Nitrate and water supplies in the United Kingdom

Status of Nitrate Contamination in Ground Water near Delhi: a Case Study

Water samples collected from public drinking water supplies in Sicily were analysed for electric conductivity and for their chloride, sulphate and nitrate contents. The samples were collected as uniformly as possible from throughout the Sicilian territory, with an average sampling density of about one sample for every 7,600 inhabitants. Chloride contents that ranged from 5.53 to 1,302mg/l were correlated strongly with electric conductivity, a parameter used as a proxy for water salinity. The highest values are attributable to seawater contamination along the coasts of the island. High chloride and sulphate values attributable to evaporitic rock dissolution were found in the central part of Sicily. The nitrate concentrations ranged from 0.05 to 296mg/l, with 31 samples (4.7% of the total) exceeding the maximum admissible concentration of 50mg/l. Anomalous samples always came from areas of intensive agricultural usage, indicating a clear anthropogenic origin. The same parameters were also measured in bottled water sold in Sicily, and they all were within the ranges for public drinking water supplies. The calculated mean nitrate intake from consuming public water supplies (16.1mg/l) did not differ significantly from that of bottled water (15.2mg/l). Although the quality of public water supplies needs to be improved by eliminating those that do not comply with the current drinking water limits, at present it does not justify the high consumption of bottled water (at least for nitrate contents).

1 term trend assessments are needed. Addition of these kinds of information would allow assess­ ment of trends associated with hydrology and geology of each area and would provide a much stronger basis for trend assessment than currently possible. INTRODUCTION In Idaho, ground water currently is the principal source of about 95 percent of public water supplies and most rural-domestic and livestock supplies (E. Hagan, Idaho Department of Water Resources, IDWR, oral commun., 2001). Many drinking-water supplies are pumped from relatively shallow zones where groundwater quality has great potential for degradation by landand water-use activities. One indicator of water quality, and one of the most widespread contaminants 1 in Idaho ground water related to land and water uses, is dissolved nitrate-nitrogen (NO3–N) concentrations. 2 The maximum U.S. Environmental Protection Agency (EPA, 2000, p. 9) limit for nitrate concentra­ tions in public water supplies is 10 mg/L. Concentra­ tions of nitrate in Idaho ground water prior to land and water development probably were less than 1 mg/L (Parliman, 2000, p. 1), but elevated nitrate concentra­ tions in ground water have been reported for more than 40 years (see Selected References). The median con­ centration (50th percentile) of nitrate in Idaho ground water from 1990 through 2000, for example, was about 1.5 mg/L, but the range of concentrations was less than 0.05 to 110 mg/L. Widespread elevated nitrate concentrations histor­ ically have been detected in some areas of Idaho more frequently than in other areas. In 1998, personnel with the Idaho Department of Environmental Quality (IDEQ) conducted a preliminary assessment of statewide nitrate concentrations and delineated 33 ground-water-quality management areas (nitrate priority areas) where more than 25 percent of nitrate concentrations exceeded 5 mg/L (S. Short, IDEQ, written commun., 2000; fig. 1). In July 2000, IDEQ convened the Ground-Water Monitoring Technical Committee to discuss groundwater-quality management issues in Idaho. One goal of 1Contaminants are components of ground-water quality that can limit the water’s suitability for use or can represent degradation of water quality. 2In this report, nitrate is reported as nitrogen, NO3–N, in milligrams per liter (mg/L), equivalent to parts per million. the committee was to prioritize the 33 ground-waterquality management areas where nitrate has signifi­ cantly degraded ground-water quality; one component of the prioritization process was identification of nitrate concentration trends within each area. In December 2000, the U.S. Geological Survey (USGS), in coopera­ tion with IDEQ, began a study to compile and assess nitrate data for ground water in the 33 priority areas. The primary objective of the study was to determine whether statistically significant trends in nitrate con­ centrations were discernible. On the basis of statistical trend analysis results, nitrate trends would be defined as increasing, decreasing, or neither increasing nor decreasing (no trend). Areas would be identified where data were insufficient for statistical assessment. The purpose of this report is to present findings of these trend analyses. DATA COMPILATION The first task of the nitrate trends study was to identify sources of electronically transferable nitrate data in Idaho and combine these data into one data set. Data were compiled from data bases maintained by the following agencies: (1) Idaho Department of Agricul­ ture (IDAG)—ground-water-monitoring networks and a one-time analysis of water from wells at dairies statewide, (2) IDEQ—individual ground-water-quality investigations statewide and the Drinking Water Infor­ mation Management System (DWIMS) public watersupply data base, (3) USGS—individual groundwater-quality investigations statewide by Idaho and Utah Districts, and (4) the USGS/IDWR Statewide Ambient Ground-Water Quality Monitoring Program (Statewide GW-QW Program).3 Data included ground-water analyses but not anal­ yses of water from springs, drains, or thermal water (greater than 84.5°F) sources. Nitrite plus nitrate as nitrogen (NO2+NO3–N) and nitrate-nitrogen (NO3–N) data were moved into one Microsoft Excel 2000 spreadsheet. Minimum required information for each analysis included sample date and agency source. Min­ imum required location information for each well 3A description of this program is available at http://www.idwr.state.id.us/planpol/techserv/gwmon/statewide.htm 4USGS laboratory analyses are reported in units of nitrite plus nitrate as nitrogen (NO2+NO3–N). Idaho State Laboratory analyses are reported in units of nitrate as nitrogen (NO3–N). Concentrations of nitrite in ground water generally are negligible. For purposes of this study, USGS and IDEQ analyses are comparable. 2 Nitrate Trends in 25 Ground-Water-Quality Management Areas, Idaho, 1961–2001 117° EXPLANATION Nitrate priority area

