Nitrate runoff

Nitrate (measured as Nitrogen) 10 10 "Blue baby syndrome" in infants under six months -life threatening without immediate medical attention. Symptoms Infant looks blue and has shortness of breath. Runoff from fertilizer use leaching from septic tanks, sewage erosion of natural deposits... 

Riparian wetlands are effective though not infinite sinks for nitrate and phosphate from agricultural runoff. Strips of wetland a few tens of metres wide have been shown to remove the bulk of nitrate and phosphate entering in runoff and groundwater, though the limits to this under different circumstances are not well quantified (Baker and Malfby, 1995 Mitsch and Gosselink, 2000). 

Atrazlne has been found in ground water in Nebraska (24,43, 56,57), Wisconsin (54), and Iowa (55). The concentrations in several dozen wells were typically 0.8 ppb. The four positives out of nine wells sampled in Iowa were associated with an adjacent river which was contaminated with atrazlne by runoff. In 1979 and 1980, positive correlations between atrazlne and nitrate in ground water were reported (56,24). It has been estimated that 0,07% of the atrazlne applied to the surface leached to a 1.5 m depth in Nebraska (57). 

Nitrite reductases (NiRs)—enzymes found in several strains of denitrifying bacteria— catalyze the one-electron reduction of nitrite anion to nitric oxide (Equation 1). - In addition to the importance of this process in the global nitrogen cycle (Figure 1), further incentive for the study of the denitrification process is provided by its environmental impact, ranging from the production of NO as a pollutant and NjO as a potent greenhouse gas, to lake eutrophication due to farm runoff that contains high concentrations of nitrates and nitrites. 

Despite the strengthening of environmental policies, problems in relation to cadmium and cyanide, dioxin, organic pollution, lake eutrophication, residential sewage, pesticide runoff, industrial discharges, and groundwater contamination by toxics and nitrates also need to be tackled. 

It has been established that the activity of both NR and NiR is induced by nitrate in plants (Rajasekhar Oelmuller, 1987), even if in a few species constitutive NR and NiR isoforms are found in addition to the inducible ones. Nitrate supply leads to an increase in the steady-state level of mRNA encoding NR in a variety of plant species and tissues (Cheng et al., 1986, 1991 Crawford et al., 1986 Smarrelli et al., 1987 Galangau et al., 1988 Gowri Campbell, 1989 Hamat et al., 1989 Hoff et al., 1991 Friemann et al., 1991). This in turn results in NR protein synthesis and increased activity, shortly after nitrate supply to the roots, and after a lag in leaves (Melzer et al., 1989). Where performed, nuclear runoff transcription assays have indicated that the high mRNA level results from increased transcriptional activity (Callaci Smarrelli, 1991 Lillo, 1991). 

Nitrates and phosphates are two important nutrients that have been increasing markedly in natural waters since the mid-1960s. Sources of nitrate contamination include fertilizers, discharge from sewage treatment plants, and leachate from septic systems and manure. Nitrates from fertilizers leach readily from soils, and it has been estimated that up to 40% of applied nitrates enter water sources as runoff and leachate. Fertilizer phosphates, however, tend to be absorbed or bound to soil particles, so that only 20% to 25% of applied nitrates are leached into water. Phosphate detergents are another source of phosphate, one that has received much media attention in recent years. 

Logan, T.J., D.J. Eckert, and D.G. Beak (1994). Tillage, crop, and climatic effects on runoff and tile drainage losses of nitrate and four herbicides. Soil Till. Res., 30 75-103. 

Patty, L., B. Real, and J.J. Gril (1997). The use of grass buffer strips to remove pesticides, nitrate, and soluble phosphorus compounds from runoff water. Pestic. Sci., 49 243-251. 

During the past decades, the basic features of the biogeochemical structure of the Black Sea have radically changed under the impact of climatic and anthropogenic factors. The amounts of selected nutrients (for example, nitrates owing to eutrophication) have increased, while those of others (such as silicon due to the regulation of the Danube runoff) have decreased. 

High nitrate concentrations can cause methaemoglobinaemia (blue-baby syndrome) in bottle-fed infants. This condition is also associated with the simultaneous presence of bacterial contamination. The primary approach to managing nitrate contamination is prevention, particularly for rural wells, which are the major problem with regard to methaemoglobinaemia. In particular, protection of wells from runoff from fields and siting of manure stores, pit latrines and septic tanks will help to prevent contamination with nitrate and microbial pathogens. 

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