Sources Of Nitrate In Groundwater Research Articles

Chemometric evaluation of nitrate contamination in the groundwater of a hard rock area in Dharapuram, south India

This paper presents the results of investigations on groundwater nitrate contamination in the Dharapuram area of Tamil Nadu in south India as a primary step to initiate denitrification. Groundwater samples were col- lected from 26 selected locations during the pre-monsoon season in July 2010 and analysed for nitrate and other water quality parameters. Two important water types were identified, viz. Ca-Na-HCO3 and mixed Ca-Mg-Cl. It is found that the majority of samples possess high nitrate concentration; 57 % of samples exceeded the permissible limit of Indian (45 mg/L) and WHO (50 mg/L) drinking water standard. Spatial distribution map of NO3 suggested that major contamination was observed in the SW and NW parts of the study area. This result was in agreement with the corresponding land-use pattern in this study area. Denitrification process at greater depths was evident from the negative correlation between NO3 and well depth. The sources and controlling factors of high nitrate were inves- tigated using cross plots of NO3 with other selected hyd- rochemical parameters. Positive correlation for NO3 was observed with EC, K, Cl and SO4. This analysis was capable of differentiating the various sources of nitrate in groundwater. The major sources of nitrate contamination are identified as areas of high fertilizer application, sew- ages and animal waste dumping yards. Regulation of these pollutant sources with appropriate and cost-effective denitrification process can restore the water quality in this area.

Assessment of sources and fate of nitrate in shallow groundwater of an agricultural area by using a multi-tracer approach

Nitrate isotopic values are often used as a tool to understand sources of contamination in order to effectively manage groundwater quality. However, recent literature describes that biogeochemical reactions may modify these values. Therefore, data interpretation is difficult and often vague. We provide a discussion on this topic and complement the study using halides as comparative tracers assessing an aquifer underneath a sub-humid to humid region in NE Mexico. Hydrogeological information and stable water isotopes indicate that active groundwater recharge occurs in the 8000km2 study area under present-day climatic and hydrologic conditions. Nitrate isotopes and halide ratios indicate a diverse mix of nitrate sources and transformations. Nitrate sources include organic waste and wastewater, synthetic fertilizers and soil processes. Animal manure and sewage from septic tanks were the causes of groundwater nitrate pollution within orchards and vegetable agriculture. Dairy activities within a radius of 1000m from a sampling point significantly contributed to nitrate pollution. Leachates from septic tanks caused nitrate pollution in residential areas. Soil nitrogen and animal waste were the sources of nitrate in groundwater under shrubland and grassland. Partial denitrification processes helped to attenuate nitrate concentration underneath agricultural lands and grassland, especially during summer months.

Analysis of Nitrate occurrence and distribution in Groundwater in the Gaza Strip using major ion chemistry by Baalousha H.

Nitrate in groundwater in the Gaza Strip, Palestine has become a serious problem in the last decade. As a result of extensive use of fertilizers, discharging of wastewater from treatment plants, and leakage of wastewater form cesspools, increased levels of nitrate up to 400 mg/l have been detected in groundwater. Nitrate concentrations more than 50 mg l-1 are very harmful to infant, foetuses, and people with health problems. The most efficient way to prevent nitrate impacts is to identify the sources of nitrate and to reduce them at the source. In this study, samples of groundwater from 63 wells were collected and chemically analyzed. Analysis of these samples revealed they have nitrate concentrations more than the maximum permissible limit recommended by World Health Organization (WHO). The major ion chemistry analysis was used to identify nitrate sources. Based on the relation between land use and nitrate concentration in groundwater, sources of nitrate were identified. These sources are: (1) leakage from wastewater treatment plants, (2) leakage from cesspits, and (3) intensive agricultural activities. It was found that the leakage of wastewater from cesspits and over-loaded treatment plants has greater influence on groundwater nitrate contamination more than agricultural activities. This study shows the important role of the type of infiltrated water into the sub-soil, combined land use, in determining the source of nitrate in groundwater.