High nitrate level in water can cause methemoglobinemia or blue baby syndrome, a condition found especially in infants under six months. For this study, 40 samples were collected from different villages of Deoli tehsil, Tonk, Rajasthan, India during the premonsoon 2011 in clean polyethylene bottles. The nitrate concentration along with physicochemical parameters in drinking water samples was determined by using standard techniques. Keywords: nitrate, blue baby syndrome, Deoli area Cite this Article Meena KS, Meena K, Gunsaria RK. Assessment of Groundwater Quality of Deoli Tehsil (Tonk District, Rajasthan) with Special Emphasis on Nitrate Analysis. Research & Reviews: Journal of Ecology. 2017; 6(3): 1–5p.

Nitrate (NO3 ) concentrations in public water supplies have risen above acceptable levels in many areas of the world, largely as a result of overuse of fertilizers and contamination by human and animal waste. The World Health Organization and the U.S. Environmental Protection Agency have set a limit of 10 mg L nitrate (as N) for drinking water because nitrate poses a health risk, especially for children, who can contract methemoglobinemia (blue-baby syndrome). Nitrate in lower concentrations is non-toxic, but the risks from long-term exposure are unknown, although nitrate is a suspected carcinogen. High concentrations of nitrate in rivers, lakes, and coastal areas can cause eutrophication, often followed by fi sh-kills, due to oxygen depletion. Increased atmospheric loads of anthropogenic nitric and sulfuric acids have caused many sensitive, low-alkalinity streams in North America and Europe to become acidifi ed. Still more streams that are not yet chronically acidic could undergo acidic episodes in response to large rain storms and/or spring snowmelt, seriously damaging sensitive local ecosystems. Future climate changes may exacerbate the situation by affecting biogeochemical controls on the transport of water, nutrients, and other materials from land to freshwater ecosystems. The development of effective management practices to preserve water quality, and remediation plans for sites that are already polluted, requires the identifi cation of actual N sources and an understanding of the processes affecting local nitrate concentrations. In particular, a better understanding of hydrologic fl owpaths and solute sources is required to determine the potential impact of contaminants on water supplies. Determination of the relation between nitrate concentrations in groundwater and surface water and the quantity of nitrate introduced from a particular source is complicated by:

