NO30050
Written evidence submitted by the European Environment Agency
Nitrates in UK waters in relation to the European average
Purpose of this document
To provide a comparison of concentrations of nitrates in UK waters with those in European waters, following a request to the European Environment Agency by the UK Parliament’s Environment Audit Committee.
Summary
Where comparable data are available, average nitrate concentrations in UK surface waters range from some of the lowest to some of the highest in Europe, with low concentrations in Wales, Scotland and Northern Ireland and higher concentrations in eastern and central England.
As in the rest of Europe, agriculture is the major diffuse pressure of the type typically reflecting nitrate pollution. In the UK, point source pollution from urban waste water affects a relatively high proportion of water bodies.
Background
The European Environment Agency (EEA) provides sound, independent information on the environment for those involved in developing, adopting, implementing and evaluating environmental policy, and also the general public.
This document summarises the information available for surface and ground waters, as at February 2018. Information relating to reporting under the Water Framework Directive second River Basin Management Plans (RBMPs) is provisional, owing to the ongoing review of Member State reporting by the European Commission.
Nutrient enrichment of freshwaters is widespread across Europe. The main sources of nitrogen and phosphorus include point source emissions from urban wastewater treatment plants and industry, and diffuse emissions from agricultural production.
Nitrates in rivers
There is a wide range of reported nitrate concentrations in UK rivers, from some of the lowest to the highest in Europe, reflecting the range of environmental pressures existing across the UK (Fig 1). Lowest concentrations are reported in Scotland and Northern Ireland, with highest levels in eastern England and the Thames region.
Fig 1: Mean annual concentrations of nitrates in European river basin districts (further detail is available through the hyperlink below, including on river concentrations)
http://www.eea.europa.eu/data-and-maps/explore-interactive-maps/nitrate-in-rivers (based on data reported for 2012)
Trends in concentrations measured over time show limited improvement in nitrate concentrations 1992-2012, while those for orthophosphate show significant reduction (Fig 2). While concentrations in UK rivers are higher than compared to the European average, orthophosphate concentrations have declined more rapidly, which likely owes to improved treatment of urban waste water and controls of phosphates in detergents.
Fig 2: Nitrate (left) and orthophosphate (right) concentrations in rivers in Europe and UK, 1992-2012
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Improvement in the degree of urban waste water treatment can be seen (Figs 3.1 and 3.2). UK is included in the central Europe group in Fig 3.1.
Fig 3.1: Changes in urban waste water treatment in Europe, 1995-2015
Fig 3.2: Changes in urban waste water treatment in UK, 1995-2015
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UK collects and treats virtually all of its urban waste water to at least secondary (i.e. biological) treatment.
Typically, tertiary treatment is used for nutrient removal and discharge of urban waste water into sensitive waters. It can also be used to lower concentrations of micropollutants. Compared to nearby countries, the UK has a relatively low proportion of tertiary treatment, at 57% of the total treated. |
Nitrates in rivers, lakes, transitional and coastal surface waters, and groundwaters
Recent reporting under the Water Framework Directive (WFD) provides indications as to the pressures affecting surface and groundwaters across EU member states (25 have reported at the current time, excluding Greece, Ireland and Lithuania). Pressures are reported where they cause failure of the waterbody to meet good ecological status (in surface waters) and good chemical status in surface and groundwaters. While pressures below do not reflect only failures for nitrate standards, the pressures selected are typical of those for which nitrates would fail.
Note: 24 Member States; Total number surface waterbodies: EU = 110862, UK = 9325; groundwater bodies: EU 4,188,338 km2, UK 229,909 km2. EU 24 excludes Greece, Ireland, Lithuania and Slovenia.
RBMP surface water pressures RBMP groundwater pressures
While there can be differences in the ways that countries report, Fig 4 suggests that for the selected pressures on surface and groundwaters, the proportion of waterbodies failing to achieve good ecological or chemical status is similar or lower in the UK than in the 24 EU Member States overall. However, pressures in UK owing to urban waste water, and urban run-off to groundwaters, are more significant than in EU 24.
