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TACKLING DIFFUSE NITRATE POLLUTION: SWAPPING
EUTROPHICATION FOR CLIMATE CHANGE?
D Reay
University of Edinburgh, School of Geosciences, Crew Building, West Mains Road,
Edinburgh, EH9 3JG, UK, E-mail: david.reay@ed.sac.uk
SUMMARY
Large areas of the UK have now been designated ‘Nitrate Vulnerable Zones’ (NVZs)
as a result of the high levels of nitrate in surface and groundwaters. Where nitrate
is lost from the fields through drainage there are two main remediation strategies
available. The first involves the creation of strips of uncultivated land, known as
‘buffer strips’ to intercept the leached nitrate before it gets into drainage waters. The
other is designed to intercept any nitrate already in drainage waters by diverting the
water through natural or constructed denitrifying wetlands.
The use of both buffer strips, often in riparian zones, and denitrifying wetlands, has
become increasingly widespread in the past few years (Mitch et al., 2001; Sabater et
al., 2003), but doubts remain over their suitability in many areas (Dosskey, 2002). As
well as the potential problem of leached nitrate by-passing the buffer strip and wetland
soils, there is also a danger that denitrification in their soils - the primary process of
nitrate removal – will lead to greatly increased nitrous oxide (N2O) emissions (Hefting
et.al., 2003), so swapping a water pollution problem for a climate change issue (Reay,
2004). Here we present a synthesis of N pollution swapping studies to date and
introduce a wide-ranging project aimed at addressing this key issue.
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