A Multi-Tracer Approach to Characterize Sources and Transport of Nitrate in Groundwater in Mantled Karst, Northern Florida

Science.gov (United States)

Katz, B. G.; Bohlke, J.; Hornsby, D.

2001-05-01

Nitrate is readily transported from agricultural activities at the surface to the Upper Floridan aquifer in northern Florida due to karst features mantled by highly permeable sands and a high recharge rate (50 cm/yr). In Suwannee and Lafayette Counties, nitrate contamination of groundwater is widespread due to the 10-30 kg/ha nitrogen (N) applied annually for the past few decades as synthetic fertilizers (the dominant source of N). Water samples were collected from 12 springs during baseflow conditions (1997-99) and monthly from 14 wells (1998-99). Springwaters were analyzed for various chemical (N species, dissolved gases, CFCs) and isotopic tracers (15N, 3H/3He, 18O, D, 13C). Water from wells was analyzed monthly for N species, and during low-flow and high-flow conditions for 15N, 18O, D, and 13C. As a result of oxic conditions in the aquifer, nitrate was the dominant N species in water samples. Large monthly fluctuations of groundwater nitrate concentrations were observed at most wells. Relatively high nitrate concentrations in groundwater from 7 wells likely resulted from seasonal agricultural practices including fertilizer applications and manure spreading on cropland. Relatively low nitrate concentrations in groundwater from two wells during high-flow conditions were related to mixing with river water. Groundwater samples had N-isotope values (3.8-11.7 per mil) that indicated varying mixtures of inorganic and organic N sources, which corresponded in part to varying proportions of synthetic fertilizers and manure applied to fields. In springwaters from Suwannee County, nitrate trends and N-isotope data (2.7-6.2 per mil) were consistent with a peak in fertilizer N input in the late 1970's and a relatively high overall ratio of artificial fertilizer/manure. In contrast, springwater nitrate trends and N-isotope data (4.5-9.1 per mil) in Lafayette County were consistent with a more monotonic increase in fertilizer N input and relatively low overall ratio of

Identification of nitrate sources in groundwater and potential impact on drinking water reservoir (Goczałkowice reservoir, Poland)

Science.gov (United States)

Czekaj, Joanna; Jakóbczyk-Karpierz, Sabina; Rubin, Hanna; Sitek, Sławomir; Witkowski, Andrzej J.

2016-08-01

Goczałkowice dammed reservoir (area - 26 km2) is a strategic object for flood control in the Upper Vistula River catchment and one of the most important source of drinking water in the Upper Silesian Industrial Region (Southern Poland). Main aims of the investigation were identification of sources of nitrate and assessment of their significance in potential risk to groundwater quality. In the catchment area monitoring network of 22 piezometers, included 14 nested, have been installed. The significant spatial and seasonal differences in chemical composition between northern and southern part of the catchment were indicated based on the groundwater sampling conducted twice - in autumn 2011 and spring 2012. Maximum observed concentrations of nitrate were identified in northern part of the study area 255 mg/L as a results of inappropriate sewage management and agriculture activity. Results, based on the combines multi-scale hydrogeological and hydrochemical field studies, groundwater flow and transport modelling, dual stable isotope approach and geochemical modelling indicate mainly agriculture and inappropriate sewage water management as a sources of NO3- contamination of groundwater which moreover is affected by geochemical processes. In general, contaminated groundwater does not impact surface water quality. However, due to high concentration of nitrate in northern part a continues measurements of nitrogen compounds should be continued and used for reducing uncertainty of the predictive scenarios of the mass transport modelling in the study area.

Nitrate contamination of groundwater: A conceptual management framework

International Nuclear Information System (INIS)

Almasri, Mohammad N.

2007-01-01

In many countries, public concern over the deterioration of groundwater quality from nitrate contamination has grown significantly in recent years. This concern has focused increasingly on anthropogenic sources as the potential cause of the problem. Evidence indicates that the nitrate (NO 3 ) levels routinely exceed the maximum contaminant level (MCL) of 10 mg/l NO 3 -N in many aquifer systems that underlie agriculture-dominated watersheds. Degradation of groundwater quality due to nitrate pollution along with the increasing demand for potable water has motivated the adoption of restoration actions of the contaminated aquifers. Restoration efforts have intensified the dire need for developing protection alternatives and management options such that the ultimate nitrate concentrations at the critical receptors are below the MCL. This paper presents a general conceptual framework for the management of groundwater contamination from nitrate. The management framework utilizes models of nitrate fate and transport in the unsaturated and saturated zones to simulate nitrate concentration at the critical receptors. To study the impact of different management options considering both environmental and economic aspects, the proposed framework incorporates a component of a multi-criteria decision analysis. To enhance spatiality in model development along with the management options, the utilization of a land use map is depicted for the allocation and computation of on-ground nitrogen loadings from the different sources

Hydrogeochemical investigation to understand nitrate movement in groundwater of volcanic island, Korea

Science.gov (United States)

Kwon, E. H.; Park, J.; Chung, E.; Kang, B. R.; Park, W. B.; Woo, N. C.

2017-12-01

Groundwater is the sole-source of water supply in the volcanic island, Jeju-do, Korea. Since early 1990s, the nitrate contamination of groundwater has increased especially in the western part of the island. High level of nitrate in water can cause not only health risk to human body but also environmental side effect such as eutrophication and algal bloom in the coastal area. Several studies have done to estimate nitrate contamination in groundwater of local areas, but none of them dealt with nitrate movement with flow paths. So, this study aimed to determine the source and migration of nitrate in groundwater in the Gosan area, located in the western part of Jeju island through seasonal monitoring of hydrogeochemistry and stable isotope analyses from pumping and monitoring wells. Water samples including rainfall and groundwater are measured for major ions (Ca, Na, K, Mg, SO4, HCO3, NO3, Cl, etc.) and stable isotopes (i.e., δ2H, δ18O, δ18O-NO3, δ15N-NO3). From the monitoring data, we could evaluate hydrochemical change during nitrate contamination, and also could identify that groundwater in Gosan area is recharged mainly by regional flow from the high-altitude region. In future study, we will conduct additional seasonal monitoring from the multi-depth monitoring wells and will use statistical analysis to understand pollution sources and paths specifically.

Bayesian nitrate source apportionment to individual groundwater wells in the Central Valley by use of elemental and isotopic tracers

Science.gov (United States)

Ransom, Katherine M; Grote, Mark N.; Deinhart, Amanda; Eppich, Gary; Kendall, Carol; Sanborn, Matthew E.; Sounders, A. Kate; Wimpenny, Joshua; Yin, Qing-zhu; Young, Megan B.; Harter, Thomas

2016-01-01

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less than 150 m deep) in agricultural areas are often contaminated by nitrate. Agricultural and rural nitrate sources include dairy manure, synthetic fertilizers, and septic waste. Knowledge of the relative proportion that each of these sources contributes to nitrate concentration in individual wells can aid future regulatory and land management decisions. We show that nitrogen and oxygen isotopes of nitrate, boron isotopes, and iodine concentrations are a useful, novel combination of groundwater tracers to differentiate between manure, fertilizers, septic waste, and natural sources of nitrate. Furthermore, in this work, we develop a new Bayesian mixing model in which these isotopic and elemental tracers were used to estimate the probability distribution of the fractional contributions of manure, fertilizers, septic waste, and natural sources to the nitrate concentration found in an individual well. The approach was applied to 56 nitrate-impacted private domestic wells located in the San Joaquin Valley. Model analysis found that some domestic wells were clearly dominated by the manure source and suggests evidence for majority contributions from either the septic or fertilizer source for other wells. But, predictions of fractional contributions for septic and fertilizer sources were often of similar magnitude, perhaps because modeled uncertainty about the fraction of each was large. For validation of the Bayesian model, fractional estimates were compared to surrounding land use and estimated source contributions were broadly consistent with nearby land use types.

An isotopic study of nitrate pollution of groundwater in Victoria, Australia

International Nuclear Information System (INIS)

Changkakoti, A.; Lawrence, C.R.; Cherstnova, L.; Chalk, P.; Krouse, H.R.

1997-01-01

Nitrate in groundwater can be a hard to human and animal health and contribute to the development of algal blooms and subsequent eutrophication of wetlands. Its presence is widespread throughout Australia and its levels overall appear to be increasing. A variety of sources of nitrate contamination of groundwater are known. These include nitrogen fixing plants, termites, animal wastes, industrial wastes, domestic wastes, sewage and fertilizers. In Victoria, nitrate-rich groundwaters have been reported from a number of localities, some of which include Colac, Nepean Peninsula, Shepparton, Deer Park, Benalla and Winchelsea. A multi-isotope method was developed to determine the probable source of pollution in these localities. Changes in the natural abundance ratio of the stable isotopes of nitrogen, 14 N and 15 N, and the differences in the isotopic ratios ( 15 N/ 14 N) of nitrate from various sources, form the basis of the N-isotope technique for source identification. Differences in the isotopic ratios of oxygen ( 18 O/ 16 O) and hydrogen (D/H) of polluted and unpolluted waters form the basis for the oxygen and hydrogen isotope technique to investigate pollution problems of groundwater. Sites which included clover, industrial wastes, animal and human wastes and fertilized sources, were selected after reviewing existing databases on nitrate concentration, earlier reports and access to a suitable network of bores for collecting reliable samples. The nitrate concentration ranged from less than 1 mg/L to in excess of 22.0 mg/L, whilst ammonium levels in most samples were less than 1 mg/L. The δ 15 N values of the various source types ranged from 8.8 to 19.0 per mill (pastures). The δ 18 O and δD data indicate seawater incursion in the coastal areas of the Nepean Peninsular. The results agree with published data on similar sources from elsewhere in the world, and indicate the potential use of this methodology in groundwater pollution studies in Australia

Topsoil N-budget model in orchard farming to evaluate groundwater nitrate contamination

Science.gov (United States)

Wijayanti, Yureana; Budihardjo, Kadarwati; Sakamoto, Yasushi; Setyandito, Oki

2017-12-01

A small scale field research was conducted in an orchard farming area in Kofu, Japan, where nitrate contamination was found in groundwater. The purpose of assessing the leaching of nitrate in this study is to understand the transformation and transport process of N-source in topsoil that leads to nitrate contamination of groundwater. In order to calculate N-budget in the soil, the model was utilized to predict the nitrogen leaching. In this res earch, the N-budget model was modified to evaluate influence of precipitation and application pattern of fertilizer and manure compost. The result shows that at the time before the addition of manure compost and fertilizer, about 75% of fertilizer leach from topsoil. Every month, the average remaining nitrate in soil from fertilizer and manure compost are 22% and 50%, respectively. The accumulation of this monthly manure compost nitrate, which stored in soil, should be carefully monitored. It could become the potential source of nitrate leaching to groundwater in the future.

Modeling effects of nitrate from non-point sources on groundwater quality in an agricultural watershed in Prince Edward Island, Canada

Science.gov (United States)

Jiang, Yefang; Somers, George

2009-05-01

Intensification of potato farming has contaminated groundwater with nitrate in many cases in Prince Edward Island, Canada, which raises concerns for drinking water quality and associated ecosystem protection. Numerical models were developed to simulate nitrate-N transport in groundwater and enhance understanding of the impacts of farming on water quality in the Wilmot River watershed. Nitrate is assumed non-reactive based on δ15N and δ18O in nitrate and geochemical information. The source functions were reconstructed from tile drain measurements, N budget and historical land-use information. The transport model was calibrated to long-term nitrate-N observations in the Wilmot River and verified against nitrate-N measurements in two rivers from watersheds with similar physical conditions. Simulations show groundwater flow is stratified and vertical flux decreases exponentially with depth. While it would take several years to reduce the nitrate-N in the shallow portion of the aquifer, it would take several decades or even longer to restore water quality in the deeper portions of the aquifer. Elevated nitrate-N concentrations in base flow are positively correlated with potato cropping intensity and significant reductions in nitrate-N loading are required if the nitrate level of surface water is to recover to the standard in the Canadian Water Quality Guidelines.

Nitrate source identification in groundwater of multiple land-use areas by combining isotopes and multivariate statistical analysis: A case study of Asopos basin (Central Greece).

Science.gov (United States)

Matiatos, Ioannis

2016-01-15

Nitrate (NO3) is one of the most common contaminants in aquatic environments and groundwater. Nitrate concentrations and environmental isotope data (δ(15)N-NO3 and δ(18)O-NO3) from groundwater of Asopos basin, which has different land-use types, i.e., a large number of industries (e.g., textile, metal processing, food, fertilizers, paint), urban and agricultural areas and livestock breeding facilities, were analyzed to identify the nitrate sources of water contamination and N-biogeochemical transformations. A Bayesian isotope mixing model (SIAR) and multivariate statistical analysis of hydrochemical data were used to estimate the proportional contribution of different NO3 sources and to identify the dominant factors controlling the nitrate content of the groundwater in the region. The comparison of SIAR and Principal Component Analysis showed that wastes originating from urban and industrial zones of the basin are mainly responsible for nitrate contamination of groundwater in these areas. Agricultural fertilizers and manure likely contribute to groundwater contamination away from urban fabric and industrial land-use areas. Soil contribution to nitrate contamination due to organic matter is higher in the south-western part of the area far from the industries and the urban settlements. The present study aims to highlight the use of environmental isotopes combined with multivariate statistical analysis in locating sources of nitrate contamination in groundwater leading to a more effective planning of environmental measures and remediation strategies in river basins and water bodies as defined by the European Water Frame Directive (Directive 2000/60/EC).

Nitrate source identification in groundwater of multiple land-use areas by combining isotopes and multivariate statistical analysis: A case study of Asopos basin (Central Greece)

International Nuclear Information System (INIS)

Matiatos, Ioannis

2016-01-01

Nitrate (NO_3) is one of the most common contaminants in aquatic environments and groundwater. Nitrate concentrations and environmental isotope data (δ"1"5N–NO_3 and δ"1"8O–NO_3) from groundwater of Asopos basin, which has different land-use types, i.e., a large number of industries (e.g., textile, metal processing, food, fertilizers, paint), urban and agricultural areas and livestock breeding facilities, were analyzed to identify the nitrate sources of water contamination and N-biogeochemical transformations. A Bayesian isotope mixing model (SIAR) and multivariate statistical analysis of hydrochemical data were used to estimate the proportional contribution of different NO_3 sources and to identify the dominant factors controlling the nitrate content of the groundwater in the region. The comparison of SIAR and Principal Component Analysis showed that wastes originating from urban and industrial zones of the basin are mainly responsible for nitrate contamination of groundwater in these areas. Agricultural fertilizers and manure likely contribute to groundwater contamination away from urban fabric and industrial land-use areas. Soil contribution to nitrate contamination due to organic matter is higher in the south-western part of the area far from the industries and the urban settlements. The present study aims to highlight the use of environmental isotopes combined with multivariate statistical analysis in locating sources of nitrate contamination in groundwater leading to a more effective planning of environmental measures and remediation strategies in river basins and water bodies as defined by the European Water Frame Directive (Directive 2000/60/EC). - Highlights: • More enriched N-isotope values were observed in the industrial/urban areas. • A Bayesian isotope mixing model was applied in a multiple land-use area. • A 3-component model explained the factors controlling nitrate content in groundwater. • Industrial/urban nitrogen source was

Nitrate source identification in groundwater of multiple land-use areas by combining isotopes and multivariate statistical analysis: A case study of Asopos basin (Central Greece)

Energy Technology Data Exchange (ETDEWEB)

Matiatos, Ioannis, E-mail: i.matiatos@iaea.org

2016-01-15

Nitrate (NO{sub 3}) is one of the most common contaminants in aquatic environments and groundwater. Nitrate concentrations and environmental isotope data (δ{sup 15}N–NO{sub 3} and δ{sup 18}O–NO{sub 3}) from groundwater of Asopos basin, which has different land-use types, i.e., a large number of industries (e.g., textile, metal processing, food, fertilizers, paint), urban and agricultural areas and livestock breeding facilities, were analyzed to identify the nitrate sources of water contamination and N-biogeochemical transformations. A Bayesian isotope mixing model (SIAR) and multivariate statistical analysis of hydrochemical data were used to estimate the proportional contribution of different NO{sub 3} sources and to identify the dominant factors controlling the nitrate content of the groundwater in the region. The comparison of SIAR and Principal Component Analysis showed that wastes originating from urban and industrial zones of the basin are mainly responsible for nitrate contamination of groundwater in these areas. Agricultural fertilizers and manure likely contribute to groundwater contamination away from urban fabric and industrial land-use areas. Soil contribution to nitrate contamination due to organic matter is higher in the south-western part of the area far from the industries and the urban settlements. The present study aims to highlight the use of environmental isotopes combined with multivariate statistical analysis in locating sources of nitrate contamination in groundwater leading to a more effective planning of environmental measures and remediation strategies in river basins and water bodies as defined by the European Water Frame Directive (Directive 2000/60/EC). - Highlights: • More enriched N-isotope values were observed in the industrial/urban areas. • A Bayesian isotope mixing model was applied in a multiple land-use area. • A 3-component model explained the factors controlling nitrate content in groundwater. • Industrial

NITRATE POLLUTION IN SHALLOW GROUNDWATER OF A HARD ROCK REGION IN SOUTH CENTRAL INDIA

Science.gov (United States)

Brindha, K.; Rajesh, R.; Murugan, R.; Elango, L.

2009-12-01

Groundwater forms a major source of drinking water in most parts of the world. Due to the lack of piped drinking water supply, the population in rural areas depend on the groundwater resources for domestic purposes. Hence, the quality of groundwater in such regions needs to be monitored regularly. Presence of high concentration of nitrate in groundwater used for drinking is a major problem in many countries as it causes health related problems. Most often infants are affected by the intake of high nitrate in drinking water and food. The present study was carried out with the objective of assessing the nitrate concentration in groundwater and determining the causes for nitrate in groundwater in parts of Nalgonda district in India which is located at a distance of about 135 km towards ESE direction from Hyderabad. Nitrate concentration in groundwater of this area was analysed by collecting groundwater samples from forty six representative wells. Samples were collected once in two months from March 2008 to March 2009. A total of 244 groundwater samples were collected during the study. Soil samples were collected from fifteen locations during May 2009 and the denitrifying bacteria were isolated from the soil using spread plate method. The nitrate concentration in groundwater samples were analysed in the laboratory using Metrohm 861 advanced compact ion chromatograph using appropriate standards. The highest concentration of nitrate recorded during the sampling period was 879.65mg/l and the lowest concentration was below detection limit. The maximum permissible limit of nitrate for drinking water as per Bureau of Indian Standards is 45mg/l. About 13% of the groundwater samples collected from this study area possessed nitrate concentration beyond this limit. The nitrate concentration was high in the southeastern part of the study area. This implies that the nitrate concentration in groundwater tends to increase along the flow direction. Application of fertilizers is one

Groundwater pollution by nitrates in irrigated areas with drainage

International Nuclear Information System (INIS)

Chandio, B.M.; Azam, M.; Abdullah, M.

2001-01-01

Field studies were conducted at three selected sites in irrigated areas of Pakistan to assess magnitude and severity of groundwater pollution by nitrates. The results of these studies indicate that concentration of nitrates in most of the samples collected from irrigated areas having drainage facility is much lower than threshold limit. The nitrate-nitrogen level within drainage projects ranges from 0.01-9.00 mg/l and in the area without drainage system ranges from 10.1-12.5 mg/l. The mineral fertilizers though are making contribution of NO3-N to the groundwater sources but that is much lower than threshold limits. The presence of septic tanks or farmyard manure dumps is also significant contributors of NO3-N to the groundwater. Thus drinking water sources near these polluting points are probable danger to human health. It is, therefore, concluded that still there is a lot of potential for fertilizer use in the agriculture but proper drainage facilities should be provided to minimize the potential threat of NO/sub 3/ pollution. (author)

Nitrate pollution of groundwater; all right…, but nothing else?

International Nuclear Information System (INIS)

Menció, Anna; Mas-Pla, Josep; Otero, Neus; Regàs, Oriol; Boy-Roura, Mercè

2016-01-01

Contamination from agricultural sources and, in particular, nitrate pollution, is one of the main concerns in groundwater management. However, this type of pollution entails the entrance of other substances into the aquifer, as well as it may promote other processes. In this study, we deal with hydrochemical and isotopic analysis of groundwater samples from four distinct zones in Catalonia (NE Spain), which include 5 different aquifer types, to investigate the influence of fertilization on the overall hydrochemical composition of groundwater. Results indicate that intense fertilizer application, causing high nitrate pollution in aquifers, also homogenize the contents of the major dissolved ions (i.e.; Cl - , SO 4 2- , Ca 2+ , Na + , K + , and Mg 2+ ). Thus, when groundwater in igneous and sedimentary aquifers is compared, significant differences are observed under natural conditions for Cl - , Na + and Ca 2+ (with p-values ranging from < 0.001 to 0.038), and when high nitrate concentrations occur, these differences are reduced (most p-values ranged between 0.054 and 0.978). Moreover, positive linear relationships between nitrate and some ions are found indicating the magnitude of the fertilization impact on groundwater hydrochemistry (with R 2 values of 0.490, 0.609 and 0.470, for SO 4 2- , Ca 2+ and Cl - , respectively). Nevertheless, the increasing concentration of specific ions is not only attributed to agricultural pollution, but to their enhancing effect upon the biogeochemical processes that control water-rock interactions. Such results raise awareness that these processes should be evaluated in advance in order to assess an adequate groundwater resources management. - Highlights: • The effects of nitrate pollution have been evaluated in five different aquifer types • Statistical and multivariate analyses are used to identify groundwater changes • Agricultural pollution modifies groundwater conditions and geochemical processes • Manure application

Trend Analyses of Nitrate in Danish Groundwater

DEFF Research Database (Denmark)

Hansen, B.; Thorling, L.; Dalgaard, Tommy

2012-01-01

This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis...... of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first...... two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded...

Identifying sources of groundwater nitrate contamination in a large alluvial groundwater basin with highly diversified intensive agricultural production

Science.gov (United States)

Lockhart, K. M.; King, A. M.; Harter, T.

2013-08-01

Groundwater quality is a concern in alluvial aquifers underlying agricultural areas worldwide. Nitrate from land applied fertilizers or from animal waste can leach to groundwater and contaminate drinking water resources. The San Joaquin Valley, California, is an example of an agricultural landscape with a large diversity of field, vegetable, tree, nut, and citrus crops, but also confined animal feeding operations (CAFOs, here mostly dairies) that generate, store, and land apply large amounts of liquid manure. As in other such regions around the world, the rural population in the San Joaquin Valley relies almost exclusively on shallow domestic wells (≤ 150 m deep), of which many have been affected by nitrate. Variability in crops, soil type, and depth to groundwater contribute to large variability in nitrate occurrence across the underlying aquifer system. The role of these factors in controlling groundwater nitrate contamination levels is examined. Two hundred domestic wells were sampled in two sub-regions of the San Joaquin Valley, Stanislaus and Merced (Stan/Mer) and Tulare and Kings (Tul/Kings) Counties. Forty six percent of well water samples in Tul/Kings and 42% of well water samples in Stan/Mer exceeded the MCL for nitrate (10 mg/L NO3-N). For statistical analysis of nitrate contamination, 78 crop and landuse types were considered by grouping them into ten categories (CAFO, citrus, deciduous fruits and nuts, field crops, forage, native, pasture, truck crops, urban, and vineyards). Vadose zone thickness, soil type, well construction information, well proximity to dairies, and dominant landuse near the well were considered. In the Stan/Mer area, elevated nitrate levels in domestic wells most strongly correlate with the combination of very shallow (≤ 21 m) water table and the presence of either CAFO derived animal waste applications or deciduous fruit and nut crops (synthetic fertilizer applications). In Tulare County, statistical data indicate that elevated

Isotopic and chemical aspects of nitrate in the groundwater of the Springbok Flats

Energy Technology Data Exchange (ETDEWEB)

Heaton, T H.E.

1985-10-01

Increases in the concentration of nitrate in groundwater are becoming a world-wide problem and are commonly ascribe to one or more of three factors associated with modern farming methods: increased fertilization, increased animal waste and increased cultivation. A combined isotopic ( VN/ UN) and chemical study of the high nitrate groundwater in the basalts of the Springbok Flats (Transvaal, South Africa) indicates that the third factor is the only important source of nitrate. Nitrification of the 'black turf' soils, accelerated by the expansion of cultivation, has resulted in most of the shallow groundwater having nitrate concentrations higher than the 'maximum allowable' limit for domestic water supply and the concentrations are still increasing. Modification of farming practices has been suggested in some countries, as a means of controlling both the increase in groundwater nitrate and the attendant decrease in soil fertility.

Isotopic and chemical aspects of nitrate in the groundwater of the Springbok Flats

International Nuclear Information System (INIS)

Heaton, T.H.E.

1985-01-01

Increases in the concentration of nitrate in groundwater are becoming a world-wide problem and are commonly ascribe to one or more of three factors associated with modern farming methods: increased fertilization, increased animal waste and increased cultivation. A combined isotopic ( 15 N/ 14 N) and chemical study of the high nitrate groundwater in the basalts of the Springbok Flats (Transvaal, South Africa) indicates that the third factor is the only important source of nitrate. Nitrification of the 'black turf' soils, accelerated by the expansion of cultivation, has resulted in most of the shallow groundwater having nitrate concentrations higher than the 'maximum allowable' limit for domestic water supply and the concentrations are still increasing. Modification of farming practices has been suggested in some countries, as a means of controlling both the increase in groundwater nitrate and the attendant decrease in soil fertility

Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China

International Nuclear Information System (INIS)

Han, Dongmei; Cao, Guoliang; McCallum, James; Song, Xianfang

2015-01-01

Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33–521 mg/L) in NO_3"− concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ"1"8O, δ"2H) analysis, "3H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from − 8.5 to − 7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92–467 years) and the NO_3"− concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8–411 years) and the NO_3"− concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be transported for tens of years, through the

Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China

Energy Technology Data Exchange (ETDEWEB)

Han, Dongmei [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Cao, Guoliang [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Center for Water Research, College of Engineering, Peking University, Beijing 100871 (China); McCallum, James [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Song, Xianfang [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China)

2015-12-15

Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33–521 mg/L) in NO{sub 3}{sup −} concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ{sup 18}O, δ{sup 2}H) analysis, {sup 3}H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from − 8.5 to − 7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92–467 years) and the NO{sub 3}{sup −} concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8–411 years) and the NO{sub 3}{sup −} concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be

Identifying the sources of nitrate contamination of groundwater in an agricultural area (Haean basin, Korea) using isotope and microbial community analyses

International Nuclear Information System (INIS)

Kim, Heejung; Kaown, Dugin; Mayer, Bernhard; Lee, Jin-Yong; Hyun, Yunjung; Lee, Kang-Kun

2015-01-01

An integrated study based on hydrogeochemical, microbiological and dual isotopic approaches for nitrate and sulfate was conducted to elucidate sources and biogeochemical reactions governing groundwater contaminants in different seasons and under different land use in a basin of Korea. The land use in the study area is comprised of forests (58.0%), vegetable fields (27.6%), rice paddy fields (11.4%) and others (3.0%). The concentrations of NO 3 –N and SO 4 2− in groundwater in vegetable fields were highest with 4.2–15.2 mg L −1 and 1.6–19.7 mg L −1 respectively, whereas under paddy fields NO 3 –N concentrations ranged from 0 to 10.7 mg L −1 and sulfate concentrations were ~ 15 mg L −1 . Groundwater with high NO 3 –N concentrations of > 10 mg L −1 had δ 15 N–NO 3 − values ranging from 5.2 to 5.9‰ and δ 18 O values of nitrate between 2.7 and 4.6‰ suggesting that the nitrate was mineralized from soil organic matter that was amended by fertilizer additions. Elevated concentrations of SO 4 2− with δ 34 S–SO 4 2− values between 1 and 6‰ in aquifers in vegetable fields indicated that a mixture of sulfate from atmospheric deposition, mineralization of soil organic matter and from synthetic fertilizers is the source of groundwater sulfate. Elevated δ 18 O–NO 3 − and δ 18 O–SO 4 2− values in samples collected from the paddy fields indicated that denitrification and bacterial sulfate reduction are actively occurring removing sulfate and nitrate from the groundwater. This was supported by high occurrences of denitrifying and sulfate reducing bacteria in groundwater of the paddy fields as evidenced by 16S rRNA pyrosequencing analysis. This study shows that dual isotope techniques combined with microbial data can be a powerful tool for identification of sources and microbial processes affecting NO 3 − and SO 4 2− in groundwater in areas with intensive agricultural land use. - Highlights: • Dual isotope analyses identified

Nitrate pollution of groundwater; all right…, but nothing else?

Energy Technology Data Exchange (ETDEWEB)

Menció, Anna, E-mail: anna.mencio@udg.edu [Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Recerca en Geologia i Cartografia Ambiental (Geocamb), Deptartament de Ciències Ambientals, Facultat de Ciències, Universitat de Girona, 17071 Girona (Spain); Mas-Pla, Josep, E-mail: jmas@icra.cat [Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Recerca en Geologia i Cartografia Ambiental (Geocamb), Deptartament de Ciències Ambientals, Facultat de Ciències, Universitat de Girona, 17071 Girona (Spain); Institut Català de Recerca de l’Aigua (ICRA) (Spain); Otero, Neus, E-mail: notero@ub.edu [Grup de Mineralogia Aplicada i Geoquímica de Fluids, Departament de Cristallografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), C/ Martí i Franquès, s/n – 08028 Barcelona (Spain); Regàs, Oriol [Grup de Geologia Aplicada i Ambiental (GAiA), Centre de Recerca en Geologia i Cartografia Ambiental (Geocamb), Deptartament de Ciències Ambientals, Facultat de Ciències, Universitat de Girona, 17071 Girona (Spain); Boy-Roura, Mercè [Institut Català de Recerca de l’Aigua (ICRA) (Spain); and others

2016-01-01

Contamination from agricultural sources and, in particular, nitrate pollution, is one of the main concerns in groundwater management. However, this type of pollution entails the entrance of other substances into the aquifer, as well as it may promote other processes. In this study, we deal with hydrochemical and isotopic analysis of groundwater samples from four distinct zones in Catalonia (NE Spain), which include 5 different aquifer types, to investigate the influence of fertilization on the overall hydrochemical composition of groundwater. Results indicate that intense fertilizer application, causing high nitrate pollution in aquifers, also homogenize the contents of the major dissolved ions (i.e.; Cl{sup -}, SO{sub 4}{sup 2-}, Ca{sup 2+}, Na{sup +}, K{sup +}, and Mg{sup 2+}). Thus, when groundwater in igneous and sedimentary aquifers is compared, significant differences are observed under natural conditions for Cl{sup -}, Na{sup +} and Ca{sup 2+} (with p-values ranging from < 0.001 to 0.038), and when high nitrate concentrations occur, these differences are reduced (most p-values ranged between 0.054 and 0.978). Moreover, positive linear relationships between nitrate and some ions are found indicating the magnitude of the fertilization impact on groundwater hydrochemistry (with R{sup 2} values of 0.490, 0.609 and 0.470, for SO{sub 4}{sup 2-}, Ca{sup 2+} and Cl{sup -}, respectively). Nevertheless, the increasing concentration of specific ions is not only attributed to agricultural pollution, but to their enhancing effect upon the biogeochemical processes that control water-rock interactions. Such results raise awareness that these processes should be evaluated in advance in order to assess an adequate groundwater resources management. - Highlights: • The effects of nitrate pollution have been evaluated in five different aquifer types • Statistical and multivariate analyses are used to identify groundwater changes • Agricultural pollution modifies

Identification of hydrogeochemical processes and pollution sources of groundwater nitrate in Leiming Basin of Hainan island, Southern China

Science.gov (United States)

Shaowen, Y.; Zhan, Y., , Dr; Li, Q.

2017-12-01

Identifying the evolution of groundwater quality is important for the control and management of groundwater resources. The main aims of the present study are to identify the major factors affecting hydrogeochemistry of groundwater resources and to evaluate the potential sources of groundwater nitrate in Leiming basin using chemical and isotopic methods. The majority of samples belong to Na-Cl water type and are followed by Ca-HCO3 and mixed Ca-Na-HCO3. The δ18O and δ2H values in groundwater indicate that the shallow fissure groundwater is mainly recharged by rainfall. The evaporated surface water is another significant origin of groundwater. The weathering and dissolution of different rocks and minerals, input of precipitation, evaporation, ion exchange and anthropogenic activities, especially agricultural activities, influence the hydrogeochemistry of the study area. NO- 3 concentration in the groundwater varies from 0.7 to 51.7 mg/L and high values are mainly occurred in the densely populated area. The combined use of isotopic values and hydrochemical data suggests that the NO- 3 load in Leiming basin is not only derived from agricultural activities but also from other sources such as waste water and atmospheric deposition. Fertilizer is considered as the major source of NO- 3 in the groundwater in Leiming basin.

Field Scale Groundwater Nitrate Loading Model for the Central Valley, California, 1945-Current

Science.gov (United States)

Harter, T.; Dzurella, K.; Bell, A.; Kourakos, G.

2015-12-01

Anthropogenic groundwater nitrate contamination in the Central Valley aquifer system, California, is widespread, with over 40% of domestic wells in some counties exceeding drinking water standards. Sources of groundwater nitrate include leaky municipal wastewater systems, municipal wastewater recharge, onsite wastewater treatment (septic) systems, atmospheric nitrogen deposition, animal farming, application of organic waste materials (sludge, biosolids, animal manure) to agricultural lands, and synthetic fertilizer. At the site or field scale, nitrogen inputs to the landscape are balanced by plant nitrogen uptake and harvest, atmospheric nitrogen losses, surface runoff of nitrogen, soil nitrogen storage changes, and leaching to groundwater. Irrigated agriculture is a dominant player in the Central Valley nitrogen cycle: The largest nitrogen fluxes are synthetic fertilizer and animal manure applications to cropland, crop nitrogen uptake, and groundwater nitrogen losses. We construct a historic field/parcel scale groundwater nitrogen loading model distinguishing urban and residential areas, individual animal farming areas, leaky wastewater lagoons, and approximately 50 different categories of agricultural crops. For non-agricultural landuses, groundwater nitrate loading is based on reported leaching values, animal population, and human population. For cropland, groundwater nitrate loading is computed from mass balance, taking into account diverse and historically changing management practices between different crops. Groundwater nitrate loading is estimated for 1945 to current. Significant increases in groundwater nitrate loading are associated with the expansion of synthetic fertilizer use in the 1950s to 1970s. Nitrate loading from synthetic fertilizer use has stagnated over the past 20 years due to improvements in nutrient use efficiency. However, an unbroken 60 year exponential increase in dairy production until the late 2000s has significantly impacted the

Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China.

Science.gov (United States)

Han, Dongmei; Cao, Guoliang; McCallum, James; Song, Xianfang

2015-12-15

Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33-521mg/L) in NO3(-) concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ(18)O, δ(2)H) analysis, (3)H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from -8.5 to -7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92-467years) and the NO3(-) concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8-411years) and the NO3(-) concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be transported for tens of years, through the complex carbonate

Development of Operation Management Model of Groundwater According to Nitrate Contamination

Directory of Open Access Journals (Sweden)

Elahe Pourfarahabadi

2014-10-01

Full Text Available Nitrate is one of the most important groundwater pollutants with such different sources as chemical fertilizers, pesticides, or domestic and industrial wastewater. In this research, the optimal operation of groundwater wells in aquifers with nitrate pollution is investigated using simulation and optimization techniques. For the simulation part, an artificial neural network (ANN model is developed, and for the optimization model, the particle swarm optimization (PSO is used. Considering the high nitrate concentration in Karaj area and its increase in recent years, the northern part of this aquifer is selected as a case study to apply the proposed methodology. A seasonal ANN model is developed with input layers including well discharge in the current and previous seasons, nitrate concentration in the previous season, aquifer thickness, and well coordinates, all selected based on sensitivity analysis. The results of PSO algorithm shows that nitrate concentration can be controlled by increasing or decreasing well discharge in different zones. Therefore, it is possible to reduce nitrate concentration in critical areas by changing the spatial distribution of groundwater extractions in different zones keeping the total discharge constant.

Microbial Degradation of Phenols and Aromatic Hydrocarbons in Creosote-contaminated Groundwater Under Nitrate-reducing Conditions

DEFF Research Database (Denmark)

Flyvbjerg, John; Arvin, Erik; Jensen, Bjørn K.

1993-01-01

of toluene, 2,4-DMP, 3,4-DMP and p-cresol depended on nitrate or nitrite as electron acceptors. 40–80% of the nitrate consumed during degradation of the aromatic compounds was recovered as nitrite, and the consumption of nitrate was accompanied by a production of ATP. Stoichiometric calculations indicated......Batch experiments were carried out to investigate the biodegradation of phenols and aromatic hydrocarbons under anaerobic, nitrate-reducing conditions in groundwater from a creosote-contaminated site at Fredensborg, Denmark. The bacteria in the creosote-contaminated groundwater degraded a mixture...... that in addition to the phenols are toluene other carbon sources present in the groundwater contributed to the consumption of nitrate. If the groundwater was incubated under anaerobic conditions without nitrate, sulphate-reducing conditions evolved after ∼ 1 month at 20°C and ∼2 months at 10°C. In the sulphate...

