Groundwater is the water under the earth’s surface that flows freely through tiny pores and cracks in rocks and
soilscalled aquifers and that can be pumped from wells. Groundwater contamination by anthropological activities
and/or infiltration of polluted surface waters has become an ubiquitous problem in many aquifers across the world
in recent decades (Gustafson 1993, Fetter 1999).Sources of groundwater contamination are widespread and include
accidental spills, landfills, storage tanks, pipelines, agricultural activities, and many other sources. These sources are
often classified into two groups, point sources or non-point sources. Dealing with the latter has become a particular
challenge in groundwater remediation, as non-point sources act on a much wider scale than point sources. One
major representative of non-point sources is diffuse pollution from agricultural activities and livestock (Rail, 1989).
One major chemical involved in this kind of groundwater contamination is nitrate which poses a significant health
risk above some critical threshold concentration (Kross et al. 1993). Agricultural activities are in fact the main
sources of high nitrate concentrations not only in groundwaterbut also in superficial water courses in many regions
of the world(Forman et al.1985, Zhang et al. 1996).The origins of the nitrates are either chemical fertilizers or
manure from livestock. The problem of nitrate groundwater pollution has really been aggravated over the last
decades, due to more intensive agriculture and the introduction of high yield crops which has raised the use of
fertilizers and so increased nitrate concentrations in groundwater.