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Freshwater - State and impacts (Belgium)

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This content has been archived on 21 Mar 2015, reason: A new version has been published
Nitrates in groundwater in the Belgian regions.
Topic
Freshwater Freshwater
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NFP-Belgium
Organisation name
NFP-Belgium
Reporting country
Belgium
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Organisation website
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Last updated
22 Dec 2010
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CC By 2.5
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NFP-Belgium
Published: 05 Nov 2010 Modified: 21 Mar 2015 Feed synced: 22 Dec 2010 original
Key message

High concentrations of nitrate in Belgian groundwater remains a point of concern

In rural areas, the degradation of groundwater quality is largely the result of excessively high concentrations of nitrate which usually appear when the amount of nitrogen fertilisers applied go beyond the needs of the crops. In urban areas, contamination of groundwater by nitrates derived mainly from the lack of sewers or leaks in the sewage network of residual urban waste water.

Generally, the highest levels of contamination (more than 50 mg NO3-/l) are observed in the northern part of Belgium (Flemish Region), especially in the less deep phreatic groundwater bodies (e.g. Quaternary sands, Tertiary Brusselian and Yperian sands, Quaternary Meuse-Rhine deposits and Terrace sediments…), in areas where agricultural activity and/or the density of population is particularly high.

Due to a change of monitoring system and monitoring practices between 2003 and 2004, no long-term trends can be determined in the three Belgian regions. For the Flemish Region, a complete new groundwater monitoring network consisting of 2.100 multi-level wells (located in agricultural areas) has been operational since 2004. For the Walloon Region, the application of the WFD required a restructuring and a redeployment of the existing groundwater monitoring network in 2006, in order to improve its representativeness by taking into account the less characterised water bodies and the non-exploited resources. The Walloon WFD network includes +/- 600 sites of control.

The nitrate concentrations in groundwater throughout Belgium have increased in recent years: the proportion of monitoring points with average nitrate concentrations higher than 25 mg/l went from 46,4 % (in 2004) to 49,8 % (over the period 2007-2008). This trend is not necessarily linked to the current development of agricultural practices, which goes towards a reduction in the application of (organic and mineral) nitrogen fertilisers. Next to the availability of external N-sources the degree of contamination of the groundwater bodies depends also on other factors such as rainfall, transfer time to aquifers, local manure, and the vulnerability of the shallow aquifers or the quantity of nitrogen still present in the soils. Groundwater bodies are ‘slow-response’ systems in general so that, due to the travel times of nitrate bearing infiltration water, effects of measures in shallow groundwater are visible earliest after several months, usually after years and locally after decennia.

 

Flemish Region

Walloon Region

Brussels Capital Region

Monitoring points

20041

20071

2004

2008

2004

2007-2008

Points sampled

1728

2031

439

615

17

24

% > 25 mg NO3/l2

45,4

48,1

50,6

55,9

41,2

37,5

% > 50 mg NO3/l3

35,7

38,2

11,1

13,8

29,4

25

1: Nitrate concentration measured in autumn

2 : Target value for (European Nitrate Directive)

3 : The European Nitrate Directive stipulates that the concentration anywhere in groundwater must not be higher than 50mg nitrate/l (norm for drinkability)

Sources : VMM (MAP- groundwater monitoring network), MIRA, IBGE-BIM, SPW-DGARNE (Survey nitrate )

 

Geographic coverage

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The country assessments are the sole responsibility of the EEA member and cooperating countries supported by the EEA through guidance, translation and editing.

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