Identifying the sources of nitrate contamination of groundwater in an agricultural area (Haean basin, Korea) using isotope and microbial community analyses

Energy Technology Data Exchange (ETDEWEB)

Kim, Heejung [School of Earth and Environmental Sciences (BK21 SEES), Seoul National University, Seoul 151–747 (Korea, Republic of); Kaown, Dugin, E-mail: dugin1@snu.ac.kr [School of Earth and Environmental Sciences (BK21 SEES), Seoul National University, Seoul 151–747 (Korea, Republic of); Mayer, Bernhard [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary T2N 1N4, Alberta (Canada); Lee, Jin-Yong [Department of Geology, Kangwon National University, Chuncheon 200–701 (Korea, Republic of); Hyun, Yunjung [Planning and Management Group, Korea Environment Institute, Sejong 339-007 (Korea, Republic of); Lee, Kang-Kun [School of Earth and Environmental Sciences (BK21 SEES), Seoul National University, Seoul 151–747 (Korea, Republic of)

2015-11-15

An integrated study based on hydrogeochemical, microbiological and dual isotopic approaches for nitrate and sulfate was conducted to elucidate sources and biogeochemical reactions governing groundwater contaminants in different seasons and under different land use in a basin of Korea. The land use in the study area is comprised of forests (58.0%), vegetable fields (27.6%), rice paddy fields (11.4%) and others (3.0%). The concentrations of NO{sub 3}–N and SO{sub 4}{sup 2−} in groundwater in vegetable fields were highest with 4.2–15.2 mg L{sup −1} and 1.6–19.7 mg L{sup −1} respectively, whereas under paddy fields NO{sub 3}–N concentrations ranged from 0 to 10.7 mg L{sup −1} and sulfate concentrations were ~ 15 mg L{sup −1}. Groundwater with high NO{sub 3}–N concentrations of > 10 mg L{sup −1} had δ{sup 15}N–NO{sub 3}{sup −} values ranging from 5.2 to 5.9‰ and δ{sup 18}O values of nitrate between 2.7 and 4.6‰ suggesting that the nitrate was mineralized from soil organic matter that was amended by fertilizer additions. Elevated concentrations of SO{sub 4}{sup 2−} with δ{sup 34}S–SO{sub 4}{sup 2−} values between 1 and 6‰ in aquifers in vegetable fields indicated that a mixture of sulfate from atmospheric deposition, mineralization of soil organic matter and from synthetic fertilizers is the source of groundwater sulfate. Elevated δ{sup 18}O–NO{sub 3}{sup −} and δ{sup 18}O–SO{sub 4}{sup 2−} values in samples collected from the paddy fields indicated that denitrification and bacterial sulfate reduction are actively occurring removing sulfate and nitrate from the groundwater. This was supported by high occurrences of denitrifying and sulfate reducing bacteria in groundwater of the paddy fields as evidenced by 16S rRNA pyrosequencing analysis. This study shows that dual isotope techniques combined with microbial data can be a powerful tool for identification of sources and microbial processes affecting NO{sub 3}{sup �

Modeling the long-term fate of agricultural nitrate in groundwater in the San Joaquin Valley, California

Science.gov (United States)

Chapelle, Francis H.; Campbell, Bruce G.; Widdowson, Mark A.; Landon, Mathew K.

2013-01-01

Nitrate contamination of groundwater systems used for human water supplies is a major environmental problem in many parts of the world. Fertilizers containing a variety of reduced nitrogen compounds are commonly added to soils to increase agricultural yields. But the amount of nitrogen added during fertilization typically exceeds the amount of nitrogen taken up by crops. Oxidation of reduced nitrogen compounds present in residual fertilizers can produce substantial amounts of nitrate which can be transported to the underlying water table. Because nitrate concentrations exceeding 10 mg/L in drinking water can have a variety of deleterious effects for humans, agriculturally derived nitrate contamination of groundwater can be a serious public health issue. The Central Valley aquifer of California accounts for 13 percent of all the groundwater withdrawals in the United States. The Central Valley, which includes the San Joaquin Valley, is one of the most productive agricultural areas in the world and much of this groundwater is used for crop irrigation. However, rapid urbanization has led to increasing groundwater withdrawals for municipal public water supplies. That, in turn, has led to concern about how contaminants associated with agricultural practices will affect the chemical quality of groundwater in the San Joaquin Valley. Crop fertilization with various forms of nitrogen-containing compounds can greatly increase agricultural yields. However, leaching of nitrate from soils due to irrigation has led to substantial nitrate contamination of shallow groundwater. That shallow nitrate-contaminated groundwater has been moving deeper into the Central Valley aquifer since the 1960s. Denitrification can be an important process limiting the mobility of nitrate in groundwater systems. However, substantial denitrification requires adequate sources of electron donors in order to drive the process. In many cases, dissolved organic carbon (DOC) and particulate organic carbon

Using delta15N- and delta18O-values to identify nitrate sources in karst ground water, Guiyang, southwest China.

Science.gov (United States)

Liu, Cong-Qiang; Li, Si-Liang; Lang, Yun-Chao; Xiao, Hua-Yun

2006-11-15

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.

Spatial assessment of animal manure spreading and groundwater nitrate pollution

Directory of Open Access Journals (Sweden)

Roberta Infascelli

2009-11-01

Full Text Available Nitrate concentration in groundwater has frequently been linked to non-point pollution. At the same time the existence of intensive agriculture and extremely intensive livestock activity increases the potential for nitrate pollution in shallow groundwater. Nitrate used in agriculture could cause adverse effects on human and animal health. In order to evaluate the groundwater nitrate pollution, and how it might evolve in time, it is essential to develop control systems and to improve policies and incentives aimed at controlling the amount of nitrate entering downstream water systems. The province of Caserta in southern Italy is characterized by high levels of animal manure loading. A comparison between manure nitrogen production and nitrate concentration in groundwater was carried out in this area, using geostatistical tools and spatial statistics. The results show a discrepancy between modelling of nitrate leaching and monitoring of the groundwater and, moreover, no spatial correlation between nitrogen production in livestock farms and nitrate concentration in groundwater, suggesting that producers are not following the regulatory procedures for the agronomic use of manure. The methodology developed in this paper could be applied also in other regions in which European Union fertilization plans are not adequately followed.

Nitrate in Danish groundwater during the last 60 years

DEFF Research Database (Denmark)

Hansen, B; Thorling, L; Dalgaard, Tommy

2011-01-01

This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis...... of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first...... two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater (see Figure 1). Regulation and technical improvements in the intensive farming in Denmark...

Determination of dominant sources of nitrate contamination in transboundary (Russian Federation/Ukraine) catchment with heterogeneous land use.

Science.gov (United States)

Vystavna, Y; Diadin, D; Grynenko, V; Yakovlev, V; Vergeles, Y; Huneau, F; Rossi, P M; Hejzlar, J; Knöller, K

2017-09-18

Nitrate contamination of surface water and shallow groundwater was studied in transboundary (Russia/Ukraine) catchment with heterogeneous land use. Dominant sources of nitrate contamination were determined by applying a dual δ 15 N-NO 3 and δ 18 O-NO 3 isotope approach, multivariate statistics, and land use analysis. Nitrate concentration was highly variable from 0.25 to 22 mg L -1 in surface water and from 0.5 to 100 mg L -1 in groundwater. The applied method indicated that sewage to surface water and sewage and manure to groundwater were dominant sources of nitrate contamination. Nitrate/chloride molar ratio was added to support the dual isotope signature and indicated the contribution of fertilizers to the nitrate content in groundwater. Groundwater temperature was found to be an additional indicator of manure and sewerage leaks in the shallow aquifer which has limited protection and is vulnerable to groundwater pollution.

Differentiation among Multiple Sources of Anthropogenic Nitrate in a Complex Groundwater System using Dual Isotope Systematics: A case study from Mortandad Canyon, New Mexico

Science.gov (United States)

Larson, T. E.; Perkins, G.; Longmire, P.; Heikoop, J. M.; Fessenden, J. E.; Rearick, M.; Fabyrka-Martin, J.; Chrystal, A. E.; Dale, M.; Simmons, A. M.

2009-12-01

The groundwater system beneath Los Alamos National Laboratory has been affected by multiple sources of anthropogenic nitrate contamination. Average NO3-N concentrations of up to 18.2±1.7 mg/L have been found in wells in the perched intermediate aquifer beneath one of the more affected sites within Mortandad Canyon. Sources of nitrate potentially reaching the alluvial and intermediate aquifers include: (1) sewage effluent, (2) neutralized nitric acid, (3) neutralized 15N-depleted nitric acid (treated waste from an experiment enriching nitric acid in 15N), and (4) natural background nitrate. Each of these sources is unique in δ18O and δ15N space. Using nitrate stable isotope ratios, a mixing model for the three anthropogenic sources of nitrate was established, after applying a linear subtraction of the background component. The spatial and temporal variability in nitrate contaminant sources through Mortandad Canyon is clearly shown in ternary plots. While microbial denitrification has been shown to change groundwater nitrate stable isotope ratios in other settings, the redox potential, relatively high dissolved oxygen content, increasing nitrate concentrations over time, and lack of observed NO2 in these wells suggest minimal changes to the stable isotope ratios have occurred. Temporal trends indicate that the earliest form of anthropogenic nitrate in this watershed was neutralized nitric acid. Alluvial wells preserve a trend of decreasing nitrate concentrations and mixing models show decreasing contributions of 15N-depleted nitric acid. Nearby intermediate wells show increasing nitrate concentrations and mixing models indicate a larger component derived from 15N-depleted nitric acid. These data indicate that the pulse of neutralized 15N-depleted nitric acid that was released into Mortandad Canyon between 1986 and 1989 has infiltrated through the alluvial aquifer and is currently affecting two intermediate wells. This hypothesis is consistent with previous

Median nitrate concentrations in groundwater in the New Jersey Highlands Region estimated using regression models and land-surface characteristics

Science.gov (United States)

Baker, Ronald J.; Chepiga, Mary M.; Cauller, Stephen J.

2015-01-01

Nitrate-concentration data are used in conjunction with land-use and land-cover data to estimate median nitrate concentrations in groundwater underlying the New Jersey (NJ) Highlands Region. Sources of data on nitrate in 19,670 groundwater samples are from the U.S. Geological Survey (USGS) National Water Information System (NWIS) and the NJ Private Well Testing Act (PWTA).

Evaluating Ecosystem Services for Reducing Groundwater Nitrate Contamination: Nitrate Attenuation in the Unsaturated and Saturated Zones

Science.gov (United States)

Wang, J.

2013-12-01

Nitrates are the most common type of groundwater contamination in agricultural regions. Environmental policies targeting nitrates have focused on input control (e.g., restricted fertilizer application), intermediate loads control (e.g., reduce nitrate leached from crop fields), and final loads control (e.g., reduce catchment nitrate loads). Nitrate loads can be affected by hydrological processes in both unsaturated and saturated zones. Although many of these processes have been extensively investigated in literature, they are commonly modeled as exogenous to farm management. A couple of recent studies by scientists from the Lawrence Livermore National Laboratory show that in some situations nitrate attenuation processes in the unsaturated/saturated zone, particularly denitrification, can be intensified by certain management practices to mitigate nitrate loads. Therefore, these nitrate attenuation processes can be regarded as a set of ecosystem services that farmers can take advantage of to reduce their cost of complying with environmental policies. In this paper, a representative California dairy farm is used as a case study to show how such ecosystem attenuation services can be framed within the farm owner's decision-making framework as an option for reducing groundwater nitrate contamination. I develop an integrated dynamic model, where the farmer maximizes discounted net farm profit over multiple periods subject to environmental regulations. The model consists of three submodels: animal-waste-crop, hydrologic, and economic model. In addition to common choice variables such as irrigation, fertilization, and waste disposal options, the farmer can also endogenously choose from three water sources: surface water, deep groundwater (old groundwater in the deep aquifer that is not affected by farm effluent in the short term), and shallow groundwater (drainage water that can be recycled via capture wells at the downstream end of the farm). The capture wells not only

Assessment of groundwater vulnerability to nitrates from agricultural sources using a GIS-compatible logic multicriteria model.

Science.gov (United States)

Rebolledo, Boris; Gil, Antonia; Flotats, Xavier; Sánchez, José Ángel

2016-04-15

In the present study an overlay method to assess groundwater vulnerability is proposed. This new method based on multicriteria decision analysis (MCDA) was developed and validated using an appropriate case study in Aragon area (NE Spain). The Vulnerability Index to Nitrates from Agricultural Sources (VINAS) incorporates a novel Logic Scoring of Preferences (LSP) approach, and it has been developed using public geographic information from the European Union. VINAS-LSP identifies areas with five categories of vulnerability, taking into account the hydrogeological and environmental characteristics of the territory as a whole. The resulting LSP map is a regional screening tool that can provide guidance on the potential risk of nitrate pollution, as well as highlight areas where specific research and farming planning policies are required. Copyright © 2016 Elsevier Ltd. All rights reserved.

Indicators to identify the source of pesticide contamination to groundwater

DEFF Research Database (Denmark)

Thorling, Lærke; Brüsch, Walter; Tuxen, Nina

In Denmark groundwater is synonym with drinking water. The mainstream Danish political approach favors prevention and action at source over advanced treatments of polluted groundwater. The main pollutants are nitrate and pesticides. Pesticides in groundwater can originate from either diffuse or p...

REMEDIATION OF NITRATE-CONTAMINATED GROUNDWATER USING A BIOBARRIER

International Nuclear Information System (INIS)

STrietelmeir, B.

2000-01-01

A biobarrier system has been developed for use in remediating shallow alluvial groundwater. This barrier is made from highly porous materials that are relatively long-lasting, carbon-based (to supply a limiting nutrient in nitrate destruction, in most cases), and extremely inexpensive and easy to emplace. In a series of laboratory studies, we have determined the effectiveness of this barrier at destroying nitrate and perchlorate in groundwater from Mortandad Canyon at Los Alamos National Laboratory (LANL). This groundwater was obtained from a monitoring well, MCO-5, which is located in the flowpath of the discharge waters from the LANL Radioactive Liquid Waste Treatment Facility (RLWTF). Water with elevated nitrate levels has been discharged from this plant for many years, until recently when the nitrate levels have been brought under the discharge limits. However, the historical discharge has resulted in a nitrate plume in the alluvial groundwater in this canyon. The LANL Multi-Barrier project was initiated this past year to develop a system of barriers that would prevent the transport of radionuclides, metals, colloids and other contaminants, including nitrate and perchlorate, further down the canyon in order to protect populations down-gradient. The biobarrier. will be part of this Multi-Barrier system. We have demonstrated the destruction of nitrate at levels up to 6.5-9.7 mhl nitrate (400-600 mg/L), and that of perchlorate at levels of about 4.3 microM perchlorate (350 ppb). We have quantified the populations of microorganisms present in the biofilm that develops on the biobarrier. The results of this research will be discussed along with other potential applications of this system

Differentiating between anthropogenic and geological sources of nitrate using multiple geochemical tracers

Science.gov (United States)

Linhoff, B.; Norton, S.; Travis, R.; Romero, Z.; Waters, B.

2017-12-01

Nitrate contamination of groundwater is a major problem globally including within the Albuquerque Basin in New Mexico. Ingesting high concentrations of nitrate (> 10 mg/L as N) can lead to an increased risk of cancer and to methemoglobinemia in infants. Numerous anthropogenic sources of nitrate have been identified within the Albuquerque Basin including fertilizers, landfills, multiple sewer pipe releases, sewer lagoons, domestic septic leach fields, and a nitric acid line outfall. Furthermore, groundwater near ephemeral streams often exhibits elevated NO3 concentrations and high NO3/Cl ratios incongruous with an anthropogenic source. These results suggest that NO3 can be concentrated through evaporation beneath ephemeral streams and mobilized via irrigation or land use change. This study seeks to use extensive geochemical analyses of groundwater and surface water to differentiate between various sources of NO3 contamination. The U.S. Geological Survey collected 54 groundwater samples from wells and six samples from ephemeral streams from within and from outside of areas of known nitrate contamination. To fingerprint the sources of nitrate pollution, samples were analyzed for major ions, trace metals, nutrients, dissolved gases, δ15N and δ18O in NO3, δ15N within N2 gas, and, δ2H and δ18O in H2O. Furthermore, most sites were sampled for artificial sweeteners and numerous contaminants of emerging concern including pharmaceutical drugs, caffeine, and wastewater indicators. This study will also investigate the age distribution of groundwater and the approximate age of anthropogenic NO3 contamination using 3He/4He, δ13C, 14C, 3H, as well as pharmaceutical drugs and artificial sweeteners with known patent and U.S. Food and Drug Administration approval dates. This broad suite of analytes will be used to differentiate between naturally occurring and multiple anthropogenic NO3 sources, and to potentially determine the approximate date of NO3 contamination.

Nitrate and ammonia as nitrogen sources for deep subsurface microorganisms

Directory of Open Access Journals (Sweden)

Heini eKutvonen

2015-10-01

Full Text Available We investigated the N-utilizing bacterial community in anoxic brackish groundwater of the low and intermediate level nuclear waste repository cave in Olkiluoto, Finland, at 100 m depth using 15N-based stable isotope probing (SIP and enrichment with 14/15N-ammonium or 14/15N-nitrate complemented with methane. 28 days of incubation at 12°C increased the concentration of bacterial 16S rRNA and nitrate reductase (narG gene copies in the substrate amended microcosms simultaneously with a radical drop in the overall bacterial diversity and OTU richness. Hydrogenophaga/Malikia were enriched in all substrate amended microcosms and Methylobacter in the ammonium and ammonium+methane supplemented microcosms. Sulfuricurvum was especially abundant in the nitrate+methane treatment and the unamended incubation control. Membrane-bound nitrate reductase genes (narG from Polarimonas sp. were detected in the original groundwater, while Burkholderia, Methylibium and Pseudomonas narG genes were enriched due to substrate supplements. Identified amoA genes belonged to Nitrosomonas sp. 15N-SIP revealed that Burkholderiales and Rhizobiales clades belonging to the minority groups in the original groundwater used 15N from ammonium and nitrate as N source indicating an important ecological function of these bacteria, despite their low number, in the groundwater N cycle in Olkiluoto bedrock system.

Evaluation of Nitrate Sources and Transformation in the Oglio River Watershed

Energy Technology Data Exchange (ETDEWEB)

Delconte, C. A. [Istituto di Geoscienze e Georisorse, CNR, U.O.S. di Pavia (Italy); Dipartimento di Scienze Della Terra e dell' Ambiente, Universita di Pavia (Italy); Sacchi, E. [Dipartimento di Scienze della Terra e dell' ambiente, Universita di Pavia (Italy); Istituto di Geoscienze e Georisorse, CNR, U.O.S. di Pavia (Italy); Allais, E. [ISO4 s.n.c., Torino (Italy); Racchetti, E. [Dipartimento di Scienze Ambientali, Universita di Parma (Italy)

2013-07-15

In agricultural watersheds, the management of nitrate contamination in rivers requires the understanding of the existing relationships between soil, groundwater and surface water. The reported data correspond to three sampling campaigns, conducted in different seasons on surface water in a nitrate Vulnerable Zone of lombardy (northern Italy). The Oglio River, its tributaries, one spring, and effluents from wastewater treatment plants were sampled to determinen content, speciation and nitrate isotopes. The nitrate content increased along the Oglio River, mostly due to groundwater inputs. In summer, nitrate tended to decrease at the downstream reach, whilst this trend was not clear in autumn and winter campaigns. In summertime chemical and isotopic data suggest the presence of weak denitrification in the Oglio riverbed. Chemical, isotopic data and flow measurements allow the definition of the N fluxes and identification of sources and processes affecting the nitrate concentration in the river. (author)

Evaluation of nitrate pollution of groundwater in Mnasra region

International Nuclear Information System (INIS)

Marouane, B.; El hajjaji, S.; Dahchour, A.; Dousset, S.

2012-01-01

Gharb area is one of the most important agricultural regions in Morocco, where the application of fertilizers is conducted in many cases without any respect of standards. This situation may generate negative environmental impact in vulnerable areas such as Mnasra groundwater. Our study tends to evaluate the level of contamination by nitrate of groundwater in a Mnasra area. The results show that 80% of the sampled wells are highly concentrated in nitrates in comparison with the standard of WHO. Intensification of agriculture in the area associated to excessive fertilizer application, repeated applications, irrigation and rainfall are reasons for an increasing nitrates pollution of water resources. Leaching of nitrate to the groundwater should receive more attention for its potential high mobile propriety which could cause serious damages for the environment and negative impact to the health of population.

Estimation of Nitrate Trends in the Groundwater of the Zagreb Aquifer

Directory of Open Access Journals (Sweden)

Zoran Kovač

2018-05-01

Full Text Available Nitrates present one of the main groundwater contaminants in the world and in the Zagreb aquifer. The Zagreb aquifer presents the main source of potable water for the inhabitants of the City of Zagreb and it is protected by the Republic of Croatia. The determination of contaminants trends presents one of the main tools in groundwater body status and risk assessment. In this paper, the use of regression analysis on the aggregated data, together with confidence and prediction intervals, at different observation scales has been evaluated. Nitrate concentrations are generally decreasing in almost all areas, observed at different observation scales. It has been shown that linear regression can be efficiently used in the estimation of nitrates trends. Results showed that the calculation of confidence and prediction intervals can provide more useful conclusions than the calculation of the trend’s statistical significance. Also, the results suggest that confidence and prediction intervals can be used in groundwater body chemical status and risk assessment, respectively. Data smoothing and data aggregation are generally desirable, but have certain limitations. If too much data is aggregated, trend estimation by regression analysis can point to false conclusions. Evaluation of trends at different observational scales can provide more realistic trend estimation, as well as more precise identification of areas where groundwater protection measures should be implemented.

Estimates of nitrate loads and yields from groundwater to streams in the Chesapeake Bay watershed based on land use and geology

Science.gov (United States)

Terziotti, Silvia; Capel, Paul D.; Tesoriero, Anthony J.; Hopple, Jessica A.; Kronholm, Scott C.

2018-03-07

The water quality of the Chesapeake Bay may be adversely affected by dissolved nitrate carried in groundwater discharge to streams. To estimate the concentrations, loads, and yields of nitrate from groundwater to streams for the Chesapeake Bay watershed, a regression model was developed based on measured nitrate concentrations from 156 small streams with watersheds less than 500 square miles (mi2 ) at baseflow. The regression model has three predictive variables: geologic unit, percent developed land, and percent agricultural land. Comparisons of estimated and actual values within geologic units were closely matched. The coefficient of determination (R2 ) for the model was 0.6906. The model was used to calculate baseflow nitrate concentrations at over 83,000 National Hydrography Dataset Plus Version 2 catchments and aggregated to 1,966 total 12-digit hydrologic units in the Chesapeake Bay watershed. The modeled output geospatial data layers provided estimated annual loads and yields of nitrate from groundwater into streams. The spatial distribution of annual nitrate yields from groundwater estimated by this method was compared to the total watershed yields of all sources estimated from a Chesapeake Bay SPAtially Referenced Regressions On Watershed attributes (SPARROW) water-quality model. The comparison showed similar spatial patterns. The regression model for groundwater contribution had similar but lower yields, suggesting that groundwater is an important source of nitrogen for streams in the Chesapeake Bay watershed.

Determination of timescales of nitrate contamination by groundwater age models in a complex aquifer system

Science.gov (United States)

Koh, E. H.; Lee, E.; Kaown, D.; Lee, K. K.; Green, C. T.

2017-12-01

Timing and magnitudes of nitrate contamination are determined by various factors like contaminant loading, recharge characteristics and geologic system. Information of an elapsed time since recharged water traveling to a certain outlet location, which is defined as groundwater age, can provide indirect interpretation related to the hydrologic characteristics of the aquifer system. There are three major methods (apparent ages, lumped parameter model, and numerical model) to date groundwater ages, which differently characterize groundwater mixing resulted by various groundwater flow pathways in a heterogeneous aquifer system. Therefore, in this study, we compared the three age models in a complex aquifer system by using observed age tracer data and reconstructed history of nitrate contamination by long-term source loading. The 3H-3He and CFC-12 apparent ages, which did not consider the groundwater mixing, estimated the most delayed response time and a highest period of the nitrate loading had not reached yet. However, the lumped parameter model could generate more recent loading response than the apparent ages and the peak loading period influenced the water quality. The numerical model could delineate various groundwater mixing components and its different impacts on nitrate dynamics in the complex aquifer system. The different age estimation methods lead to variations in the estimated contaminant loading history, in which the discrepancy in the age estimation was dominantly observed in the complex aquifer system.

Nitrogen-isotopes and multi-parameter sewage water test for identification of nitrate sources: Groundwater body Marchfeld East of Vienna

Science.gov (United States)

Kralik, Martin

2017-04-01

The application of nitrogen and oxygen isotopes in nitrate allows, under favourable circumstances, to identify potential sources such as precipitation, chemical fertilisers and manure or sewage water. Without any additional tracer, the source distinction of nitrate from manure or sewage water is still difficult. Even the application of boron isotopes can in some cases not avoid ambiguous interpretation. Therefore, the Environment Agency Austria developed a new multi parametrical indicator test to allow the identification and quantification of pollution by domestic sewage water. The test analyses 8 substances well known to occur in sewage water: Acesulfame and sucralose (two artificial, calorie-free sweeteners), benzotriazole and tolyltriazole (two industrial chemicals/corrosion inhibitors), metoprolol, sotalol, carbamazepine and the metabolite 10,11-Dihydro-10,11-dihydroxycarbamazepine (pharmaceuticals) [1]. These substances are polar and degradation in the aquatic system by microbiological processes is not documented. These 8 Substances do not occur naturally which make them ideal tracers. The test can detect wastewater in the analysed water sample down to 0.1 %. This ideal coupling of these analytic tests helps to identify the nitrogen sources in the groundwater body Marchfeld East of Vienna to a high confidence level. In addition, the results allow a reasonable quantification of nitrogen sources from different types of fertilizers as well as sewage water contributions close to villages and in wells recharged by bank filtration. Recent investigations of groundwater in selected wells in Marchfeld [2] indicated a clear nitrogen contribution by wastewater leakages (sewers or septic tanks) to the total nitrogen budget. However, this contribution is shrinking and the main source comes still from agricultural activities. [1] Humer, F.; Weiss, S.; Reinnicke, S.; Clara, M.; Grath, J.; Windhofer, G. (2013): Multi parametrical indicator test for urban wastewater influence

The use of nitrate isotopes to identify contamination sources in the Bou-Areg aquifer (Morocco)

Energy Technology Data Exchange (ETDEWEB)

Re, Viviana [Ca' Foscari University of Venice, Department of Molecular Sciences and Nanosystems, Dorsoduro 2137, Venice, 30123 (Italy); Sacchi, Elisa [University of Pavia, Department of Earth and Environmental Sciences, Via Ferrata 1, Pavia, 27100 (Italy); Allais, Enrico [ISO4 s.n.c., Via Ferrata 1, Pavia, 27100 (Italy)

2013-07-01

The Bou-Areg coastal aquifer (Morocco) is affected by high nitrate levels in groundwater, with possible consequences for the natural environment and human health. The use of environmental tracers, including δ{sup 15}NNO{sub 3} and δ{sup 18}ONO{sub 3}, allowed identifying the main sources of nitrate contamination in groundwater samples collected in 2010. These are manure and septic effluents, especially in urban areas, and synthetic fertilizers in agricultural areas. This work represents a preliminary step for a more detailed nitrate vulnerability assessment to support groundwater management and protection in the studied region. (authors)

Residence time as a key for comprehensive assessment of the relationship between changing land use and nitrates in regional groundwater systems.

Science.gov (United States)

Cao, Yingjie; Tang, Changyuan; Song, Xianfang; Liu, Changming; Zhang, Yinghua

2013-04-01

In this study, an approach is put forward to study the relationship between changing land use and groundwater nitrate contamination in the Sanjiang Plain. This approach emphasizes the importance of groundwater residence time when relating the nitrates to the changing land use. The principles underlying the approach involve the assessment of groundwater residence time by CFCs and the Vogel age model and the reconstruction of the land use at the groundwater recharge time by interpolation. Nitrate trend analysis shows that nitrates have begun to leach into the aquifers since agricultural activities boomed after the 1950s. Hydrochemical analysis implies that the possible process relating to the nitrate reduction in the groundwater is the oxidation of Fe(ii)-silicates. However, the chemical kinetics of the oxidation of Fe(ii)-silicates is slow, so this denitrification process contributes little to the nitrate variations. Stepwise regression shows that the nitrate concentrations of samples had no direct relationship with the land use at the groundwater sampling time, but had a relatively strong relationship with the land use at the groundwater recharge time. Dry land is recognized as the dominant factor contributing to the elevated concentration of nitrates. The nitrogen isotope for nitrate (δ(15)N-NO3) gives a more direct result of the identification of nitrate sources: the use of manure in agricultural activities. Principle component (PC) regression shows that the process of the dry land exploitation is the major process that controls the nitrate contamination in the Sanjiang Plain.

ArcNLET: A GIS-based software to simulate groundwater nitrate load from septic systems to surface water bodies

Science.gov (United States)

Rios, J. Fernando; Ye, Ming; Wang, Liying; Lee, Paul Z.; Davis, Hal; Hicks, Rick

2013-03-01

Onsite wastewater treatment systems (OWTS), or septic systems, can be a significant source of nitrates in groundwater and surface water. The adverse effects that nitrates have on human and environmental health have given rise to the need to estimate the actual or potential level of nitrate contamination. With the goal of reducing data collection and preparation costs, and decreasing the time required to produce an estimate compared to complex nitrate modeling tools, we developed the ArcGIS-based Nitrate Load Estimation Toolkit (ArcNLET) software. Leveraging the power of geographic information systems (GIS), ArcNLET is an easy-to-use software capable of simulating nitrate transport in groundwater and estimating long-term nitrate loads from groundwater to surface water bodies. Data requirements are reduced by using simplified models of groundwater flow and nitrate transport which consider nitrate attenuation mechanisms (subsurface dispersion and denitrification) as well as spatial variability in the hydraulic parameters and septic tank distribution. ArcNLET provides a spatial distribution of nitrate plumes from multiple septic systems and a load estimate to water bodies. ArcNLET's conceptual model is divided into three sub-models: a groundwater flow model, a nitrate transport and fate model, and a load estimation model which are implemented as an extension to ArcGIS. The groundwater flow model uses a map of topography in order to generate a steady-state approximation of the water table. In a validation study, this approximation was found to correlate well with a water table produced by a calibrated numerical model although it was found that the degree to which the water table resembles the topography can vary greatly across the modeling domain. The transport model uses a semi-analytical solution to estimate the distribution of nitrate within groundwater, which is then used to estimate a nitrate load using a mass balance argument. The estimates given by ArcNLET are

Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas

Energy Technology Data Exchange (ETDEWEB)

Musgrove, M., E-mail: mmusgrov@usgs.gov [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Opsahl, S.P. [U.S. Geological Survey, 5563 DeZavala, Ste. 290, San Antonio, TX 78249 (United States); Mahler, B.J. [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Herrington, C. [City of Austin Watershed Protection Department, Austin, TX 78704 (United States); Sample, T.L. [U.S. Geological Survey, 19241 David Memorial Dr., Ste. 180, Conroe, TX 77385 (United States); Banta, J.R. [U.S. Geological Survey, 5563 DeZavala, Ste. 290, San Antonio, TX 78249 (United States)

2016-10-15

Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO{sub 3}{sup −}) loading to surface and groundwater. We investigate variability and sources of NO{sub 3}{sup −} in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO{sub 3}{sup −} stable isotopes (δ{sup 15}N and δ{sup 18}O). These data were augmented by historical data collected from 1937 to 2007. NO{sub 3}{sup −} concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO{sub 3}{sup −} concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO{sub 3}{sup −} concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO{sub 3}{sup −}. These results highlight the vulnerability of karst aquifers to NO{sub 3}{sup −} contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO{sub 3}{sup −} than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates

Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas

International Nuclear Information System (INIS)

Musgrove, M.; Opsahl, S.P.; Mahler, B.J.; Herrington, C.; Sample, T.L.; Banta, J.R.

2016-01-01

Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO 3 − ) loading to surface and groundwater. We investigate variability and sources of NO 3 − in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO 3 − stable isotopes (δ 15 N and δ 18 O). These data were augmented by historical data collected from 1937 to 2007. NO 3 − concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO 3 − concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO 3 − concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO 3 − . These results highlight the vulnerability of karst aquifers to NO 3 − contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO 3 − than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates that subaqueous nitrification of organic N in the aquifer, as opposed to in soils, might be a

Evaluating sources and processing of nonpoint source nitrate in a small suburban watershed in China

Science.gov (United States)

Han, Li; Huang, Minsheng; Ma, Minghai; Wei, Jinbao; Hu, Wei; Chouhan, Seema

2018-04-01

Identifying nonpoint sources of nitrate has been a long-term challenge in mixed land-use watershed. In the present study, we combine dual nitrate isotope, runoff and stream water monitoring to elucidate the nonpoint nitrate sources across land use, and determine the relative importance of biogeochemical processes for nitrate export in a small suburban watershed, Longhongjian watershed, China. Our study suggested that NH4+ fertilizer, soil NH4+, litter fall and groundwater were the main nitrate sources in Longhongjian Stream. There were large changes in nitrate sources in response to season and land use. Runoff analysis illustrated that the tea plantation and forest areas contributed to a dominated proportion of the TN export. Spatial analysis illustrated that NO3- concentration was high in the tea plantation and forest areas, and δ15N-NO3 and δ18O-NO3 were enriched in the step ponds. Temporal analysis showed high NO3- level in spring, and nitrate isotopes were enriched in summer. Study as well showed that the step ponds played an important role in mitigating nitrate pollution. Nitrification and plant uptake were the significant biogeochemical processes contributing to the nitrogen transformation, and denitrification hardly occurred in the stream.

Use of '15N/14N ratio to evaluate the anthropogenic source of nitrates in surface and groundwaters in the upper Orontes Basin (central Syria)

International Nuclear Information System (INIS)

Kattan, Z.

2002-01-01

The 15 N/ 14 N ratio of dissolved nitrogen species has long been used for the identification of the different sources of nitrate contamination of water systems. This study, which aims at providing a practical example of the utility of the 15 N stable isotope in identifying the natural and anthropogenic sources of nitrate in surface and groundwaters in the upper Orontes Basin, was implemented within the framework of the IAEA Regional technical project entitled 'Isotope Hydrology Techniques in Water Resources Management (RAW/8/002)'. The selected area for this work is located in the upper part of the Orontes River Basin, which occupies the central zone of the Syrian territories. This heavily populated region is characterized by intensive agricultural and industrial developments. Hence, the influence of the growing domestic activities is reflected by rapidly deteriorating of the surface and groundwaters qualities in this area

Assessing biosynthetic potential of agricultural groundwater through metagenomic sequencing: A diverse anammox community dominates nitrate-rich groundwater.

Directory of Open Access Journals (Sweden)

William B Ludington

Full Text Available Climate change produces extremes in both temperature and precipitation causing increased drought severity and increased reliance on groundwater resources. Agricultural practices, which rely on groundwater, are sensitive to but also sources of contaminants, including nitrate. How agricultural contamination drives groundwater geochemistry through microbial metabolism is poorly understood.On an active cow dairy in the Central Valley of California, we sampled groundwater from three wells at depths of 4.3 m (two wells and 100 m (one well below ground surface (bgs as well as an effluent surface water lagoon that fertilizes surrounding corn fields. We analyzed the samples for concentrations of solutes, heavy metals, and USDA pathogenic bacteria of the Escherichia coli and Enterococcus groups as part of a long term groundwater monitoring study. Whole metagenome shotgun sequencing and assembly revealed taxonomic composition and metabolic potential of the community.Elevated nitrate and dissolved organic carbon occurred at 4.3m but not at 100m bgs. Metagenomics confirmed chemical observations and revealed several Planctomycete genomes, including a new Brocadiaceae lineage and a likely Planctomycetes OM190, as well novel diversity and high abundance of nano-prokaryotes from the Candidate Phyla Radiation (CPR, the Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, Nanohaloarchaea (DPANN and the Thaumarchaeota, Aigarchaeota, Crenarchaeota, Korarchaeota (TACK superphyla. Pathway analysis suggests community interactions based on complimentary primary metabolic pathways and abundant secondary metabolite operons encoding antimicrobials and quorum sensing systems.The metagenomes show strong resemblance to activated sludge communities from a nitrogen removal reactor at a wastewater treatment plant, suggesting that natural bioremediation occurs through microbial metabolism. Elevated nitrate and rich secondary metabolite biosynthetic capacity suggest

Correlation between nitrate concentration in groundwater and parameters affecting aquifer intrinsic vulnerability

Science.gov (United States)

Debernardi, Laura; de Luca, Domenico Antonio; Lasagna, Manuela

2008-08-01

This paper is the result of a study which was carried out in order to verify if the traditional methods to evaluate the intrinsic vulnerability or vulnerability related parameters, are able to clarify the problem of nitrate pollution in groundwater. In particular, the aim was to evaluate limitations and problems connected to aquifer vulnerability methods applied to nitrate contamination prevision in groundwater. The investigation was carried out by comparing NO3 - concentrations, measured in March and November 2004 in the shallow aquifer, and the vulnerability classes, obtained by using GOD and TOT methods. Moreover, it deals with a comparison between NO3 - concentrations and single parameters (depth to water table, land use and nitrogen input). The study area is the plain sector of Piemonte (Northern Italy), where an unconfined aquifer nitrate contamination exists. In this area the anthropogenic presence is remarkable and the input of N-fertilizers and zootechnical effluents to the soil cause a growing amount of nitrates in groundwater. This approach, used in a large area (about 10,000 km2) and in several monitoring wells (about 500), allowed to compare the efficiency of different vulnerability methods and to verify the importance of every parameter on the nitrate concentrations in the aquifer. Furthermore it allowed to obtain interesting correlations in different hydrogeological situations. Correlations between depth to water table, land use and nitrogen input to the soil with nitrate concentrations in groundwater show unclear situations: in fact these comparisons describe the phenomenon trend and highlight the maximum nitrate concentrations for each circumstance but often show wide ranges of possible nitrate concentrations. The same situation could be observed by comparing vulnerability indexes and nitrate concentrations in groundwater. These results suggest that neither single parameters nor vulnerability methods (GOD and TOT) are able to describe individually

Isotopic Evidence of Nitrate Sources and its Relationship to Algae in the San Joaquin River, California

Science.gov (United States)

Silva, S. R.; Kendall, C.; Young, M. B.; Stringfellow, W. T.; Borglin, S. E.; Kratzer, C. R.; Dahlgren, R. A.; Schmidt, C.; Rollog, M. E.

