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Groundwater pollution remediation and protection 271

Fig. 7.11 Areas of Nitrate Vulnerable
Zones (NVZs) in England. The following
rules apply under this mandatory,
uncompensated scheme based on ‘good
agricultural practice’: (i) closed periods for
inorganic nitrogen (fertilizer) applications
during the autumn and winter and for
organic nitrogen (manure) applications
during the autumn for both arable and
grass lands; (ii) nitrogen limits applied for
inorganic and organic nitrogen applied to
arable and grass lands that do not exceed
crop requirements; (iii) spreading controls
to restrict fertilizer and manure
applications on steep slopes or close to
water courses; (iv) slurry storage for
manure during the autumn closed period;
and (v) record keeping of agricultural
practices for at least 5 years. Further,
specific details are provided by DEFRA
(2002).

It is likely that the impact of NVZs on reducing and safest source. Waste water disposal is often by
nitrate leaching will be modest and probably smaller means of unsewered, pour-flush pit latrines that pro-
than the 16–28% reduction achieved in nitrate leach- vide adequate waste disposal at a much lower cost
ing fluxes reported for the earlier NSA scheme. In than main sewerage systems. In cases where thin soils
critical areas, land-use change similar to the Premium are developed on aquifer outcrops, then there is the
NSA scheme will be needed if nitrate concentrations risk of direct migration of pathogenic microbes, especi-
in surface waters and groundwaters are to meet the ally viruses, to underlying groundwater resources.
EU drinking water quality standard of 50 mg L −1 The inevitable result will be the transmission of
(Appendix 9). water-borne diseases. A further problem with human
wastes is the organic nitrogen content which can
cause widespread and persistent problems of nitrate
7.4 Groundwater protection strategies in in water, even where dilution and biological reduc-
developing countries tion processes occur.
Groundwater pollution problems are exacerbated
Groundwater is extensively used for drinking water in less developed areas without significant regional
supplies in developing countries, especially in smaller groundwater flow to provide dilution and by the use
towns and rural areas where it is often the cheapest of inorganic fertilizers and pesticides in an effort to