NO30006

Written evidence submitted by Dr Paul Kay, University of Leeds

1. What is the scale of nitrate pollution in the UK and what is the likelihood of the pollution getting worse?

Over recent decades, nitrate concentrations have continued to increase in many rivers due to continued fertiliser use and the long residence times of nitrate in groundwaters (Figure 1) (Heathwaite et al., 1996; Lord et al., 1999; Neal et al., 2006). The annual average nitrate increase in waters is estimated to be 0.1–0.2 mg N l-1 and average nitrate concentrations in a number of English rivers are now approaching 9 mg N l-1 (Neal et al., 2006). Peak concentrations frequently exceed the drinking water limit of 11.3 mg N l-1 and high nitrate concentrations in rivers and groundwater are experienced across many intensive farming areas in England, such as East Yorkshire, Lincolnshire, Norfolk, Suffolk and Cambridgeshire (Grayson et al., 2009; Neal et al. 2008; Neal et al, 2008b; Burt et al. 2008). In contrast, upland areas with less intensive arable production experience much lower nitrate concentrations (Grayson et al., 2009; Kay et al., 2012).

Figure 1: Historic measured nitrate concentrations (mg N l-1) at Hempholme, River Hull, East Yorkshire (Grayson et al., 2009).

What are the consequences of nitrate pollution for the environment and for human life?

Due to nutrient concentrations in waterbodies (P more so than N), eutrophication is now widespread in the UK. Elevated nitrate concentrations in drinking water have been associated with impacts in humans, including methemoglobinemia and reproductive and developmental problems (Fan and Steinberg, 1996). The water industry must therefore remove nitrate from water which costs an estimated £16 M per annum (Pretty et al., 2000).

How important are the different sources of nitrate pollution? Where should action be undertaken?

70-80 % of nitrate in English rivers is thought to come from agriculture, predominantly the application of fertilisers (Neal et al., 2006). It has previously been postulated that, whilst some progress has been made in reducing pollution from point sources, diffuse pollution, particularly that from agriculture, still represents as large aproblem as ever (Defra, 2004).

How effectively does Government regulate nitrate usage so that nitrate pollution is reduced as quickly as possible?

Recent work has suggested that agricultural stewardship could help to control this problem at source but that, whilst there is scientifically robust evidence to show the effectiveness of some measures for reducing nutrient pollution, a dearth of data exists to describe and explain the effects of many (Kay et al., 2009). Moreover, these papers and others (Krutz et al., 2005) highlighted the almost complete lack of evidence at the catchment scale which is particularly important given that this is the unit employed in the management of rivers (e.g. EC, 2000).

Some studies have examined the impacts of Nitrate Vulnerable Zones (NVZs). Neal et al. (2006) have hypothesised that NVZs may be one of the reasons for decreasing nitrate concentrations in the Thames at Howberry Park although Lord et al. (2007) found that the overall impact of NVZ measures was small, with only a 3% reduction in nitrate leaching losses and nitrate levels still exceeding 11.3 mg N l-1 in many of the monitored catchments. Other studies (Kay et al., 2012; Worrall et al., 2009) similarly found little impact at the catchment scale, perhaps because NVZs have not been found to change farmers’ behaviour (Barnes et al., 2009). This would indicate that they were already operating in a fashion to meet NVZ requirements or that policing of their implementation is not rigorous enough to require farmers to actually change.

Despite the England Catchment Sensitive Farming Delivery Initiative (ECSFDI) being the main mechanism by which farm advice has been delivered in England in recent years no studies have measured its impact on water quality. Instead, the number of farmers attending meetings seems to be taken as a measure of success. It has been postulated that targeted advice and financial incentives could achieve promising results although the actions taken often depend on the personal relationships between farmers and advisors (Posthumus et al., 2011) and the intrinsic view of conservation held by the farmer (Robinson, 2006). Kay et al. (2012) showed in an NVZ and ECSFDI catchment that during the previous 20–30 years N concentrations have varied although the general trend has not changed. This concurs with some other recent work that found the Environment Agency of England and Wales’ (EA) work to reduce diffuse pollution has had little impact (National Audit Office, 2010; Howarth, 2011).

Posthumus et al. (2011) found that the money available to farmers through Environmental (or Countryside) Stewardship was often insufficient to allow them to change their practices. Moreover, the schemes were too inflexible to allow farmers to respond to changes in markets. Two recent criticisms made of the EA’s work were that it worked with a lack

of information on diffuse pollution sources and struggled to provide evidence of the impacts of its actions. It should be recognised however that the EA itself believes that its legal power to control nutrient pollution is limited which highlights that policy reform may be needed in addition to improved scientific understanding to address the problem. Further work has also confirmed that farmers do not feel sufficiently threatened by prosecution to change to more environmentally friendly practices (Posthumus et al., 2011). In order to address problems in identified source areas it will be necessary to further convince farmers that they are part

of the problem and need to help find the solution (Barnes et al., 2009; National Audit Office, 2010; Howarth, 2011). Moreover, in future, the money spent on mitigation options could achieve much greater gains in terms of the health of the aquatic environment if it was targeted towards key areas of land contributing runoff to streams rather than spread over other areas of catchments.