2007-12-01

Many competing demands have been placed on the San Joaquin River including deep water shipping, use as agricultural and drinking water, transport of agricultural and urban runoff, and recreation. These long-established demands limit the management options and increase the importance of understanding the river dynamics. The relationships among sources of water, nitrate, and algae in the San Joaquin River must be understood before management decisions can be made to optimize aquatic health. Isotopic analyses of water samples collected along the San Joaquin River in 2005-2007 have proven useful in assessing these relationships: sources of nitrate, the productivity of the San Joaquin River, and the relationship between nitrate and algae in the river. The San Joaquin River receives water locally from wetlands and agricultural return flow, and from three relatively large tributaries whose headwaters are in the Sierra Nevada. The lowest nitrate concentrations occur during periods of high flow when the proportion of water from the Sierra Nevada is relatively large, reflecting the effect of dilution from the big tributaries and indicating that a large fraction of the nitrate is of local origin. Nitrogen isotopes of nitrate in the San Joaquin River are relatively high (averaging about 12 per mil), suggesting a significant source from animal waste or sewage and/or the effects of denitrification. The d15N of nitrate varies inversely with concentration, indicating that these high isotopic values are also a local product. The d15N values of nitrate from most of the local tributaries is lower than that in the San Joaquin suggesting that nitrate from these tributaries does not account for a significant fraction of nitrate in the river. The source of the non-tributary nitrate must be either small unmeasured surface inputs or groundwater. To investigate whether groundwater might be a significant source of nitrate to the San Joaquin River, groundwater samples are being collected

California GAMA Special Study: An isotopic and dissolved gas investigation of nitrate source and transport to a public supply well in California's Central Valley

Energy Technology Data Exchange (ETDEWEB)

Singleton, M J; Moran, J E; Esser, B K; Roberts, S K; Hillegonds, D J

2010-04-14

This study investigates nitrate contamination of a deep municipal drinking water production well in Ripon, CA to demonstrate the utility of natural groundwater tracers in constraining the sources and transport of nitrate to deep aquifers in the Central Valley. The goal of the study was to investigate the origin (source) of elevated nitrate and the potential for the deep aquifer to attenuate anthropogenic nitrate. The site is ideal for such an investigation. The production well is screened from 165-325 feet below ground surface and a number of nearby shallow and deep monitoring wells were available for sampling. Furthermore, potential sources of nitrate contamination to the well had been identified, including a fertilizer supply plant located approximately 1000 feet to the east and local almond groves. A variety of natural isotopic and dissolved gas tracers including {sup 3}H-{sup 3}He groundwater age and the isotopic composition of nitrate are applied to identify nitrate sources and to characterize nitrate transport. An advanced method for sampling production wells is employed to help identify contaminant contributions from specific screen intervals. Nitrate transport: Groundwater nitrate at this field site is not being actively denitrified. Groundwater parameters indicate oxic conditions, the dissolved gas data shows no evidence for excess nitrogen as the result of denitrification, and nitrate-N and -O isotope compositions do not display patterns typical of denitrification. Contaminant nitrate source: The ambient nitrate concentration in shallow groundwater at the Ripon site ({approx}12 mg/L as nitrate) is typical of shallow groundwaters affected by recharge from agricultural and urban areas. Nitrate concentrations in Ripon City Well 12 (50-58 mg/L as nitrate) are significantly higher than these ambient concentrations, indicating an additional source of anthropogenic nitrate is affecting groundwater in the capture zone of this municipal drinking water well. This

Fertilizer standards for controlling groundwater nitrate pollution from agriculture: El Salobral-Los Llanos case study, Spain

Science.gov (United States)

Peña-Haro, S.; Llopis-Albert, C.; Pulido-Velazquez, M.; Pulido-Velazquez, D.

2010-10-01

SummaryAlthough the legislation on groundwater quality targets pollutant concentration, the effects of measures on non-point source pollution control are often evaluated in terms of their emission reduction potential at the source, not on their capacity of reducing the pollutant concentration in groundwater. This paper applies a hydro-economic modelling framework to an aquifer, El Salobral-Los Llanos aquifer (Mancha Oriental, Spain), where nitrate concentrations higher than those allowed by the EU Water Framework Directive and Groundwater Directive are locally found due to the intense fertilizer use in irrigated crops. The approach allows defining the economically optimal allocation of spatially variable fertilizer standards in agricultural basins using a hydro-economic model that links the fertilizer application with groundwater nitrate concentration at different control sites while maximizing net economic benefits. The methodology incorporates results from agronomic simulations, groundwater flow and transport into a management framework that yields the fertilizer allocation that maximizes benefits in agriculture while meeting the environmental standards. The cost of applying fertilizer standards was estimated as the difference between the private net revenues from actual application and the scenarios generated considering the application of the standards. Furthermore, the cost of applying fertilizer standards was compared with the cost of taxing nitrogen fertilizers in order to reduce the fertilizer use to a level that the nitrate concentration in groundwater was below the limit. The results show the required reduction of fertilizer application in the different crop areas depending on its location with regards to the control sites, crop types and soil-plant conditions, groundwater flow and transport processes, time horizon for meeting the standards, and the cost of implementing such a policy (as forgone benefits). According to the results, a high fertilizer price

Village-Level Identification of Nitrate Sources: Collaboration of Experts and Local Population in Benin, Africa

Science.gov (United States)

Crane, P.; Silliman, S. E.; Boukari, M.; Atoro, I.; Azonsi, F.

2005-12-01

Deteriorating groundwater quality, as represented by high nitrates, in the Colline province of Benin, West Africa was identified by the Benin national water agency, Direction Hydraulique. For unknown reasons the Colline province had consistently higher nitrate levels than any other region of the country. In an effort to address this water quality issue, a collaborative team was created that incorporated professionals from the Universite d'Abomey-Calavi (Benin), the University of Notre Dame (USA), Direction l'Hydraulique (a government water agency in Benin), Centre Afrika Obota (an educational NGO in Benin), and the local population of the village of Adourekoman. The goals of the project were to: (i) identify the source of nitrates, (ii) test field techniques for long term, local monitoring, and (iii) identify possible solutions to the high levels of groundwater nitrates. In order to accomplish these goals, the following methods were utilized: regional sampling of groundwater quality, field methods that allowed the local population to regularly monitor village groundwater quality, isotopic analysis, and sociological methods of surveys, focus groups, and observations. It is through the combination of these multi-disciplinary methods that all three goals were successfully addressed leading to preliminary identification of the sources of nitrates in the village of Adourekoman, confirmation of utility of field techniques, and initial assessment of possible solutions to the contamination problem.

Particulate Pyrite Autotrophic Denitrification (PPAD) for Remediation of Nitrate-contaminated Groundwater

Science.gov (United States)

Tong, S.; Rodriguez-Gonzalez, L. C.; Henderson, M.; Feng, C.; Ergas, S. J.

2015-12-01

The rapid movement of human civilization towards urbanization, industrialization, and increased agricultural activities has introduced a large amount of nitrate into groundwater. Nitrate is a toxic substance discharged from groundwater to rivers and leads to decreased dissolved oxygen and eutrophication. For this experiment, an electron donor is needed to convert nitrate into non-toxic nitrogen gas. Pyrite is one of the most abundant minerals in the earth's crust making it an ideal candidate as an electron donor. The overall goal of this research was to investigate the potential for pyrite to be utilized as an electron donor for autotrophic denitrification of nitrate-contaminated groundwater. Batch studies of particulate pyrite autotrophic denitrification (PPAD) of synthetic groundwater (100 mg NO3--N L-1) were set up with varying biomass concentration, pyrite dose, and pyrite particle size. Reactors were seeded with mixed liquor volatile suspended solids (VSS) from a biological nitrogen removal wastewater treatment facility. PPAD using small pyrite particles (exhibited substantial nitrate removal rate, lower sulfate accumulation (5.46 mg SO42-/mg NO3--N) and lower alkalinity consumption (1.70 mg CaCO3/mg NO3--N) when compared to SOD (7.54 mg SO42-/mg NO3--N, 4.57 mg CaCO3/mg NO3--N based on stoichiometric calculation). This research revealed that the PPAD process is a promising technique for nitrate-contaminated groundwater treatment and promoted the utilization of pyrite in the field of environmental remediation.

Removal of Selenium and Nitrate in Groundwater Using Organic Carbon-Based Reactive Mixtures

Science.gov (United States)

An, Hyeonsil; Jeen, Sung-Wook

2016-04-01

Treatment of selenium and nitrate in groundwater was evaluated through column experiments. Four columns consisting of reactive mixtures, either organic carbon-limestone (OC-LS) or organic carbon-zero valent iron (OC-ZVI), were used to determine the removal efficiency of selenium with different concentrations of nitrate. The source waters were collected from a mine site in Korea or were prepared artificially based on the mine drainage water or deionized water, followed by spiking of elevated concentrations of Se (40 mg/L) and nitrate (100 or 10 mg/L as NO3-N). The results for the aqueous chemistry showed that selenium and nitrate were effectively removed both in the mine drainage water and deionized water-based artificial input solution. However, the removal of selenium was delayed when selenium and nitrate coexisted in the OC-LS columns. The removal of selenium was not significant when the influent nitrate concentration was 100 mg/L as NO3-N, while most of nitrate was gradually removed within the columns. In contrast, 94% of selenium was removed when the influent nitrate concentration was reduced to 10 mg/L as NO3-N. In the OC-ZVI column, selenium and nitrate was removed almost simultaneously and completely even with the high nitrate concentration; however, a high concentration of ammonia was produced as a by-product of abiotic reaction between ZVI and nitrate. The elemental analysis for the solid samples after the termination of the experiments showed that selenium was accumulated in the reactive materials where removal of aqueous-phase selenium mostly occurred. The X-ray absorption near-edge structure (XANES) study indicated that selenium existed in the forms of SeS2 and Se(0) in the OC-LS column, while selenium was present in the forms of FeSe, SeS2 and absorbed Se(IV) in the OC-ZVI column. This study shows that OC-based reactive mixtures have an ability to remove selenium and nitrate in groundwater. However, the removal of selenium was influenced by the high

Groundwater nitrate concentration evolution under climate change and agricultural adaptation scenarios: Prince Edward Island, Canada

Science.gov (United States)

Paradis, Daniel; Vigneault, Harold; Lefebvre, René; Savard, Martine M.; Ballard, Jean-Marc; Qian, Budong

2016-03-01

Nitrate (N-NO3) concentration in groundwater, the sole source of potable water in Prince Edward Island (PEI, Canada), currently exceeds the 10 mg L-1 (N-NO3) health threshold for drinking water in 6 % of domestic wells. Increasing climatic and socio-economic pressures on PEI agriculture may further deteriorate groundwater quality. This study assesses how groundwater nitrate concentration could evolve due to the forecasted climate change and its related potential changes in agricultural practices. For this purpose, a tridimensional numerical groundwater flow and mass transport model was developed for the aquifer system of the entire Island (5660 km2). A number of different groundwater flow and mass transport simulations were made to evaluate the potential impact of the projected climate change and agricultural adaptation. According to the simulations for year 2050, N-NO3 concentration would increase due to two main causes: (1) the progressive attainment of steady-state conditions related to present-day nitrogen loadings, and (2) the increase in nitrogen loadings due to changes in agricultural practices provoked by future climatic conditions. The combined effects of equilibration with loadings, climate and agricultural adaptation would lead to a 25 to 32 % increase in N-NO3 concentration over the Island aquifer system. The change in groundwater recharge regime induced by climate change (with current agricultural practices) would only contribute 0 to 6 % of that increase for the various climate scenarios. Moreover, simulated trends in groundwater N-NO3 concentration suggest that an increased number of domestic wells (more than doubling) would exceed the nitrate drinking water criteria. This study underlines the need to develop and apply better agricultural management practices to ensure sustainability of long-term groundwater resources. The simulations also show that observable benefits from positive changes in agricultural practices would be delayed in time due to

Stochastic analysis to assess the spatial distribution of groundwater nitrate concentrations in the Po catchment (Italy)

International Nuclear Information System (INIS)

Cinnirella, Sergio; Buttafuoco, Gabriele; Pirrone, Nicola

2005-01-01

A large database including temporal trends of physical, ecological and socio-economic data was developed within the EUROCAT project. The aim was to estimate the nutrient fluxes for different socio-economic scenarios at catchment and coastal zone level of the Po catchment (Northern Italy) with reference to the Water Quality Objectives reported in the Water Framework Directive (WFD 2000/60/CE) and also in Italian legislation. Emission data derived from different sources at national, regional and local levels are referred to point and non-point sources. While non-point (diffuse) sources are simply integrated into the nutrient flux model, point sources are irregularly distributed. Intensive farming activity in the Po valley is one of the main Pressure factors Driving groundwater pollution in the catchment, therefore understanding the spatial variability of groundwater nitrate concentrations is a critical issue to be considered in developing a Water Quality Management Plan. In order to use the scattered point source data as input in our biogeochemical and transport models, it was necessary to predict their values and associated uncertainty at unsampled locations. This study reports the spatial distribution and uncertainty of groundwater nitrate concentration at a test site of the Po watershed using a probabilistic approach. Our approach was based on geostatistical sequential Gaussian simulation used to yield a series of stochastic images characterized by equally probable spatial distributions of the nitrate concentration across the area. Post-processing of many simulations allowed the mapping of contaminated and uncontaminated areas and provided a model for the uncertainty in the spatial distribution of nitrate concentrations. - The stochastic simulation should be preferred to kriging in environmental studies, whenever it is critical to preserve the variation of a variable

Assessing Contamination Potential of Nitrate-N in Groundwater of Lanyang Plain

Science.gov (United States)

Liang, Ching-Ping; Tu, Yu-Lin; Lin, Chien-Wen; Jang, Cheng-Shin

2013-04-01

Nitrate-N pollution is often relevant to agricultural activities such as the fertilization of crops. Significant increases in the nitrate-N pollution of groundwater are found in natural recharging zones of Taiwan. The increasing nitrate-N contamination seriously threatens public drinking water supply and human health. Constructing a correct map of aquifer contamination potential is an effective and feasible way to protect groundwater for quality assessment and management. Therefore, in this study, we use DRASTIC model with the help of geographic information system (GIS) to assess and predict the contamination potential of nitrate-N in the aquifer of Lanyang Plain, Taiwan. Seven factors of hydrogeology and hydrology, which includes seven parameters - Depth to groundwater, net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone, and hydraulic Conductivity, are considered to carry out this assessment. The validity of the presented model is established by comparing the results with the measured nitrate concentration in wells within the study area. Adjusting factor weightings via the discriminant analysis is performed to improve the assessment and prediction. The analyzed results can provide residents with suggestive strategies against nitrate-N pollution in agricultural regions and government administrators with explicit information of Nitrate-N pollution extents when plans of water resources are considered.

Effect of wheat-maize straw return on the fate of nitrate in groundwater in the Huaihe River Basin, China.

Science.gov (United States)

Li, Rongfu; Ruan, Xiaohong; Bai, Ying; Ma, Tianhai; Liu, Congqiang

2017-08-15

Straw return is becoming a routine practice in disposing of crop residues worldwide. However, the potential effect of such operation on the chemistry of local groundwater is not well documented. Here, shallow groundwater in an area where wheat-maize straw return is practiced was analyzed, and the seasonal changes in the nitrate concentration and the isotope compositions of NO 3 - and H 2 O were determined along two flow paths. Measured δD and δ 18 O in waters indicated that the groundwater was mainly recharged by atmospheric precipitation, while measured δ 15 N and δ 18 O in nitrate suggested that the sources for groundwater NO 3 - included urea fertilizer, soil nitrogen, and sewage/manure. Reduced NO 3 - concentrations coincided with an enrichment of organic matter in the groundwater of the straw return area, revealing an environmental condition that facilitates nitrate reduction, whereas increased δ 15 N-NO 3 - and δ 18 O-NO 3 - along the flow path suggested the occurrence of denitrification. Further analyses showed that, compared to the cases in the absence of straw return, as much as 80% and 90% of groundwater nitrate was removed in low and high water seasons in the straw return area, pointing to a potential positive effect of straw return to groundwater quality. Copyright © 2017 Elsevier B.V. All rights reserved.

Stable Isotopes of Dissolved Nitrate and Boron as Indicators of the Origin and Fate of Nitrate Contamination in Groundwater. Results from the Western Po Plain (Northern Italy)

Energy Technology Data Exchange (ETDEWEB)

Sacchi, E. [Dipartimento di Scienze della Terra e dell' Ambiente, Universita di Pavia (Italy); Istituto di Geoscienze e Georisorse, CNR, Pavia (Italy); Delconte, C. A. [Istituto di Geoscienze e Georisorse, CNR (Italy); Dipartimento di Scienze della Terra e dell' Ambiente, Universita di Pavia (Italy); Pennisi, M. [Istituto di Geoscienze e Georisorse, CNR, Pisa (Italy); Allais, E. [ISO4 s.n.c., Torino (Italy)

2013-07-15

Stable isotopes of dissolved nitrates and boron represent a powerful tool, complementary to existing monitoring data, enabling the identification of nitrate sources, the assessment of their relative contribution to nitrate pollution and the quantification of nitrate transport and removal processes. This contribution aims to present groundwater isotope data obtained in an area of 15 000 km{sup 2} of the western Po plain. Nitrate isotope data show that synthetic fertilisers and anthropogenic organic matter are the main sources of contamination. {delta}{sup 11}B allows the discrimination between manure derived and sewage derived contamination. Results indicate that even in agricultural areas, contamination from sewage exists. Samples from the suburban area of Milan, where sewage was considered the most likely source of contamination, show instead a {delta}{sup 11}B typical for cattle manure. This study demonstrates that the attribution of the contamination to a source based solely on present-day land use may lead to inappropriate conclusions. (author)

Studying The Contamination Status And The Sources Of Nitrogen Compounds In Groundwater In Ho Chi Minh City Area Using The Isotope Hydrology Techniques

International Nuclear Information System (INIS)

Nguyen Kien Chinh; Le Danh Chuan; Nguyen Van Nhien; Huynh Long; Tran Bich Lien; Luong Thu Tra

2013-01-01

The obtained data on nitrate, ammonium and total nitrogen concentration of 100 groundwater samples collected from 3 main aquifers show that although the nitrate concentration is still lower than the authorized limit of this compound in groundwater but the concentration and, specially the distribution of nitrate in shallow aquifer (Pleistocene) shows the increasing tendency in pollution level while ammonium and also total nitrogen content exceeded the authorized limit of these compounds in groundwater. For deeper aquifers (Upper and Lower Pliocene) groundwater is less polluted by nitrogen compounds. Analysis data on isotopic composition δ 15 N and δ 18 O of nitrate of the collected groundwater samples in compiling with other environmental isotopes data as δ 2 H, δ 18 O of water and natural radioactive isotopes in groundwater ( 3 H and 14 C) show that nitrate in Pleistocene groundwater is derived from both sources, geogenic source such as organic matter buried in aquifer soil layers and anthropogenic source like fertilizers, manure and septic wastes with the dominance of anthropogenic source. At the same time, obtained isotopic data proved the geogenic source of nitrate in water of the deeper aquifers. Study results on infiltration rate and infiltration depth of fertilizers and water using tracer techniques in the zone specializing in legume cultivation of the study area show the possible infiltration into shallow groundwater of water and also fertilizers. The obtained results prove the need of better management of the use of fertilizers for cultivation activities in the study area and to apply the advanced cultural manners for minimizing amount of fertilizers used. At the same time to strengthen wastes management and treatment in whole study area, especially in the zones which intake rain water as a recharge source to shallow groundwater such as Cu Chi, Hoc Mon and also inner city districts. (author)

Can nitrate contaminated groundwater be remediated by optimizing flood irrigation rate with high nitrate water in a desert oasis using the WHCNS model?

Science.gov (United States)

Liang, Hao; Qi, Zhiming; Hu, Kelin; Prasher, Shiv O; Zhang, Yuanpei

2016-10-01

Nitrate contamination of groundwater is an environmental concern in intensively cultivated desert oases where this polluted groundwater is in turn used as a major irrigation water resource. However, nitrate fluxes from root zone to groundwater are difficult to monitor in this complex system. The objectives of this study were to validate and apply the WHCNS (soil Water Heat Carbon Nitrogen Simulator) model to simulate water drainage and nitrate leaching under different irrigation and nitrogen (N) management practices, and to assess the utilization of groundwater nitrate as an approach to remediate nitrate contaminated groundwater while maintain crop yield. A two-year field experiment was conducted in a corn field irrigated with high nitrate groundwater (20 mg N L(-1)) in Alxa, Inner Mongolia, China. The experiment consisted of two irrigation treatments (Istd, standard, 750 mm per season; Icsv, conservation, 570 mm per season) factorially combined with two N fertilization treatments (Nstd, standard, 138 kg ha(-1); Ncsv, conservation, 92 kg ha(-1)). The validated results showed that the WHCNS model simulated values of crop dry matter, yield, soil water content and soil N concentration in soil profile all agreed well with the observed values. Compared to the standard water management (Istd), the simulated drainage and nitrate leaching decreased about 65% and 59%, respectively, under the conservation water management (Icsv). Nearly 55% of input N was lost by leaching under the IstdNstd and IstdNcsv treatments, compared to only 26% under the IcsvNstd and IcsvNcsv treatments. Simulations with more than 240 scenarios combing different levels of irrigation and fertilization indicated that irrigation was the main reason leading to the high risk of nitrate leaching, and the nitrate in irrigation groundwater can be best utilized without corn yield loss when the total irrigation was reduced from the current 750 mm to 491 mm. This reduced irrigation rate facilitated

Effects of groundwater-flow paths on nitrate concentrations across two riparian forest corridors

Science.gov (United States)

Speiran, Gary K.

2010-01-01

Groundwater levels, apparent age, and chemistry from field sites and groundwater-flow modeling of hypothetical aquifers collectively indicate that groundwater-flow paths contribute to differences in nitrate concentrations across riparian corridors. At sites in Virginia (one coastal and one Piedmont), lowland forested wetlands separate upland fields from nearby surface waters (an estuary and a stream). At the coastal site, nitrate concentrations near the water table decreased from more than 10 mg/L beneath fields to 2 mg/L beneath a riparian forest buffer because recharge through the buffer forced water with concentrations greater than 5 mg/L to flow deeper beneath the buffer. Diurnal changes in groundwater levels up to 0.25 meters at the coastal site reflect flow from the water table into unsaturated soil where roots remove water and nitrate dissolved in it. Decreases in aquifer thickness caused by declines in the water table and decreases in horizontal hydraulic gradients from the uplands to the wetlands indicate that more than 95% of the groundwater discharged to the wetlands. Such discharge through organic soil can reduce nitrate concentrations by denitrification. Model simulations are consistent with field results, showing downward flow approaching toe slopes and surface waters to which groundwater discharges. These effects show the importance of buffer placement over use of fixed-width, streamside buffers to control nitrate concentrations.

Upscaling of lysimeter measurements to regional groundwater nitrate distribution

Science.gov (United States)

Klammler, Gernot; Fank, Johann; Kupfersberger, Hans; Rock, Gerhard

2015-04-01

For many European countries nitrate leaching from the soil zone into the aquifer due to surplus application of mineral fertilizer and animal manure by farmers constitutes the most important threat to groundwater quality. This is a diffuse pollution situation and measures to change agricultural production have to be investigated at the aquifer scale to safeguard drinking water supply from shallow groundwater resources Lysimeters are state-of-the-art measurements for water and solute fluxes through the unsaturated zone towards groundwater at the point scale, but due to regional heterogeneities (especially concerning soil conditions) lysimeters cannot provide aquifer-wide groundwater recharge and solute leaching. Thus, in this work the numerical simulation model SIMWASER/STOTRASIM (Stenitzer, 1988; Feichtinger, 1998) for quantifying groundwater recharge and nitrate leaching at aquifer scale is applied. Nevertheless, according to Groenendijk et al. (2014) a model calibration by means of lysimeter measurements is essential, since uncalibrated models are generally far from acceptable. Thus, a lysimeter provides the basis for the parameterization of numerical simulation models. To quantify also the impact on regional nitrate distribution in the groundwater, we couple the unsaturated zone model SIMWASER/STOTRASIM with the saturated groundwater flow and solute transport model FELOW (Diersch, 2009) sequentially. In principal, the problem could be solved by the 3 dimensional equation describing variable saturated groundwater flow and solute transport. However, this is computationally prohibitive due to the temporal and spatial scope of the task, particularly in the framework of running numerous simulations to compromise between conflicting interests (i.e. good groundwater status and high agricultural yield). To account for the unknown regional distribution of crops grown and amount, timing and kind of fertilizers used a stochastic tool (Klammler et al, 2011) is developed that

Sources of nitrate contamination and age of water in large karstic springs of Florida

Science.gov (United States)

Katz, B.G.

2004-01-01

In response to concerns about the steady increase in nitrate concentrations over the past several decades in many of Florida's first magnitude spring waters (discharge ???2.8 m3/s), multiple isotopic and other chemical tracers were analyzed in water samples from 12 large springs to assess sources and timescales of nitrate contamination. Nitrate-N concentrations in spring waters ranged from 0.50 to 4.2 mg/L, and ??15N values of nitrate in spring waters ranged from 2.6 to 7.9 per mil. Most ??15N values were below 6 per mil indicating that inorganic fertilizers were the dominant source of nitrogen in these waters. Apparent ages of groundwater discharging from springs ranged from 5 to about 35 years, based on multi-tracer analyses (CFC-12, CFC-113, SF6, 3H/3He) and a piston flow assumption; however, apparent tracer ages generally were not concordant. The most reliable spring-water ages appear to be based on tritium and 3He data, because concentrations of CFCs and SF6 in several spring waters were much higher than would be expected from equilibration with modern atmospheric concentrations. Data for all tracers were most consistent with output curves for exponential and binary mixing models that represent mixtures of water in the Upper Floridan aquifer recharged since the early 1960s. Given that groundwater transit times are on the order of decades and are related to the prolonged input of nitrogen from multiple sources to the aquifer, nitrate could persist in groundwater that flows toward springs for several decades due to slow transport of solutes through the aquifer matrix.

Nitrate-nitrogen contamination in groundwater: Spatiotemporal variation and driving factors under cropland in Shandong Province, China

Science.gov (United States)

Liu, J.; Jiang, L. H.; Zhang, C. J.; Li, P.; Zhao, T. K.

2017-08-01

High groundwater nitrate-N is a serious problem especially in highly active agricultural areas. In study, the concentration and spatialtemporal distribution of groundwater nitrate-N under cropland in Shandong province were assessed by statistical and geostatistical techniques. Nitrate-N concentration reached a maximum of 184.60 mg L-1 and 29.5% of samples had levels in excess of safety threshold concentration (20 mg L-1). The median nitrate-N contents after rainy season were significantly higher than those before rainy season, and decreased with increasing groundwater depth. Nitrate-N under vegetable and orchard area are significantly higher than ones under grain. The kriging map shows that groundwater nitrate-N has a strong spatial variability. Many districts, such as Weifang, Linyi in Shandong province are heavily contaminated with nitrate-N. However, there are no significant trends of NO3 --N for most cities. Stepwise regression analysis showed influencing factors are different for the groundwater in different depth. But overall, vegetable yield per unit area, percentages of orchard area, per capita agricultural production, unit-area nitrogen fertilizer, livestock per unit area, percentages of irrigation areas, population per unit area and annual mean temperature are significant variables for groundwater nitrate-N variation.

Transformation of Nitrate and Toluene in Groundwater by Sulfur Modified Iron(SMI-III)

Science.gov (United States)

Lee, W.; Park, S.; Lim, J.; Hong, U.; Kwon, S.; Kim, Y.

2009-12-01

In Korea, nitrate and benzene, toluene, ethylbenzene, and xylene isomers (BTEX) are frequently detected together as ground water contaminants. Therefore, a system simultaneously treating both nitrate (inorganic compound) and BTEX (organic compounds) is required to utilize groundwater as a water resource. In this study, we investigated the efficiency of Sulfur Modified Iron (SMI-III) in treating both nitrate and BTEX contaminated groundwater. Based on XRD (X-Ray Diffraction) analysis, the SMI-III is mainly composed of Fe3O4, S, and Fe. A series of column tests were conducted at three different empty bed contact times (EBCTs) for each compound. During the experiments, removal efficiency for both nitrate and toluene were linearly correlated with EBCT, suggesting that SMI-III have an ability to transform both nitrate and toluene. The concentration of SO42- and oxidation/reduction potential (ORP) were also measured. After exposed to nitrate contaminated groundwater, the composition of SMI-III was changed to Fe2O3, Fe3O4, Fe, and Fe0.95S1.05. The trends of effluent sulfate concentrations were inversely correlated with effluent nitrate concentrations, while the trends of ORP values, having the minimum values of -480 mV, were highly correlated with effluent nitrate concentrations. XRD analysis before and after exposed to nitrate contaminated groundwater, sulfate production, and nitrite detection as a reductive transformation by-product of nitrate suggest that nitrate is reductively transformed by SMI-III. Interestingly, in the toluene experiments, the trends of ORP values were inversely correlated with effluent toluene concentrations, suggesting that probably degrade through oxidation reaction. Consequently, nitrate and toluene probably degrade through reduction and oxidation reaction, respectively and SMI-III could serve as both electron donor and acceptor.

Verifiable metamodels for nitrate losses to drains and groundwater in the Corn Belt, USA

Science.gov (United States)

Nolan, Bernard T.; Malone, Robert W.; Gronberg, Jo Ann M.; Thorp, K.R.; Ma, Liwang

2012-01-01

Nitrate leaching in the unsaturated zone poses a risk to groundwater, whereas nitrate in tile drainage is conveyed directly to streams. We developed metamodels (MMs) consisting of artificial neural networks to simplify and upscale mechanistic fate and transport models for prediction of nitrate losses by drains and leaching in the Corn Belt, USA. The two final MMs predicted nitrate concentration and flux, respectively, in the shallow subsurface. Because each MM considered both tile drainage and leaching, they represent an integrated approach to vulnerability assessment. The MMs used readily available data comprising farm fertilizer nitrogen (N), weather data, and soil properties as inputs; therefore, they were well suited for regional extrapolation. The MMs effectively related the outputs of the underlying mechanistic model (Root Zone Water Quality Model) to the inputs (R2 = 0.986 for the nitrate concentration MM). Predicted nitrate concentration was compared with measured nitrate in 38 samples of recently recharged groundwater, yielding a Pearson’s r of 0.466 (p = 0.003). Predicted nitrate generally was higher than that measured in groundwater, possibly as a result of the time-lag for modern recharge to reach well screens, denitrification in groundwater, or interception of recharge by tile drains. In a qualitative comparison, predicted nitrate concentration also compared favorably with results from a previous regression model that predicted total N in streams.

Impact of irrigation-practices on nitrate-leaching to contaminate groundwater and its risk to rural community

International Nuclear Information System (INIS)

Latif, M.

2003-01-01

A study was conducted to investigate contamination of shallow groundwater by nitrogen fertilizers. Results of the study show that the concentration of nitrate-nitrogen varies from 0.03 to 3.25 mg/l in the water samples collected from the tile-drainage areas, which is much below the maximum permissible limit of 10 mg/l. The nitrate-nitrogen concentration exceeded the permissible limit in about 15% of the samples collected from outside the tile-drainage areas. In general, it is found that there is no danger of shallow groundwater pollution by nitrate if the agricultural drainage system (tile drains) is functioning well. In contrast to this, there are chances of groundwater pollution where there is no such drainage-system. Further, the analysis of the water-samples collected from hand pumps and tube wells indicates that nitrates accumulate in the top surface of groundwater, after their leaching with downward percolating water. For this reason, the concentration of nitrate was found a maximum in the shallower groundwater. It decreases rather sharply with increase in groundwater depth. Thus, it is safer to tap deeper groundwater to lesson the danger of pollution by nitrates for human health. Soil-samples were also collected from selected points, along with water samples. These results indicate that soil-texture has a significant impact on production of nitrates, as well as their leaching and subsequent pollution of groundwater. There is more risk of groundwater-pollution in areas occupied by coarse-textured material, containing more than 50 percent sand particles. (author)

Integrated socio-hydrogeological approach to tackle nitrate contamination in groundwater resources. The case of Grombalia Basin (Tunisia).

Science.gov (United States)

Re, V; Sacchi, E; Kammoun, S; Tringali, C; Trabelsi, R; Zouari, K; Daniele, S

2017-09-01

Nitrate contamination still remains one of the main groundwater quality issues in several aquifers worldwide, despite the perduring efforts of the international scientific community to effectively tackle this problem. The classical hydrogeological and isotopic investigations are obviously of paramount importance for the characterization of contaminant sources, but are clearly not sufficient for the correct and long-term protection of groundwater resources. This paper aims at demonstrating the effectiveness of the socio-hydrogeological approach as the best tool to tackle groundwater quality issues, while contributing bridging the gap between science and society. An integrated survey, including land use, hydrochemical (physicochemical parameters and major ions) and isotopic (δ 15 N NO3 and δ 18 O NO3 ) analyses, coupled to capacity building and participatory activities was carried out to correctly attribute the nitrate origin in groundwater from the Grombalia Basin (North Tunisia), a region where only synthetic fertilizers have been generally identified as the main source of such pollution. Results demonstrates that the basin is characterized by high nitrate concentrations, often exceeding the statutory limits for drinking water, in both the shallow and deep aquifers, whereas sources are associated to both agricultural and urban activities. The public participation of local actors proved to be a fundamental element for the development of the hydrogeological investigation, as it permitted to obtain relevant information to support data interpretation, and eventually guaranteed the correct assessment of contaminant sources in the studied area. In addition, such activity, if adequately transferred to regulators, will ensure the effective adoption of management practices based on the research outcomes and tailored on the real needs of the local population, proving the added value to include it in any integrated investigation. Copyright © 2017 Elsevier B.V. All rights

Estimating Discharge and Nonpoint Source Nitrate Loading to Streams From Three End-Member Pathways Using High-Frequency Water Quality Data

Science.gov (United States)

Miller, Matthew P.; Tesoriero, Anthony J.; Hood, Krista; Terziotti, Silvia; Wolock, David M.

2017-12-01

The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high-frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the coupled groundwater-surface water system. A new approach for separating the streamflow hydrograph into three components was developed and coupled with high-frequency nitrate data to estimate time-variable nitrate loads from chemically dilute quick flow, chemically concentrated quick flow, and slowflow groundwater end-member pathways for periods of up to 2 years in a groundwater-dominated and a quick-flow-dominated stream in central Wisconsin, using only streamflow and in-stream water quality data. The dilute and concentrated quick flow end-members were distinguished using high-frequency specific conductance data. Results indicate that dilute quick flow contributed less than 5% of the nitrate load at both sites, whereas 89 ± 8% of the nitrate load at the groundwater-dominated stream was from slowflow groundwater, and 84 ± 25% of the nitrate load at the quick-flow-dominated stream was from concentrated quick flow. Concentrated quick flow nitrate concentrations varied seasonally at both sites, with peak concentrations in the winter that were 2-3 times greater than minimum concentrations during the growing season. Application of this approach provides an opportunity to assess stream vulnerability to nonpoint source nitrate loading and expected stream responses to current or changing conditions and practices in watersheds.

Microbial Oxidation of Pyrite Coupled to Nitrate Reduction in Anoxic Groundwater Sediment

DEFF Research Database (Denmark)

Jørgensen, Christian Juncher; Elberling, Bo; Jacobsen, Ole Stig

2009-01-01

denitrification process with pyrite as the primary electron donor. The process demonstrates a temperature dependency (Q10) of 1.8 and could be completely inhibited by addition of a bactericide (NaN3). Experimentally determined denitrification rates show that more than 50% of the observed nitrate reduction can...... be ascribed to pyrite oxidation. The apparent zero-order denitrification rate in anoxic pyrite containing sediment at groundwater temperature has been determined to be 2-3 µmol NO3- kg-1 day-1. The in situ groundwater chemistry at the boundary between the redoxcline and the anoxic zone reveals that between 65......-anoxic boundary in sandy aquifers thus determining the position and downward progression of the redox boundary between nitrate-containing and nitrate-free groundwater....

Using StorAge Selection Functions to Improve Simulation of Groundwater Nitrate Lag Times in the SWAT Modeling Framework.

Science.gov (United States)

Wilusz, D. C.; Fuka, D.; Cho, C.; Ball, W. P.; Easton, Z. M.; Harman, C. J.

2017-12-01

Intensive agriculture and atmospheric deposition have dramatically increased the input of reactive nitrogen into many watersheds worldwide. Reactive nitrogen can leach as nitrate into groundwater, which is stored and eventually released over years to decades into surface waters, potentially degrading water quality. To simulate the fate and transport of groundwater nitrate, many researchers and practitioners use the Soil and Water Assessment Tool (SWAT) or an enhanced version of SWAT that accounts for topographically-driven variable source areas (TopoSWAT). Both SWAT and TopoSWAT effectively assume that nitrate in the groundwater reservoir is well-mixed, which is known to be a poor assumption at many sites. In this study, we describe modifications to TopoSWAT that (1) relax the assumption of groundwater well-mixedness, (2) more flexibly parameterize groundwater transport as a time-varying distribution of travel times using the recently developed theory of rank StorAge Selection (rSAS) functions, and (3) allow for groundwater age to be represented by position on the hillslope or hydrological distance from the stream. The approach conceptualizes the groundwater aquifer as a population of water parcels entering as recharge with a particular nitrate concentration, aging as they move through storage, and eventually exiting as baseflow. The rSAS function selects the distribution of parcel ages that exit as baseflow based on a parameterized probability distribution; this distribution can be adjusted to preferentially select different distributions of young and old parcels in storage so as to reproduce (in principle) any form of transport. The modified TopoSWAT model (TopoSWAT+rSAS) is tested at a small agricultural catchment in the Eastern Shore, MD with an extensive hydrologic and hydrochemical data record for calibration and evaluation. The results examine (1) the sensitivity of TopoSWAT+rSAS modeling of nitrate transport to assumptions about the distribution of travel

Sources and chronology of nitrate contamination in spring waters, Suwannee River basin, Florida

Science.gov (United States)

Katz, Brian G.; Hornsby, H.D.; Bohlke, J.K.; Mokray, M.F.