Evaluation of historical nitrate sources in groundwater and impact of current irrigation practices on groundwater quality

Large-scale agricultural activities cause deterioration of groundwater resources throughout the world. This study focuses on the irrigated agricultural district of Jinghuiqu in Shaanxi, China. The objectives are to identify the main sources and processes that control nitrate transport, and to assess the impact of long-term irrigation practices on nitrate leaching. The hydrogeochemistry of major solute constituents and stable isotope ratios of NO3 − in groundwater were used to identify historical sources of contamination and transformation processes occurring in the shallow groundwater of the Jinghuiqu irrigation district. The N-NO3 − concentrations in groundwater ranged from 0.0 to more than 100 mg L−1 in April 1990, and from 0.47 to 42.0 mg L−1 in December 2009. Our measurements of N-NO3 − show that the main reasons for this dramatic decline in N-NO3 − concentrations from 1990 to 2009 are denitrification, which controls nitrogen types, together with the sharp decline of the groundwater table. The isotope ratios in collected samples showed that the source of nitrate was mainly manure, a result that corresponds with historical data showing that manure was the main nitrate source before the 1980s, and that fertilizers became dominant thereafter. A numerical model was then used to evaluate future impacts of current irrigation practices on groundwater sources. The HYDRUS-1D model was employed first to evaluate the water movement and the N-NO3 − solute transport for a single irrigation pulse experiment carried out under field conditions, and then in evaluating the long-term impact of irrigation on N-NO3 − leaching. Simulations showed that, after introducing irrigation, the downward drainage fluxes of N-NO3 −, and the N-NO3 − and N-tot concentrations increased at all depths within the 2-m soil profile. This indicates that N concentrations below 1-m depth and in the groundwater could become even more elevated with increased future irrigation. Editor D. Koutsoyiannis Citation Liu, X.-H., Sun, S.-J., Ji, P., and Šimůnek, J., 2013. Evaluation of historical nitrate sources in groundwater and impact of current irrigation practices on groundwater quality. Hydrological Sciences Journal, 58 (1), 1–15.

Identification of the Potential Sources of Nitrate in Groundwater from Shallow Aquifer in Wadi Qudaid, Western Part of Saudi Arabia

Identification of the Potential Sources of Nitrate in Groundwater from Shallow Aquifer in Wadi Qudaid, Western Part of Saudi Arabia

Using δ15N- and δ18O-Values To Identify Nitrate Sources in Karst Ground Water, Guiyang, Southwest China

Nitrate pollution of the karstic groundwater is an increasingly serious problem with the development of Guiyang, the capital city of Guizhou Province, southwest China. The higher content of NO3- in groundwater compared to surface water during both summer and winter seasons indicates that the karstic groundwater system cannot easily recover once contaminated with nitrate. In order to assess the sources and conversion of nitrate in the groundwater of Guiyang, we analyzed the major ions, delta(15)N-NH4+, delta(15)N-NO3-, and delta(18)O-NO3- in surface and groundwater samples collected during both summer and winter seasons. The results show that nitrate is the major dominant species of nitrogen in most water samples and there is a big variation of nitrate sources in groundwater between winter and summer season, due to fast response of groundwater to rain or surface water in the karst area. Combined with information on NO3- /Cl-, the variations of the isotope values of nitrate in the groundwater show a mixing process of multiple sources of nitrate, especially in the summer season. Chemical fertilizer and nitrification of nitrogen-containing organic materials contribute nitrate to suburban groundwater, while the sewage effluents and denitrification mainly control the nitrate distribution in urban groundwater.

Identification of nitrate sources in groundwater by δ15Nnitrate and δ18Onitrate isotopes: a study of the shallow Pleistocene aquifer in the Jericho area, Palestine

AbstractThis study describes the impact of septic tanks on the groundwater quality of the shallow Pleistocene aquifer in Jericho area, Westbank, Palestine. Septic tanks are widely used for storage and disposal of sewage in the populated and agricultural city of Jericho. Routine hydrochemical tests for groundwater quality performed for several years identified the problem of a gradual nitrate increase, without pinpointing its definite sources. The geological formations of the Jericho area and the shallow nature of the Pleistocene aquifer, together with the mechanism of recharge, make the groundwater in this aquifer highly susceptible to contamination, particularly along sewers. The lithology of the Samara (high hydraulic conductivity) and the Lisan formation (low conductivity but increased infiltration along fractures) promote easy seepage of agricultural and anthropogenic inputs into the groundwater. Nitrate concentrations are elevated near septic tanks and animal farms, with nitrate values exceeding 74 mg/L. δ15Nnitrate and δ18Onitrate signatures suggest sewage and manure as the main sources of high nitrate concentration in the groundwater. Samples taken during the end of the dry season indicate that a slight denitrification in the aquifer.