What more could Government do to reduce nitrate pollution as quickly as possible?

Posthumus et al. (2011) have stated that improved monitoring (in terms of spatial

and temporal intensity and overall monitoring campaign length) is needed to fill knowledge gaps and, even though this may be expensive, it is likely to be cheaper than the costs of water pollution (Howarth, 2011). This will better establish key pollution source areas in which to target stewardship measures and measure the impacts of these and allow us to move beyond making assessments based on qualitative and anecdotal evidence (Posthumus et al., 2011). Better information is also needed to describe the actions taken by farmers as at present there is much debate about its accuracy and usefulness. Many farmers will need to be further incentivised to do this through greater financial rewards or an increased threat of prosecution. Furthermore, there is still a need to ensure that farmers recognise themselves as part of the problem and the solution. Previous work (Kay et al., 2009, 2012) has suggested that it is the implementation and regulation of stewardship actions, rather than their inherent ability to alter water quality, that are likely to be the most important factors in the success of such measures or otherwise at the catchment scale.

January 2018

References

Barnes, A.P., Willock, J., Toma, L. (2009). Farmer perspectives and practices regarding

water pollution control programmes in Scotland. Agricultural Water Management. 96,

1715–1722.

Burt, T.P., Howden, N.J.K., Worrall, F., Whelan, M.J. (2008) Importance of long-term monitoring for detecting environmental change: lessons from a lowland river in south east England. Biogeosciences 5(6), 1529-1535.  

Defra, (2004). Developing Measures to Promote Catchment Sensitive Farming: A Joint

Defra-HM Treasury Consultation. Defra, London.

Fan, A.M., Steinberg, V.E. (1996). Health implications of nitrate and nitrite in drinking

water: an update on methemoglobinemia occurrence and reproductive and

developmental toxicity. Regul. Toxicol. Pharmacol. 23 (1), 35–43.

Gale, I.N., Rutter, H.K. (2006). The Chalk aquifer of Yorkshire. Research Report RR/06/04.  British Geological Survey, Keyworth, UK

Grayson, R., Kay, P, Nixson, N. (2009). Identification of nitrate sources in the River Hull catchment. Leeds University report for Yorkshire Water

Heathwaite, A.L., Johnes, P.J. and Peters, N.E. (1996). Trends in nutrients. Hydrological Processes, 10(2), 263-293.

Howarth, W., 2011. Diffuse water pollution and diffuse environmental laws. J.

Environmental Law 23 (1), 129–141.

Kay P; Grayson R; Phillips M; Stanley K; Dodsworth A; Hanson A; Walker A; Foulger M; McDonnell I; Taylor S. (2012). The effectiveness of agricultural stewardship for improving water quality at the catchment scale: Experiences from an NVZ and ECSFDI watershed, Journal of Hydrology, 422, pp.10-16.

Kay P; Edwards AC; Foulger M. (2009). A review of the efficacy of contemporary agricultural stewardship measures for ameliorating water pollution problems of key concern to the UK water industry, Agricultural Systems, 99, pp.67-75.

Krutz, L.J., Senseman, S.A., Zablotowicz, R.M., Matocha, M.A. (2005). Reducing

herbicide runoff from agricultural fields with vegetative filter strips: a review.

Weeds Sci. 53, 353–367.

Lord, E.I., Johnson, P.A. and Archer, J.R. (1999). Nitrate Sensitive Areas: a study of large scale control of nitrate loss in England. Soil Use and Management, 15(4), 201-207.

National Audit Office. (2010). Takling diffuse water pollution in England. NAO report.

Neal, C., Jarvie, H.P., Neal, M., Hill, L. and Wickham, H. (2006). Nitrate concentrations in river waters of the upper Thames and its tributaries. Science of the Total Environment, 365(1-3), 15-32.

Neal, C., Davies, H., Neal, M. (2008) Water quality, nutrients and the water framework directive in an agricultural region: The lower Humber Rivers, northern England. Journal of Hydrology 350 (3-4), 232-245.

Neal, C., Jarvie, H.P., Love, A., Neal, M., Wickham, H., Harman, S. (2008b) Water quality along a river continuum subject to point and diffuse sources. Journal of Hydrology
350 (3-4), 154-165.

Posthumus, H., Deeks, L.K., Fenn, I., Rickson, R.J. (2011). Soil conservation in two

English catchments: linking soil management with policies. Land Degrad. Dev.

22, 97–110.

Pretty, J.N., Brett, C., Gee, D., Hine, R.E., Mason, C.F., Morison, J.I.L., Raven, H.,

Rayment, M.D., van der Bijl, G. (2000). An assessment of the total external costs

of UK agriculture. Agric. Syst. 65 (2), 113–136.

Robinson, G.M. (2006). Ontario’s environmental farm plan: evaluation and research

agenda. Geoforum 37, 859–873.

Worrall, F., Spencer, E., Burt, T.P., (2009). The effectiveness of nitrate vulnerable zones

for limiting surface water nitrate concentrations. J. Hydrol. 370 (1–4), 21–28.