1999-01-01

A multi-tracer approach, which consisted of analyzing water samples for n aturally occurring chemical and isotopic indicators, was used to better understand sources and chronology of nitrate contamination in spring wate rs discharging to the Suwannee and Santa Fe Rivers in northern Florida. Dur ing 1997 and 1998, as part of a cooperative study between the Suwannee River Water Management District and the U.S. Geological Survey, water samples were collected and analyzed from 24 springs and two wells for major ions, nutrients, dissolved organic carbon, and selected environmental isotopes [18O/16O, D/H, 13C/12C, 15N/14N]. To better understand when nitrate entered the ground-water system, water samples were analyzed for chlorofluorocarbons (CFCs; CCl3F, CCl2F2, and C2Cl3F3) and tritium (3H); in this way, the apparent ages and residence times of spring waters and water from shallow zones in the Upper Floridan aquifer were determined. In addition to information obtained from the use of isotopic and other chemical tracers, information on changes in land-use activities in the basin during 1954-97 were used to estimate nitrogen inputs from nonpoint sources for five counties in the basin. Changes in nitrate concentrations in spring waters with time were compared with estimated nitrogen inputs for Lafayette and Suwannee Counties. Agricultural activities [cropland farming, animal farming operations (beef and dairy cows, poultry, and swine)] along with atmospheric deposition have contributed large quantities of nitrogen to ground water in the Suwannee River Basin in northern Florida. Changes in agricultural land use during the past 40 years in Alachua, Columbia, Gilchrist, Lafayette, and Suwannee Counties have contributed variable amounts of nitrogen to the ground-water system. During 1955-97, total estimated nitrogen from all nonpoint sources (fertilizers, animal wastes, atmospheric deposition, and septic tanks) increased continuously in Gilchrist and Lafayette Counties. In

Regional analysis of groundwater nitrate concentrations and trends in Denmark in regard to agricultural influence

DEFF Research Database (Denmark)

Hansen, B.; Dalgaard, Tommy; Thorling, L.

2012-01-01

The act of balancing between an intensive agriculture with a high potential for nitrate pollution and a drinking water supply almost entirely based on groundwater is a challenge faced by Denmark and similar regions around the globe. Since the 1980s, regulations implemented by Danish farmers have...... succeeded in optimizing the N (nitrogen) management at farm level. As a result, the upward agricultural N surplus trend has been reversed, and the N surplus has reduced by 30–55% from 1980 to 2007 depending on region. The reduction in the N surplus served to reduce the losses of N from agriculture......, approximately 48% of the oxic monitored groundwater has nitrate concentrations above the groundwater and drinking water standards of 50 mg l−1. Furthermore, trend analyses show that 33% of all the monitored groundwater has upward nitrate trends, while only 18% of the youngest groundwater has upward nitrate...

Nested-scale discharge and groundwater level monitoring to improve predictions of flow route discharges and nitrate loads

Science.gov (United States)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.

2010-10-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for predictions of catchment-scale discharge and nitrate loads. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate the groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements simulates better nitrate loads and better predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.

Intrinsic and specific vulnerability of groundwater in central Spain: the risk of nitrate pollution

Science.gov (United States)

Martínez-Bastida, Juan J.; Arauzo, Mercedes; Valladolid, Maria

2010-05-01

The intrinsic vulnerability of groundwater in the Comunidad de Madrid (central Spain) was evaluated using the DRASTIC and GOD indexes. Groundwater vulnerability to nitrate pollution was also assessed using the composite DRASTIC (CD) and nitrate vulnerability (NV) indexes. The utility of these methods was tested by analyzing the spatial distribution of nitrate concentrations in the different aquifers located in the study area: the Tertiary Detrital Aquifer, the Moor Limestone Aquifer, the Cretaceous Limestone Aquifer and the Quaternary Aquifer. Vulnerability maps based on these four indexes showed very similar results, identifying the Quaternary Aquifer and the lower sub-unit of the Moor Limestone Aquifer as deposits subjected to a high risk of nitrate pollution due to intensive agriculture. As far as the spatial distribution of groundwater nitrate concentrations is concerned, the NV index showed the greatest statistical significance ( p Comunidad de Madrid, in line with European Union Directive 91/676/EEC.

Chemical and Microbial Quality of Groundwater in Siloam Village, Implications to Human Health and Sources of Contamination

Directory of Open Access Journals (Sweden)

John Ogony Odiyo

2018-02-01

Full Text Available Due to inaccessibility of potable water, rural communities drill boreholes within their homesteads despite vulnerability to groundwater contamination and associated health risks. This study assessed the quality of groundwater, identified potential sources of contamination and potential human health risks in Siloam Village, South Africa. Statistical difference between similar water quality parameters at different sites was determined at a significance level (α of 0.05. Water quality parameters with serious potential health effects on human beings were correlated with selected water quality parameters to understand the nature of correlation and possible sources of contamination. Fluorides and nitrates had excessively high concentrations associated with tooth damage and pronounced skeletal fluorosis, and methaemoglobinaemia in infants and mucous membrane irritation in adults, respectively. There were statistically significant differences between means of most water quality parameters. Contrasting correlation of fluoride with calcium and pH indicated the need to further identify local sources and fluoride control mechanisms. Correlation of nitrate with chloride mostly indicated that faecal contamination is the potential source of high nitrates in groundwater. This requires further verification. Presence of total coliforms and E. coli in most boreholes indicated potential presence of faecal contamination. The need to educate borehole owners’ on possible strategies to minimise groundwater pollution was identified.

The changing trend in nitrate concentrations in major aquifers due to historical nitrate loading from agricultural land across England and Wales from 1925 to 2150

Energy Technology Data Exchange (ETDEWEB)

Wang, L., E-mail: lei.wang@bgs.ac.uk [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Stuart, M.E.; Lewis, M.A. [British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Ward, R.S. [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Skirvin, D. [ADAS UK Ltd., Pendeford House, Pendeford Business Park, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Naden, P.S. [Centre for Ecology and Hydrology, Maclean Building, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Collins, A.L. [Sustainable Soils and Grassland Systems Department, Rothamsted Research, North Wyke, Okehampton EX20 2SB (United Kingdom); Ascott, M.J. [British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB (United Kingdom)

2016-01-15

Nitrate is necessary for agricultural productivity, but can cause considerable problems if released into aquatic systems. Agricultural land is the major source of nitrates in UK groundwater. Due to the long time-lag in the groundwater system, it could take decades for leached nitrate from the soil to discharge into freshwaters. However, this nitrate time-lag has rarely been considered in environmental water management. Against this background, this paper presents an approach to modelling groundwater nitrate at the national scale, to simulate the impacts of historical nitrate loading from agricultural land on the evolution of groundwater nitrate concentrations. An additional process-based component was constructed for the saturated zone of significant aquifers in England and Wales. This uses a simple flow model which requires modelled recharge values, together with published aquifer properties and thickness data. A spatially distributed and temporally variable nitrate input function was also introduced. The sensitivity of parameters was analysed using Monte Carlo simulations. The model was calibrated using national nitrate monitoring data. Time series of annual average nitrate concentrations along with annual spatially distributed nitrate concentration maps from 1925 to 2150 were generated for 28 selected aquifer zones. The results show that 16 aquifer zones have an increasing trend in nitrate concentration, while average nitrate concentrations in the remaining 12 are declining. The results are also indicative of the trend in the flux of groundwater nitrate entering rivers through baseflow. The model thus enables the magnitude and timescale of groundwater nitrate response to be factored into source apportionment tools and to be taken into account alongside current planning of land-management options for reducing nitrate losses. - Highlights: • An approach to modelling groundwater nitrate at the national scale is presented. • The long time-lag for nitrate in the

The changing trend in nitrate concentrations in major aquifers due to historical nitrate loading from agricultural land across England and Wales from 1925 to 2150

International Nuclear Information System (INIS)

Wang, L.; Stuart, M.E.; Lewis, M.A.; Ward, R.S.; Skirvin, D.; Naden, P.S.; Collins, A.L.; Ascott, M.J.

2016-01-01

Nitrate is necessary for agricultural productivity, but can cause considerable problems if released into aquatic systems. Agricultural land is the major source of nitrates in UK groundwater. Due to the long time-lag in the groundwater system, it could take decades for leached nitrate from the soil to discharge into freshwaters. However, this nitrate time-lag has rarely been considered in environmental water management. Against this background, this paper presents an approach to modelling groundwater nitrate at the national scale, to simulate the impacts of historical nitrate loading from agricultural land on the evolution of groundwater nitrate concentrations. An additional process-based component was constructed for the saturated zone of significant aquifers in England and Wales. This uses a simple flow model which requires modelled recharge values, together with published aquifer properties and thickness data. A spatially distributed and temporally variable nitrate input function was also introduced. The sensitivity of parameters was analysed using Monte Carlo simulations. The model was calibrated using national nitrate monitoring data. Time series of annual average nitrate concentrations along with annual spatially distributed nitrate concentration maps from 1925 to 2150 were generated for 28 selected aquifer zones. The results show that 16 aquifer zones have an increasing trend in nitrate concentration, while average nitrate concentrations in the remaining 12 are declining. The results are also indicative of the trend in the flux of groundwater nitrate entering rivers through baseflow. The model thus enables the magnitude and timescale of groundwater nitrate response to be factored into source apportionment tools and to be taken into account alongside current planning of land-management options for reducing nitrate losses. - Highlights: • An approach to modelling groundwater nitrate at the national scale is presented. • The long time-lag for nitrate in the

Comparison of policies for controlling groundwater nitrate pollution from agriculture in the Eastern Mancha aquifer (Spain).

Science.gov (United States)

Peña-Haro, S.; Llopis-Albert, C.; Pulido-Velazquez, M.; Stalder, A.; Garcia-Prats, A.; Henriquez-Dole, L.

2012-04-01

Groundwater nitrate pollution from agriculture has given rise to different legal frameworks. The European Water Framework Directive (WFD) is the most recent one. This work aims to help in the definition of the most cost-efficient policy to control non-point groundwater to attain the objectives established in the WFD. In this study we performed a cost-effectiveness analysis of different policies for controlling groundwater nitrate pollution from agriculture. The policies considered were taxes on nitrogen fertilizers, water price, taxes on emissions and fertilizer standards. We used a hydro-economic model, where we maximized the farmer's benefits. The benefits were calculated as sum of crop revenue minus variable and fixed cost per hectare minus the damage costs from nitrogen leaching. In the cost-effectiveness analysis we considered the costs as the reduction on benefits due to the application of a policy and the effectiveness the reduction on nitrate leaching. The methodology was applied to Eastern Mancha aquifer in Spain. The aquifer is part of the Júcar River Basin, which was declared as EU Pilot Basin in 2002 for the implementation of the WFD. Over the past 30 years the area has undertaken a significant socioeconomic development, mainly due to the intensive groundwater use for irrigated crops, which has provoked a steady decline of groundwater levels and a reduction of groundwater discharged into the Júcar River, as well as nitrate concentrations higher than those allowed by the WFD at certain locations (above 100 mg/l.). Crop revenue was calculated using production functions and the amount of nitrate leached was estimated by calibrated leaching functions. These functions were obtained by using an agronomic model (a GIS version of EPIC, GEPIC), and they depend on the water and the fertilizer use. The Eastern Mancha System was divided into zones of homogeneous crop production and nitrate leaching properties. Given the different soil types and climatic

Modeling the impact of the nitrate contamination on groundwater at the groundwater body scale : The Geer basin case study (Invited)

Science.gov (United States)

Brouyere, S.; Orban, P.; Hérivaux, C.

2009-12-01

In the next decades, groundwater managers will have to face regional degradation of the quantity and quality of groundwater under pressure of land-use and socio-economic changes. In this context, the objectives of the European Water Framework Directive require that groundwater be managed at the scale of the groundwater body, taking into account not only all components of the water cycle but also the socio-economic impact of these changes. One of the main challenges remains to develop robust and efficient numerical modeling applications at such a scale and to couple them with economic models, as a support for decision support in groundwater management. An integrated approach between hydrogeologists and economists has been developed by coupling the hydrogeological model SUFT3D and a cost-benefit economic analysis to study the impact of agricultural practices on groundwater quality and to design cost-effective mitigation measures to decrease nitrate pressure on groundwater so as to ensure the highest benefit to the society. A new modeling technique, the ‘Hybrid Finite Element Mixing Cell’ approach has been developed for large scale modeling purposes. The principle of this method is to fully couple different mathematical and numerical approaches to solve groundwater flow and solute transport problems. The mathematical and numerical approaches proposed allows an adaptation to the level of local hydrogeological knowledge and the amount of available data. In combination with long time series of nitrate concentrations and tritium data, the regional scale modelling approach has been used to develop a 3D spatially distributed groundwater flow and solute transport model for the Geer basin (Belgium) of about 480 km2. The model is able to reproduce the spatial patterns of nitrate concentrations together nitrate trends with time. The model has then been used to predict the future evolution of nitrate trends for two types of scenarios: (i) a “business as usual scenario�

Nitrate removal by Fe0/Pd/Cu nano-composite in groundwater.

Science.gov (United States)

Liu, Hongyuan; Guo, Min; Zhang, Yan

2014-01-01

Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe0/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe0/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe0/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe0/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe0/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe-6.0%Pd-3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe0 alone or Fe-Cu, nano-Fe-6%Pd-3%Cu composites showed a better selectivity to N2.

Determination, Source Identification and GIS Mapping for Nitrate Concentration in Groundwater from Bara Aquifer

Energy Technology Data Exchange (ETDEWEB)

Elami, G. M.; Sam, A. K.; Yagob, T. I.; Siddeeg, S. E.M.B.; Hatim, E.; Hajo, I. [Sudan Atomic Energy Commission, Sudan, Khartoum (Sudan)

2013-07-15

This study was carried out to determine the level of nitrate concentration in well water from Bara aquifer in north Kordofan state (west central sudan). The analysis was conducted for 69 wells from different villages within the Bara basin. Spectophotometric analysis was used to determine nitrate, nitrite and ammonia. Results revealed that nitrate concentration range was from 9.68 to 891 mg L in the sampled well with 81% exceeding the maximum permissible limits set for drinking water by WHO and SSMO. Animal waste and organic soil nitrogen were found to be the source of nitrate in these wells as indicated by {sup 15}N. The majority of wells with high nitrate are in the north and the north east part of the study area are shown by the GIS predictive map. (author)

Water quality and possible sources of nitrate in the Cimarron Terrace Aquifer, Oklahoma, 2003

Science.gov (United States)

Masoner, Jason R.; Mashburn, Shana L.

2004-01-01

Water from the Cimarron terrace aquifer in northwest Oklahoma commonly has nitrate concentrations that exceed the maximum contaminant level of 10 milligrams per liter of nitrite plus nitrate as nitrogen (referred to as nitrate) set by the U.S. Environmental Protection Agency for public drinking water supplies. Starting in July 2003, the U.S. Geological Survey, in cooperation with the Oklahoma Department of Environmental Quality, conducted a study in the Cimarron terrace aquifer to assess the water quality and possible sources of nitrate. A qualitative and quantitative approach based on multiple lines of evidence from chemical analysis of nitrate, nitrogen isotopes in nitrate, pesticides (indicative of cropland fertilizer application), and wastewater compounds (indicative of animal or human wastewater) were used to indicate possible sources of nitrate in the Cimarron terrace aquifer. Nitrate was detected in 44 of 45 ground-water samples and had the greatest median concentration (8.03 milligrams per liter) of any nutrient analyzed. Nitrate concentrations ranged from chemicals, 3 compounds were hydrocarbons, 2 compounds were industrial chemicals, 2 compounds were pesticides, 1 compound was of animal source, and 1 compound was a detergent compound. The most frequently detected wastewater compound was phenol, which was detected in 23 wells. N,N-diethyl-meta-toluamide (DEET) was detected in water samples from 5 wells. Benzophenone, ethanol- 2-butoxy-phosphate, and tributylphosphate were detected in water samples from 3 wells. Fertilizer was determined to be the possible source of nitrate in samples from 13 of 45 wells sampled, with a15N values ranging from 0.43 to 3.46 permil. The possible source of nitrate for samples from the greatest number of wells (22 wells) was from mixed sources of nitrate from fertilizer, septic or manure, or natural sources. Mixed nitrate sources had a 15N values ranging from 0.25 to 9.83 permil. Septic or manure was determined as the possible

Monitoring of Nitrate and Pesticide Pollution in Mnasra, Morocco Soil and Groundwater.

Science.gov (United States)

Marouane, Bouchra; Dahchour, Abdelmalek; Dousset, Sylvie; El Hajjaji, Souad

2015-06-01

This study evaluates the levels of nitrates and pesticides occurring in groundwater and agricultural soil in the Mnasra, Morocco area, a zone with intensive agricultural activity. A set of 108 water samples and 68 soil samples were collected from ten selected sites in the area during agricultural seasons, from May 2010 to September 2012. The results reveal that 89.7% of water samples exceeded the standard limit of nitrate concentrations for groundwater (50 mg/L). These results can be explained by the prevailing sandy nature of the soil in the area, the frequency of fertilizer usage, and the shallow level of the water table, which favors the leaching of nitrate from field to groundwater. In contrast, the selected pesticide molecules were not detected in the analysed soil and water samples; levels were below the quantification limit in all samples. This situation could be explained by the probable partial or total transformation of the molecules in soil.

Relation between Nitrates in Water Wells and Potential Sources in the Lower Yakima Valley, Washington State

Science.gov (United States)

Results of a study EPA conducted to investigate the contribution of various sources to the high nitrate levels in groundwater and residential drinking water wells in the Lower Yakima Valley of Washington State.

Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China, 2004-2010.

Science.gov (United States)

Zhang, Xinyu; Xu, Zhiwei; Sun, Xiaomin; Dong, Wenyi; Ballantine, Deborah

2013-05-01

The nitrate-nitrogen (NO3(-)-N) concentrations from shallow groundwater wells situated in 29 of the Chinese Ecosystem Research Network field stations, representing typical agro- and forest ecosystems, were assessed using monitoring data collected between 2004 and 2010. Results from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater, and allow linkages between nitrate concentrations in groundwater and broad land use categories to be made. Results indicated that most of the NO3(-)-N concentrations in groundwater from the agro- and forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard: Quality Standard for Ground Water (ecosystems (4.1 +/- 0.33 mg/L) than in forest ecosystems (0.5 +/- 0.04 mg/L). NO3(-)-N concentrations were relatively higher (> 10 mg N /L) in 10 of the 43 wells sampled in the agricultural ecosystems. These elevated concentrations occurred mainly in the Ansai, Yucheng, Linze, Fukang, Akesu, and Cele field sites, which were located in arid and semi-arid areas where irrigation rates are high. We suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.

Estimating discharge and non-point source nitrate loading to streams from three end-member pathways using high-frequency water quality and streamflow data

Science.gov (United States)

Miller, M. P.; Tesoriero, A. J.; Hood, K.; Terziotti, S.; Wolock, D.

2017-12-01

The myriad hydrologic and biogeochemical processes taking place in watersheds occurring across space and time are integrated and reflected in the quantity and quality of water in streams and rivers. Collection of high-frequency water quality data with sensors in surface waters provides new opportunities to disentangle these processes and quantify sources and transport of water and solutes in the coupled groundwater-surface water system. A new approach for separating the streamflow hydrograph into three components was developed and coupled with high-frequency specific conductance and nitrate data to estimate time-variable watershed-scale nitrate loading from three end-member pathways - dilute quickflow, concentrated quickflow, and slowflow groundwater - to two streams in central Wisconsin. Time-variable nitrate loads from the three pathways were estimated for periods of up to two years in a groundwater-dominated and a quickflow-dominated stream, using only streamflow and in-stream water quality data. The dilute and concentrated quickflow end-members were distinguished using high-frequency specific conductance data. Results indicate that dilute quickflow contributed less than 5% of the nitrate load at both sites, whereas 89±5% of the nitrate load at the groundwater-dominated stream was from slowflow groundwater, and 84±13% of the nitrate load at the quickflow-dominated stream was from concentrated quickflow. Concentrated quickflow nitrate concentrations varied seasonally at both sites, with peak concentrations in the winter that were 2-3 times greater than minimum concentrations during the growing season. Application of this approach provides an opportunity to assess stream vulnerability to non-point source nitrate loading and expected stream responses to current or changing conditions and practices in watersheds.

Multiobjective optimization for Groundwater Nitrate Pollution Control. Application to El Salobral-Los Llanos aquifer (Spain).

Science.gov (United States)

Llopis-Albert, C.; Peña-Haro, S.; Pulido-Velazquez, M.; Molina, J.

2012-04-01

Water quality management is complex due to the inter-relations between socio-political, environmental and economic constraints and objectives. In order to choose an appropriate policy to reduce nitrate pollution in groundwater it is necessary to consider different objectives, often in conflict. In this paper, a hydro-economic modeling framework, based on a non-linear optimization(CONOPT) technique, which embeds simulation of groundwater mass transport through concentration response matrices, is used to study optimal policies for groundwater nitrate pollution control under different objectives and constraints. Three objectives were considered: recovery time (for meeting the environmental standards, as required by the EU Water Framework Directive and Groundwater Directive), maximum nitrate concentration in groundwater, and net benefits in agriculture. Another criterion was added: the reliability of meeting the nitrate concentration standards. The approach allows deriving the trade-offs between the reliability of meeting the standard, the net benefits from agricultural production and the recovery time. Two different policies were considered: spatially distributed fertilizer standards or quotas (obtained through multi-objective optimization) and fertilizer prices. The multi-objective analysis allows to compare the achievement of the different policies, Pareto fronts (or efficiency frontiers) and tradeoffs for the set of mutually conflicting objectives. The constraint method is applied to generate the set of non-dominated solutions. The multi-objective framework can be used to design groundwater management policies taking into consideration different stakeholders' interests (e.g., policy makers, agricultures or environmental groups). The methodology was applied to the El Salobral-Los Llanos aquifer in Spain. Over the past 30 years the area has undertaken a significant socioeconomic development, mainly due to the intensive groundwater use for irrigated crops, which has

Treatment of groundwater for nitrate removal by portable ion exchange resin, OSE

International Nuclear Information System (INIS)

Iriburo, A.; Pessi, M.; Castagnino, G.; Garat, S.; Hackenbruch, R.; Laguardia, J.; Yelpo, L.; Amondarain, A.; Brunetto, C.

2010-01-01

The locations of Palmitas in the Province of Soriano is supplied with groundwater from a shallow and high nitrogen content in sedimentary aquifer (Asencio Formation). Due to lack of alternative sources, groundwater or surface water, it was decided to test the water treatment from a perforation whose tenors were of the order of 51-66 mg / L of nitrates. The methodology used for the removal of nitrate is ion exchange resins .The main issue raised in this case was the disposal of effluent from the washing of the resins, because there is no collective sanitation network Palmitas nor a sufficient stream flow for discharge . Several alternatives (installation of a transitional deposit, haulage trucks, dumping at distant points, etc.), which were ruled by their poor viability and / or high costs were studied. Finally it was decided to install a device that will have three cylinders with resins were transportable, for which should have a weight less than 75 kg and those which would be used alternately. Regeneration of the resins is carried out in the city of Mercedes, distant 40 km, where the necessary water for the discharge conditions exist with a high content of sodium chloride, resulting from ion exchange. This pilot project represents a first step in treatment for nitrate removal in groundwater using transportable resins which aims to supply the public . Due to the nature of the above location , the chosen methodology had to be adapted to fulfill their duties satisfactorily. The first results of this project to a year of commissioning implementation, which has been funded by SBI and developed by his staff, in order to be used in other places with similar problems are presented in this report

Assessment of regional change in nitrate concentrations in groundwater in the Central Valley, California, USA, 1950s-2000s

Science.gov (United States)

Burow, Karen R.; Jurgens, Bryant C.; Belitz, Kenneth; Dubrovsky, Neil M.

2013-01-01

A regional assessment of multi-decadal changes in nitrate concentrations was done using historical data and a spatially stratified non-biased approach. Data were stratified into physiographic subregions on the basis of geomorphology and soils data to represent zones of historical recharge and discharge patterns in the basin. Data were also stratified by depth to represent a shallow zone generally representing domestic drinking-water supplies and a deep zone generally representing public drinking-water supplies. These stratifications were designed to characterize the regional extent of groundwater with common redox and age characteristics, two factors expected to influence changes in nitrate concentrations over time. Overall, increasing trends in nitrate concentrations and the proportion of nitrate concentrations above 5 mg/L were observed in the east fans subregion of the Central Valley. Whereas the west fans subregion has elevated nitrate concentrations, temporal trends were not detected, likely due to the heterogeneous nature of the water quality in this area and geologic sources of nitrate, combined with sparse and uneven data coverage. Generally low nitrate concentrations in the basin subregion are consistent with reduced geochemical conditions resulting from low permeability soils and higher organic content, reflecting the distal portions of alluvial fans and historical groundwater discharge areas. Very small increases in the shallow aquifer in the basin subregion may reflect downgradient movement of high nitrate groundwater from adjacent areas or overlying intensive agricultural inputs. Because of the general lack of regionally extensive long-term monitoring networks, the results from this study highlight the importance of placing studies of trends in water quality into regional context. Earlier work concluded that nitrate concentrations were steadily increasing over time in the eastern San Joaquin Valley, but clearly those trends do not apply to other

The nitrate time bomb: a numerical way to investigate nitrate storage and lag time in the unsaturated zone.

Science.gov (United States)

Wang, L; Butcher, A S; Stuart, M E; Gooddy, D C; Bloomfield, J P

2013-10-01

Nitrate pollution in groundwater, which is mainly from agricultural activities, remains an international problem. It threatens the environment, economics and human health. There is a rising trend in nitrate concentrations in many UK groundwater bodies. Research has shown it can take decades for leached nitrate from the soil to discharge into groundwater and surface water due to the 'store' of nitrate and its potentially long travel time in the unsaturated and saturated zones. However, this time lag is rarely considered in current water nitrate management and policy development. The aim of this study was to develop a catchment-scale integrated numerical method to investigate the nitrate lag time in the groundwater system, and the Eden Valley, UK, was selected as a case study area. The method involves three models, namely the nitrate time bomb-a process-based model to simulate the nitrate transport in the unsaturated zone (USZ), GISGroundwater--a GISGroundwater flow model, and N-FM--a model to simulate the nitrate transport in the saturated zone. This study answers the scientific questions of when the nitrate currently in the groundwater was loaded into the unsaturated zones and eventually reached the water table; is the rising groundwater nitrate concentration in the study area caused by historic nitrate load; what caused the uneven distribution of groundwater nitrate concentration in the study area; and whether the historic peak nitrate loading has reached the water table in the area. The groundwater nitrate in the area was mainly from the 1980s to 2000s, whilst the groundwater nitrate in most of the source protection zones leached into the system during 1940s-1970s; the large and spatially variable thickness of the USZ is one of the major reasons for unevenly distributed groundwater nitrate concentrations in the study area; the peak nitrate loading around 1983 has affected most of the study area. For areas around the Bowscar, Beacon Edge, Low Plains, Nord Vue

Sources of nitrate in water from springs and the Upper Floridan aquifer, Suwannee River basin, Florida

Science.gov (United States)

Katz, B.G.; Hornsby, H.D.; Böhlke, John Karl

1999-01-01

In the Suwannee River basin of northern Florida, nitrate-N concentrations are 1.5 to 20 mg 1-1 in waters of the karstic Upper Floridan aquifer and in springs that discharge into the middle reach of the Suwannee River. During 1996-1997, fertilizers and animal wastes from farming operations in Suwannee County contributed approximately 49% and 45% of the total N input, respectively. Values of ??15N-NO3 in spring waters range from 3.9??? to 5.8???, indicating that nitrate most likely originates from a mixture of inorganic (fertilizers) and organic (animal waste) sources. In Lafayette County, animal wastes from farming operations and fertilizers contributed approximately 53% and 39% of the total N input, respectively, but groundwater near dairy and poultry farms has ??15N-NO3 values of 11.0-12.1???, indicative of an organic source of nitrate. Spring waters that discharge to the Suwannee River from Lafayette County have ??15N-NO3 values of 5.4-8.39???, which are indicative of both organic and inorganic sources. Based on analyses of CFCs, the mean residence time of shallow groundwater and spring water ranges between 8-12 years and 12-25 years, respectively.

REMOVAL OF ADDED NITRATE IN COTTON BURR COMPOST, MULCH COMPOST, AND PEAT: MECHANISMS AND POTENTIAL USE FOR GROUNDWATER NITRATE REMEDIATION

Science.gov (United States)

We conducted batch tests on the nature and kinetics of removal of added nitrate in cotton burr compost, mulch compost, and sphagnum peat that may be potentially used in a permeable reactive barrier (PRB) for groundwater nitrate remediation. A rigorous steam autoclaving protocol (...

The Transboundary Aquifer Management Challenge: Linking Landscape Patterns and Groundwater Nitrate Concentrations in the Abbotsford-Sumas Aquifer, USA/Canada

Science.gov (United States)

Gallagher, T.; Gergel, S. E.

2015-12-01

Changes in land use and landscape pattern can have an array of impacts on aquatic systems, including impacts which span international waters and borders. Globally, agricultural land use patterns and practices are among the factors responsible for elevated nitrate concentrations in groundwater aquifers. Coordination of landscape monitoring across trans-boundary aquifers is needed to monitor and address contamination issues as landscape patterns can vary widely among different political jurisdictions. Landscape indicators, which quantify the amount and arrangement of land cover (such as proportion and abundance of land cover types), are one such way to improve our understanding of cross-border aquatic system interactions. In Western North America, the Abbotsford-Sumas Aquifer (ASA) spans the US-Canada border and provides drinking water for over 100,000 people. Intensive agriculture combined with high precipitation and well-drained soils make this aquifer susceptible to nitrate leaching. To understand how landscape patterns influence nitrate concentrations, we ask: Which landscape indicators correlate most strongly with elevated nitrate concentrations? A seamless cross-border land cover mosaic was created by harmonizing a variety of US and Canadian geodata. Auxiliary high spatial resolution imagery (e.g., 5m RapidEye and historical Google Earth) were used to quantify fine-scale landscape features (such as number of farm field renovations) with suspected mechanistic links to nitrate sources. We examined groundwater nitrate concentrations in shallow wells (screens Environment Canada. Surrounding each well, terrestrial zones of influence (aligned with the directional flow of groundwater) were delineated within which landscape patterns were characterized. Multiple regression was used to compare the strength of relationships between land use practices and nitrate concentrations. Preliminary results show strong positive correlations between area of raspberry renovations and

Identification of nitrate sources and discharge-depending nitrate dynamics in a mesoscale catchment

Science.gov (United States)

Mueller, Christin; Strachauer, Ulrike; Brauns, Mario; Musolff, Andreas; Kunz, Julia Vanessa; Brase, Lisa; Tarasova, Larisa; Merz, Ralf; Knöller, Kay

2017-04-01

During the last decades, nitrate concentrations in surface and groundwater have increased due to land use change and accompanying application of fertilizer in agriculture as well as increased atmospheric deposition. To mitigate nutrient impacts on downstream aquatic ecosystems, it is important to quantify potential nitrate sources, instream nitrate processing and its controls in a river system. The objective of this project is to characterize and quantify (regional) scale dynamics and trends in water and nitrogen fluxes of the entire Holtemme river catchment in central Germany making use of isotopic fingerprinting methods. Here we compare two key date sampling campaigns in 2014 and 2015, with spatially highly resolved measurements of discharge at 23 sampling locations including 11 major tributaries and 12 locations at the main river. Additionally, we have data from continuous runoff measurements at 10 locations operated by the local water authorities. Two waste water treatment plants contribute nitrogen to the Holtemme stream. This contribution impacts nitrate loads and nitrate isotopic signatures depending on the prevailing hydrological conditions. Nitrogen isotopic signatures in the catchment are mainly controlled by different sources (nitrified soil nitrogen in the headwater and manure/ effluents from WWTPs in the lowlands) and increase with raising nitrate concentrations along the main river. Nitrate loads at the outlet of the catchment are extremely different between both sampling campaigns (2014: NO3- = 97 t a-1, 2015: NO3- = 5 t a-1) which is associated with various runoff (2014: 0.8 m3 s-1, 2015: 0.2 m3 s-1). In 2015, the inflow from WWTP's raises the NO3- loads and enriches δ18O-NO3 values. Generally, oxygen isotope signatures from nitrate are more variable and are controlled by biogeochemical processes in concert with the oxygen isotopic composition of the ambient water. Elevated δ18O-NO3 in 2015 are most likely due to higher temperatures and lower

Utilization of granular activated carbon adsorber for nitrates removal from groundwater of the Cluj region.

Science.gov (United States)

Moşneag, Silvia C; Popescu, Violeta; Dinescu, Adrian; Borodi, George

2013-01-01

The level of nitrates from groundwater from Cluj County and other areas from Romania have increased values, exceeding or getting close to the allowed limit values, putting in danger human and animal heath. In this study we used granular activated carbon adsorbent (GAC) for nitrate (NO(-)3) removal for the production of drinking water from groundwater of the Cluj county. The influences of the contact time, nitrate initial concentration, and adsorbent concentration have been studied. We determined the equilibrium adsorption capacity of GAC, used for NO(-)3 removal and we applied the Langmuir and Freundlich isotherm models. Ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, X ray diffraction (XRD), Scanning Electron Microscopy (SEM) were used for process characterization. We also determined: pH, conductivity, Total Dissolved Solids and Total Hardness. The GAC adsorbents have excellent capacities of removing nitrate from groundwater from Cluj County areas.

Residence time, chemical and isotopic analysis of nitrate in the groundwater and surface water of a small agricultural watershed in the Coastal Plain, Bucks Branch, Sussex County, Delaware

Science.gov (United States)

Clune, John W.; Denver, Judith M.

2012-01-01

Nitrate is a common contaminant in groundwater and surface water throughout the Nation, and water-resource managers need more detailed small-scale watershed research to guide conservation efforts aimed at improving water quality. Concentrations of nitrate in Bucks Branch are among the highest in the state of Delaware and a scientific investigation was performed to provide water-quality information to assist with the management of agriculture and water resources. A combination of major-ion chemistry, nitrogen isotopic composition and age-dating techniques was used to estimate the residence time and provide a chemical and isotopic analysis of nitrate in the groundwater in the surficial aquifer of the Bucks Branch watershed in Sussex County, Delaware. The land use was more than 90 percent agricultural and most nitrogen inputs were from manure and fertilizer. The apparent median age of sampled groundwater is 18 years and the estimated residence time of groundwater contributing to the streamflow for the entire Bucks Branch watershed at the outlet is approximately 19 years. Concentrations of nitrate exceeded the U.S. Environmental Protection Agency drinking-water standard of 10 milligrams per liter (as nitrogen) in 60 percent of groundwater samples and 42 percent of surface-water samples. The overall geochemistry in the Bucks Branch watershed indicates that agriculture is the predominant source of nitrate contamination and the observed patterns in major-ion chemistry are similar to those observed in other studies on the Mid-Atlantic Coastal Plain. The pattern of enrichment in nitrogen and oxygen isotopes (δ15N and δ18O) of nitrate in groundwater and surface water indicates there is some loss of nitrate through denitrification, but this process is not sufficient to remove all of the nitrate from groundwater discharging to streams, and concentrations of nitrate in streams remain elevated.

Nitrate variability in groundwater of North Carolina using monitoring and private well data models.

Science.gov (United States)

Messier, Kyle P; Kane, Evan; Bolich, Rick; Serre, Marc L

2014-09-16

Nitrate (NO3-) is a widespread contaminant of groundwater and surface water across the United States that has deleterious effects to human and ecological health. This study develops a model for predicting point-level groundwater NO3- at a state scale for monitoring wells and private wells of North Carolina. A land use regression (LUR) model selection procedure is developed for determining nonlinear model explanatory variables when they are known to be correlated. Bayesian Maximum Entropy (BME) is used to integrate the LUR model to create a LUR-BME model of spatial/temporal varying groundwater NO3- concentrations. LUR-BME results in a leave-one-out cross-validation r2 of 0.74 and 0.33 for monitoring and private wells, effectively predicting within spatial covariance ranges. Results show significant differences in the spatial distribution of groundwater NO3- contamination in monitoring versus private wells; high NO3- concentrations in the southeastern plains of North Carolina; and wastewater treatment residuals and swine confined animal feeding operations as local sources of NO3- in monitoring wells. Results are of interest to agencies that regulate drinking water sources or monitor health outcomes from ingestion of drinking water. Lastly, LUR-BME model estimates can be integrated into surface water models for more accurate management of nonpoint sources of nitrogen.

Regional Variability of Agriculturally-Derived Nitrate-Nitrogen in Shallow Groundwater in China, 2004–2014

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Jing Li

2018-05-01

Full Text Available Increasing diffuse nitrate loading of groundwater has long been a major environmental and health concern in China, but little is known about the spatial and temporal variability of nitrate concentrations in groundwater at regional scales. The aim of this study was to assess the spatial distribution and variation of nitrate-nitrogen (NO3−-N concentrations in groundwater. We used groundwater quality monitoring data and soil physical characteristics from 21 agro-ecosystems in China for years 2004 to 2014. The results indicated that NO3−-N concentrations were highly variable in shallow groundwater across the landscape. Over the study period, most of the NO3−-N concentrations were below the World Health Organization permissible limit for drinking water (<10 mg N·L. NO3−-N concentrations in groundwater neither significantly increased nor decreased in most agro-ecosystems, but fluctuated with seasons. In addition, groundwater NO3−-N under purple soil (6.81 mg·L−1 and Aeolian sandy soil (6.02 mg·L−1 were significantly higher (p < 0.05 than that under other soil types, and it was medium-high (4.49 mg·L−1 under aquic cinnamon soil. Elevated nitrate concentrations occurred mainly in oasis agricultural areas of northwestern China, where farmlands with coarse-textured soils use flood irrigation. Therefore, arid and semi-arid areas are expected to sustain high NO3−-N concentrations in groundwater. Mitigation strategies can prevent this problem, and include control of N fertilizer input, balanced fertilization, proper rotation system, adoption of improved irrigation methods, and establishment of environmental policies.