Tracking the Sources of Nitrate in Groundwater Using Coupled Nitrogen and Boron Isotopes: A Synthesis

Nitrate (NO3) is one of the world's major pollutants of drinking water resources. Although recent European Directives have reduced input from intensive agriculture, NO3 levels in groundwater are approaching the drinking water limit of 50 mg L(-1) almost everywhere. Determining the sources of groundwater contamination is an important first step toward improving its quality by emission control. It is with this aim that we review here the benefit of using a coupled isotopic approach (delta15N and delta11B), in addition to conventional hydrogeological analyses, to trace the origin of NO3 in water. The studied watersheds include both fractured bedrock and alluvial (subsurface and deep) hydrogeological contexts. The joint use of nitrogen and boron isotope systematics in each context deciphers the origin of NO3 in the groundwater and allows a semi-quantification of the contributions of the respective pollution sources (mineral fertilizers, wastewater, and animal manure).

Evaluation of contamination sources of groundwater NO3 − using nitrogen isotope data: A review

It has been accepted that variations in stable N isotope ratios (15N/14N) can potentially provide useful, sometimes unique, information on the sources of nitrate in groundwater, because N isotope compositions are generally different among various N pools such as atmospheric N2, soil, chemical fertilizer, and manure. However, this review strongly suggests that interpretation of the nitrate source based on a single measurement of δ15N may not be accurate because the isotopic composition of groundwater nitrate is a function of its source and any isotope fractionation that may occur during its generation or transport to groundwater. This review, therefore, shows that to evaluate the nitrate contamination source using δ15N technique, it is more reasonable to use correlation between the concentrations and δ15N of NO3 −. For example, a positive correlation indicates15N-enriched source such as manure, while15N-depleted source results in a negative correlation. The correlation analysis can also be used in evaluation of denitrification and nitrification. Denitrification is a key process affecting δ15N of NO3 −, i.e. if significant amount of nitrate is removed through denitrification, it is not easy to discriminate fertilizer-derived nitrate from manure-or compost-derived one because denitrification increase the δ15N of the remaining NO3 −. Therefore, it is important to assess whether denitrification may be occurring or not when evaluating isotope data on nitrate. By using dual (δ15N air and δ18O vsmow ) isotopic indicators, denitrification can be evaluated more accurately.

Application of classification-tree methods to identify nitrate sources in ground water.

A study was conducted to determine if nitrate sources in ground water (fertilizer on crops, fertilizer on golf courses, irrigation spray from hog (Sus scrofa) wastes, and leachate from poultry litter and septic systems) could be classified with 80% or greater success. Two statistical classification-tree models were devised from 48 water samples containing nitrate from five source categories. Model 1 was constructed by evaluating 32 variables and selecting four primary predictor variables (delta 15N, nitrate to ammonia ratio, sodium to potassium ratio, and zinc) to identify nitrate sources. A delta 15N value of nitrate plus potassium > 18.2 indicated animal sources; a value < 18.2 indicated inorganic or soil organic N. A nitrate to ammonia ratio > 575 indicated inorganic fertilizer on agricultural crops; a ratio < 575 indicated nitrate from golf courses. A sodium to potassium ratio > 3.2 indicated septic-system wastes; a ratio < 3.2 indicated spray or poultry wastes. A value for zinc > 2.8 indicated spray wastes from hog lagoons; a value < 2.8 indicated poultry wastes. Model 2 was devised by using all variables except delta 15N. This model also included four variables (sodium plus potassium, nitrate to ammonia ratio, calcium to magnesium ratio, and sodium to potassium ratio) to distinguish categories. Both models were able to distinguish all five source categories with better than 80% overall success and with 71 to 100% success in individual categories using the learning samples. Seventeen water samples that were not used in model development were tested using Model 2 for three categories, and all were correctly classified. Classification-tree models show great potential in identifying sources of contamination and variables important in the source-identification process.