Inorganic nitrate and nitrite are plant nutrients, legally mandated additives to processed meats, and components of foods and dietary supplements associated with blood pressure–lowering and performance-enhancing effects. Controversy around dietary nitrate and nitrite consumption exists because of the potential for increased risk of certain cancers in adults and methemoglobinemia (ie, blue baby syndrome) in infants. However, more recent evidence suggests that dietary nitrate, as an exogenous source for endogenous nitric oxide production via the human nitrate–nitrite–nitric oxide pathway, exerts blood pressure–lowering effects and athletic performance–enhancing activities in humans. Nitrate and nitrite content in foods is lacking from nutrient databases, which limits the ability to study health-related epidemiological associations. Therefore, we estimated human nitrate and nitrite intakes from cultural meal patterns, foods, and dietary supplements in order to determine the potential exposure range from available foods. Examination of prototypical daily meal patterns from 4 cultures showed that meal patterns with the greatest nitrate and nitrite concentrations were those with an abundant amount of leafy greens and root vegetables, such as the Japanese and Chinese diet, whereas concentrations in the American and Indian diet were considerably lower. Furthermore, consumption of 1 serving of a nitrate-rich food or supplement can exceed the World Health Organization acceptable daily intake for nitrate (0-3.7 mg/kg body weight per day or 222 mg/d for a 60-kg adult). Given the potential health benefits and risks for dietary nitrate and nitrite intakes, there is a need for rational dietary guidance regarding nitrate- and nitrite-containing foods in order to achieve optimal cardiovascular health and athletic performance, while taking into account the potential negative health risks.

Anthropogenic load on the environment continuously grows which results in pollution of landscape single components and the landscape complex on the whole. The content of nitrogen-containing compounds in potable water represents an important indicator of its medico-ecological situation. The present work is an attempt to disclose regularities in territorial differentiation of water quality in the village of Valya Kuzmin, Hlyboka District, Chernivtsi Region, when anthropogenic factor and landscape predicament of the territory are taken into account. The settlement of Valya Kuzmin is located in the Prut-Siret interfluve within the limits of the Delerui valley-hollow physic-geographical rayon. The village itself situates within two natural-territorial complexes (NTC) (or, landscape complexes (LC)) as follows: hilly-slope landscapes with turfy-podzol surface-gleyed and grey forest soils under pastures, arable lands and development; bottom-valley landscapes with sod-meadow and dark-grey forest soils under arable lands and development. Subsurface waters within the studied territory are characterized by relatively high content of calcium and hydro carbonates (with predominance of hydro carbonate-calcium type of waters). Average mineralization amounts to 0,66 - 0,85 g/dm3, while the same within the hilly-slope natural-territorial complex increases by 0,2 g/dm3 with general water hardness value amounting to 12,4 mg-equivalent/dm3. Concentration of nitrates in subsurface waters within the village of Valya Kuzmin reaches 186 mg/dm3, and maximum concentration limit (MCL) was found in 45% out of 22 studied wells. The content of nitrates in subsurface waters in hilly-slope landslide and bottom-valley NTCs significantly differs. In the first case, water samples with the excess of nitrate content amounted to 75 %, while MCL was 2-3 times over the limit. In the second, the same excess amounted to only 10%, while more samples from single sources of water (subsurface water) had only a slight amount of nitrates – up to 10 mg/dm3, and the surface artificial water tanks within the limits of this NTC showed the nitrate concentration to be 12-15 mg/dm3, which is the evidence of their (tanks’) subsurface feeding. Single wells within both NTCs show the presence of ammonium and nitrite pollutions. Since the level of subsoil waters within the hilly-slope NTC is considerably higher than the same in the bottom-valley complex, we can not but note that the subsoil water capacity for self-cleaning is much higher in the second case. Major factors that determine the level of nitrogen-containing compound pollution of individual sources of water supply within the limits of the village are the residential houses’ distance to conventional sources of pollution, as well as the depth and the sanitary state of wells. As a rule, nitrates appear in subsurface waters through wastewater of the objects of economic activity. The likely object of anthropogenic eco-geochemical load that affects the first LC type is the “Valya Kuzmin Poultry”, a farming economy where the reaction rim of the nitrate highest concentration spreads from the pollution source in the north-eastern direction towards the valley of the Derelui River and the estuary of the Nevilnytsia River. The second LC type features the hotel & restaurant complexes, such as “Zelena Dibrova Hotel”, “Smerekova Khata Restaurant”, and “Hostynna Sadyba Restaurant”. Settling within the limits of the village is uneven, with population density amounting to 110 people/km2 (LC first type), and 77 people/km2 (second LC type). Both landscape complexes feature farmers’ subsidiary plots. This tense medico-ecological situation may lead to burden of disease. Thus, the last three years was the evidence of 11 annual doctor’s addresses (NTC first type), and 3 addresses (NTC second type) (the data available with the rural ambulance station presented by D.O. Honchar, local doctor). Key words: landscape complexes, pollution, water quality, nitrate distribution.