Nitrate retention in a sand plains stream and the importance of groundwater discharge

Science.gov (United States)

Robert S. Stelzer; Damion R. Drover; Susan L. Eggert; Maureen A. Muldoon

2011-01-01

We measured net nitrate retention by mass balance in a 700-m upwelling reach of a third-order sand plains stream, Emmons Creek, from January 2007 to November 2008. Surface water and ground-water fluxes of nitrate were determined from continuous records of discharge and from nitrate concentrations based on weekly and biweekly sampling at three surface water stations and...

Assessment of seawater intrusion and nitrate contamination on the groundwater quality in the Korba coastal plain of Cap-Bon (North-east of Tunisia)

Science.gov (United States)

Zghibi, Adel; Tarhouni, Jamila; Zouhri, Lahcen

2013-11-01

In recent years, seawater intrusion and nitrate contamination of groundwater have become a growing concern for people in rural areas in Tunisia where groundwater is always used as drinking water. The coastal plain of Korba (north-east of Tunisia) is a typical area where the contamination of the aquifer in the form of saltwater intrusion and high nitrate concentrations is very developed and represents the major consequence of human activities. The objective of this study is to evaluate groundwater resource level, to determine groundwater quality and to assess the risk of NO3- pollution in groundwater using hydrogeochemical tools. Groundwater were sampled and analyzed for physic-chemical parameters: Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, NO3-, Total Dissolved Solid and of the physical parameters (pH, electrical conductivity and the temperature). The interpretation of the analytical results is shown numerically and graphically through the ionic deviations, Piper Diagram, seawater fractions and binary diagrams. Moreover, electrical conductivity investigations have been used to identify the location of the major intrusion plumes in this coastal area and to obtain new information on the spatial scales and dynamics of the fresh water-seawater interface. Those processes can be used as indicators of seawater intrusion progression. First, the hydrogeochemical investigation of this aquifer reveals the major sources of contamination, represented by seawater intrusion. Thus, the intensive extraction of groundwater from aquifer reduces freshwater outflow to the sea, creates several drawdown cones and lowering of the water table to as much as 12 m below mean sea level in the center part of the study area especially between Diarr El Hojjej and Tafelloun villages, causing seawater migration inland and rising toward the wells. Moreover, the results of this study revealed the presence of direct cation exchange linked to seawater intrusion and dissolution processes associated with

Ecosystem and human health impacts from increased corn production: vulnerability assessment of exposure to high nitrate concentrations in groundwater and blue baby syndrome

Science.gov (United States)

Garcia, V.; Cooter, E. J.

2013-12-01

The Renewable Fuel Standard (RFS) requires oil refiners to reach a target of 15 billion gallons of corn-based ethanol by 2022. However, there are concerns that the broad-scale use of corn as a source of ethanol may lead to unintended economic and environmental consequences. This study applies the geophysical relationships captured with linked meteorological, air quality and agriculture models to examine the impact of corn production before enactment of the RFS in 2002 and at the height of the RFS targets in 2022. In particular, we investigate the probability of high-levels of nitrate in groundwater resulting from increased corn production and then relate this vulnerability to the potential for infants to acquire Methemoglobinemia, or 'Blue Baby Syndrome'. Blue Baby Syndrome (BBS) is a potentially fatal condition that occurs when the hemoglobin (Fe2+) in an infant's red blood cells is oxidized to methemoglobin (Fe3+), preventing the uptake of oxygen from the baby's blood. Exposure to high levels of nitrate in groundwater occur near the intersection of areas where surface water can more readily leach into shallow aquifers, wells are the main source of drinking water, and high nitrogen inputs exist. We use a coupled meteorological, agricultural and air quality model to identify areas vulnerable to increased nitrate contamination and associated risk to acquiring BBS. We first verify the relationship between predictive variables (e.g., nitrogen deposition and fertilization rates, landcover, soils and aquifer type) and nitrate groundwater levels by applying a regression model to over 800 nitrate measurements taken from wells located throughout the US (Figure 1). We then apply the regression coefficients to the coupled model output to identify areas that are at an increased risk for high nitrate groundwater levels in 2022. Finally, we examine the potential change in risk for acquiring BBS resulting from increased corn production by applying an Oral Reference Dose (Rf

A GIS-based groundwater travel time model to evaluate stream nitrate concentration reductions from land use change

Science.gov (United States)

Schilling, K.E.; Wolter, C.F.

2007-01-01

Excessive nitrate-nitrogen (nitrate) loss from agricultural watersheds is an environmental concern. A common conservation practice to improve stream water quality is to retire vulnerable row croplands to grass. In this paper, a groundwater travel time model based on a geographic information system (GIS) analysis of readily available soil and topographic variables was used to evaluate the time needed to observe stream nitrate concentration reductions from conversion of row crop land to native prairie in Walnut Creek watershed, Iowa. Average linear groundwater velocity in 5-m cells was estimated by overlaying GIS layers of soil permeability, land slope (surrogates for hydraulic conductivity and gradient, respectively) and porosity. Cells were summed backwards from the stream network to watershed divide to develop a travel time distribution map. Results suggested that groundwater from half of the land planted in prairie has reached the stream network during the 10 years of ongoing water quality monitoring. The mean travel time for the watershed was estimated to be 10.1 years, consistent with results from a simple analytical model. The proportion of land in the watershed and subbasins with prairie groundwater reaching the stream (10-22%) was similar to the measured reduction of stream nitrate (11-36%). Results provide encouragement that additional nitrate reductions in Walnut Creek are probable in the future as reduced nitrate groundwater from distal locations discharges to the stream network in the coming years. The high spatial resolution of the model (5-m cells) and its simplicity may make it potentially applicable for land managers interested in communicating lag time issues to the public, particularly related to nitrate concentration reductions over time. ?? 2007 Springer-Verlag.

A multi-tracer approach to assess fingerprints of nitrate in an aquifer under agriculturally used land

Science.gov (United States)

Pasten-Zapata, Ernesto; Ledesma-Ruiz, Rogelio; Ramirez, Aldo; Harter, Thomas; Mahlknecht, Jürgen

2014-05-01

To effectively manage groundwater quality it is essential to understand sources of contamination and underground processes. The objective of the study was to identify sources and fate of nitrate pollution occurring in an aquifer underneath a sub-humid to humid region in NE Mexico which provides 10% of national citrus production. Nitrate isotopes and halide ratios were applied to understand nitrate sources and transformations in relation to land use/land cover. It was found that the study area is subject to diverse nitrate sources including 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 1,000m from a sampling point increased nitrate pollution. Leachates from septic tanks incited nitrate pollution in residential areas. Soil nitrogen and animal waste were the sources of nitrate in groundwater under shrubland and grassland. Partial denitrification processes were evidenced. The denitrification process helped to attenuate nitrate concentration in the agricultural lands and grassland particularly during summer months.

Vadose Zone Nitrate Transport Dynamics Resulting from Agricultural Groundwater Banking

Science.gov (United States)

Murphy, N. P.; McLaughlin, S.; Dahlke, H. E.

2017-12-01

In recent years, California's increased reliance on groundwater resources to meet agricultural and municipal demands has resulted in significant overdraft and water quality issues. Agricultural groundwater banking (AGB) has emerged as a promising groundwater replenishment opportunity in California; AGB is a form of managed aquifer recharge where farmland is flooded during the winter using excess surface water in order to recharge the underlying groundwater. Suitable farmland that is connected to water delivery systems is available for AGB throughout the Central Valley. However, questions remain how AGB could be implemented on fertilized agricultural fields such that nitrate leaching from the root zone is minimized. Here, we present results from field and soil column studies that investigate the transport dynamics of nitrogen in the root and deeper vadose zone during flooding events. We are specifically interested in estimating how timing and duration of flooding events affect percolation rates, leaching and nitrification/denitrification processes in three soil types within the Central Valley. Laboratory and field measurements include nitrogen (NO3-, NH4+, NO2-, N2O), redox potentials, total organic carbon, dissolved oxygen, moisture content and EC. Soil cores are collected in the field before and after recharge events up to a depth of 4m, while other sensors monitor field conditions continuously. Preliminary results from the three field sites show that significant portions of the applied floodwater (12-62 cm) infiltrated below the root zone: 96.1% (Delhi), 88.6% (Modesto) and 76.8% (Orland). Analysis of the soil cores indicate that 70% of the residual nitrate was flushed from the sandy soil, while the fine sandy loam showed only a 5% loss and in some cores even an increase in soil nitrate (in the upper 20cm). Column experiments support these trends and indicate that increases in soil nitrate in the upper root zone might be due to organic nitrogen mineralization and

Agriculture and groundwater nitrate contamination in the Seine basin. The STICS-MODCOU modelling chain

International Nuclear Information System (INIS)

Ledoux, E.; Gomez, E.; Monget, J.M.; Viavattene, C.; Viennot, P.; Ducharne, A.; Benoit, M.; Mignolet, C.; Schott, C.; Mary, B.

2007-01-01

A software package is presented here to predict the fate of nitrogen fertilizers and the transport of nitrate from the rooting zone of agricultural areas to surface water and groundwater in the Seine basin, taking into account the long residence times of water and nitrate in the unsaturated and aquifer systems. Information on pedological characteristics, land use and farming practices is used to determine the spatial units to be considered. These data are converted into input data for the crop model STICS which simulates the water and nitrogen balances in the soil-plant system with a daily time-step. A spatial application of STICS has been derived at the catchment scale which computes the water and nitrate fluxes at the bottom of the rooting zone. These fluxes are integrated into a surface and groundwater coupled model MODCOU which calculates the daily water balance in the hydrological system, the flow in the rivers and the piezometric variations in the aquifers, using standard climatic data (rainfall, PET). The transport of nitrate and the evolution of nitrate contamination in groundwater and to rivers is computed by the model NEWSAM. This modelling chain is a valuable tool to predict the evolution of crop productivity and nitrate contamination according to various scenarios modifying farming practices and/or climatic changes. Data for the period 1970-2000 are used to simulate the past evolution of nitrogen contamination. The method has been validated using available data bases of nitrate concentrations in the three main aquifers of the Paris basin (Oligocene, Eocene and chalk). The approach has then been used to predict the future evolution of nitrogen contamination up to 2015. A statistical approach allowed estimating the probability of transgression of different concentration thresholds in various areas in the basin. The model is also used to evaluate the cost of the damage resulting of the treatment of drinking water at the scale of a groundwater management

Agriculture and groundwater nitrate contamination in the Seine basin. The STICS-MODCOU modelling chain

Energy Technology Data Exchange (ETDEWEB)

Ledoux, E. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France)]. E-mail: emmanuel.ledoux@ensmp.fr; Gomez, E. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Monget, J.M. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Viavattene, C. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Viennot, P. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Ducharne, A. [Laboratoire Sisyphe, CNRS/Universite Pierre et Marie Curie, Paris (France); Benoit, M. [INRA, Station de Recherche SAD, 662 avenue Louis Buffet, 88500 Mirecourt (France); Mignolet, C. [INRA, Station de Recherche SAD, 662 avenue Louis Buffet, 88500 Mirecourt (France); Schott, C. [INRA, Station de Recherche SAD, 662 avenue Louis Buffet, 88500 Mirecourt (France); Mary, B. [INRA, Unite d' Agronomie Laon-Reims-Mons, Laon (France)

2007-04-01

A software package is presented here to predict the fate of nitrogen fertilizers and the transport of nitrate from the rooting zone of agricultural areas to surface water and groundwater in the Seine basin, taking into account the long residence times of water and nitrate in the unsaturated and aquifer systems. Information on pedological characteristics, land use and farming practices is used to determine the spatial units to be considered. These data are converted into input data for the crop model STICS which simulates the water and nitrogen balances in the soil-plant system with a daily time-step. A spatial application of STICS has been derived at the catchment scale which computes the water and nitrate fluxes at the bottom of the rooting zone. These fluxes are integrated into a surface and groundwater coupled model MODCOU which calculates the daily water balance in the hydrological system, the flow in the rivers and the piezometric variations in the aquifers, using standard climatic data (rainfall, PET). The transport of nitrate and the evolution of nitrate contamination in groundwater and to rivers is computed by the model NEWSAM. This modelling chain is a valuable tool to predict the evolution of crop productivity and nitrate contamination according to various scenarios modifying farming practices and/or climatic changes. Data for the period 1970-2000 are used to simulate the past evolution of nitrogen contamination. The method has been validated using available data bases of nitrate concentrations in the three main aquifers of the Paris basin (Oligocene, Eocene and chalk). The approach has then been used to predict the future evolution of nitrogen contamination up to 2015. A statistical approach allowed estimating the probability of transgression of different concentration thresholds in various areas in the basin. The model is also used to evaluate the cost of the damage resulting of the treatment of drinking water at the scale of a groundwater management

Three-dimensional modeling of nitrate-N transport in vadose zone: Roles of soil heterogeneity and groundwater flux

Science.gov (United States)

Akbariyeh, Simin; Bartelt-Hunt, Shannon; Snow, Daniel; Li, Xu; Tang, Zhenghong; Li, Yusong

2018-04-01

Contamination of groundwater from nitrogen fertilizers in agricultural lands is an important environmental and water quality management issue. It is well recognized that in agriculturally intensive areas, fertilizers and pesticides may leach through the vadose zone and eventually reach groundwater. While numerical models are commonly used to simulate fate and transport of agricultural contaminants, few models have considered a controlled field work to investigate the influence of soil heterogeneity and groundwater flow on nitrate-N distribution in both root zone and deep vadose zone. In this work, a numerical model was developed to simulate nitrate-N transport and transformation beneath a center pivot-irrigated corn field on Nebraska Management System Evaluation area over a three-year period. The model was based on a realistic three-dimensional sediment lithology, as well as carefully controlled irrigation and fertilizer application plans. In parallel, a homogeneous soil domain, containing the major sediment type of the site (i.e. sandy loam), was developed to conduct the same water flow and nitrate-N leaching simulations. Simulated nitrate-N concentrations were compared with the monitored nitrate-N concentrations in 10 multi-level sampling wells over a three-year period. Although soil heterogeneity was mainly observed from top soil to 3 m below the surface, heterogeneity controlled the spatial distribution of nitrate-N concentration. Soil heterogeneity, however, has minimal impact on the total mass of nitrate-N in the domain. In the deeper saturated zone, short-term variations of nitrate-N concentration correlated with the groundwater level fluctuations.

Compliance Groundwater Monitoring of Nonpoint Sources - Emerging Approaches

Science.gov (United States)

Harter, T.

2008-12-01

Groundwater monitoring networks are typically designed for regulatory compliance of discharges from industrial sites. There, the quality of first encountered (shallow-most) groundwater is of key importance. Network design criteria have been developed for purposes of determining whether an actual or potential, permitted or incidental waste discharge has had or will have a degrading effect on groundwater quality. The fundamental underlying paradigm is that such discharge (if it occurs) will form a distinct contamination plume. Networks that guide (post-contamination) mitigation efforts are designed to capture the shape and dynamics of existing, finite-scale plumes. In general, these networks extend over areas less than one to ten hectare. In recent years, regulatory programs such as the EU Nitrate Directive and the U.S. Clean Water Act have forced regulatory agencies to also control groundwater contamination from non-incidental, recharging, non-point sources, particularly agricultural sources (fertilizer, pesticides, animal waste application, biosolids application). Sources and contamination from these sources can stretch over several tens, hundreds, or even thousands of square kilometers with no distinct plumes. A key question in implementing monitoring programs at the local, regional, and national level is, whether groundwater monitoring can be effectively used as a landowner compliance tool, as is currently done at point-source sites. We compare the efficiency of such traditional site-specific compliance networks in nonpoint source regulation with various designs of regional nonpoint source monitoring networks that could be used for compliance monitoring. We discuss advantages and disadvantages of the site vs. regional monitoring approaches with respect to effectively protecting groundwater resources impacted by nonpoint sources: Site-networks provide a tool to enforce compliance by an individual landowner. But the nonpoint source character of the contamination

'Low-acid' sulfide oxidation using nitrate-enriched groundwater

Science.gov (United States)

Donn, Michael; Boxall, Naomi; Reid, Nathan; Meakin, Rebecca; Gray, David; Kaksonen, Anna; Robson, Thomas; Shiers, Denis

2016-04-01

Acid drainage (AMD/ARD) is undoubtedly one of the largest environmental, legislative and economic challenges facing the mining industry. In Australia alone, at least 60m is spent on AMD related issues annually, and the global cost is estimated to be in the order of tens of billions US. Furthermore, the challenge of safely and economically storing or treating sulfidic wastes will likely intensify because of the trend towards larger mines that process increasingly higher volumes of lower grade ores and the associated sulfidic wastes and lower profit margins. While the challenge of managing potentially acid forming (PAF) wastes will likely intensify, the industrial approaches to preventing acid production or ameliorating the effects has stagnated for decades. Conventionally, PAF waste is segregated and encapsulated in non-PAF tips to limit access to atmospheric oxygen. Two key limitations of the 'cap and cover' approach are: 1) the hazard (PAF) is not actually removed; only the pollutant linkage is severed; and, 2) these engineered structures are susceptible to physical failure in short-to-medium term, potentially re-establishing that pollutant linkage. In an effort to address these concerns, CSIRO is investigating a passive, 'low-acid' oxidation mechanism for sulfide treatment, which can potentially produce one quarter as much acidity compared with pyrite oxidation under atmospheric oxygen. This 'low-acid' mechanism relies on nitrate, rather than oxygen, as the primary electron accepter and the activity of specifically cultured chemolithoautotrophic bacteria and archaea communities. This research was prompted by the observation that, in deeply weathered terrains of Australia, shallow (oxic to sub-oxic) groundwater contacting weathering sulfides are commonly inconsistent with the geochemical conditions produced by ARD. One key characteristic of these aquifers is the natural abundance of nitrate on a regional scale, which becomes depleted around the sulfide bodies, and

Assessing the relationship between groundwater nitrate and animal feeding operations in Iowa (USA)

Science.gov (United States)

Zirkle, Keith W.; Nolan, Bernard T.; Jones, Rena R.; Weyer, Peter J.; Ward, Mary H.; Wheeler, David C.

2016-01-01

Nitrate-nitrogen is a common contaminant of drinking water in many agricultural areas of the United States of America (USA). Ingested nitrate from contaminated drinking water has been linked to an increased risk of several cancers, specific birth defects, and other diseases. In this research, we assessed the relationship between animal feeding operations (AFOs) and groundwater nitrate in private wells in Iowa. We characterized AFOs by swine and total animal units and type (open, confined, or mixed), and we evaluated the number and spatial intensities of AFOs in proximity to private wells. The types of AFO indicate the extent to which a facility is enclosed by a roof. Using linear regression models, we found significant positive associations between the total number of AFOs within 2 km of a well (p trend nitrate concentration. Additionally, we found significant increases in log nitrate in the top quartiles for AFO spatial intensity, open AFO spatial intensity, and mixed AFO spatial intensity compared to the bottom quartile (0.171 log(mg/L), 0.319 log(mg/L), and 0.541 log(mg/L), respectively; all p nitrate-nitrogen in drinking wells and found significant spatial clustering of high-nitrate wells (> 5 mg/L) compared with low-nitrate (≤ 5 mg/L) wells (p = 0.001). A generalized additive model for high-nitrate status identified statistically significant areas of risk for high levels of nitrate. Adjustment for some AFO predictor variables explained a portion of the elevated nitrate risk. These results support a relationship between animal feeding operations and groundwater nitrate concentrations and differences in nitrate loss from confined AFOs vs. open or mixed types.

Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin.

Science.gov (United States)

Narula, Kapil K; Gosain, A K

2013-12-01

The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11,600 km(2) with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO3) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO3 transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash-Sutcliffe and R(2) correlations greater than +0.7). Nitrate loading obtained after nitrification, denitrification, and NO3 removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO3 concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the century. Water yield estimates under

Application of δ18O, δD, 3H-3He and CFCs to characterize the nitrate contamination of groundwater in Eumsung, Korea

Science.gov (United States)

Ju, Y. J.; Kaown, D.; Hahm, D.; Kim, I.; Lee, S. S.; Koh, E. H.; Kim, M.; Yoon, Y. Y.; Lee, K. K.

2015-12-01

We measured the major ions, stable oxygen and hydrogen isotopes, 3H-3He and CFCs concentration in groundwater to identify the characteristics of nitrate contamination and to understand the groundwater recharge patterns. In this study, 17 groundwater samples were collected for 5days (from March 3rd to 7th, 2015) in Eumseong, Korea. In the study area, NO3- concentrations in some groundwater samples (16 of 17) ranged from 5.7 to 103.7 mg/L (avg. 43.3 mg/L), which were substantially higher than the drinking water quality standard (10 mg/L). These excess NO3- inputs in groundwater seem to be originated from the agricultural use of chemical fertilizers because major ions associated with fertilizers were significantly correlated with NO3-. It seems that major groundwater recharge event during monsoon season is highly probable from the analysis of δ18O and δD. The apparent groundwater age using 3H-3He and CFCs varies from 5 to 40 yrs although the study area is small (1 km2). For the samples showed large deficiency of 3He, the sensitivity analysis was performed using NOBLE 90 in an effort to quantify the degassed amount. Since nitrate sources are quite evenly distributed through the field site, groundwater ages from shallow aquifer is inversely correlated with the nitrate concentrations. Our result implies that the 3H-3He ratio can be a useful indicator of tracing the recharge pattern of groundwater but also the nitrate loading characteristic in a small scale agricultural area. Acknowlegments: Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003) and the research project of "Advanced Technology for Groundwater Development and Application in Riversides (Geowater+)" in "Water Resources Management Program (code 11 Technology Innovation C05)" of the MOLIT and the KAIA in Korea.

Nitrate and Perchlorate removal from groundwater by ion exchange; TOPICAL

International Nuclear Information System (INIS)

Burge, S; Halden, R

1999-01-01

This study was conducted to evaluate the performance of a small scale ion exchange unit (Krudico, Inc of Auborn, IA) for removal of nitrate and perchlorate from groundwater at Lawrence Livermore National Laboratory's Site 300. The unit was able to treat 3,600 gallons of Site 300 groundwater, at an average influent concentration of 100 mg/L NO(sub 3)(sup -) before breakthrough occurred. The unit contained 2.5 ft(sup 3) of Sybron SR-7 resin. Seventy gallons of regeneration waste were generated (water treated to waste ratio of 51:1). The effluent concentration was about 20 mg/L NO(sub 3)(sup -), which is equivalent to a treatment efficiency of at least 80%. There are several options for implementing this technology at Site 300. A target well, in the 817 area, has been selected. It has a 3 to 4 gpm flow rate, and concentrations of 90 mg/L NO(sub 3)(sup -) and 40(micro)g/L perchlorate. The different treatment options include ion exchange treatment of nitrate only, nitrate and perchlorate, or perchlorate only. Option 1: For the treatment of nitrate only, this unit will be able to treat 3,700 gallons of water before regeneration is required. If both columns of the ion exchange unit are used, 7,400 gallons could be treated before the columns will need to be regenerated (producing 140 gallons of waste, per cycle or every 1.5 days). The effluent nitrate concentration is expected to be about 17 mg/L. Annual operation and maintenance costs are estimated to be$0.14 per gallon of water treated. Option 2: If only perchlorate is to be removed with ion exchange at the 817 area, a smaller unit should be considered. A 55 gallon canister filled with ion exchange resin should be able to reduce perchlorate concentrations in the groundwater from 40(micro)g/L to non-detect levels for three years before the resin would need to be replaced. The contaminant-laden resin would be disposed of as hazardous waste. It is not practical to regenerate the resin because of the extreme difficulty of

Impacts of Agriculture on Nitrates in Soil and Groundwater in the Southeastern Coastal Plain

Science.gov (United States)

Nitrogen (N) contamination of surface and groundwater is a health concern for both humans and animals. Excess N in surface water bodies may contribute to eutrophication. Elevated nitrate (NO3-N) concentrations in drinking water have caused infant death from the disease methemoglobinemia. Nitrates...

Geochemical and isotopic study to determine sources and processes affecting nitrate and sulphate in groundwater influenced by intensive human activity - carbonate aquifer Gliwice (southern Poland)

International Nuclear Information System (INIS)

Jakóbczyk-Karpierz, Sabina; Sitek, Sławomir; Jakobsen, Rasmus; Kowalczyk, Andrzej

2017-01-01

A multi-species, multi-stable-isotope approach (δ"1"5N_N_O_3, δ"1"8O_N_O_3_, δ"3"4S_S_O_4, δ"1"8O_S_O_4, δ"1"8O_H_2_O and δ"2H_H_2_O) was used together with environmental tracers (Ar, Ne, CFC-11 and CFC-12) and geochemical modelling to characterize sources and processes controlling concentrations of NO_3"− and SO_4"2"- in groundwater of the carbonate aquifer Gliwice (southern Poland). The study area represents a strongly transformed environment with a range of human activities i.a. Agriculture, urbanization and industry. The δ"1"5N_N_O_3 and δ"1"8O_N_O_3 indicated that most samples contained NO_3"− of mixed sources: artificial fertilizers, municipal and industrial sewage, while very good correlation between NO_3"− and CFC-12 suggested that nitrate originated primarily from residential and industrial sewage. Conversely, isotopic composition of sulphate in groundwater suggested agriculture as well as oxidation of sulphides as dominant. The conclusion was supported by the comparison of CFCs and sulphate concentrations which revealed no relevant correlation. Geochemical modelling confirmed the presence of sulphate reduction in areas where isotopic analyses were not possible due to undetectable sulphate. Thus, the integrated application of stable isotopes, environmental tracers, groundwater chemistry and geochemical modelling shows a complex origin of groundwater pollution in the study area as well as variety of geochemical processes controlling chemistry of groundwater in a triple-porosity aquifer influenced by different types of human activity. - Highlights: • CFCs helped to identify municipal and industrial sources of NO_3"− in groundwater. • δ"1"8O and δ"3"4S suggested domination of SO_4"2"- from agriculture and sulphide oxidation. • Sulphate reduction was confirmed using geochemical modelling for SO_4"2"-free water.

Vadose zone processes delay groundwater nitrate reduction response to BMP implementation as observed in paired cultivated vs. uncultivated potato rotation fields

Science.gov (United States)

Jiang, Y.; Nyiraneza, J.; Murray, B. J.; Chapman, S.; Malenica, A.; Parker, B.

2017-12-01

Nitrate leaching from crop production contributes to groundwater contamination and subsequent eutrophication of the receiving surface water. A study was conducted in a 7-ha potato-grain-forages rotation field in Prince Edward Island (PEI), Canada during 2011-2016 to link potato rotation practices and groundwater quality. The field consists of fine sandy loam soil and is underlain by 7-9 m of glacial till, which overlies the regional fractured ;red-bed; sandstone aquifer. The water table is generally located in overburden close to the bedrock interface. Field treatments included one field zone taken out of production in 2011 with the remaining zones kept under a conventional potato rotation. Agronomy data including crop tissue, soil, and tile-drain water quality were collected. Hydrogeology data including multilevel monitoring of groundwater nitrate and hydraulic head and data from rock coring for nitrate distribution in overburden and bedrock matrix were also collected. A significant amount of nitrate leached below the soil profile after potato plant kill (referred to as topkill) in 2011, most of it from fertilizer N. A high level of nitrate was also detected in the till vadose zone through coring in December 2012 and through multilevel groundwater sampling from January to May 2014 in both cultivated and uncultivated field zones. Groundwater nitrate concentrations increased for about 2.5 years after the overlying potato field was removed from production. Pressure-driven uniform flow processes dominate water and nitrate transport in the vadose zone, producing an apparently instant water table response but a delayed groundwater quality response to nitrate leaching events. These data suggest that the uniform flow dominated vadose zone in agricultural landscapes can cause the accumulation of a significant amount of nitrate originated from previous farming activities, and the long travel time of this legacy nitrate in the vadose zone can result in substantially delayed

Nitrate pollution of shallow ground water in chaj doab

International Nuclear Information System (INIS)

Hussain, S. D.; Akram, W.; Ahmad, M.; Rafiq, M.

2000-01-01

Chaj Doab is an interfluvial tract of land bounded by the rivers Chenab and Jhelum. Agriculture is the main economic activity in the area. In order to increase crop production,. natural and industrial fertilizers are excessively used. Shallow groundwater is the main source of water for domestic and agricultural usage. Nitrate in the soil is carried to the groundwater by precolating water. Concentration of nitrate in groundwater which used to be less than 3 mg/l has crossed the WHO limit of 45 mg/l at several places principally due to the excessive use of fertilizers. In order to avoid serious consequences of nitrate pollution of groundwater, application of fertilizers will have to be judiciously practiced. (author)

Ground-water discharge and base-flow nitrate loads of nontidal streams, and their relation to a hydrogeomorphic classification of the Chesapeake Bay Watershed, middle Atlantic Coast

Science.gov (United States)

Bachman, L. Joseph; Lindsey, Bruce D.; Brakebill, John W.; Powars, David S.

1998-01-01

Existing data on base-flow and groundwater nitrate loads were compiled and analyzed to assess the significance of groundwater discharge as a source of the nitrate load to nontidal streams of the Chesapeake Bay watershed. These estimates were then related to hydrogeomorphic settings based on lithology and physiographic province to provide insight on the areal distribution of ground-water discharge. Base-flow nitrate load accounted for 26 to about 100 percent of total-flow nitrate load, with a median value of 56 percent, and it accounted for 17 to 80 percent of total-flow total-nitrogen load, with a median value of 48 percent. Hydrograph separations were conducted on continuous streamflow records from 276 gaging stations within the watershed. The values for base flow thus calculated were considered an estimate of ground-water discharge. The ratio of base flow to total flow provided an estimate of the relative importance of ground-water discharge within a basin. Base-flow nitrate loads, total-flow nitrate loads, and total-flow total-nitrogen loads were previously computed from water-quality and discharge measurements by use of a regression model. Base-flow nitrate loads were available from 78 stations, total-flow nitrate loads were available from 86 stations, and total-flow total-nitrogen loads were available for 48 stations. The percentage of base-flow nitrate load to total-flow nitrate load could be computed for 57 stations, whereas the percentage of base-flow nitrate load to totalflow total-nitrogen load could be computed for 36 stations. These loads were divided by the basin area to obtain yields, which were used to compare the nitrate discharge from basins of different sizes. The results indicate that ground-water discharge is a significant source of water and nitrate to the total streamflow and nitrate load. Base flow accounted for 16 to 92 percent of total streamflow at the 276 sampling sites, with a median value of 54 percent. It is estimated that of the 50

Determination of nitrate pollution sources in the Marano Lagoon (Italy) by using a combined approach of hydrochemical and isotopic techniques

Energy Technology Data Exchange (ETDEWEB)

Saccon, Pierpaolo; Leis, Albrecht [JOANNEUM RESEARCH Forschungsgesellschaft mbH, Institute for Water, Energy and Sustainability, 8010 Graz (Austria); Marca, Alina; Kaiser, Jan; Campisi, Laura [School of Environmental Sciences, University of East Anglia, NR4 7TJ Norwich (United Kingdom); Boettcher, Michael E.; Escher, Peter [Leibniz Institute for Baltic Sea Research (IOW), Geochemistry and Isotope Geochemistry Group, D-18119 Rostock (Germany); Savarino, Joel; Erbland, Joseph [UJF-Grenoble 1/CNRS-INSU, Laboratoire de Glaciologie et Geophysique de l' Environnement (LGGE) UMR 5183 (France); Eisenhauer, Anton [GEOMAR, Helmholtz Zentrum fuer Ozean Forschung Kiel, Wischhofstr. 1-3, 24148 Kiel (Germany)

2013-07-01

Due to increased pollution by nitrate from intensive agricultural and other anthropogenic activities the Marano lagoon (northeast Italy) and part of its catchment area have been investigated, applying a combined approach of hydrochemical and isotopic techniques. Thus, to identify and characterize the potential multiple-sources of nitrate pollution the isotopic compositions of nitrate (δ{sup 15}N, δ{sup 18}O, and Δ{sup 17}O), boron (δ{sup 11}B), water (δ{sup 2}H and δ{sup 18}O), and sulphate (δ{sup 34}S and δ{sup 18}O), as well as the chemical composition of different water types have been determined. In the monitoring program water samples from the lagoon, its tributary rivers, the groundwater upwelling line, groundwater, sewage, and open sea on a quarterly interval from 2009 to 2010 have been collected and analyzed. Coupling isotopic and hydrochemical results indicate that the nitrate load in the lagoon was not only derived from agriculture activities but also from other sources such as urban wastewaters, in situ nitrification, and atmospheric deposition. However, none of the samples showed the isotopic characteristics of synthetic fertilizers. (authors)

Nitrate and herbicide loading in two groundwater basins of Illinois' sinkhole plain

Science.gov (United States)

Panno, S.V.; Kelly, W.R.

2004-01-01

This investigation was designed to estimate the mass loading of nitrate (NO3-) and herbicides in spring water discharging from groundwater basins in an agriculturally dominated, mantled karst terrain. The loading was normalized to land use and NO3- and herbicide losses were compared to estimated losses in other agricultural areas of the Midwestern USA. Our study area consisted of two large karst springs that drain two adjoining groundwater basins (total area of 37.7 km2) in southwestern Illinois' sinkhole plain, USA. The springs and stream that they form were monitored for almost 2 years. Nitrate-nitrogen (NO3-N) concentrations at three monitoring sites were almost always above the background concentration (1.9 mg/l). NO3-N concentrations at the two springs ranged from 1.08 to 6.08 with a median concentration of 3.61 mg/l. Atrazine and alachlor concentrations ranged from <0.01 to 34 ??g/l and <0.01 to 0.98 ??g/l, respectively, with median concentrations of 0.48 and 0.12 ??g/l, respectively. Approximately 100,000 kg/yr of NO3-N, 39 kg/yr of atrazine, and 2.8 kg/yr of alachlor were discharged from the two springs. Slightly more than half of the discharged NO3- came from background sources and most of the remainder probably came from fertilizer. This represents a 21-31% loss of fertilizer N from the groundwater basins. The pesticide losses were 3.8-5.8% of the applied atrazine, and 0.05-0.08% of the applied alachlor. The loss of atrazine adsorbed to the suspended solid fraction was about 2 kg/yr, only about 5% of the total mass of atrazine discharged from the springs. ?? 2004 Elsevier B.V. All rights reserved.

Vulnerability of shallow groundwater and drinking-water wells to nitrate in the United States

Science.gov (United States)

Nolan, Bernard T.; Hitt, Kerie J.

2006-01-01

Two nonlinear models were developed at the national scale to (1) predict contamination of shallow ground water (typically drinking. The new models have several advantages over previous national-scale approaches. First, they predict nitrate concentration (rather than probability of occurrence), which can be directly compared with water-quality criteria. Second, the models share a mechanistic structure that segregates nitrogen (N) sources and physical factors that enhance or restrict nitrate transport and accumulation in ground water. Finally, data were spatially averaged to minimize small-scale variability so that the large-scale influences of N loading, climate, and aquifer characteristics could more readily be identified. Results indicate that areas with high N application, high water input, well-drained soils, fractured rocks or those with high effective porosity, and lack of attenuation processes have the highest predicted nitrate concentration. The shallow groundwater model (mean square error or MSE = 2.96) yielded a coefficient of determination (R2) of 0.801, indicating that much of the variation in nitrate concentration is explained by the model. Moderate to severe nitrate contamination is predicted to occur in the High Plains, northern Midwest, and selected other areas. The drinking-water model performed comparably (MSE = 2.00, R2 = 0.767) and predicts that the number of users on private wells and residing in moderately contaminated areas (>5 to ≤10 mg/L nitrate) decreases by 12% when simulation depth increases from 10 to 50 m.

Impact of intensive horticulture practices on groundwater content of nitrates, sodium, potassium, and pesticides.

Science.gov (United States)

Melo, Armindo; Pinto, Edgar; Aguiar, Ana; Mansilha, Catarina; Pinho, Olívia; Ferreira, Isabel M P L V O

2012-07-01

A monitoring program of nitrate, nitrite, potassium, sodium, and pesticides was carried out in water samples from an intensive horticulture area in a vulnerable zone from north of Portugal. Eight collecting points were selected and water-analyzed in five sampling campaigns, during 1 year. Chemometric techniques, such as cluster analysis, principal component analysis (PCA), and discriminant analysis, were used in order to understand the impact of intensive horticulture practices on dug and drilled wells groundwater and to study variations in the hydrochemistry of groundwater. PCA performed on pesticide data matrix yielded seven significant PCs explaining 77.67% of the data variance. Although PCA rendered considerable data reduction, it could not clearly group and distinguish the sample types. However, a visible differentiation between the water samples was obtained. Cluster and discriminant analysis grouped the eight collecting points into three clusters of similar characteristics pertaining to water contamination, indicating that it is necessary to improve the use of water, fertilizers, and pesticides. Inorganic fertilizers such as potassium nitrate were suspected to be the most important factors for nitrate contamination since highly significant Pearson correlation (r = 0.691, P < 0.01) was obtained between groundwater nitrate and potassium contents. Water from dug wells is especially prone to contamination from the grower and their closer neighbor's practices. Water from drilled wells is also contaminated from distant practices.

Fertilizer source effects on phosphate and nitrate leaching through simulated golf greens

International Nuclear Information System (INIS)

Shuman, L.M.