More specific information is provided for nitrates in groundwater, where there is a common maximum threshold value across the EU of 50mg/l, although some countries, including the UK, apply lower thresholds. In this case, 18.8% (by area) of the 24 EU Member States fail to meet good chemical status in groundwaters owing to nitrate, compared to 27.2% of UK groundwaters.
The information reported on pressures represents those now seen as being current. Concentrations of nitrates in groundwater may reflect pollution which occurred some time ago, owing to the long timescales over which groundwater contamination may act.
Measures to address diffuse pollution
A range of measures have been taken to tackle diffuse pollution. Some of those used in Europe to successfully reduce nutrients are shown in Table 1.
Table 1: Examples of measures to address pollution from diffuse sources
River basin district or country | Measures |
Baltic Sea | The Nordic countries (Denmark, Finland and Sweden) and Baltic States (Estonia, Latvia and Lithunia) have introduced a wide range of measures to reduce diffuse pollution from agriculture (Andersen et al. 2014) |
Nitrate Directive implementation NW-EU Member States | The impact of the Nitrate Directive implementation in the North-Western EU Member States has been reviewed for the period 1995-2008. The most significant environmental effect of the implementation of the Nitrates Directive since 1995 is a major contribution to the decrease of the soil N (nitrogen) balance (N surplus). This decrease is accompanied by a modest decrease of nitrate concentrations since 2000 in fresh surface waters in most countries (Grinsven et al. 2012). |
Denmark | A series of policy action plans have been implemented since the mid-1980s with significant effects on the surplus, efficiency and environmental loadings of N. Over the last 30 years the N-leaching from the field root zone has been halved, and N losses to the aquatic and atmospheric environment have been significantly reduced. |
Leipzig, Germany | Reduction of groundwater nitrate concentration from 40 mg to 20 mg per litre by incentivising organic farming and implementing hydrological measures in drinking water protected areas (BMUB/UBA, 2016) |
Schleswig Holstein, Germany | Nitrogen use has in some cases halved (i.e. from 120 to 60 kilograms per ha) at the level of individual farms (BMUB/UBA, 2016) |
French Loire-Bretagne RBD | Identification of priority catchments and focus on drinking water protected areas. Increase in the number of balanced manure plans on phosphorus from 53% to 81% between 2009-2012 (Loire-Bretagne RBMP 2015) |
Ireland | In addition to application standards required by the Nitrates Directive, no organic or chemical fertiliser nor soiled water can be applied when heavy rain is forecast within 48 hours or when the ground slopes steeply and there is a risk of water pollution (Amery and Schoumans 2014) |
References
Andersen et al. 2014 Mitigating diffuse nitrogen losses in the Nordic-Baltic countries. http://www.sciencedirect.com/science/article/pii/S0167880914002990
Grinsven et al. 2012: Management, regulation and environmental impacts of nitrogen fertilization in northwestern Europe under the Nitrates Directive: a benchmark study. https://biblio.ugent.be/publication/3072131
Dalgaard et al. 2014: Policies for agricultural nitrogen management—trends, challenges and prospects for improved efficiency in Denmark. http://iopscience.iop.org/article/10.1088/1748-9326/9/11/115002/meta
BMUB/UBA, 2016 Water Framework Directive The status of German waters 2015. https://www.umweltbundesamt.de/publikationen/water-framework-directive
Loire-Bretagne RBMP 2015 https://sdage-sage.eau-loire-bretagne.fr/files/live/sites/sdage-sage/files/Planification-gestion%20des%20eaux/Sdage/Elaborer%20le%20Sdage/PUBLI_Sdage16-21_20151104.pdf
Amery, F. and O.F. Schoumans, 2014. Agricultural phosphorus legislation in Europe. Merelbeke, ILVO, 45 p.
EEA European Topic Centre on Inland, Coastal and Marine waters, 2016, European assessment of eutrophication abatement measures across land-based sources, inland, coastal and marine waters http://icm.eionet.europa.eu/ETC_Reports/EutrophicationAbatementReport_201612
February 2018
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