( 1996) showed that the concentration of nitrate in the water from the well in sandy soil, at the distance of 6 m from the point source pollution (animal feedlot or barnyard), was twice as high (3.6 mg/l) compared to the concentration of nitrate (1.8 mg/l) from the wells located 60 m from the pollution. However, they point out that the contamination occurred in the wells located on sandy soil, while at locations where there is clay soil, there was no significant pollution. ( 1979) showed that point source (lagoon with liquid pig manure) affected the concentration of nitrate in the water at the distance of 36 meters from the well. 1999 US EPA 1987).Įffects of point sources of pollution are usually localized and limited (Krapac et al.
2007, 2013 Drake and Bauder 2005 Melian et al. Dense populations and discharges from point sources like septic systems or broken sewer systems contribute significantly to water pollution by nitrate in urban and suburban areas (Nemčić-Jurec et al. Point source pollution refers to contaminants that enter a waterway from a single, identifiable source such as livestock farms, slurry lagoons or manure depots with an inappropriate building or location (US EPA 1987). They point out that the use of fertilizers in doses of 500 kg/ha increases the nitrate concentration in the water up to a distance of 2 km from the well. ( 2006) also evaluated the importance of the excessive use of agrochemicals. Mild climate and favorable winter temperatures allow the extension of the growing season of plants, which reduces nitrate leaching (Hooker et al. Nitrate leaching depends on a variety of environmental factors. ( 2003) showed that agricultural activities contribute to an increased nitrate concentration in groundwater either directly by nitrate leaching from agrochemicals or by agrochemicals that affect the processes in the soil and increase nitrate leaching from the soil.
Numerous scientists have shown nitrate leaching from agricultural areas. Pollution is often a cumulative effect of small amounts of contaminants gathered from a large area (US EPA 1987). The maximum acceptable value (MAV) is 50 mg/l NO 3 − (Regulation 2013), but the recommended limit value (RLV) is only 25 mg/l NO 3 − (Council Directive 1991).Īgriculture is the biggest source of pollution because of the so-called diffuse source pollution that does not originate from a single discrete source. This problem has become even more significant by introducing the stricter standards concerning the nitrate content of drinking water in the EU. Nitrate concentration in natural waters has been increasing during the last few decades, coinciding with the increased use of mineral fertilizers and a higher yield of cultivated plants in agriculture. 2014).Īs nitrogen is the key factor in a high and stable cultivated plant production, it is no surprise that modern agriculture affects nitrogen content in water, as it is a high nitrogen user (Addiscott et al. The Nitrate Directive is one of the main policies to reduce nitrate leaching from agriculture primarily through good agricultural practise and the application of organic and mineral fertilizers according to regulations (Velthof et al.
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1991), and a series of environmental policies have been implemented in the EU to decrease nitrogen (N) emissions from agriculture. Nitrate pollution from agriculture is an issue of major concern for the UN (Addiscott et al. Pollution of groundwater is caused by different pollutants, among which nitrate plays the most important role. The most important and abundant source of drinking water in the European Union (EU) is groundwater constituting over 80 % of the supply (Council Directive 2000). These results will contribute to the implementation of the Nitrate Directive in Croatia and the EU. Differences in water quality were found as a result of different environmental factors. Principal component analysis showed that there is only one significant factor, proximity, which explains 91.6 % of the total variability of nitrate. Results of k-means clustering confirmed division into four clusters according to the pollution. Average annual concentrations of nitrate during the years studied are not statistically different, but interaction between proximity and years is statistically significant ( F = 2.07 p = 0.04). The concentration of nitrate ranged from 20 m ( F = 10.6 p < 0.001). Pollution of groundwater by nitrate from 19 shallow wells was studied in a typical agricultural region, middle Podravina, in northwest Croatia. Point sources like septic systems and broken sewage systems also contribute to water pollution. Agriculture is one of the several major sources of nitrate pollution, and therefore the EU Nitrate Directive, designed to decrease pollution, has been implemented.
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