2003-01-01

In general, more P than N leached from both field and greenhouse lysimeters. - Phosphorus and nitrogen leached from high-porosity golf greens can adversely affect surface water and groundwater quality. Greenhouse and field lysimeter experiments were carried out to determine the effects of eight fertilizer sources on P and N leaching from simulated golf greens. Phosphorus appeared in the leachate later than nitrate-N, and the highest concentrations were for the soluble 20-20-20 and the 16-25-12 starter fertilizers. The other six sources resulted in lower P concentrations. The soluble 20-20-20 and the 16-25-12 sources each resulted in 43% of the added P eluting in the leachate, whereas the others varied from 15 to 25%. For nitrate-N the lowest cumulative mass was for the controlled-release 13-13-13 and sulfur-coated urea. A higher percentage of applied P than applied N leached from both field and greenhouse lysimeters. However, the amounts of P leached for the field lysimeters were lower than for the greenhouse columns

Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin

International Nuclear Information System (INIS)

Narula, Kapil K.; Gosain, A.K.

2013-01-01

The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11 600 km 2 with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO 3 ) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO 3 transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash–Sutcliffe and R 2 correlations greater than + 0.7). Nitrate loading obtained after nitrification, denitrification, and NO 3 removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO 3 concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the century. Water yield estimates

Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin

Energy Technology Data Exchange (ETDEWEB)

Narula, Kapil K., E-mail: kkn2104@columbia.edu [Columbia Water Center (India Office), Columbia University, New Delhi 110 016 (India); Gosain, A.K. [Department of Civil Engineering, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110 016 (India)

2013-12-01

The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11 600 km{sup 2} with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO{sub 3}) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO{sub 3} transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash–Sutcliffe and R{sup 2} correlations greater than + 0.7). Nitrate loading obtained after nitrification, denitrification, and NO{sub 3} removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO{sub 3} concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the

Water quality, sources of nitrate, and chemical loadings in the Geronimo Creek and Plum Creek watersheds, south-central Texas, April 2015–March 2016

Science.gov (United States)

Lambert, Rebecca B.; Opsahl, Stephen P.; Musgrove, MaryLynn

2017-12-22

Located in south-central Texas, the Geronimo Creek and Plum Creek watersheds have long been characterized by elevated nitrate concentrations. From April 2015 through March 2016, an assessment was done by the U.S. Geological Survey, in cooperation with the Guadalupe-Blanco River Authority and the Texas State Soil and Water Conservation Board, to characterize nitrate concentrations and to document possible sources of elevated nitrate in these two watersheds. Water-quality samples were collected from stream, spring, and groundwater sites distributed across the two watersheds, along with precipitation samples and wastewater treatment plant (WWTP) effluent samples from the Plum Creek watershed, to characterize endmember concentrations and isotopic compositions from April 2015 through March 2016. Stream, spring, and groundwater samples from both watersheds were collected during four synoptic sampling events to characterize spatial and temporal variations in water quality and chemical loadings. Water-quality and -quantity data from the WWTPs and stream discharge data also were considered. Samples were analyzed for major ions, selected trace elements, nutrients, and stable isotopes of water and nitrate.The dominant land use in both watersheds is agriculture (cultivated crops, rangeland, and grassland and pasture). The upper part of the Plum Creek watershed is more highly urbanized and has five major WWTPs; numerous smaller permitted wastewater outfalls are concentrated in the upper and central parts of the Plum Creek watershed. The Geronimo Creek watershed, in contrast, has no WWTPs upstream from or near the sampling sites.Results indicate that water quality in the Geronimo Creek watershed, which was evaluated only during base-flow conditions, is dominated by groundwater, which discharges to the stream by numerous springs at various locations. Nitrate isotope values for most Geronimo Creek samples were similar, which indicates that they likely have a common source (or

An isotopic view of water and nitrate transport through the vadose zone in Oregon's southern Willamette Valley's Groundwater Management Area

Science.gov (United States)

Brooks, J. R.; Pearlstein, S.; Hutchins, S.; Faulkner, B. R.; Rugh, W.; Willard, K.; Coulombe, R.; Compton, J.

2017-12-01

Groundwater nitrate contamination affects thousands of households in Oregon's southern Willamette Valley and many more across the USA. The southern Willamette Valley Groundwater Management Area (GWMA) was established in 2004 due to nitrate levels in the groundwater exceeding the human health standard of 10 mg nitrate-N L-1. Much of the nitrogen (N) inputs to the GWMA comes from agricultural fertilizers, and thus efforts to reduce N inputs to groundwater are focused upon improving N management. However, the effectiveness of these improvements on groundwater quality is unclear because of the complexity of nutrient transport through the vadose zone and long groundwater residence times. Our objective was to focus on vadose zone transport and understand the dynamics and timing of N and water movement below the rooting zone in relation to N management and water inputs. Stable isotopes are a powerful tool for tracking water movement, and understanding N transformations. In partnership with local farmers and state agencies, we established lysimeters and groundwater wells in multiple agricultural fields in the GWMA, and have monitored nitrate, nitrate isotopes, and water isotopes weekly for multiple years. Our results indicate that vadose zone transport is highly complex, and the residence time of water collected in lysimeters was much longer than expected. While input precipitation water isotopes were highly variable over time, lysimeter water isotopes were surprisingly consistent, more closely resembling long-term precipitation isotope means rather than recent precipitation isotopic signatures. However, some particularly large precipitation events with unique isotopic signatures revealed high spatial variability in transport, with some lysimeters showing greater proportions of recent precipitation inputs than others. In one installation where we have groundwater wells and lysimeters at multiple depths, nitrate/nitrite concentrations decreased with depth. N concentrations

Validation of regression models for nitrate concentrations in the upper groundwater in sandy soils

International Nuclear Information System (INIS)

Sonneveld, M.P.W.; Brus, D.J.; Roelsma, J.

2010-01-01

For Dutch sandy regions, linear regression models have been developed that predict nitrate concentrations in the upper groundwater on the basis of residual nitrate contents in the soil in autumn. The objective of our study was to validate these regression models for one particular sandy region dominated by dairy farming. No data from this area were used for calibrating the regression models. The model was validated by additional probability sampling. This sample was used to estimate errors in 1) the predicted areal fractions where the EU standard of 50 mg l -1 is exceeded for farms with low N surpluses (ALT) and farms with higher N surpluses (REF); 2) predicted cumulative frequency distributions of nitrate concentration for both groups of farms. Both the errors in the predicted areal fractions as well as the errors in the predicted cumulative frequency distributions indicate that the regression models are invalid for the sandy soils of this study area. - This study indicates that linear regression models that predict nitrate concentrations in the upper groundwater using residual soil N contents should be applied with care.

A hybrid machine learning model to estimate nitrate contamination of production zone groundwater in the Central Valley, California

Science.gov (United States)

Ransom, K.; Nolan, B. T.; Faunt, C. C.; Bell, A.; Gronberg, J.; Traum, J.; Wheeler, D. C.; Rosecrans, C.; Belitz, K.; Eberts, S.; Harter, T.

2016-12-01

A hybrid, non-linear, machine learning statistical model was developed within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500 m below ground surface in the Central Valley, California. A database of 213 predictor variables representing well characteristics, historical and current field and county scale nitrogen mass balance, historical and current landuse, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6,000 private supply and public supply wells measured previously for nitrate and located throughout the study area. The machine learning method, gradient boosting machine (GBM) was used to screen predictor variables and rank them in order of importance in relation to the groundwater nitrate measurements. The top five most important predictor variables included oxidation/reduction characteristics, historical field scale nitrogen mass balance, climate, and depth to 60 year old water. Twenty-two variables were selected for the final model and final model errors for log-transformed hold-out data were R squared of 0.45 and root mean square error (RMSE) of 1.124. Modeled mean groundwater age was tested separately for error improvement in the model and when included decreased model RMSE by 0.5% compared to the same model without age and by 0.20% compared to the model with all 213 variables. 1D and 2D partial plots were examined to determine how variables behave individually and interact in the model. Some variables behaved as expected: log nitrate decreased with increasing probability of anoxic conditions and depth to 60 year old water, generally decreased with increasing natural landuse surrounding wells and increasing mean groundwater age, generally increased with increased minimum depth to high water table and with increased base flow index value. Other variables exhibited much more erratic or noisy behavior in

Land-use change and costs to rural households: a case study in groundwater nitrate contamination

Science.gov (United States)

Keeler, Bonnie L.; Polasky, Stephen

2014-07-01

Loss of grassland from conversion to agriculture threatens water quality and other valuable ecosystem services. Here we estimate how land-use change affects the probability of groundwater contamination by nitrate in private drinking water wells. We find that conversion of grassland to agriculture from 2007 to 2012 in Southeastern Minnesota is expected to increase the future number of wells exceeding 10 ppm nitrate-nitrogen by 45% (from 888 to 1292 wells). We link outputs of the groundwater well contamination model to cost estimates for well remediation, well replacement, and avoidance behaviors to estimate the potential economic value lost due to nitrate contamination from observed land-use change. We estimate 0.7-12 million in costs (present values over a 20 year horizon) to address the increased risk of nitrate contamination of private wells. Our study demonstrates how biophysical models and economic valuation can be integrated to estimate the welfare consequences of land-use change.

Land-use change and costs to rural households: a case study in groundwater nitrate contamination

International Nuclear Information System (INIS)

Keeler, Bonnie L; Polasky, Stephen

2014-01-01

Loss of grassland from conversion to agriculture threatens water quality and other valuable ecosystem services. Here we estimate how land-use change affects the probability of groundwater contamination by nitrate in private drinking water wells. We find that conversion of grassland to agriculture from 2007 to 2012 in Southeastern Minnesota is expected to increase the future number of wells exceeding 10 ppm nitrate-nitrogen by 45% (from 888 to 1292 wells). We link outputs of the groundwater well contamination model to cost estimates for well remediation, well replacement, and avoidance behaviors to estimate the potential economic value lost due to nitrate contamination from observed land-use change. We estimate $0.7–12 million in costs (present values over a 20 year horizon) to address the increased risk of nitrate contamination of private wells. Our study demonstrates how biophysical models and economic valuation can be integrated to estimate the welfare consequences of land-use change. (letter)

Reducing nitrate leaching to groundwater in an intensive dairy farming system

NARCIS (Netherlands)

Verloop, J.; Boumans, L.J.M.; Keulen, van H.; Oenema, J.; Hilhorst, G.J.; Aarts, H.F.M.; Sebek, L.B.J.

2006-01-01

Dairy farming is one of the main contributors to nitrate leaching to groundwater, particularly on soils that are susceptible to leaching, such as light well-drained sandy soils. In the Netherlands, as in many other European countries, these soils are predominantly used for dairy farming. A prototype

Use of 15N/14N Ratio to Evaluate the Sources of Nitrate Pollution in Surface and Groundwaters in the Upper Orontes Basin (Central Syria)

International Nuclear Information System (INIS)

Kattan, Z.

2004-01-01

This work represents the results of using of 15 N technique in the evaluation and interpretation of nitrate pollution sources of surface and groundwaters in the Upper Orontes Basin (Central Syria). Based on this method, it was possible to distinguish between two groups of water bodies: 1) the group of fresh and non polluted water, which effectively reflects natural mineralization in nitrogen, such as the waters in the Upper Orontes River, the Qattineh Lake in its western and southern parts, as well as the Al-Qoussier well; 2) the group of polluted water, such as the waters in the other sampling sites. The chemical and isotopic 15 N characteristics of this group reflect the impact of different intensities of pollution processes, which could mainly be derived from anthropogenic source. The intensity of this source was maximum in the Al-Domineh well, which was practically close to a sewage sink. (author)

Effects of process operating conditions on the autotrophic denitrification of nitrate-contaminated groundwater using bioelectrochemical systems.

Science.gov (United States)

Cecconet, D; Devecseri, M; Callegari, A; Capodaglio, A G

2018-02-01

Nitrates have been detected in groundwater worldwide, and their presence can lead to serious groundwater use limitations, especially because of potential health problems. Amongst different options for their removal, bioelectrochemical systems (BESs) have achieved promising results; in particular, attention has raised on BES-driven autotrophic denitrification processes. In this work, the performance of a microbial electrolysis cell (MEC) for groundwater autotrophic denitrification, is assessed in different conditions of nitrate load, hydraulic retention time (HRT) and process configuration. The system obtained almost complete nitrate removal under all conditions, while nitrite accumulation was recorded at nitrate loads higher than 100mgNO 3 - L -1 . The MEC system achieved, in different tests, a maximum nitrate removal rate of 62.15±3.04gNO 3 - -Nm -3 d -1 , while the highest TN removal rate observed was 35.37±1.18gTNm -3 d -1 . Characteristic of this process is a particularly low (in comparison with other reported works) energy consumption: 3.17·10 -3 ±2.26·10 -3 kWh/gNO 3 - N removed and 7.52·10 -2 ±3.58·10 -2 kWhm -3 treated. The anolyte configuration in closed loop allowed the process to use less clean water, while guaranteeing identical performances as in other conventional configurations. Copyright © 2017 Elsevier B.V. All rights reserved.

An Isotopic View of Water and Nitrate Transport Through the Vadose Zone in Oregon’s Southern Willamette Valley’s Groundwater Management Area (S-GWMA)

Science.gov (United States)

Groundwater nitrate contamination affects thousands of households in Oregon’s southern Willamette Valley and many more across the USA. The southern Willamette Valley Groundwater Management Area (GWMA) was established in 2004 due to nitrate levels in the groundwater exceedi...

Hydrogeological and multi-isotopic approach to define nitrate pollution and denitrification processes in a coastal aquifer (Sardinia, Italy)

Science.gov (United States)

Pittalis, Daniele; Carrey, Raul; Da Pelo, Stefania; Carletti, Alberto; Biddau, Riccardo; Cidu, Rosa; Celico, Fulvio; Soler, Albert; Ghiglieri, Giorgio

2018-02-01

Agricultural coastal areas are frequently affected by the superimposition of various processes, with a combination of anthropogenic and natural sources, which degrade groundwater quality. In the coastal multi-aquifer system of Arborea (Italy)—a reclaimed morass area identified as a nitrate vulnerable zone, according to Nitrate Directive 91/676/EEC—intensive agricultural and livestock activities contribute to substantial nitrate contamination. For this reason, the area can be considered a bench test for tuning an appropriate methodology aiming to trace the nitrate contamination in different conditions. An approach combining environmental isotopes, water quality and hydrogeological indicators was therefore used to understand the origins and attenuation mechanisms of nitrate pollution and to define the relationship between contaminant and groundwater flow dynamics through the multi-aquifer characterized by sandy (SHU), alluvial (AHU), and volcanic hydrogeological (VHU) units. Various groundwater chemical pathways were consistent with both different nitrogen sources and groundwater dynamics. Isotope composition suggests a mixed source for nitrate (organic and synthetic fertilizer), especially for the AHU and SHU groundwater. Moreover, marked heterotrophic denitrification and sulfate reduction processes were detected; although, for the contamination related to synthetic fertilizer, the attenuation was inefficient at removing NO3 - to less than the human consumption threshold of 50 mg/L. Various factors contributed to control the distribution of the redox processes, such as the availability of carbon sources (organic fertilizer and the presence of lagoon-deposited aquitards), well depth, and groundwater flow paths. The characterization of these processes supports water-resource management plans, future actions, and regulations, particularly in nitrate vulnerable zones.

Forecasting the effects of EU policy measures on the nitrate pollution of groundwater based on a coupled agroeconomic - hydro(geo)logic model (Invited)

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Wendland, F.

2010-12-01

The fundamental objectives of the European Union-Water Framework Directive and the EU Groundwater Directive are to attain a good status of water and groundwater resources in the member states of the EU by 2015. For river basins, whose good status cannot be guaranteed by 2015, catchment wide operational plans and measurement programs have to be drafted and implemented until 2009. In the river basin district Weser, Germany, which comprises a catchment area of ca. 49.000 km2, the achievement of the good status is unclear, or rather unlikely for 63% of the groundwater bodies. Inputs from diffuse sources and most of all nitrate losses from agriculturally used land have been identified as the main reasons for exceeding the groundwater threshold value for nitrate (50 mg/l) and for failing the good qualitative status of groundwater. The achievement of good qualitative status of groundwater bodies entails a particular challenge as the complex ecological, hydrological, hydrogeological and agro-economic relationships have to be considered simultaneously. We used an interdisciplinary model network to predict the nitrogen intakes into groundwater at the regional scale using an area differentiated approach. The model system combines the agro-economic model RAUMIS for estimating nitrogen surpluses from agriculture and the hydrological models GROWA/DENUZ/WEKU for describing the reactive nitrate transport in the soil-groundwater system. In a first step the model is used to analyze the present situation using N surpluses from agriculture for the year 2003. In many region of the Weser basin, particularly in the northwestern part which is characterized by high livestock densities, predicted nitrate concentrations in percolation water exceed the EU groundwater quality standard of 50 mg/L by far. In a second step the temporal and spatial impacts of the common agricultural policy (CAP) of the EU, already implemented agri-environmental measures of the Federal States and the expected

Nitrate bioreduction in redox-variable low permeability sediments

Energy Technology Data Exchange (ETDEWEB)

Yan, Sen [China University of Geosciences, Wuhan 430074 (China); Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Liu, Yuanyuan [Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Liu, Chongxuan, E-mail: chongxuan.liu@pnnl.gov [China University of Geosciences, Wuhan 430074 (China); Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Shi, Liang; Shang, Jianying [Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Shan, Huimei [China University of Geosciences, Wuhan 430074 (China); Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Zachara, John; Fredrickson, Jim; Kennedy, David; Resch, Charles T.; Thompson, Christopher; Fansler, Sarah [Pacific Northwest National Laboratory, Richland, WA 99354 (United States)

2016-01-01

Low permeability zone (LPZ) can play an important role as a sink or secondary source in contaminant transport in groundwater system. This study investigated the rate and end product of nitrate bioreduction in LPZ sediments. The sediments were from the U.S. Department of Energy's Hanford Site, where nitrate is a groundwater contaminant as a by-product of radionuclide waste discharges. The LPZ at the Hanford site consists of two layers with an oxidized layer on top and reduced layer below. The oxidized layer is directly in contact with the overlying contaminated aquifer, while the reduced layer is in contact with an uncontaminated aquifer below. The experimental results showed that nitrate bioreduction rate and end-product differed significantly in the sediments. The bioreduction rate in the oxidized sediment was significantly faster than that in the reduced one. A significant amount of N{sub 2}O was accumulated in the reduced sediment; while in the oxidized sediment, N{sub 2}O was further reduced to N{sub 2}. RT-PCR analysis revealed that nosZ, the gene that codes for N{sub 2}O reductase, was below detection limit in the reduced sediment. Batch experiments and kinetic modeling were performed to provide insights into the role of organic carbon bioavailability, biomass growth, and competition between nitrate and its reducing products for electrons from electron donors. The results revealed that it is important to consider sediment redox conditions and functional genes in understanding and modeling nitrate bioreduction in subsurface sediments. The results also implied that LPZ sediments can be important sink of nitrate and a potential secondary source of N{sub 2}O as a nitrate bioreduction product in groundwater. - Highlights: • Low permeability zones (LPZ) can microbially remove nitrate in groundwater. • The rate and end product of nitrate bioreduction vary within LPZ. • Greenhouse gas N{sub 2}O can be the end product of nitrate bioreduction in LPZ. �

Understanding Land Use Impacts on Groundwater Quality Using Chemical Analysis

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Nitka, A.; Masarik, K.; Masterpole, D.; Johnson, B.; Piette, S.

2017-12-01

Chippewa County, in western Wisconsin, has a unique historical set of groundwater quality data. The county conducted extensive groundwater sampling of private wells in 1985 (715 wells) and 2007 (800 wells). In 2016, they collaborated with UW-Extension and UW-Stevens Point to evaluate the current status of groundwater quality in Chippewa County by sampling of as many of the previously studied wells as possible. Nitrate was a primary focus of this groundwater quality inventory. Of the 744 samples collected, 60 were further analyzed for chemical indicators of agricultural and septic waste, two major sources of nitrate contamination. Wells for nitrate source analysis were selected from the 2016 participants based upon certain criteria. Only wells with a Wisconsin Unique Well Number were considered to ensure well construction information was available. Next, an Inverse Distance Weighting tool in ESRI ArcMap was used to assign values categorizing septic density. Two-thirds of the wells were selected in higher density areas and one-third in lower density areas. Equally prioritized was an even distribution of nitrate - N concentrations, with 28 of the wells having nitrate - N concentrations higher than the drinking water standard of 10 mg/L and 32 wells with concentrations between 2 and 10 mg/L. All wells with WUWN and nitrate - N concentrations greater than 20 mg/L were selected. The results of the nitrate source analyses will aid in determining temporal changes and spatial relationships of groundwater quality to soils, geology and land use in Chippewa County.

Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor.

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Zhao, Yingxin; Feng, Chuanping; Wang, Qinghong; Yang, Yingnan; Zhang, Zhenya; Sugiura, Norio

2011-09-15

An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO(3)(-)-N50 mg L(-1)) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO(3)(-)-N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO(2) produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate. Copyright © 2011 Elsevier B.V. All rights reserved.

Agricultural Recharge Practices for Managing Nitrate in Regional Groundwater: Time-Resolution Assessment of Numerical Modeling Approach

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Bastani, M.; Harter, T.

2017-12-01

Intentional recharge practices in irrigated landscapes are promising options to control and remediate groundwater quality degradation with respect to nitrate. To better understand the effect of these practices, a fully 3D transient heterogeneous transport model simulation is developed using MODFLOW and MT3D. The model is developed for a long-term study of nitrate improvements in an alluvial groundwater basin in Eastern San Joaquin Valley, CA. Different scenarios of agricultural recharge strategies including crop type change and winter flood flows are investigated. Transient simulations with high spatio-temporal resolutions are performed. We then consider upscaling strategies that would allow us to simplify the modeling process such that it can be applied at a very large basin-scale (1000s of square kilometers) for scenario analysis. We specifically consider upscaling of time-variant boundary conditions (both internal and external) that have significant influence on calculation cost of the model. We compare monthly transient stresses to upscaled annual and further upscaled average steady-state stresses on nitrate transport in groundwater under recharge scenarios.

[Removal of nitrate from groundwater using permeable reactive barrier].

Science.gov (United States)

Li, Xiu-Li; Yang, Jun-Jun; Lu, Xiao-Xia; Zhang, Shu; Hou, Zhen

2013-03-01

To provide a cost-effective method for the remediation of nitrate-polluted groundwater, column experiments were performed to study the removal of nitrate by permeable reactive barrier filled with fermented mulch and sand (biowall), and the mechanisms and influence factors were explored. The experimental results showed that the environmental condition in the simulated biowall became highly reduced after three days of operation (oxidation-reduction potential was below - 100 mV), which was favorable for the reduction of nitrate. During the 15 days of operation, the removal rate of nitrate nitrogen (NO3(-) -N) by the simulated biowall was 80%-90% (NO3(-)-N was reduced from 20 mg x L(-1) in the inlet water to 1.6 mg x L(-1) in the outlet water); the concentration of nitrite nitrogen (NO2(-) -N) in the outlet water was below 2.5 mg x L(-1); the concentration of ammonium nitrogen (NH4(+) -N) was low in the first two days but increased to about 12 mg x L(-1) since day three. The major mechanisms involved in the removal of nitrate nitrogen were adsorption and biodegradation. When increasing the water flow velocity in the simulated biowall, the removal rate of NO3(-) -N was reduced and the concentration of NH4(+) -N in the outlet water was significantly reduced. A simulated zeolite wall was set up following the simulated biowall and 98% of the NH4(+) -N could be removed from the water.

Groundwater recharge and agricultural contamination in alluvial fan of Eastern Kofu basin, JAPAN

Science.gov (United States)

Nakamura, T.

2009-12-01

Agriculture has significant effects on the rate and composition of groundwater recharge. The chemical loading into groundwater have been dominated by the constituents derived directly or indirectly from agricultural practices and additives. The contamination of groundwater with nitrate is a major public health and environmental concern around the world. The inorganic constituents like, K+, Ca2+, Mg2+, SO42-, Cl- and variety of other minor elements of groundwater are often used as agricultural additives; and the natural occurrence of these elements are dominated by the agricultural sources. A recent study has reported that Kofu basin groundwater aquifer is contaminated by nitrate from agricultural areas because of the fertilizer application for the orchard (Kazama and Yoneyama, 2002; Sakamoto et al., 1997, Nakamura et al., 2007). The water-oxygen and hydrogen stable isotope (δ18O and δD) and nitrate-nitrogen stable isotope (δ15N) of groundwater, river water and precipitation samples were investigated to identify the source of groundwater and nitrate nitrogen contamination in groundwater in the Fuefukigawa and Hikawa_Kanegawa alluvial fans in Kofu basin. The plot of δD versus δ18O values of groundwater, river water and precipitation samples suggest that the groundwater is a mixture of precipitation and river water. And nitrate-nitrogen isotope values have suggested the nitrate contamination of groundwater is from agricultural area. The study revealed positive correlation between groundwater δ18O values and NO3-, Cl-, SO42-, Ca2+, Mg2+ concentration, which shows the agricultural contamination is carried by the recharge of groundwater from precipitation in alluvial fan. Whereas, NO3-, Cl-, SO42-, Ca2+, Mg2+ are diluted by the river water recharges. This study showed the quality of groundwater is resulted from the mixing of water from the different source during the groundwater recharge in the study area. References Kazama F, Yoneyama M (2002) Nitrogen generation

Influence of organic carbon sources and isotope exchange processes between water and nitrate on the fractionation of the stable isotopes 15N/14N and 18O/16O in dissolved nitrate during microbial dentrification in groundwater

International Nuclear Information System (INIS)

Wunderlich, Anja A.L.

2012-01-01

Stable isotopes of nitrate are commonly used to determine sources and degradation of nitrate. In this study, nitrite oxidizing bacteria were found to promote an oxygen isotope exchange between water and nitrate under anoxic conditions. Also, different carbon sources were found to influence the enrichment of stable isotopes in nitrate during microbial denitrification. Both results refine the stable isotope model of nitrate in respect to nitrate source determination and microbial nitrate reduction.

Quantifying an aquifer nitrate budget and future nitrate discharge using field data from streambeds and well nests

Science.gov (United States)

Gilmore, Troy E.; Genereux, David P.; Solomon, D. Kip; Farrell, Kathleen M.; Mitasova, Helena

2016-11-01

Novel groundwater sampling (age, flux, and nitrate) carried out beneath a streambed and in wells was used to estimate (1) the current rate of change of nitrate storage, dSNO3/dt, in a contaminated unconfined aquifer, and (2) future [NO3-]FWM (the flow-weighted mean nitrate concentration in groundwater discharge) and fNO3 (the nitrate flux from aquifer to stream). Estimates of dSNO3/dt suggested that at the time of sampling (2013) the nitrate storage in the aquifer was decreasing at an annual rate (mean = -9 mmol/m2yr) equal to about one-tenth the rate of nitrate input by recharge. This is consistent with data showing a slow decrease in the [NO3-] of groundwater recharge in recent years. Regarding future [NO3-]FWM and fNO3, predictions based on well data show an immediate decrease that becomes more rapid after ˜5 years before leveling out in the early 2040s. Predictions based on streambed data generally show an increase in future [NO3-]FWM and fNO3 until the late 2020s, followed by a decrease before leveling out in the 2040s. Differences show the potential value of using information directly from the groundwater—surface water interface to quantify the future impact of groundwater nitrate on surface water quality. The choice of denitrification kinetics was similarly important; compared to zero-order kinetics, a first-order rate law levels out estimates of future [NO3-]FWM and fNO3 (lower peak, higher minimum) as legacy nitrate is flushed from the aquifer. Major fundamental questions about nonpoint-source aquifer contamination can be answered without a complex numerical model or long-term monitoring program.

Belgrade waterworks groundwater source

International Nuclear Information System (INIS)

Sotic, A.; Dasic, M.; Vukcevic, G.; Vasiljevic, Lj.; Nikolic, S.

2002-01-01

Paper deals with Belgrade Waterworks groundwater source, its characteristics, conception of protection programme, contaminations on source and with parameters of groundwater quality degradation. Groundwaters present natural heritage with their strategic and slow renewable natural resources attributes, and as such they require priority in protection. It is of greatest need that existing source is to be protected and used optimally for producing quality drinkable water. The concept of source protection programme should be based on regular water quality monitoring, identification of contaminators, defining areas of their influences on the source and their permanent control. However, in the last 10 years, but drastically in the last 3, because of the overall situation in the country, it is very characteristic downfall in volume of business, organisation and the level of supply of the technical equipment

Denitrification and dilution along fracture flowpaths influence the recovery of a bedrock aquifer from nitrate contamination

International Nuclear Information System (INIS)

Kim, Jonathan J.; Comstock, Jeff; Ryan, Peter; Heindel, Craig; Koenigsberger, Stephan

2016-01-01

In 2000, elevated nitrate concentrations ranging from 12 to 34 mg/L NO_3−N were discovered in groundwater from numerous domestic bedrock wells adjacent to a large dairy farm in central Vermont. Long-term plots and contours of nitrate vs. time for bedrock wells showed “little/no”, “moderate”, and “large” change patterns that were spatially separable. The metasedimentary bedrock aquifer is strongly anisotropic and groundwater flow is controlled by fractures, bedding/foliation, and basins and ridges in the bedrock surface. Integration of the nitrate concentration vs. time data and the physical and chemical aquifer characterization suggest two nitrate sources: a point source emanating from a waste ravine and a non-point source that encompasses the surrounding fields. Once removed, the point source of NO_3 (manure deposited in a ravine) was exhausted and NO_3 dropped from 34 mg/L to 10 mg/L. Our multidisciplinary methods of aquifer characterization are applicable to groundwater contamination in any complexly-deformed and metamorphosed bedrock aquifer. - Highlights: • Bedrock wells contaminated with nitrates at a dairy farm in Vermont, U.S.A. • Nitrate concentration vs. time patterns for wells were spatially separable. • Multidisciplinary aquifer characterization used physical and chemical methods. • Denitrification dominant over dilution along fracture flowpaths • Conceptual model shows exhaustion of a nitrate point-source over 12 years.

Hydrogeology, groundwater seepage, nitrate distribution, and flux at the Raleigh hydrologic research station, Wake County, North Carolina, 2005-2007

Science.gov (United States)

McSwain, Kristen Bukowski; Bolich, Richard E.; Chapman, Melinda J.

2013-01-01

gradients in the groundwater discharge area near the Neuse River were complex and were affected by fluctuations in river stage, with the exception of a well completed in a diabase dike. Water-quality data from the wells and surface-water sites at the RHRS were collected continuously as well as during periodic sampling events. Surface-water samples collected from a tributary were most similar in chemical composition to groundwater found in the regolith and transition zone. Nitrate (measured as nitrite plus nitrate, as nitrogen) concentrations in the sampled wells and tributary ranged from about 5 to more than 120 milligrams per liter as nitrogen. Waterborne continuous resistivity profiling conducted on the Neuse River in the area of the RHRS measured areas of low apparent resistivity that likely represent groundwater contaminated by high concentrations of nitrate. These areas were located on either side of a diabase dike and at the outfall of two unnamed tributaries. The diabase dike preferentially directed the discharge of groundwater to the Neuse River and may isolate groundwater movement laterally. Discrete temperature measurements made within the pore water beneath the Neuse River revealed seeps of colder groundwater discharging into warmer surface water near a diabase dike. Water-quality samples collected from the pore water beneath the Neuse River indicated that nitrate was present at concentrations as high as 80 milligrams per liter as nitrogen on the RHRS side of the river. The highest concentrations of nitrate were located within pore water collected from an area near a diabase dike that was identified as a suspected seepage area. Hydraulic head was measured and pore water samples were collected from two 140-centimeter-deep (55.1-inch-deep) multiport piezometers that were installed in bed sediments on opposite sides of a diabase dike. The concentration of nitrate in pore water at a suspected seepage area ranged from 42 to 82 milligrams per liter as nitrogen with a

Association of Land Use With Detections of VOCs, Pesticides, and Nitrate in Untreated Groundwater Used for Drinking Water in the United States, 1992-99

Science.gov (United States)

Squillace, P. J.; Moran, M. J.

2001-05-01

Between 1992 and 1999, samples of untreated groundwater from 1,497 drinking-water wells were analyzed as part of the National Water-Quality Assessment Program of the U.S. Geological Survey. Well depths ranged from 1.8 to 823 m, with a median depth of 46 m. Domestic wells (1255) had a median well depth of 43 m, and public supply wells (242) had a median depth of 77 m. Up to 144 compounds were analyzed for each sample. Seventy percent of the samples contained at least one volatile organic compound (VOC), pesticide, or anthropogenic nitrate---conservatively assuming concentrations of nitrate >= 3 mg/L were from an anthropogenic source. The total concentration of VOCs and pesticides ranged from about 0.001 to 100 μ g/L, with a median of 0.02 μ g/L. About 12% of the samples exceeded health criteria, primarily due to nitrate concentrations exceeding the Maximum Contaminant Level of 10 mg/L. Almost half (46%) of the samples contained a mixture of two compounds; and 33% contained at least three compounds. There were 402 common mixtures; each mixture was detected in at least one percent of the samples. Although VOCs were detected more frequently (44%) than pesticides (38%) or anthropogenic nitrate (28%), the top 100 common mixtures consisted primarily of persistent pesticides and nitrate, which frequently are applied either together, or sequentially on row crops. VOCs, on the other hand, tended to co-occur with a wider variety of compounds and were common in the remaining 302 mixtures. Groundwater samples with VOCs, pesticides, anthropogenic nitrate, or at least one of the common mixtures of these compounds were associated with areas of higher population density compared to samples without these compounds. The common mixtures had higher concentrations of VOCs, pesticides, and nitrate, and were associated with more intense land development (urban areas, cultivated land, or orchards). Well type, well depth, dissolved oxygen, and aquifer type were tested for their

Trends in Nitrate Drinking Water Violations Across the US

Science.gov (United States)

Background/Question/Methods Safe drinking water is essential for the health and well-being of humans and life on Earth. Previous studies have shown that groundwater and other sources of drinking water can be contaminated with nitrate above the 10 mg nitrate-N L-1 maximum contami...

Pesticides and nitrate in groundwater underlying citrus croplands, Lake Wales Ridge, central Florida, 1999-2005.

Science.gov (United States)

Choquette, Anne F.

2014-01-01

This report summarizes pesticide and nitrate (as nitrogen) results from quarterly sampling of 31 surficial-aquifer wells in the Lake Wales Ridge Monitoring Network during April 1999 through January 2005. The wells, located adjacent to citrus orchards and used for monitoring only, were generally screened (sampled) within 5 to 40 feet of the water table. Of the 44 citrus pesticides and pesticide degradates analyzed, 17 were detected in groundwater samples. Parent pesticides and degradates detected in quarterly groundwater samples, ordered by frequency of detection, included norflurazon, demethyl norflurazon, simazine, diuron, bromacil, aldicarb sulfone, aldicarb sulfoxide, deisopropylatrazine (DIA), imidacloprid, metalaxyl, thiazopyr monoacid, oxamyl, and aldicarb. Reconnaissance sampling of five Network wells yielded detection of four additional pesticide degradates (hydroxysimazine, didealkylatrazine, deisopropylhydroxyatrazine, and hydroxyatrazine). The highest median concentration values per well, based on samples collected during the 1999–2005 period (n=14 to 24 samples per well), included 3.05 µg/L (micrograms per liter) (simazine), 3.90 µg/L (diuron), 6.30 µg/L (aldicarb sulfone), 6.85 µg/L (aldicarb sulfoxide), 22.0 µg/L (demethyl norflurazon), 25.0 µg/ (norflurazon), 89 µg/ (bromacil), and 25.5 mg/L (milligrams per liter) (nitrate). Nitrate concentrations exceeded the 10 mg/L (as nitrogen) drinking water standard in one or more groundwater samples from 28 of the wells, and the median nitrate concentration among these wells was 14 mg/L. Sampled groundwater pesticide concentrations exceeded Florida’s health-guidance benchmarks for aldicarb sulfoxide and aldicarb sulfone (4 wells), the sum of aldicarb and its degradates (6 wells), simazine (2 wells), the sum of simazine and DIA (3 wells), diuron (2 wells), bromacil (1 well), and the sum of norflurazon and demethyl norflurazon (1 well). The magnitude of fluctuations in groundwater pesticide

ASPECTS CONCERNING NITRATE AND NITRITE POLLUTION OF GROUNDWATERS

Directory of Open Access Journals (Sweden)

A. UNGUREANU

2011-03-01

Full Text Available Aspects concerning nitrate and nitrite pollution of groundwaters. Water is a basic natural resource for the good functioning of all thebiological processes in nature. It is very important for life and for the developmentof human activities. The quality of the ground water has begun to degrade moreand more, as a result of the physical, chemical and bacteriological changes.Nitrogen compounds pollution of the underground has increased lately. This hasbeen caused by the excessive and irrational use of nitrogen derived fertilizers, bythe wrong storage of the dejections resulted from zootechnical processes and byother chemical substances discharged into water. Samples were collected fromdifferent wells in order to check whether the well water was drinkable. The resultof the test revealed the existence of high concentrations of nitrates as well asvalues exceeding normal microbiological parameters. The value recorded in thetown of Segarcea, the county of Dolj, showed extremely high concentrations ofnitrates of the drinking water in the wells. Thus, Segarcea is the town with thegreatest number of contaminated wells in the country.

A Spatial and Temporal Assessment of Non-Point Groundwater Pollution Sources, Tutuila Island, American Samoa

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Shuler, C. K.; El-Kadi, A. I.; Dulaiova, H.; Glenn, C. R.; Fackrell, J.

