is found for the western and the southern European rivers, while the lowest proportion is found for the northern European rivers. Based on the sum of significant and marginally significant trends the trends for the rivers in different geographic regions are: West: 68.1 % negative, 0.7 % positive, South: 62.7 % negative, 1.9 % positive, East: 58.6 % negative, 7.2 % positive, Southeast: 50 % negative, 8.8 % positive, North: 26.7 % negative, 6.7 % positive). Countries with more than 60 % of the stations with negative trend in BOD are Hungary, the United Kingdom, Spain, the Czech Republic, Luxembourg, Ireland, Austria, France, Denmark, Slovakia and Slovenia.

The decrease of total ammonium from 1992 to 2009 is the largest in the eastern (77 %) and the western European rivers (75 %), followed by the decrease in the southeastern European rivers (66 %) (Figure 3). The concentrations in the southern European rivers (Spanish rivers, respectively) have decreased by 47 %. These concentrations are very fluctuating and the highest in Europe (above 900 µg N/l since 2006). On the contrary, concentrations in the northern European rivers are the lowest (below 40 µg N/l since 2007) and relatively stable with a decrease of 22 %.
The largest proportion of monitoring stations with significant or marginally significant negative trend in total ammonium is found for the western and eastern European rivers, while the lowest proportion is found for the northern European rivers as follows: West: 71.2 % negative, 3.0 % positive, East: 64.5 % negative, 2.8 % positive, Southeast: 62.1 % negative, 2.1 % positive, South: 54.1 % negative, 7 % positive, North: 27.8 % negative, 11.5 % positive (sum of significant and marginally significant trends). Countries with 60 % or more stations with negative trend in total ammonium are Norway, Austria, Bulgaria, France, Latvia, Luxembourg, FYR of Macedonia, Belgium, Poland, Ireland, the United Kingdom, Germany, Lithuania and Slovenia.

BOD and total ammonium time series and trends per sea regions (Fig.  4 and Fig. 5)
The largest decrease of BOD from 1992 to 2009 has occurred in the rivers draining to the Mediterranean Sea (72 %), followed by the decrease in the rivers draining to the Black Sea (52 %) (Figure 4). The decrease is somewhat lower in the rivers draining to the Greater North Sea (34 %) and the Celtic Seas, the Bay of Biscay and the Iberian Coast (30 %). The lowest decrease has occurred in the rivers draining to the Baltic Sea (24 %) with more or less stable concentrations since 1992 (around 2 mg O2/l). The concentrations among rivers in different sea catchments have become similar in recent years (Baltic Sea - Mediterranean Sea: below 2 mg O2/l; Greater North Sea - Black Sea: above 2 mg O2/l), except for the rivers draining to the Celtic Seas, the Bay of Biscay and the Iberian Coast. Their concentrations are the highest in Europe (about 3 mg O2/l) and have increased since 2005.

The trend analysis also shows that the largest proportion of monitoring stations with significant or marginally significant negative trend in BOD is found for the rivers draining to the Mediterranean Sea, while the lowest proportion is found for the rivers draining to the Baltic Sea (Mediterranean Sea: 80.4 % negative, 4.2 % positive, Black Sea: 70.9 % negative, 1.5 % positive, Greater North Sea: 59.4 % negative, 2.8 % positive, Celtic Seas, Bay of Biscay, Iberian Coast: 42.7 % negative, 1.9 % positive, Baltic Sea: 39.9 % negative, 11.9 % positive; sum of significant and marginally significant trends).

The largest decrease of total ammonium from 1992 to 2009 has occurred in the rivers draining to the Black Sea, the Greater North Sea, the Mediterranean Sea (all 74 %) and the Baltic Sea (73 %) (Figure 5). Concentrations in these sea catchments have become similar in recent years (between 130 and 300 µg N/l). Furthermore, the decrease is similar for the rivers draining to the Arctic Ocean (48 %), and the Celtic Seas, the Bay of Biscay and the Iberian Coast (46 %). The concentrations of the first are the lowest in Europe (about 5 µg N/l), while the concentrations of the second are very fluctuating and the highest in Europe (above 800 µg N/l since 2006).

The largest proportion of monitoring stations with significant or marginally significant negative trend in total ammonium is found for the rivers draining to the Greater North Sea and the lowest proportion is found for the rivers draining to the Arctic Ocean (Greater North Sea: 69.6 % negative, 2.8 % positive, Black Sea: 59.9 % negative, 3.0 % positive, Mediterranean Sea: 59.2 % negative, 4.9 % positive, Celtic Seas, Bay of Biscay, Iberian Coast: 58.2 % positive, 7.0 % negative, Baltic Sea: 54.3 % negative, 6.3 % positive, Arctic Ocean: 30.8 % negative, 7.7 % positive; sum of significant and marginally significant trends).

BOD and total ammonium present concentrations by countries

See WISE interactive maps for information displayed for countries, for river basin districts (BOD) and for individual stations: 

Mean annual BOD in rivers and Mean annual Total Ammonium in rivers

Countries with more than 50 % of all river stations with the lowest BOD concentrations (class 1: < 1.4 mg O2/l) for 2009 or the latest reported year are the United Kingdom, Latvia, Austria, Croatia, Spain, the Netherlands, Ireland, Denmark and Slovenia. Countries with more than 20 % of the stations with the highest BOD concentrations (class 5: >= 4 mg O2/l) are Lithuania, Romania, Hungary, Belgium, Bulgaria, Sweden, Albania, Turkey and FYR of Macedonia.

Countries with more than 50 % of all river stations with the lowest total ammonium concentrations (class 1: < 0.04 mg N/l) for 2009 or the latest reported year are Spain, Austria, Cyprus, Croatia, Sweden, Bosnia and Herzegovina, Ireland, Slovenia, Finland, the United Kingdom, Iceland, Liechtenstein and Norway. Countries with 20 % or more stations with the highest total ammonium concentrations (class 5: >= 0.4 mg N/l) are FYR of Macedonia, Greece, Romania, Bulgaria, Luxembourg, Albania and Belgium.





Data sources

More information about this indicator

See this indicator specification for more details.

Contacts and ownership

EEA Contact Info

Peter Kristensen

Ownership

EEA Management Plan

2011 1.4.2 (note: EEA internal system)

Dates

Frequency of updates

Updates are scheduled once per year in July-September (Q3)
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Denmark
Phone: +45 3336 7100