A 2-month-old girl with severe cyanosis was brought to the emergency department of a local hospital. Because an acute asthma attack was suspected, she was immediately prescribed oxygen therapy, corticosteroids, aerosol with β2-adrenergic agents, and steroids. The infant did not improve after treatment, and she was transferred to the Children's Hospital. On arrival, the infant, the first child of an Italian nonconsanguineous couple and born at term after a noncomplicated pregnancy, was described as irritable. Physical examination showed a pale, cyanotic, and mottled baby. Local emergency room staff noted that the infant was dehydrated, dusky, and cold to the touch. Her temperature was 90°F and her oxygen saturation remained in the low 80s while on 100% oxygen by nasal cannula. The infant had tachycardia (between 150 and 195 beats/min) and tachypnea (60 breaths/min). On auscultation, pulmonary findings were normal. Abdominal examination showed no hepatomegaly, splenomegaly, or tenderness. Neurologic examination did not reveal any deficiency, and the bregmatic fontanel was normal. The infant's weight was 4,720 g (10–25th percentile), length was 54 cm (10–25th percentile), and head circumference 39 cm (10–25th percentile). The growth charts show no failure to thrive. Laboratory tests showed increased leukocytes, normal platelet count, and normal concentrations of hemoglobin and hematocrit. An important finding was significant methemoglobinemia (30.4%) and profound hypoxia (20.4 mm Hg). Radiography and electrocardiography findings were normal. According to her parents, the infant's skin color had become “grey” and she had been particularly irritable for a couple of weeks. For the first 2 weeks of life, the child was exclusively breast-fed. She was then artificially fed because breast milk was not available. The parents reported that at 4 weeks of age, the baby experienced constipation. A pediatrician whom they consulted suggested a conventional, adapted milk formula reconstituted with courgette soup (120 mL for six meals). What is the diagnosis? 1. Eisenmenger syndrome 2. Blue baby syndrome 3. Ebstein anomaly 4. Deficit of very long-chain acyl dehydrogenase 5. Sepsis 6. Carbon monoxide intoxication Answer: Blue baby syndrome. When a cardiorespiratory problem had been excluded, intoxication was suspected. The parents reported that the child was fed formula reconstituted with courgette soup to resolve constipation. In fact, the available data supported the final diagnosis of infant methemoglobinemia caused by the ingestion of concentrated vegetable soup (blue baby syndrome). Treatment with 0.1 mL/kg 1% methylene blue and 1 g vitamin C soon resolved the symptoms. Comment: Accumulation of methemoglobin in red cells can occur for three reasons: 1) a dominantly inherited abnormality in hemoglobin that prevents the reduction of methemoglobin to hemoglobin; 2) a recessively inherited deficiency in the enzyme methemoglobin reductase; or 3) exposure to hemoglobin-oxidizing chemicals or drugs, such as nitrates or nitrites contained in water and in some vegetables (such as carrots, spinach, courgette, cauliflower, red beets), Xylocaine, or benzene derivatives. Blue baby syndrome, known as infant methemoglobinemia, is not an infrequent condition. Infants younger than 6 months of age are particularly susceptible to methemoglobinemia because they have smaller amounts of a key enzyme, NADH-cytochrome b5 reductase, which converts methemoglobin back to hemoglobin (2). For more than 40 years, nitrates in drinking water have been believed to be a primary cause of infantile methemoglobinemia. Nonetheless (3–5), some cases of infantile methemoglobinemia have involved infants who became ill after being fed formula that was reconstituted with vegetable soup and nitrate-free water. Our case suggests not feeding infants with increased amounts of vegetable foods, such as carrots, courgette, spinach, red beets, and cauliflower, to resolve constipation, because doing so may be a risk factor, particularly in the first months of life, for severe methemoglobinemia (1,6).