2015-12-01

The quality of municipal groundwater supplies on Tutuila, the main island in American Samoa, is currently in question. A high vulnerability for contamination from surface activities has been recognized, and there exists a strong need to clearly identify anthropogenic sources of pollution and quantify their influence on the aquifer. This study examines spatial relationships and time series measurements of nutrients and other tracers to identify predominant pollution sources and determine the water quality impacts of the island's diverse land uses. Elevated groundwater nitrate concentrations are correlated with areas of human development, however, the mixture of residential and agricultural land use in this unique village based agrarian setting makes specific source identification difficult using traditional geospatial analysis. Spatial variation in anthropogenic impact was assessed by linking NO3- concentrations and δ15N(NO3) from an extensive groundwater survey to land-use types within well capture zones and groundwater flow-paths developed with MODFLOW, a numerical groundwater model. Land use types were obtained from high-resolution GIS data and compared to water quality results with multiple-regression analysis to quantify the impact that different land uses have on water quality. In addition, historical water quality data and new analyses of δD and δ18O in precipitation, groundwater, and mountain-front recharge waters were used to constrain the sources and mechanisms of contamination. Our analyses indicate that groundwater nutrient levels on Tutuila are controlled primarily by residential, not agricultural activity. Also a lack of temporal variation suggests that episodic pollution events are limited to individual water sources as opposed to the entire aquifer. These results are not only valuable for water quality management on Tutuila, but also provide insight into the sustainability of groundwater supplies on other islands with similar hydrogeology and land

Nitrate leaching from short-hydroperiod floodplain soils

Directory of Open Access Journals (Sweden)

B. Huber

2012-11-01

Full Text Available Numerous studies have shown the importance of riparian zones to reduce nitrate (NO₃⁻ contamination coming from adjacent agricultural land. Much less is known about nitrogen (N transformations and nitrate fluxes in riparian soils with short hydroperiods (1–3 days of inundation and there is no study that could show whether these soils are a N sink or source. Within a restored section of the Thur River in NE Switzerland, we measured nitrate concentrations in soil solutions as an indicator of the net nitrate production. Samples were collected along a quasi-successional gradient from frequently inundated gravel bars to an alluvial forest, at three different depths (10, 50 and 100 cm over a one-year period. Along this gradient we quantified N input (atmospheric deposition and sedimentation and N output (leaching to create a nitrogen balance and assess the risk of nitrate leaching from the unsaturated soil to the groundwater. Overall, the main factor explaining the differences in nitrate concentrations was the field capacity (FC. In subsoils with high FCs and VWC near FC, high nitrate concentrations were observed, often exceeding the Swiss and EU groundwater quality criterions of 400 and 800 μmol L⁻¹, respectively. High sedimentation rates of river-derived nitrogen led to apparent N retention up to 200 kg N ha⁻¹ yr⁻¹ in the frequently inundated zones. By contrast, in the mature alluvial forest, nitrate leaching exceeded total N input most of the time. As a result of the large soil N pools, high amounts of nitrate were produced by nitrification and up to 94 kg N-NO₃⁻ ha⁻¹ yr⁻¹ were leached into the groundwater. Thus, during flooding when water fluxes are high, nitrate from soils can contribute up to 11% to the total nitrate load in groundwater.

Analytical developments in the measurements of boron, nitrate, phosphate and sulphate isotopes and case examples of discrimination of nitrogen and sulphur sources in pollution studies

International Nuclear Information System (INIS)

Aggarwal, J.; Sheppard, D.S.; Robinson, B.W.

1998-01-01

Methods are documented for the analysis of B isotopes, O and N isotopes in nitrates. B isotopes can be measured by negative ion thermal ionisation mass spectrometry. Nitrate is recovered from groundwaters by ion exchange and the resulting silver nitrate combusted for stable isotope gas analysis. Oxygen isotope analysis of phosphates can be determined by generating and analysing CO 2 gas from the combustion of silver phosphate produced from aqueous samples. Sulphate in ground and surface waters can be separated and concentrated by ion exchange and precipitated as barium sulphate. This is reacted with graphite to yield CO 2 and CO, the latter being spark discharged to CO 2 and the total CO 2 measured for oxygen isotope analysis. Barium sulphide from this reaction is converted to silver sulphide which is reacted with cuprous oxide to give SO 2 gas for sulphur isotope measurements. A case study of the semi-rural Manakau area in New Zealand was conducted to see if nitrate isotopes could be used to detect the source of nitrate contamination (groundwater nitrate - 3- N). Nitrogen isotope (+4 to +12 per mille) coupled with oxygen isotope measurements (+5 to +9 per mille) demonstrated that the nitrogen is not sources from fertilisers but from some combination of septic tank and animal waste. For the case study of sulphate isotope use, sulphur and oxygen isotopic compositions of sulphate in river and lake water from seven major catchments of New Zealand were determined. The isotope analyses have allowed the distinction between natural (geological, geothermal and volcanic) and anthropogenic (fertiliser) sulphur sources. (author)

Evaluation of energy consumption of treating nitrate-contaminated groundwater by bioelectrochemical systems.

Science.gov (United States)

Cecconet, Daniele; Zou, Shiqiang; Capodaglio, Andrea G; He, Zhen

2018-09-15

Nitrate contamination of groundwater is a mounting concern for drinking water production due to its healthy and ecological effects. Bioelectrochemical systems (BES) are a promising method for energy efficient nitrate removal, but its energy consumption has not been well understood. Herein, we conducted a preliminary analysis of energy consumption based on both literature information and multiple assumptions. Four scenarios were created for the purpose of analysis based on two treatment approaches, microbial fuel cells (MFCs) and controlled biocathodic denitrification (CBD), under either in situ or ex situ deployment. The results show a specific energy consumption based on the mass of NO 3 - -N removed (SEC N ) of 0.341 and 1.602 kWh kg NO 3 - -N -1 obtained from in situ and ex situ treatments with MFCs, respectively; the main contributor was the extraction of the anolyte (100%) in the former and pumping the groundwater (74.8%) for the latter. In the case of CBD treatment, the energy consumption by power supply outcompeted all the other energy items (over 85% in all cases), and a total SEC N of 19.028 and 10.003 kWh kg NO 3 - -N -1 were obtained for in situ and ex situ treatments, respectively. The increase in the water table depth (from 10 to 30 m) and the decrease of the nitrate concentration (from 25 to 15 mg NO 3 - -N) would lead to a rise in energy consumption in the ex situ treatment. Although some data might be premature due to the lack of sufficient information in available literature, the results could provide an initial picture of energy consumption by BES-based groundwater treatment and encourage further thinking and analysis of energy consumption (and production). Copyright © 2018 Elsevier B.V. All rights reserved.

[Assessment of shallow groundwater nitrate concentrations in typical terrestrial ecosystems of Chinese Ecosystem Research Network (CERN) during 2004-2009].

Science.gov (United States)

Xu, Zhi-Wei; Zhang, Xin-Yu; Sun, Xiao-Min; Yuan, Guo-Fu; Wang, Sheng-Zhong; Liu, Wen-Hua

2011-10-01

The nitrate-N (NO3(-) -N) concentrations of 38 shallow groundwater wells from 31 of the typical terrestrial ecosystems on Chinese Ecosystem Research Network (CERN) were assessed using the monitoring data from 2004 to 2009. The results showed that the average values of NO3(-) -N concentrations were significantly higher in the agricultural (4.85 mg x L(-1) +/- 0.42 mg x L(-1)), desert (oasis) (3.72 mg x L(-1) +/- 0.42 mg x L(-1)) and urban ecosystems (3.77 mg x L(-1) 0.51 mg x L(-1)) than in the grass (1.59 mg x L(-1) +/- 0.35 mg L(-1)) and forest ecosystems (0.39 mg x L(-1) +/- 0.03 mg x L(-1)). Nitrate was the major form of nitrogen, with between 56% to 88% of nitrogen in the nitrate-N form in the shallow groundwater of desert (oasis), urban and agricultural ecosystems. Nitrate-N concentrations for some agricultural ecosystems (Ansai, Yanting, Yucheng) and desert (oasis) ecosystems (Cele, Linze, Akesu) analysis exceeded the 10 mg x L(-1) World Health Organization drinking water standards between 14.3% and 84.6%. Significant seasonality was found in Ansai, Fengqiu, Yanting agricultural ecosystems and the Beijing urban ecosystem using the relatively high frequency monitoring data, with the higher nitrate concentrations usually found during summer and winter months. The monitoring results indicated that the shallow groundwater of agricultural ecosystems was contaminated by agricultural management practices, i.e. fertilization, while the shallow groundwater of forest ecosystems was under natural condition with no contamination from human activities.

Redox reaction rates in shallow aquifers: Implications for nitrate transport in groundwater and streams

Science.gov (United States)

Tesoriero, Anthony J.

2012-01-01

Groundwater age and water chemistry data along flow paths from recharge areas to streams were used to evaluate the trends and transformations of agricultural chemicals. Results from this analysis indicate that median nitrate recharge concentrations in these agricultural areas have increased markedly over the last 50 years from 4 mg N/L in samples collected prior to 1983 to 7.5 mg N/L in samples collected since 1983. The effect that nitrate accumulation in shallow aquifers will have on drinking water quality and stream ecosystems is dependent on the rate of redox reactions along flow paths and on the age distribution of nitrate discharging to supply wells and streams.

Evidence for Legacy Contamination of Nitrate in Groundwater of North Carolina Using Monitoring and Private Well Data Models

Science.gov (United States)

Messier, K. P.; Kane, E.; Bolich, R.; Serre, M. L.

2014-12-01

Nitrate (NO3-) is a widespread contaminant of groundwater and surface water across the United States that has deleterious effects to human and ecological health. Legacy contamination, or past releases of NO3-, is thought to be impacting current groundwater and surface water of North Carolina. This study develops a model for predicting point-level groundwater NO3- at a state scale for monitoring wells and private wells of North Carolina. A land use regression (LUR) model selection procedure known as constrained forward nonlinear regression and hyperparameter optimization (CFN-RHO) is developed for determining nonlinear model explanatory variables when they are known to be correlated. Bayesian Maximum Entropy (BME) is then used to integrate the LUR model to create a LUR-BME model of spatial/temporal varying groundwater NO3- concentrations. LUR-BME results in a leave-one-out cross-validation r2 of 0.74 and 0.33 for monitoring and private wells, effectively predicting within spatial covariance ranges. The major finding regarding legacy sources NO3- in this study is that the LUR-BME models show the geographical extent of low-level contamination of deeper drinking-water aquifers is beyond that of the shallower monitoring well. Groundwater NO3- in monitoring wells is highly variable with many areas predicted above the current Environmental Protection Agency standard of 10 mg/L. Contrarily, the private well results depict widespread, low-level NO3-concentrations. This evidence supports that in addition to downward transport, there is also a significant outward transport of groundwater NO3- in the drinking water aquifer to areas outside the range of sources. Results indicate that the deeper aquifers are potentially acting as a reservoir that is not only deeper, but also covers a larger geographical area, than the reservoir formed by the shallow aquifers. Results are of interest to agencies that regulate surface water and drinking water sources impacted by the effects of

TREATMENT TESTS FOR EX SITU REMOVAL OF CHROMATE & NITRATE & URANIUM (VI) FROM HANFORD (100-HR-3) GROUNDWATER FINAL REPORT

Energy Technology Data Exchange (ETDEWEB)

BECK MA; DUNCAN JB

1994-01-03

This report describes batch and ion exchange column laboratory scale studies investigating ex situ methods to remove chromate (chromium [VI]), nitrate (NO{sub 3}{sup -}) and uranium (present as uranium [VI]) from contaminated Hanford site groundwaters. The technologies investigated include: chemical precipitation or coprecipitation to remove chromate and uranium; and anion exchange to remove chromate, uranium and nitrate. The technologies investigated were specified in the 100-HR-3 Groundwater Treatability Test Plan. The method suggested for future study is anion exchange.

Surface and groundwater Nitrate distribution in the area of Vicenza

International Nuclear Information System (INIS)

Altissimo, L.; Dal Pra, A.

1999-01-01

Public aqueducts in the Province of Vicenza (Italy) are supplied entirely by various kinds of water sources: the sub river bed strata of the mountain valleys, water-bearing aquifers of the high plan, pressurized water-bearing aquifers of the middle plain, karstic reservoirs of the mountain massifs and local springs. Progressive increase in nitrate concentration has long been detected in the underground water of many parts of the Vicenza region. The nitrates originate from various sources: human waste, industrial dumping (e.g. the tanning industry) and the use of animal and chemical fertilizers. Nitrate distribution was studied in all wells used for extracting underground water including source waters which replenishing underground aquifers. During the study period ('91-'95), water courses in the recharge areas were found to have nitrate concentrations ranging between 2.0 and 42.0 mg/l. These values remained substantially stable in time. Underground aquifers showed stable nitrate concentration between 5.0 mg/l (mountain karstic aquifers; sub-river bed strata of valley bottom) and 44.0 mg/l (water bearing strata of the high plain of Astico and Brenta rivers). The pressurized flooding aquifers of the middle plain have lower concentrations (6.0-21.0 mg/l) but tend to increase by about 0.5 mg/l per year [it

The nitrate contents in the groundwater in the south end of Buenos Aires conurbation

International Nuclear Information System (INIS)

Carol, E.

2004-01-01

The study area is in the south end of Buenos Aires outskirts. The population is of 42000 inhabitants, from which 69% is supplied of water by means of domiciliary wells. The water for human consumption is located in Pampeano and Puelches aquifers, which form a series of semi-free aquifers of the multi-layer type that are hydraulically connected. The aim of this work was to analyze the nitrate content in the groundwater (Pampeano and Puelches aquifers) and to evaluate the pollution type. The percentage of wells that overcome the range 40-50 mg/l of nitrates was 34% for Pampeano aquifer and 36% for Puelches aquifer. Results obtained for the Pampeano aquifer suggest that the pollution would be produced by a pseudo diffuse process associated to septic wells. Meanwhile, in the Puelches aquifer, the same process of pseudo diffuse pollution would be produced but in this case its origin would be caused by the water migration with nitrates from the Pampeano aquifer. Results mentioned in this work make evident the deterioration process of groundwater, where the pollution would be related to the anthropic activity, coming principally from the urban zone [es

LITERATURE SURVEY FOR GROUNDWATER TREATMENT OPTIONS FOR NITRATE IODINE-129 AND URANIUM 200-ZP-1 OPERABLE UNIT HANFORD SITE

Energy Technology Data Exchange (ETDEWEB)

BYRNES ME

2008-06-05

This literature review presents treatment options for nitrate, iodine-129, and uranium, which are present in groundwater at the 200-ZP-I Groundwater Operable Unit (OU) within the 200 West Area of the Hanford Site. The objective of this review is to determine available methods to treat or sequester these contaminants in place (i.e., in situ) or to pump-and-treat the groundwater aboveground (i.e., ex situ). This review has been conducted with emphasis on commercially available or field-tested technologies, but theoretical studies have, in some cases, been considered when no published field data exist. The initial scope of this literature review included only nitrate and iodine-I 29, but it was later expanded to include uranium. The focus of the literature review was weighted toward researching methods for treatment of nitrate and iodine-129 over uranium because of the relatively greater impact of those compounds identified at the 200-ZP-I OU.

LITERATURE SURVEY FOR GROUNDWATER TREATMENT OPTIONS FOR NITRATE, IODINE-129 AND URANIUM 200-ZP-1 OPERABLE UNIT, HANFORD SITE

International Nuclear Information System (INIS)

BYRNES ME

2008-01-01

This literature review presents treatment options for nitrate, iodine-129, and uranium, which are present in groundwater at the 200-ZP-I Groundwater Operable Unit (OU) within the 200 West Area of the Hanford Site. The objective of this review is to determine available methods to treat or sequester these contaminants in place (i.e., in situ) or to pump-and-treat the groundwater aboveground (i.e., ex situ). This review has been conducted with emphasis on commercially available or field-tested technologies, but theoretical studies have, in some cases, been considered when no published field data exist. The initial scope of this literature review included only nitrate and iodine-I 29, but it was later expanded to include uranium. The focus of the literature review was weighted toward researching methods for treatment of nitrate and iodine-129 over uranium because of the relatively greater impact of those compounds identified at the 200-ZP-I OU

Assessment of nitrate pollution of groundwater in South-East of Isfahan region

International Nuclear Information System (INIS)

Gheisari, M. M.; Hoodaji, M.; Najafi, P.; Abdollahi, A.

2007-01-01

Because the increasing population and food in the world, as well as unavailability and limitation of agricultural lands, needs to increase the agricultural yield quality and quantity. One way to have high quality products is applying fertilizers. Nitrogen fertilizer is the most common one used for this purpose. Impractical and weak management in controlling the improper use of fertilizer causes high concentration of Nitrate in soil and groundwater resources. High concentration of Nitrate in water causes many health problems. This research is conducted to determine the rate of Nitrate polluted water in South-East of Isfahan. In this research, sampling was done from selected water wells and the amount of Nitrate in water was determined by using special Electrodes and Ion -Selective method. Surfer Software identified the variation process. Then, the results were compared with US-Environmental Protected Agency (US-EPA). In some areas, the results show the concentration of Nitrate more than US-EPA standards, especially in South-East of the region. The highest Nitrate concentrations in the first and second sampling in the polluted area were 189.1 and 248.3 mg per liters, respectively. In the first sampling 80.0% and in the second sampling 90.0% of wells were identified to have high concentration of Nitrate. The Nitrate pollution averages in the first and second sampling were 76.9 ppm and 93.1 ppm, respectively. Therefore, in order to apply this kind of fertilizer, proper management, scientific and practical control must be employed so that increasing concentration of Nitrate can be controlled

Use of environmental isotopes for studying human induced change in groundwater environment in Lahore, Pakistan

International Nuclear Information System (INIS)

Ahmad, M.; Akram, W.; Sajjad, M.I.; Rafiq, M.; Tasneem, Azam M.

2002-01-01

Lahore is the second biggest city of Pakistan where groundwater is the only source of drinking water supply for the city. On the other hand, the quality of groundwater is being degraded due to various human activities especially due to waste disposal practices. Untreated domestic and industrial wastes are discharged into open channels, drains, etc. which leads to surface water and groundwater pollution. This study was undertaken to assess the changes in groundwater environment due to such activities. Water samples were collected on periodical basis from existing handpumps, tube wells and drains and analyzed for isotopic ( 2 H, 3 H, 13 C, 18 O) and major dissolved ions. Samples having high nitrate were analyzed for 15 N. Selected samples were also analyzed for Coliform bacteria. Results of only selected parameters are discussed here. The data showed that quality of shallow groundwater has deteriorated at most of the locations and concentrations of several chemical parameters are higher than WHO permissible levels for drinking water. Comparison with a previous study carried out in 1991, indicated a clear increasing trend of total dissolved salts in groundwater. An outstanding feature of the data is the increasing trend of nitrate concentrations both in shallow and deep groundwater. Results of nitrate analysis indicate that concentrations vary from 10 to 188 mg/l in shallow groundwater and 9 to 41 mg/l in deep groundwater. Frequency histogram of nitrate concentrations is shown. Nitrates which were generally a few ppm have increased at almost all the surveyed locations and have even crossed the WHO limit of 45 mg/l at several shallow locations. High nitrate waters exist as isolated pockets. Results of tritium analysis indicated that shallow groundwater has generally high tritium values. Presence of more nitrate at shallow depths, occurrence of high nitrate waters as isolated pockets and high tritium in contaminated waters suggest that nitrates are derived from as

Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA

Science.gov (United States)

Nolan, Bernard T.; Green, Christopher T.; Juckem, Paul F.; Liao, Lixia; Reddy, James E.

2018-04-01

Nitrate contamination of groundwater in agricultural areas poses a major challenge to the sustainability of water resources. Aquifer vulnerability models are useful tools that can help resource managers identify areas of concern, but quantifying nitrogen (N) inputs in such models is challenging, especially at large spatial scales. We sought to improve regional nitrate (NO3-) input functions by characterizing unsaturated zone NO3- transport to groundwater through use of surrogate, machine-learning metamodels of a process-based N flux model. The metamodels used boosted regression trees (BRTs) to relate mappable landscape variables to parameters and outputs of a previous "vertical flux method" (VFM) applied at sampled wells in the Fox, Wolf, and Peshtigo (FWP) river basins in northeastern Wisconsin. In this context, the metamodels upscaled the VFM results throughout the region, and the VFM parameters and outputs are the metamodel response variables. The study area encompassed the domain of a detailed numerical model that provided additional predictor variables, including groundwater recharge, to the metamodels. We used a statistical learning framework to test a range of model complexities to identify suitable hyperparameters of the six BRT metamodels corresponding to each response variable of interest: NO3- source concentration factor (which determines the local NO3- input concentration); unsaturated zone travel time; NO3- concentration at the water table in 1980, 2000, and 2020 (three separate metamodels); and NO3- "extinction depth", the eventual steady state depth of the NO3- front. The final metamodels were trained to 129 wells within the active numerical flow model area, and considered 58 mappable predictor variables compiled in a geographic information system (GIS). These metamodels had training and cross-validation testing R2 values of 0.52 - 0.86 and 0.22 - 0.38, respectively, and predictions were compiled as maps of the above response variables. Testing

Nitrogen-isotope ratios of nitrate in ground water under fertilized fields, Long Island, New York

Science.gov (United States)

Flipse, W.J.; Bonner, F.T.

1985-01-01

Ground-water samples from two heavily fertilized sites in Suffolk County, New York, were collected through the 1978 growing season and analyzed for nitrate-N concentrations and nitrogen-isotope ratios. Six wells were at a potato farm; six were on a golf course. The purpose of this study was to determine whether the 15N/14N ratios (??15N values) of fertilizer are increased during transit from land surface to ground water to an extent which would preclude use of this ratio to distinguish agricultural from animal sources of nitrate in ground water. Ground water at both sites contained a greater proportion of 15N than the fertilizers being applied. At the potato farm, the average ??15N value of the fertilizers was 0.2???; the average ??15N value of the ground-water nitrate was 6.2???. At the golf course, the average ??15N value of the fertilizers was -5.9???, and that of ground-water nitrate was 6.5???. The higher ??15N values of ground-water nitrate are probably caused by isotopic fractionation during the volatile loss of ammonia from nitrogen applied in reduced forms (NH4+ and organic-N). The ??15N values of most ground-water samples from both areas were less than 10???, the upper limit of the range characteristic of agricultural sources of nitrate; these sources include both fertilizer nitrate and nitrate derived from increased mineralization of soil nitrogen through cultivation. Previous studies have shown that the ??15N values of nitrate derived from human or animal waste generally exceed 10???. The nitrogen-isotope ratios of fertilizer-derived nitrate were not altered to an extent that would make them indistinguishable from animal-waste-derived nitrates in ground water.Ground-water samples from two heavily fertilized sites in Suffolk County, New York, were collected through the 1978 growing season and analyzed for nitrate-N concentrations and nitrogen-isotope ratios. Six wells were at a potato farm; six were on a golf course. The purpose of this study was to

Using rates of oxygen and nitrate reduction to map the subsurface distribution of groundwater denitrification

Science.gov (United States)

Kolbe, T.; De Dreuzy, J. R.; Abbott, B. W.; Aquilina, L.; Babey, T.; Green, C. T.; Fleckenstein, J. H.; Labasque, T.; Laverman, A.; Marçais, J.; Peiffer, S.; Thomas, Z.; Pinay, G.

2017-12-01

Widespread fertilizer application over the last 70 years has caused serious ecological and socioeconomic problems in aquatic and estuarine ecosystems. When surplus nitrogen leaches as nitrate (a major groundwater pollutant) to the aquifer, complex flow dynamics and naturally occurring degradation processes control its transport. Under the conditions of depleted oxygen and abundant electron donors, microorganisms reduce NO3- to N2 (denitrification). Denitrification rates vary over orders of magnitude among sites within the same aquifer, complicating estimation of denitrification capacity at the catchment scale. Because it is impractical or impossible to access the subsurface to directly quantify denitrification rates, reactivity is often assumed to occur continuous along flowlines, potentially resulting in substantial over- or underestimation of denitrification. Here we investigated denitrification in an unconfined crystalline aquifer in western France using a combination of common tracers (chlorofluorocarbons, O2, NO3-, and N2) measured in 16 wells to inform a time-based modeling approach. We found that spatially variable denitrification rates arise from the intersection of nitrate rich water with reactive zones defined by the abundance of electron donors (primarily pyrite). Furthermore, based on observed reaction rates of the sequential reduction of oxygen and nitrate, we present a general framework to estimate the location and intensity of the reactive zone in aquifers. Accounting for the vertical distribution of reaction rates results in large differences in estimations of net denitrification rates that assume homogeneous reactivity. This new framework provides a tractable approach for quantifying catchment and regional groundwater denitrification rates that could be used to improve estimation of groundwater resilience to nitrate pollution and develop more realistic management strategies.

Real-time continuous nitrate monitoring in Illinois in 2013

Science.gov (United States)

Warner, Kelly L.; Terrio, Paul J.; Straub, Timothy D.; Roseboom, Donald; Johnson, Gary P.

2013-01-01

Many sources contribute to the nitrogen found in surface water in Illinois. Illinois is located in the most productive agricultural area in the country, and nitrogen fertilizer is commonly used to maximize corn production in this area. Additionally, septic/wastewater systems, industrial emissions, and lawn fertilizer are common sources of nitrogen in urban areas of Illinois. In agricultural areas, the use of fertilizer has increased grain production to meet the needs of a growing population, but also has resulted in increases in nitrogen concentrations in many streams and aquifers (Dubrovsky and others, 2010). The urban sources can increase nitrogen concentrations, too. The Federal limit for nitrate nitrogen in water that is safe to drink is 10 milligrams per liter (mg/L) (http://water.epa.gov/drink/contaminants/basicinformation/nitrate.cfm, accessed on May 24, 2013). In addition to the concern with nitrate nitrogen in drinking water, nitrogen, along with phosphorus, is an aquatic concern because it feeds the intensive growth of algae that are responsible for the hypoxic zone in the Gulf of Mexico. The largest nitrogen flux to the waters feeding the Gulf of Mexico is from Illinois (Alexander and others, 2008). Most studies of nitrogen in surface water and groundwater include samples for nitrate nitrogen collected weekly or monthly, but nitrate concentrations can change rapidly and these discrete samples may not capture rapid changes in nitrate concentrations that can affect human and aquatic health. Continuous monitoring for nitrate could inform scientists and water-resource managers of these changes and provide information on the transport of nitrate in surface water and groundwater.

Multi-scale nitrate transport in a sandstone aquifer system under intensive agriculture

Science.gov (United States)

Paradis, Daniel; Ballard, Jean-Marc; Lefebvre, René; Savard, Martine M.

2018-03-01

Nitrate transport in heterogeneous bedrock aquifers is influenced by mechanisms that operate at different spatial and temporal scales. To understand these mechanisms in a fractured sandstone aquifer with high porosity, a groundwater-flow and nitrate transport model—reproducing multiple hydraulic and chemical targets—was developed to explain the actual nitrate contamination observed in groundwater and surface water in a study area on Prince Edward Island, Canada. Simulations show that nitrate is leached to the aquifer year-round, with 61% coming from untransformed and transformed organic sources originating from fertilizers and manure. This nitrate reaches the more permeable shallow aquifer through fractures in weathered sandstone that represent only 1% of the total porosity (17%). Some of the nitrate reaches the underlying aquifer, which is less active in terms of groundwater flow, but most of it is drained to the main river. The river-water quality is controlled by the nitrate input from the shallow aquifer. Groundwater in the underlying aquifer, which has long residence times, is also largely influenced by the diffusion of nitrate in the porous sandstone matrix. Consequently, following a change of fertilizer application practices, water quality in domestic wells and the river would change rapidly due to the level of nitrate found in fractures, but a lag time of up to 20 years would be necessary to reach a steady level due to diffusion. This demonstrates the importance of understanding nitrate transport mechanisms when designing effective agricultural and water management plans to improve water quality.

Influence of organic carbon sources and isotope exchange processes between water and nitrate on the fractionation of the stable isotopes {sup 15}N/{sup 14}N and {sup 18}O/{sup 16}O in dissolved nitrate during microbial dentrification in groundwater

Energy Technology Data Exchange (ETDEWEB)

Wunderlich, Anja A.L.

2012-11-02

Stable isotopes of nitrate are commonly used to determine sources and degradation of nitrate. In this study, nitrite oxidizing bacteria were found to promote an oxygen isotope exchange between water and nitrate under anoxic conditions. Also, different carbon sources were found to influence the enrichment of stable isotopes in nitrate during microbial denitrification. Both results refine the stable isotope model of nitrate in respect to nitrate source determination and microbial nitrate reduction.

Resolving superimposed ground-water contaminant plumes characterized by chromium, nitrate, uranium, and technetium--99

International Nuclear Information System (INIS)

Hall, S.H.

1990-02-01

Leakage from a liquid waste storage and solar evaporation basin at the Hanford Site in southeastern Washington State has resulted in a ground-water contaminant plume characterized by nitrate, hexavalent chromium, uranium, and technetium-99. The plume is superimposed on a larger, pre-existing plume extending from upgradient sites and having the same suite of contaminants. However, the relative abundance of contaminant species is quite different for each plume source. Thus, characteristic concentration ratios, rather than concentrations of individual species, are used as geochemical tracers, with emphasis on graphical analysis. Accordingly, it has been possible to resolve the boundaries of the smaller plume and to estimate the contribution of each plume to the observed contamination downgradient from the storage basin. 11 refs., 7 figs

Nitrate leaching affected by management options with respect to urine-affected areas and groundwater levels for grazed grassland

NARCIS (Netherlands)

Hack-ten Broeke, M.J.D.; Putten, van der A.H.J.

1997-01-01

Simulations were performed to quantify the effects of management options on nitrate leaching to the groundwater in grazed pastures. At the experimental farm for sustainable dairy farming ‘De Marke’, experimental data on soil water and nitrates were gathered for two fields during the years 1991–1995.

NITRATES IN INDIVIDUAL GROUNDWATER RESOURCES IN NITRA AND THEIR POSSIBLE RISKS TO THE POPULATION

Directory of Open Access Journals (Sweden)

Peter Lazor

2015-02-01

Full Text Available The content of nitrates (NO3- were assessed in the period 2012 - 2013 in samples taken from individual groundwater sources (Svorad´s spring, Puškin´s spring, spring on Pivoňková street, spring on Mriánska dolina, spring Šindolka and spring Buganka in the administrative area of Nitra and Zobor , also used for human consumption. The content of NO3- were assessed by Photocolorimetric method. We also evaluate the results achieved in relation to the current legislation of the area. From the result of the performed analyzes during the whole period shows that the average concentration of NO3- represented in samples of water from the source Svorad´s spring 12,1 mg.dm-3, Puškin´s spring 14,6 mg.dm-3, from spring St. Martina 117,0 mg.dm-3, from spring on Pivoňkova street 6,4 mg.dm-3, from spring Šindolka 39,5 mg.dm-3 and spring Buganka 101,7 mg.dm-3. The nitrate concentration exceeded the limit value in 16 % of cases in 2012 and it was 17 % of cases in 2013. Based on the measured values, therefore we do not recommend to use the water for human consumption from springs Buganka and St. Martina at the endpoint.

Sources and behaviour of nitrogen compounds in the shallow groundwater of agricultural areas (Poyang Lake basin, China).

Science.gov (United States)

Soldatova, Evgeniya; Guseva, Natalia; Sun, Zhanxue; Bychinsky, Valeriy; Boeckx, Pascal; Gao, Bai

2017-07-01

Nitrogen contamination of natural water is a typical problem for various territories throughout the world. One of the regions exposed to nitrogen pollution is located in the Poyang Lake basin. As a result of agricultural activity and dense population, the shallow groundwater of this area is characterised by a high concentration of nitrogen compounds, primarily NO 3 - , with the concentration varying from 0.1mg/L to 206mg/L. Locally, high ammonium content occurs in the shallow groundwater with low reduction potential Eh (shallow groundwater of the Poyang Lake basin has Eh>100mV. To identify sources of nitrogen species and the factors that determine their behaviour, the dual stable isotope approach (δ 15 N and δ 18 О) and physical-chemical modelling were applied. Actual data were collected by sampling shallow groundwater from domestic water supply wells around the lake. The δ 18 О values from -4.1‰ to 13.9‰ with an average value of 5.3 permille indicate a significant influence of nitrification on nitrogen balance. The enrichment of nitrate with the 15 N isotope indicates that manure and domestic sewage are the principal sources of nitrogen compounds. Inorganic nitrogen speciation and thermodynamic calculations demonstrate the high stability of nitrate in the studied groundwater. Computer simulation and field observations indicate the reducing conditions formed under joint effects of anthropogenic factors and appropriate natural conditions, such as the low-level topography in which decreased water exchange rate can occur. The simulation also demonstrates the growth in pH of the groundwater as a consequence of fertilisation, which, in turn, conduced to the clay mineral formation at lower concentrations of aqueous clay-forming components than the ones under the natural conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Sources and behaviour of nitrogen compounds in the shallow groundwater of agricultural areas (Poyang Lake basin, China)

Science.gov (United States)

Soldatova, Evgeniya; Guseva, Natalia; Sun, Zhanxue; Bychinsky, Valeriy; Boeckx, Pascal; Gao, Bai

2017-07-01

Nitrogen contamination of natural water is a typical problem for various territories throughout the world. One of the regions exposed to nitrogen pollution is located in the Poyang Lake basin. As a result of agricultural activity and dense population, the shallow groundwater of this area is characterised by a high concentration of nitrogen compounds, primarily NO3-, with the concentration varying from 0.1 mg/L to 206 mg/L. Locally, high ammonium content occurs in the shallow groundwater with low reduction potential Eh ( 100 mV. To identify sources of nitrogen species and the factors that determine their behaviour, the dual stable isotope approach (δ15N and δ18О) and physical-chemical modelling were applied. Actual data were collected by sampling shallow groundwater from domestic water supply wells around the lake. The δ18О values from - 4.1‰ to 13.9‰ with an average value of 5.3 permille indicate a significant influence of nitrification on nitrogen balance. The enrichment of nitrate with the 15N isotope indicates that manure and domestic sewage are the principal sources of nitrogen compounds. Inorganic nitrogen speciation and thermodynamic calculations demonstrate the high stability of nitrate in the studied groundwater. Computer simulation and field observations indicate the reducing conditions formed under joint effects of anthropogenic factors and appropriate natural conditions, such as the low-level topography in which decreased water exchange rate can occur. The simulation also demonstrates the growth in pH of the groundwater as a consequence of fertilisation, which, in turn, conduced to the clay mineral formation at lower concentrations of aqueous clay-forming components than the ones under the natural conditions.

Spatial and temporal changes in the structure of groundwater nitrate concentration time series (1935 1999) as demonstrated by autoregressive modelling

Science.gov (United States)

Jones, A. L.; Smart, P. L.

2005-08-01

Autoregressive modelling is used to investigate the internal structure of long-term (1935-1999) records of nitrate concentration for five karst springs in the Mendip Hills. There is a significant short term (1-2 months) positive autocorrelation at three of the five springs due to the availability of sufficient nitrate within the soil store to maintain concentrations in winter recharge for several months. The absence of short term (1-2 months) positive autocorrelation in the other two springs is due to the marked contrast in land use between the limestone and swallet parts of the catchment, rapid concentrated recharge from the latter causing short term switching in the dominant water source at the spring and thus fluctuating nitrate concentrations. Significant negative autocorrelation is evident at lags varying from 4 to 7 months through to 14-22 months for individual springs, with positive autocorrelation at 19-20 months at one site. This variable timing is explained by moderation of the exhaustion effect in the soil by groundwater storage, which gives longer residence times in large catchments and those with a dominance of diffuse flow. The lags derived from autoregressive modelling may therefore provide an indication of average groundwater residence times. Significant differences in the structure of the autocorrelation function for successive 10-year periods are evident at Cheddar Spring, and are explained by the effect the ploughing up of grasslands during the Second World War and increased fertiliser usage on available nitrogen in the soil store. This effect is moderated by the influence of summer temperatures on rates of mineralization, and of both summer and winter rainfall on the timing and magnitude of nitrate leaching. The pattern of nitrate leaching also appears to have been perturbed by the 1976 drought.

Effects of nitrate on the treatment of lead contaminated groundwater by nanoscale zerovalent iron.

Science.gov (United States)

Su, Yiming; Adeleye, Adeyemi S; Zhou, Xuefei; Dai, Chaomeng; Zhang, Weixian; Keller, Arturo A; Zhang, Yalei

2014-09-15

Nanoscale zerovalent iron (nZVI) is efficient for removing Pb(2+) and nitrate from water. However, the influence of nitrate, a common groundwater anion, on Pb(2+) removal by nZVI is not well understood. In this study, we showed that under excess Fe(0) conditions (molar ratio of Fe(0)/nitrate>4), Pb(2+) ions were immobilized more quickly (nitrate-free systems (∼ 15 min) due to increasing pH. With nitrate in excess (molar ratio of Fe(0)/nitratenitrate stimulated the formation of crystal PbxFe3-xO4 (ferrite), which provided additional Pb(2+) removal. However, ∼ 7% of immobilized Pb(2+) ions were released into aqueous phase within 2h due to ferrite deformation. Oxidation-reduction potential (ORP) values below -600 mV correlated with excess Fe(0) conditions (complete Pb(2+) immobilization), while ORP values ≥-475 mV characterized excess nitrate conditions (ferrite process and Pb(2+) release occurrence). This study indicates that ORP monitoring is important for proper management of nZVI-based remediation in the subsurface to avoid lead remobilization in the presence of nitrate. Copyright © 2014 Elsevier B.V. All rights reserved.

The nitrate time bomb : a numerical way to investigate nitrate storage and lag time in the unsaturated zone

OpenAIRE

Wang, L.; Butcher, A.S.; Stuart, M.E.; Gooddy, D.C.; Bloomfield, J.P.

2013-01-01

Nitrate pollution in groundwater, which is mainly from agricultural activities, remains an international problem. It threatens the environment, economics and human health. There is a rising trend in nitrate concentrations in many UK groundwater bodies. Research has shown it can take decades for leached nitrate from the soil to discharge into groundwater and surface water due to the ‘store’ of nitrate and its potentially long travel time in the unsaturated and satura...