Human exposure to nitrogen (N) pollution via nitrate in food and water and nitrogen oxides in the ambient air is reviewed. Increased risks of myocardial infarction, respiratory problems, and asthma have been linked to higher exposures to nitrogen oxides in ambient air. Excess nitrate/nitrite exposure in food and water may be harmful to human health by: (1) its contribution to the endogenous formation of N-nitroso compounds, demonstrated carcinogens and teratogens in animal models; (2) its potential role in methemoglobinemia; and (3) in high doses, its ability to competitively inhibit iodine uptake and induce changes in the thyroid. High nitrate levels in drinking water have been linked to methemoglobinemia in infants (“blue baby syndrome”) and children. In 2006, an International Agency for Research on Cancer expert panel concluded that ingested nitrate/nitrite under conditions that result in endogenous nitrosation is probably carcinogenic to humans; subsequent studies have continued to support this conclusion. Maternal exposures to higher nitrate levels in drinking water have been associated with a variety of adverse pregnancy outcomes. In contrast, maternal dietary intake of nitrate/nitrite has not been associated with birth defects in offspring unless coupled with prenatal nitrosatable drug exposure. Further research is indicated on the beneficial and harmful effects of nitrate on human health. Given what is currently known about the harmful effects of nitrogen oxides and ingested nitrate/nitrite, it appears prudent to support measures to reduce nitrogen emissions in the atmosphere and to continue to maintain current limits and guidelines on nitrate concentration in drinking water.

Nutrient and organic compound data from the U.S. Geological Survey and the U.S. Environmental Protection Agency STORET data bases provided information for development of a preliminary conceptual model of spatial and temporal ground-water quality in the upper Snake River Basin. Nitrite plus nitrate (as nitrogen; hereafter referred to as nitrate) concentrations exceeded the Federal drinking-water regulation of 10 milligrams per liter in three areas in Idaho" the Idaho National Engineering Laboratory, the area north of Pocatello (Fort Hall area), and the area surrounding Burley. Water from many wells in the Twin Falls area also contained elevated (greater than two milligrams per liter) nitrate concentrations. Water from domestic wells contained the highest median nitrate concentrations; water from industrial and public supply wells contained the lowest. Nitrate concentrations decreased with increasing well depth, increasing depth to water (unsaturated thickness), and increasing depth below water table (saturated thickness). Kjeldahl nitrogen concentrations decreased with increasing well depth and depth below water table. The relation between kjeldahl nitrogen concentrations and depth to water was poor. Nitrate and total phosphorus concentrations in water from wells were correlated among three hydrogeomorphic regions in the upper Snake River Basin, Concentrations of nitrate were statistically higher in the eastern Snake River Plain and local aquifers than in the tributary valleys. There was no statistical difference in total phosphorus concentrations among the three hydrogeomorphic regions. Nitrate and total phosphorus concentrations were correlated with land-use classifications developed using the Geographic Information Retrieval and Analysis System. Concentrations of nitrate were statistically higher in area of agricultural land than in areas of rangeland. There was no statistical difference in concentrations between rangeland and urban land and between urban land and agricultural land. There was no statistical difference in total phosphorus concentrations among any of the land-use classifications. Nitrate and total phosphorus concentrations also were correlated with land-use classifications developed by the Idaho Department of Water Resources for the Idaho part of the upper Snake River Basin. Nitrate concentrations were statistically higher in areas of irrigated agriculture than in areas of dryland agriculture and rangeland. There was no statistical difference in total phosphorus concentrations among any of the Idaho Department of Water Resources land-use classifications. Data were sufficient to assess long-term trends of nitrate concentrations in water from only eight wells: four wells north of Burley and four wells northwest of Pocatello. The trend in nitrate concentrations in water from all wells in upward. The following organic compounds were detected in ground water in the upper Snake River Basin: cyanazine, 2,4-D DDT, dacthal, diazinon, dichloropropane, dieldrin, malathion, and metribuzin. Of 211 wells sampled for organic compounds, water from 17 contained detectable concentrations.

of treatment. However, as the coagulated surface waters are generally corrosive, the treated waters would dissolve iron from mains and service pipes but for the fact that most of them receive final adjustment of pH (hydrogen-ion concentration) to inhibit corrosion. The analyses of the ground waters show that generally in those in which the iron or manganese content was sufficient to cause trouble it has been removed by the treatment. Only a few of the ground waters as furnished to consumers are corrosive enough to dissolve troublesome quantities of iron.

Data on rock, ground water, vadose water, and vadose gas chemistry were collected for two years after sewage sludge was applied at a reclaimed surface coal mine in Pennsylvania to determine if surface‐applied sludge is an effective barrier to oxygen influx, contributes metals and nutrients to ground water, and promotes the acidification of ground water. Acidity, sulfate, and metals concentrations were elevated in the ground water (6‐ to 21‐m depth) from spoil relative to unmined rock because of active oxidation of pyrite and dissolution of aluminosilicate, carbonate, and Mn‐Fe‐oxide minerals in the spoil. Concentrations of acidity, sulfate, metals (Fe, Mn, Al, Cd, Cu, Cr, Ni, Zn), and nitrate, and abundances of iron‐oxidizing bacteria were elevated in the ground water from sludge‐treated spoil relative to untreated spoil having a similar mineral composition; however, gaseous and dissolved oxygen concentrations did not differ between the treatments. Abundances of iron‐oxidizing bacteria in the ground water samples were positively correlated with concentrations of ammonia, nitrate, acidity, metals, and sulfate. Concentrations of metals in vadose water samples (<5‐m depth) from sludge‐treated spoil (pH 5.9) were not elevated relative to untreated spoil (pH 4.4). In contrast, concentrations of nitrate were elevated in vadose water samples from sludge‐treated spoil, frequently exceeding 10 mg/L. Downgradient decreases in nitrate to less than 3 mg/L and increases in sulfate concentrations in underlying ground water could result from oxidation of pyrite by nitrate. Thus, sewage sludge added to pyritic spoil can increase the growth of iron‐oxidizing bacteria, the oxidation of pyrite, and the acidification of ground water. Nevertheless, the overall effects on ground water chemistry from the sludge were small and probably short‐lived relative to the effects from mining only.

Historical data on nutrient (nitrogen and phosphorus species) concentrations in ground-and surface-water samples were compiled from 20 study units of the National Water-Quality Assessment (NAWQA) Program and 5 supplemental study areas. The resultant national retrospective data sets contained analyses of about 12,000 Found-water and more than 22,000 surface-water samples. These data were interpreted on regional and national scales by relating the distributions of nutrient concentrations to ancillary data, such as land use, soil characteristics, and hydrogeology, provided by local study-unit personnel. The information provided in this report on environmental factors that affect nutrient concentrations in ground and surface water can be used to identify areas of the Nation where the vulnerability to nutrient contamination is greatest. Nitrate was the nutrient of greatest concern in the historical ground-water data. It is the only nutrient that is regulated by a national drinking-water standard. Nitrate concentrations were significantly different in ground water affected by various land uses. Concentrations in about 16 percent of the samples collected in agricultural areas exceeded the drinking-water standard. However, the standard was exceeded in only about 1 percent of samples collected from public-supply wells. A variety of ancillary factors had significant relations to nitrate concentrations in ground water beneath agricultural areas. Concentrations generally were highest within 100 feet of the land surface. They were also higher in areas where soil and geologic characteristics promoted rapid movement of water to the aquifer. Elevated concentrations commonly occurred in areas underlain by permeable materials, such as carbonate bedrock or unconsolidated sand and gravel, and where soils are generally well drained. In areas where water movement is impeded, denitrification might lead to low concentrations of nitrate in the ground water. Low concentrations were also related to interspersion of pasture and woodland with cropland in agricultural areas. Elevated nitrate concentrations in areas of more homogeneous cropland probably were a result of intensive nitrogen fertilizer application on large tracts of land. Certain regions of the United States seemed more vulnerable to nitrate contamination of ground water in agricultural areas. Regions of greater vulnerability included parts of the Northeast, Midwest, and West Coast. The well-drained soils, typical in these regions, have little capacity to hold water and nutrients; therefore, these soils receive some of the largest applications of fertilizer and irrigation in the Nation. The agricultural land is intensively cultivated for row crops, with little interspersion of pasture and woodland. Nutrient concentrations in surface water also were generally related to land use. Nitrate concentrations were highest in samples from sites downstream from agricultural or urban areas. However, concentrations were not as high as in ground water and rarely exceeded the drinking-water standard. Elevated concentrations of nitrate in surface water of the Northeastern United States might be related to large amounts of atmospheric deposition (acid rain). High concentrations in parts of the Midwest might be related to tile drainage of agricultural fields. Ammonia and phosphorus concentrations were highest downstream from urban areas. These concentrations generally were high enough to warrant concerns about toxicity to fish and accelerated eutrophication. Recent improvements in wastewater treatment have decreased ammonia concentrations downstream from some urban areas, but the result has been an increase in nitrate concentrations. Information on environmental factors that affect water quality is useful to identify drainage basins throughout the Nation with the greatest vulnerability for nutrient contamination and to delineate areas where ground-water or surface-water contamination is most likely to oc

This report describes the reconnaissance phase of a study to determine the occurrence of agricultural chemicals from nonpoint sources in ground water in six areas, which are representative of the major provinces of the High Plains aquifer in Nebraska. Nitrate and triazine-herbicide concentrations in ground water were assessed to establish preliminary relations between these constituents and selected hydrogeologic, climatic, and land-use variables. In 1984, water from 82 wells in the 6 study areas was analyzed for nitrate, and water from 57 of the 82 wells was analysed for triazine herbicides. Data for 9 of the 21 independent variables suspected of affecting concentrations of nitrate and triazine herbicides in ground water were compiled from the 82 well sites. The variables and their ranges are: hydraulic gradient (XI), 0.0006-0.0053; hydraulic conductivity (X2), 5-149 feet per day; specific discharge (X3), 0.0128-0.2998 foot per day; depth to water (X4), 3-239 feet; well depth (X5), 40-550 feet; annual precipitation (X6), 12.0-39.3 inches; soil permeability (X7), 0.76-9.0 inches; irrigation-well density (X8), 0-8 irrigation wells per square mile; and annual nitrogen fertilizer use (X9), 0-260 pounds of nitrogen per acre. Nitrate concentrations ranged from less than 0.1 to 45 milligrams per liter as nitrogen. Triazine-herbicide concentrations were detected in samples from five of the six study areas in concentrations ranging from less than 0.1 to 2.3 micrograms per liter. Statistical tests indicated that there were significant differences in nitrate concentrations among the six study areas, while no significant differences in triazine-herbicide concentrations were found. Concentrations of nitrate and triazine herbicide were determined, by use of nonparametric statistics, to be significantly larger in more intensively irrigated areas than in less intensively irrigated areas. Preliminary correlations with the independent variables and nitrate concentrations indicated significant relations at the 95-percent confidence level with variables X2, X5, and X8. Correlations with triazine-herbicide concentrations indicated significant relations with variables X2, X3, X5, X6 and X8, and with nitrate concentrations (X10). By use of a simple multiple-regression technique, variables X5, X8, and X9 explained about 51 percent of the variation in nitrate concentrations. Variables X3 and X5 explained about 60 percent of the variation in triazine-herbicide concentrations. With the addition of nitrate concentration as an independent variable, two variables, X10 and X3, explained 84 percent of the total variation in triazine-herbicide concentrations.

Aquitard characteristics of clay-rich till deposits in East Anglia, Eastern England