Dissolved nitrates in the groundwater of the Cecina Plain (Tuscany, Central-Western Italy): Clues from the isotopic signature of NO3-

International Nuclear Information System (INIS)

Nisi, B.; Vaselli, O.; Delgado Huertas, A.; Tassi, F.

2013-01-01

Highlights: ► Nitrate pollution in the Cecina Plain (Tuscany, Italy) multi-aquifer system. ► Anthropogenic pollution by fertilizers, manure and sewage. ► δ 15 N–NO 3 and δ 18 O–NO 3 to recognize NO 3 sources and processes. ► Monitoring of δ 15 N–NO 3 and δ 18 O–NO 3 for remediation programs. - Abstract: Anthropogenic NO 3 - is one of the most serious pollutants in the groundwaters from the multi-aquifer system of the Cecina Plain (Tuscany, central-western Italy). According to the EC Directive (91/676/CEE), the local administration of Tuscany has declared the Cecina Plain as “vulnerable by nitrates”. Determining the origin and the source(s) of NO 3 - contamination is an important step prior to any remediation program. In the present work a geochemical survey was carried out on 92 groundwater samples collected in June and October 2006 to highlight the natural and anthropogenic features that concur with the observed chemical composition. The geochemical facies of the water samples is dominated by Ca(Mg)–HCO 3 and Ca(Mg)–SO 4 (Cl) and, subordinately, by Na(Ca)–Cl(SO 4 ), likely resulting by water–rock interaction processes between meteoric-derived groundwaters with the sedimentary formations characterizing the Cecina Plain, at which ingression of seawater in the coastal area is also added. A mixing model, based on ionic ratios (NO 3 /Na, Cl/Na, Cl/Br), was applied to distinguish the anthropogenic sources (e.g. sewage, agriculture input) from natural sources (e.g. seawater intrusion). Selected samples were analyzed for the isotopic composition of NO 3 - (δ 15 N–NO 3 and δ 18 O–NO 3 ) to formulate hypotheses on its origin and the processes this component may suffer in the water system. Nitrate concentrations range from ∼0.01 to 354 mg/L. About 35% and 19% of the sampled wells in June and October 2006, respectively, had levels of NO 3 - higher that those recommended by the World Health Organization (<50 mg/L). The δ 18 O–e δ 15

Vinegar-amended anaerobic biosand filter for the removal of arsenic and nitrate from groundwater.

Science.gov (United States)

Snyder, Kathryn V; Webster, Tara M; Upadhyaya, Giridhar; Hayes, Kim F; Raskin, Lutgarde

2016-04-15

The performance of a vinegar-amended anaerobic biosand filter was evaluated for future application as point-of-use water treatment in rural areas for the removal of arsenic and nitrate from groundwater containing common ions. Due to the importance of sulfate and iron in arsenic removal and their variable concentrations in groundwater, influent sulfate and iron concentrations were varied. Complete removal of influent nitrate (50 mg/L) and over 50% removal of influent arsenic (200 μg/L) occurred. Of all conditions tested, the lowest median effluent arsenic concentration was 88 μg/L. Iron removal occurred completely when 4 mg/L was added, and sulfate concentrations were lowered to a median concentration arsenic concentrations remained above the World Health Organization's arsenic drinking water standard. Further research is necessary to determine if anaerobic biosand filters can be improved to meet the arsenic drinking water standard and to evaluate practical implementation challenges. Copyright © 2016. Published by Elsevier Ltd.

Groundwater vulnerability to pollution mapping of Ranchi district using GIS

Science.gov (United States)

Krishna, R.; Iqbal, J.; Gorai, A. K.; Pathak, G.; Tuluri, F.; Tchounwou, P. B.

2015-12-01

Groundwater pollution due to anthropogenic activities is one of the major environmental problems in urban and industrial areas. The present study demonstrates the integrated approach with GIS and DRASTIC model to derive a groundwater vulnerability to pollution map. The model considers the seven hydrogeological factors [Depth to water table ( D), net recharge ( R), aquifer media ( A), soil media ( S), topography or slope ( T), impact of vadose zone ( I) and hydraulic Conductivity( C)] for generating the groundwater vulnerability to pollution map. The model was applied for assessing the groundwater vulnerability to pollution in Ranchi district, Jharkhand, India. The model was validated by comparing the model output (vulnerability indices) with the observed nitrate concentrations in groundwater in the study area. The reason behind the selection of nitrate is that the major sources of nitrate in groundwater are anthropogenic in nature. Groundwater samples were collected from 30 wells/tube wells distributed in the study area. The samples were analyzed in the laboratory for measuring the nitrate concentrations in groundwater. A sensitivity analysis of the integrated model was performed to evaluate the influence of single parameters on groundwater vulnerability index. New weights were computed for each input parameters to understand the influence of individual hydrogeological factors in vulnerability indices in the study area. Aquifer vulnerability maps generated in this study can be used for environmental planning and groundwater management.

Groundwater vulnerability to pollution mapping of Ranchi district using GIS.

Science.gov (United States)

Krishna, R; Iqbal, J; Gorai, A K; Pathak, G; Tuluri, F; Tchounwou, P B

2015-12-01

Groundwater pollution due to anthropogenic activities is one of the major environmental problems in urban and industrial areas. The present study demonstrates the integrated approach with GIS and DRASTIC model to derive a groundwater vulnerability to pollution map. The model considers the seven hydrogeological factors [Depth to water table ( D ), net recharge ( R ), aquifer media ( A ), soil media ( S ), topography or slope ( T ), impact of vadose zone ( I ) and hydraulic Conductivity( C )] for generating the groundwater vulnerability to pollution map. The model was applied for assessing the groundwater vulnerability to pollution in Ranchi district, Jharkhand, India. The model was validated by comparing the model output (vulnerability indices) with the observed nitrate concentrations in groundwater in the study area. The reason behind the selection of nitrate is that the major sources of nitrate in groundwater are anthropogenic in nature. Groundwater samples were collected from 30 wells/tube wells distributed in the study area. The samples were analyzed in the laboratory for measuring the nitrate concentrations in groundwater. A sensitivity analysis of the integrated model was performed to evaluate the influence of single parameters on groundwater vulnerability index. New weights were computed for each input parameters to understand the influence of individual hydrogeological factors in vulnerability indices in the study area. Aquifer vulnerability maps generated in this study can be used for environmental planning and groundwater management.

The discharge of nitrate-contaminated groundwater from developed shoreline to marsh-fringed estuary

Science.gov (United States)

Portnoy, J.W.; Nowicki, B.L.; Roman, C.T.; Urish, D.W.

1998-01-01

As residential development, on-site wastewater disposal, and groundwater contamination increase in the coastal zone, assessment of nutrient removal by soil and sedimentary processes becomes increasingly important. Nitrogen removal efficiency depends largely on the specific flow paths taken by groundwater as it discharges into nitrogen-limited estuarine waters. Shoreline salinity surveys, hydraulic studies, and thermal infrared imagery indicated that groundwater discharge into the Nauset Marsh estuary (Eastham, Massachusetts) occurred in high-velocity seeps immediately seaward of the upland-fringing salt marsh. Discharge was highly variable spatially and occurred through permeable, sandy sediments during low tide. Seepage chamber monitoring showed that dissolved inorganic nitrogen (principally nitrate) traversed nearly conservatively from the aquifer through shallow estuarine sediments to coastal waters at flux rates of 1–3 mmol m−2 h−1. A significant relationship between pore water NO3-N concentrations and NO3-N flux rates may provide a rapid method of estimating nitrogen loading from groundwater to the water column.

A comparative study of two approaches to analyse groundwater recharge, travel times and nitrate storage distribution at a regional scale

Science.gov (United States)

Turkeltaub, T.; Ascott, M.; Gooddy, D.; Jia, X.; Shao, M.; Binley, A. M.

2017-12-01

Understanding deep percolation, travel time processes and nitrate storage in the unsaturated zone at a regional scale is crucial for sustainable management of many groundwater systems. Recently, global hydrological models have been developed to quantify the water balance at such scales and beyond. However, the coarse spatial resolution of the global hydrological models can be a limiting factor when analysing regional processes. This study compares simulations of water flow and nitrate storage based on regional and global scale approaches. The first approach was applied over the Loess Plateau of China (LPC) to investigate the water fluxes and nitrate storage and travel time to the LPC groundwater system. Using raster maps of climate variables, land use data and soil parameters enabled us to determine fluxes by employing Richards' equation and the advection - dispersion equation. These calculations were conducted for each cell on the raster map in a multiple 1-D column approach. In the second approach, vadose zone travel times and nitrate storage were estimated by coupling groundwater recharge (PCR-GLOBWB) and nitrate leaching (IMAGE) models with estimates of water table depth and unsaturated zone porosity. The simulation results of the two methods indicate similar spatial groundwater recharge, nitrate storage and travel time distribution. Intensive recharge rates are located mainly at the south central and south west parts of the aquifer's outcrops. Particularly low recharge rates were simulated in the top central area of the outcrops. However, there are significant discrepancies between the simulated absolute recharge values, which might be related to the coarse scale that is used in the PCR-GLOBWB model, leading to smoothing of the recharge estimations. Both models indicated large nitrate inventories in the south central and south west parts of the aquifer's outcrops and the shortest travel times in the vadose zone are in the south central and east parts of the

Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA

Science.gov (United States)

Nolan, Bernard T.; Green, Christopher T.; Juckem, Paul F.; Liao, Lixia; Reddy, James E.

2018-01-01

Nitrate contamination of groundwater in agricultural areas poses a major challenge to the sustainability of water resources. Aquifer vulnerability models are useful tools that can help resource managers identify areas of concern, but quantifying nitrogen (N) inputs in such models is challenging, especially at large spatial scales. We sought to improve regional nitrate (NO3−) input functions by characterizing unsaturated zone NO3− transport to groundwater through use of surrogate, machine-learning metamodels of a process-based N flux model. The metamodels used boosted regression trees (BRTs) to relate mappable landscape variables to parameters and outputs of a previous “vertical flux method” (VFM) applied at sampled wells in the Fox, Wolf, and Peshtigo (FWP) river basins in northeastern Wisconsin. In this context, the metamodels upscaled the VFM results throughout the region, and the VFM parameters and outputs are the metamodel response variables. The study area encompassed the domain of a detailed numerical model that provided additional predictor variables, including groundwater recharge, to the metamodels. We used a statistical learning framework to test a range of model complexities to identify suitable hyperparameters of the six BRT metamodels corresponding to each response variable of interest: NO3− source concentration factor (which determines the local NO3− input concentration); unsaturated zone travel time; NO3− concentration at the water table in 1980, 2000, and 2020 (three separate metamodels); and NO3− “extinction depth”, the eventual steady state depth of the NO3−front. The final metamodels were trained to 129 wells within the active numerical flow model area, and considered 58 mappable predictor variables compiled in a geographic information system (GIS). These metamodels had training and cross-validation testing R2 values of 0.52 – 0.86 and 0.22 – 0.38, respectively, and predictions were compiled as maps of the above

Denitrification and dilution along fracture flowpaths influence the recovery of a bedrock aquifer from nitrate contamination

Energy Technology Data Exchange (ETDEWEB)

Kim, Jonathan J., E-mail: jon.kim@vermont.gov [Vermont Geological Survey, 1 National Life Drive, Main 2, Montpelier, VT 05620 (United States); Comstock, Jeff [Vermont Agency of Agriculture, 116 State Street, Montpelier, VT 05620 (United States); Ryan, Peter [Dept. of Geology, Middlebury College, Middlebury, VT 05753 (United States); Heindel, Craig [Waite-Heindel Environmental Management, 7 Kilburn Street, Suite 301, Burlington, VT 05401 (United States); Koenigsberger, Stephan [Dept. of Geology, Middlebury College, Middlebury, VT 05753 (United States)

2016-11-01

In 2000, elevated nitrate concentrations ranging from 12 to 34 mg/L NO{sub 3}−N were discovered in groundwater from numerous domestic bedrock wells adjacent to a large dairy farm in central Vermont. Long-term plots and contours of nitrate vs. time for bedrock wells showed “little/no”, “moderate”, and “large” change patterns that were spatially separable. The metasedimentary bedrock aquifer is strongly anisotropic and groundwater flow is controlled by fractures, bedding/foliation, and basins and ridges in the bedrock surface. Integration of the nitrate concentration vs. time data and the physical and chemical aquifer characterization suggest two nitrate sources: a point source emanating from a waste ravine and a non-point source that encompasses the surrounding fields. Once removed, the point source of NO{sub 3} (manure deposited in a ravine) was exhausted and NO{sub 3} dropped from 34 mg/L to < 10 mg/L after ~ 10 years; however, persistence of NO{sub 3} in the 3 to 8 mg/L range (background) reflects the long term flux of nitrates from nutrients applied to the farm fields surrounding the ravine over the years predating and including this study. Inferred groundwater flow rates from the waste ravine to either moderate change wells in basin 2 or to the shallow bedrock zone beneath the large change wells are 0.05 m/day, well within published bedrock aquifer flow rates. Enrichment of {sup 15}N and {sup 18}O in nitrate is consistent with lithotrophic denitrification of NO{sub 3} in the presence of dissolved Mn and Fe. Once the ravine point-source was removed, denitrification and dilution collectively were responsible for the down-gradient decrease of nitrate in this bedrock aquifer. Denitrification was most influential when NO{sub 3}−N was > 10 mg/L. Our multidisciplinary methods of aquifer characterization are applicable to groundwater contamination in any complexly-deformed and metamorphosed bedrock aquifer. - Highlights: • Bedrock wells contaminated

Nitrogen-isotope ratio studies of soils and groundwater nitrate from alluvial fan aquifers in Texas

International Nuclear Information System (INIS)

Kreitler, C.W.

1979-01-01

Kreitler has previously identified two ranges of nitrogen-isotope values (delta 15 N) for soil nitrate under different land uses in west Texas: nitrate originating from nonfertilized, cultivated fields (delta 14 N range, 2 to +8per thousand with an average of +4.9per thousand), and nitrate from animal wastes (delta 15 N range, +10 to +22per thousand with an average of +14.4per thousand). The delta 15 N of groundwater nitrate from irrigation wells on the Lockhart and Taylor and alluvial fans range from +3.3 to +10.8per thousand with an average of +7.3per thousand. Ground water from domestic wells on the two fans has higher nitrate concentrations and a more positive delta 15 N range (+6.7 to 18.2per thousand with an average of +11.1per thousand) than wells located in the cultivated fields. Nitrate contamination of wells located in cultivated fields results primarily from cultivation with ammonium-type fertilizers, whereas animal wastes are contaminating domestic well waters. (Auth.)

Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yingxin [School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 3058572 (Japan); Feng, Chuanping, E-mail: fengchuangping@gmail.com [School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Wang, Qinghong; Yang, Yingnan; Zhang, Zhenya; Sugiura, Norio [Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 3058572 (Japan)

2011-09-15

Highlights: {yields} Intensified biofilm-electrode reactor using cooperative denitrification is developed. {yields} IBER combines heterotrophic and autotrophic denitrification. {yields} CO{sub 2} formed by heterotrophic denitrification is used by autotrophic bacteria. {yields} Optimum running conditions are C/N = 0.75, HRT = 8 h, and I = 40 mA. {yields} A novel degradation mechanism for cooperating denitrification process is proposed. - Abstract: An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO{sub 3}{sup -}N50 mg L{sup -1}) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8 h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO{sub 3}{sup -}N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO{sub 2} produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate.

Groundwater nitrate pollution and climate change: learnings from a water balance-based analysis of several aquifers in a western Mediterranean region (Catalonia).

Science.gov (United States)

Mas-Pla, Josep; Menció, Anna

2018-04-11

Climate change will affect the dynamics of the hydrogeological systems and their water resources quality; in particular nitrate, which is herein taken as a paradigmatic pollutant to illustrate the effects of climate change on groundwater quality. Based on climatic predictions of temperature and precipitation for the horizon of 2021 and 2050, as well as on land use distribution, water balances are recalculated for the hydrological basins of distinct aquifer systems in a western Mediterranean region as Catalonia (NE Spain) in order to determine the reduction of available water resources. Besides the fact that climate change will represent a decrease of water availability, we qualitatively discuss the modifications that will result from the future climatic scenarios and their impact on nitrate pollution according to the geological setting of the selected aquifers. Climate effects in groundwater quality are described according to hydrological, environmental, socio-economic, and political concerns. Water reduction stands as a major issue that will control stream-aquifer interactions and subsurface recharge, leading to a general modification of nitrate in groundwater as dilution varies. A nitrate mass balance model provides a gross estimation of potential nitrate evolution in these aquifers, and it points out that the control of the fertilizer load will be crucial to achieve adequate nitrate content in groundwater. Reclaimed wastewater stands as local reliable resource, yet its amount will only satisfy a fraction of the loss of available resources due to climate change. Finally, an integrated management perspective is necessary to avoid unplanned actions from private initiatives that will jeopardize the achievement of sustainable water resources exploitation under distinct hydrological scenarios.

Concentrations of nitrate in drinking water in the lower Yakima River Basin, Groundwater Management Area, Yakima County, Washington, 2017

Science.gov (United States)

Huffman, Raegan L.

2018-05-29

The U.S. Geological Survey, in cooperation with the lower Yakima River Basin Groundwater Management Area (GWMA) group, conducted an intensive groundwater sampling collection effort of collecting nitrate concentration data in drinking water to provide a baseline for future nitrate assessments within the GWMA. About every 6 weeks from April through December 2017, a total of 1,059 samples were collected from 156 wells and 24 surface-water drains. The domestic wells were selected based on known location, completion depth, ability to collect a sample prior to treatment on filtration, and distribution across the GWMA. The drains were pre-selected by the GWMA group, and further assessed based on ability to access sites and obtain a representative sample. More than 20 percent of samples from the domestic wells and 12.8 percent of drain samples had nitrate concentrations that exceeded the maximum contaminant level (MCL) of 10 milligrams per liter established by the U.S. Environmental Protection Agency. At least one nitrate concentration above the MCL was detected in 26 percent of wells and 33 percent of drains sampled. Nitrate was not detected in 13 percent of all samples collected.

Determination of nitrate pollution sources by using isotopes and hydro-chemical techniques in the shallow Aquifer of Bara basin Northern Kordofan State Sudan

International Nuclear Information System (INIS)

Alamien, S. A. A.

2010-10-01

This study investigates the nature of the nitrate concentration and its effect on the quality of groundwater in the Bara basin in North Kordofan State Sudan. The principal objective of this study is to: detect possible NO 3 sources affecting groundwater quality. The δ 15 N results included two range of values, which suggested two different nitrogen sources in different parts of the study area. The data used in this study includes lithological logs, pumping and recovery data and chemical analysis. Rock ware, surfer, aquitest and aquichem software programs were used to analyze the data. which is the based on the lithological logs from nine shallow wells and seven deep boreholes. The geological formation was found to be the Umm Ruwaba formation which consists of two aquifers an upper shallow one and the other deep aquifer. The transmissivity of the upper aquifer was found to be 0.528m 2 / day, which is good and the average of hydraulic conductivity was found to be 0.08 4 m/ day, which is high and the storativity is 0.08 1 . The direction of flow of groundwater was found to be from North West to North East over all the area. Chemical analysis showed that the TDS concentration in the study area is within the permissible limits of the Sudanese and the WHO standards. The calcium concentration in the study area also found to be within the permissible limits of the Sudanese and the WHO standards. The nitrate concentration in the upper aquifer ranges between 9.68 and 891 mg/1 which is above the permissible limit of the Sudanese and the WHO standards. The water type in the upper aquifer was found to be calcium-nitrate-chloride-bicarbonate. It appears that the source of the calcium is either for the decay of dead animal bones or the dissolution of calcareous deposits within the upper aquifer. It can be concluded that the quality of groundwater in the study area is good for the human consumption. (Author)

Hydrochemical characterization and pollution sources identification of groundwater in Salawusu aquifer system of Ordos Basin, China.

Science.gov (United States)

Yang, Qingchun; Wang, Luchen; Ma, Hongyun; Yu, Kun; Martín, Jordi Delgado

2016-09-01

Ordos Basin is located in an arid and semi-arid region of northwestern China, which is the most important energy source bases in China. Salawusu Formation (Q3 s) is one of the most important aquifer systems of Ordos Basin, which is adjacent to Jurassic coalfield areas. A large-scale exploitation of Jurassic coal resources over ten years results in series of influences to the coal minerals, such as exposed to the oxidation process and dissolution into the groundwater due to the precipitation infiltration. Therefore, how these processes impact groundwater quality is of great concerns. In this paper, the descriptive statistical method, Piper trilinear diagram, ratios of major ions and canonical correspondence analysis are employed to investigate the hydrochemical evolution, determine the possible sources of pollution processes, and assess the controls on groundwater compositions using the monitored data in 2004 and 2014 (before and after large-scale coal mining). Results showed that long-term exploration of coal resources do not result in serious groundwater pollution. The hydrochemical types changed from HCO3(-)-CO3(2-) facies to SO4(2-)-Cl facies during 10 years. Groundwater hardness, nitrate and sulfate pollution were identified in 2014, which was most likely caused by agricultural activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Denitrification in groundwater at uranium mill tailings sites

International Nuclear Information System (INIS)

Goering, Timothy J.; Groffman, Armando; Thomson, Bruce

1992-01-01

Nitrates are a major contaminant in groundwater at many Uranium Mill Tailings Remedial Action (UMTRA) sites. Microbial denitrification, the transformation of nitrate to nitrogen gas, may be occurring in groundwater at several UMTRA sites. Denitrification is a biologically mediated process whereby facultative anaerobes use nitrate for respiration under anaerobic conditions. Denitrifying bacteria are ubiquitous in soils, sediments, and water. Denitrification requires nitrate, organic carbon, oxygen-limiting conditions, and trace nutrients, especially phosphorus. The lack of organic carbon is the most common limiting factor for denitrification. Denitrification occurs under a limited range of temperature and pH. The uranium milling processes used at UMTRA sites provided a readily available source of carbon and nitrates for denitrifying bacteria. At the Maybell, Colorado, site, the denitrifying organisms Pseudomonas, Flavobacterium and Acinetobacter were identified in core samples of materials from beneath the tailings. In addition, microcosm experiments simulating aquifer conditions beneath the tailings pile showed an average 40 percent decrease in nitrate concentrations over 13 days. At the New Rifle, Colorado, site, aquifer conditions appear favorable for denitrification. Nitrate and organic carbon are readily available in the groundwater, and redox conditions beneath and downgradient of the tailings pile are relatively anoxic. Downgradient from the tailings, total nitrogen is being removed from the groundwater system at a greater rate than the geochemically conservative anion, chloride. This removal may be due to denitrification and adsorption of ammonium onto clay and silt particles. (author)

Denitrification in groundwater at uranium mill tailings sites

Energy Technology Data Exchange (ETDEWEB)

Goering, Timothy J [Jacobs Engineering Group, Inc., Albuquerque, NM (United States); Groffman, Armando [Roy F. Weston, Inc., Albuquerque, NM (United States); Thomson, Bruce [University of New Mexico, Albuquerque, NM (United States)

1992-07-01

Nitrates are a major contaminant in groundwater at many Uranium Mill Tailings Remedial Action (UMTRA) sites. Microbial denitrification, the transformation of nitrate to nitrogen gas, may be occurring in groundwater at several UMTRA sites. Denitrification is a biologically mediated process whereby facultative anaerobes use nitrate for respiration under anaerobic conditions. Denitrifying bacteria are ubiquitous in soils, sediments, and water. Denitrification requires nitrate, organic carbon, oxygen-limiting conditions, and trace nutrients, especially phosphorus. The lack of organic carbon is the most common limiting factor for denitrification. Denitrification occurs under a limited range of temperature and pH. The uranium milling processes used at UMTRA sites provided a readily available source of carbon and nitrates for denitrifying bacteria. At the Maybell, Colorado, site, the denitrifying organisms Pseudomonas, Flavobacterium and Acinetobacter were identified in core samples of materials from beneath the tailings. In addition, microcosm experiments simulating aquifer conditions beneath the tailings pile showed an average 40 percent decrease in nitrate concentrations over 13 days. At the New Rifle, Colorado, site, aquifer conditions appear favorable for denitrification. Nitrate and organic carbon are readily available in the groundwater, and redox conditions beneath and downgradient of the tailings pile are relatively anoxic. Downgradient from the tailings, total nitrogen is being removed from the groundwater system at a greater rate than the geochemically conservative anion, chloride. This removal may be due to denitrification and adsorption of ammonium onto clay and silt particles. (author)

Probabilistic risk assessment of nitrate groundwater contamination from greenhouses in Albenga plain (Liguria, Italy) using lysimeters.

Science.gov (United States)

Paladino, Ombretta; Seyedsalehi, Mahdi; Massabò, Marco

2018-04-05

The use of fertilizers in greenhouse-grown crops can pose a threat to groundwater quality and, consequently, to human beings and subterranean ecosystem, where intensive farming produces pollutants leaching. Albenga plain (Liguria, Italy) is an alluvial area of about 45km 2 historically devoted to farming. Recently the crops have evolved to greenhouses horticulture and floriculture production. In the area high levels of nitrates in groundwater have been detected. Lysimeters with three types of reconstituted soils (loamy sand, sandy clay loam and sandy loam) collected from different areas of Albenga plain were used in this study to evaluate the leaching loss of nitrate (NO 3 - ) over a period of 12weeks. Leaf lettuce (Lactuca sativa L.) was selected as a representative green-grown crop. Each of the soil samples was treated with a slow release fertilizer, simulating the real fertilizing strategy of the tillage. In order to estimate the potential risk for aquifers as well as for organisms exposed via pore water, nitrate concentrations in groundwater were evaluated by applying a simplified attenuation model to the experimental data. Results were refined and extended from comparison of single effects and exposure values (Tier I level) up to the evaluation of probabilistic distributions of exposure and related effects (Tier II, III IV levels). HHRA suggested HI >1 and about 20% probability of exceeding RfD for all the greenhouses, regardless of the soil. ERA suggested HQ>100 for all the greenhouses; 93% probability of PNEC exceedance for greenhouses containing sand clay loam. The probability of exceeding LC50 for 5% of the species was about 40% and the probability corresponding to DBQ of DEC/EC50>0.001 was >90% for all the greenhouses. The significantly high risk, related to the detected nitrate leaching loss, can be attributed to excessive and inappropriate fertigation strategies. Copyright © 2018 Elsevier B.V. All rights reserved.

Temporal trends in concentrations of DBCP and nitrate in groundwater in the eastern San Joaquin Valley, California, USA

Science.gov (United States)

Burow, K.R.; Dubrovsky, N.M.; Shelton, James L.

2007-01-01

Temporal monitoring of the pesticide 1,2-dibromo-3-chloropropane (DBCP) and nitrate and indicators of mean groundwater age were used to evaluate the transport and fate of agricultural chemicals in groundwater and to predict the long-term effects in the regional aquifer system in the eastern San Joaquin Valley, California. Twenty monitoring wells were installed on a transect along an approximate groundwater flow path. Concentrations of DBCP and nitrate in the wells were compared to concentrations in regional areal monitoring networks. DBCP persists at concentrations above the US Environmental Protection Agency's maximum contaminant level (MCL) at depths of nearly 40 m below the water table, more than 25 years after it was banned. Nitrate concentrations above the MCL reached depths of more than 20 m below the water table. Because of the intensive pumping and irrigation recharge, vertical flow paths are dominant. High concentrations (above MCLs) in the shallow part of the regional aquifer system will likely move deeper in the system, affecting both domestic and public-supply wells. The large fraction of old water (unaffected by agricultural chemicals) in deep monitoring wells suggests that it could take decades for concentrations to reach MCLs in deep, long-screened public-supply wells, however. ?? Springer-Verlag 2007.

Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion.

Science.gov (United States)

Zhou, Xiaobo; Helmers, Matthew J; Asbjornsen, Heidi; Kolka, Randy; Tomer, Mark D

2010-01-01

Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3-N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed-scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20 PFS (distributed on toe and as contour strips). All treatments were established in fall 2006 on watersheds that were under bromegrass (Bromus L.) cover for at least 10 yr. Nonperennial areas were maintained under a no-till 2-yr corn (Zea mays L.)--soybean [Glycine max. (L.) Merr.] rotation since spring 2007. Suction lysimeter and shallow groundwater wells located at upslope and toeslope positions were sampled monthly during the growing season to determine NO3-N concentration from 2005 to 2008. The results indicated significant increases in NO3-N concentration in soil and groundwater following grassland-to-cropland conversion. Nitrate-nitrogen levels in the vadose zone and groundwater under PFS were lower compared with 100% cropland, with the most significant differences occurring at the toeslope position. During the years following conversion, PFS mitigated increases in subsurface nitrate, but long-term monitoring is needed to observe and understand the full response to land-use conversion.

Comparative evaluation of nitrate removal technologies

International Nuclear Information System (INIS)

Darbi, A.; Viraraghavan, T.; Butler, R.; Corkal, D.

2002-01-01

Due to the extensive application of artificial nitrogen-based fertilizers and animal manure on land, many water agencies face problems of increasing concentrations of nitrate in groundwater. The contamination of groundwater by nitrate may pose a significant public health problem. The threat of methemoglobinemia is well documented and reflected in the U.S. drinking water standard of 10 mg/L as nitrate-nitrogen. Approximately 45% of Saskatchewan's population use groundwater for drinking purposes, out of which, approximately 23% (230,000) are rural residents. The water used is made available from over 48,000 privately owned wells in regions where there is an extensive application of chemical fertilizers. Biological denitrification, ion exchange and reveres osmosis (RO) processes were selected for further study. Field studies were conducted on these processes. The sulfur/limestone autotrophic denitrification (SLAD) process was selected to achieve biological removal of nitrate from groundwater. The feasibility of the system was evaluated under anaerobic conditions. An ion exchange study was conducted using Ionac A554 which is strong anion exchange resins. In the case of groundwater containing low sulfate concentrations, A554 offered high nitrate removal. However, the disposal of regenerant brine can be a problem. A reverse osmosis unit with Filmtec membrane elements (FT30-Element Family) was used in the study on nitrate removal. The unit effluent average nitrate concentration was less than the maximum allowable concentration. (author)

Geochemistry of Groundwater: An Overview of Sporadic Fluoride and Nitrate Contamination in Parts of Yamuna River Basin, India

Directory of Open Access Journals (Sweden)

Shadab Khurshid

2013-06-01

Full Text Available The chemical characteristics of groundwater in parts of Yamuna river sub-basin utilized for both irrigation and domestic purposes were investigated by analyzing samples collected from the western part of Yamuna basin. It is observed that majority of the ground water samples are saline due to the presence of more clayey material with low permeability leading to longer residence time. Occurrence and distribution of fluoride and nitrate in groundwater on either bank of Yamuna river are studied and high concentrations of F and NO3 exceeding standard limits of various organization were observed at places suggesting their non-solubility for drinking purposes. Low concentration of nitrate is due to denitrification. Fluoride correlates positively with HCO3 and negatively with Ca. Discharge of untreated industrial effluents in unlined drains, dumping of solid wastes in open field and increased utilization of nitrogenous and phosphate fertilizers are responsible for the degradation of groundwater quality in parts of Yamuna basin.

Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas.

Science.gov (United States)

Musgrove, MaryLynn; Opsahl, Stephen P.; Mahler, Barbara J.; Herrington, Chris; Sample, Thomas; Banta, John

2016-01-01

Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO3−) loading to surface and groundwater. We investigate variability and sources of NO3− in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO3− stable isotopes (δ15N and δ18O). These data were augmented by historical data collected from 1937 to 2007. NO3− concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO3− concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO3− concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO3−. These results highlight the vulnerability of karst aquifers to NO3− contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO3−than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates that subaqueous nitrification of organic N in the aquifer, as opposed to in soils, might be a previously

Assessing aquifer vulnerability from lumped parameter modeling of modern water proportions in groundwater mixtures - Application to nitrate pollution in California's South Coast Range

Science.gov (United States)

Hagedorn, B.; Ruane, M.; Clark, N.

2017-12-01

In California, the overuse of synthetic fertilizers and manure in agriculture have caused nitrate (NO3) to be one of the state's most widespread groundwater pollutants. Given that nitrogen fertilizer applications have steadily increased since the 1950s and given that soil percolation and recharge transit times in California can exceed timescales of decades, the nitrate impact on groundwater resources is likely a legacy for years and even decades to come. This study presents a methodology for groundwater vulnerability assessment that operates independently of difficult-to-constrain soil and aquifer property data (i.e., saturated thickness, texture, porosity, conductivity, etc.), but rather utilizes groundwater age and, more importantly, groundwater mixing information to illustrate actual vulnerability at the water table. To accomplish this, the modern (i.e., less than 60-year old) water proportion (MWP) in groundwater mixtures is computed via lumped parameter modeling of chemical tracer (i.e., 3H, 14C and 3Hetrit) data. These MWPs are then linked to groundwater dissolved oxygen (DO) values to describe the risk for soil zone-derived nitrate to accumulate in the saturated zone. Preliminary studies carried out for 71 wells in California's South Coast Range-Coastal (SCRC) study unit reveal MWP values derived from binary dispersion models of 3.24% to 21.8%. The fact that high MWPs generally coincide with oxic (DO ≥1.5 mg/L) groundwater conditions underscores the risk towards increased groundwater NO3 pollution for many of the tested wells. These results support the conclusion that best agricultural management and policy objectives should incorporate groundwater vulnerability models that are developed at the same spatial scale as the decision making.

Groundwater Quality Assessment for Waste Management Area U: First Determination

Energy Technology Data Exchange (ETDEWEB)

FN Hodges; CJ Chou

2000-08-04

Waste Management Area U (TWA U) is located in the 200 West Area of the Hanford Site. The area includes the U Tank Farm, which contains 16 single-shell tanks and their ancillary equipment and waste systems. WMA U is regulated under the Resource Conservation and Recovery Act of 1976 (RCRA) as stipulated in 40 CFR Part 265, Subpart F, which is incorporated into the Washington State dangerous waste regulations (WAC 173-303400) by reference. Groundwater monitoring at WMA U has been guided by an interim status indicator evaluation program. As a result of changes in the direction of groundwater flow, background values for the WMA have been recalculated several times during its monitoring history. The most recent recalculation revealed that one of the indicator parameters, specific conductance, exceeded its background value in downgradient well 299-W19-41. This triggered a change from detection monitoring to a groundwater quality assessment program. The major contributors to the higher specific conductance are nonhazardous constituents, such as bicarbonate, calcium, chloride, magnesium, sodium and sulfate. Chromium, nitrate, and technetium-99 are present and are increasing; however, they are significantly below their drinking water standards. The objective of this study is to determine whether the increased concentrations of chromium, nitrate, and technetium-99 in groundwater are from WMA U or from an upgradient source. Interpretation of groundwater monitoring data indicates that both the nonhazardous constituents causing elevated specific conductance in groundwater and the tank waste constituents present in groundwater at the WMA are a result of surface water infiltration in the southern portion of the WMA. There is evidence that both upgradient and WMA sources contribute to the nitrate concentrations that were detected. There is no indication of an upgradient source for the chromium and technetium-99 that was detected. Therefore, a source of contamination appears to

Groundwater Quality Assessment for Waste Management Area U: First Determination

International Nuclear Information System (INIS)

FN Hodges; CJ Chou

2000-01-01

Waste Management Area U (TWA U) is located in the 200 West Area of the Hanford Site. The area includes the U Tank Farm, which contains 16 single-shell tanks and their ancillary equipment and waste systems. WMA U is regulated under the Resource Conservation and Recovery Act of 1976 (RCRA) as stipulated in 40 CFR Part 265, Subpart F, which is incorporated into the Washington State dangerous waste regulations (WAC 173-303400) by reference. Groundwater monitoring at WMA U has been guided by an interim status indicator evaluation program. As a result of changes in the direction of groundwater flow, background values for the WMA have been recalculated several times during its monitoring history. The most recent recalculation revealed that one of the indicator parameters, specific conductance, exceeded its background value in downgradient well 299-W19-41. This triggered a change from detection monitoring to a groundwater quality assessment program. The major contributors to the higher specific conductance are nonhazardous constituents, such as bicarbonate, calcium, chloride, magnesium, sodium and sulfate. Chromium, nitrate, and technetium-99 are present and are increasing; however, they are significantly below their drinking water standards. The objective of this study is to determine whether the increased concentrations of chromium, nitrate, and technetium-99 in groundwater are from WMA U or from an upgradient source. Interpretation of groundwater monitoring data indicates that both the nonhazardous constituents causing elevated specific conductance in groundwater and the tank waste constituents present in groundwater at the WMA are a result of surface water infiltration in the southern portion of the WMA. There is evidence that both upgradient and WMA sources contribute to the nitrate concentrations that were detected. There is no indication of an upgradient source for the chromium and technetium-99 that was detected. Therefore, a source of contamination appears to

Groundwater Quality Assessment for Waste Management Area U: First Determination

Energy Technology Data Exchange (ETDEWEB)

Hodges, Floyd N.; Chou, Charissa J.

2000-08-04

As a result of the most recent recalculation one of the indicator parameters, specific conductance, exceeded its background value in downgradient well 299-W19-41, triggering a change from detection monitoring to groundwater quality assessment program. The major contributors to the higher specific conductance are nonhazardous constituents (i.e., sodium, calcium, magnesium, chloride, sulfate, and bicarbonate). Nitrate, chromium, and technetium-99 are present and are increasing; however, they are significantly below their drinking waster standards. Interpretation of groundwater monitoring data indicates that both the nonhazardous constituents causing elevated specific conductance in groundwater and the tank waste constituents present in groundwater at the waste management area are a result of surface water infiltration in the southern portion of the facility. There is evidence for both upgradient and waste management area sources for observed nitrate concentrations. There is no indication of an upgradient source for the observed chromium and technetium-99.

Nitrate pollution in intensively farmed regions: What are the prospects for sustaining high-quality groundwater?

Science.gov (United States)

Howden, Nicholas J. K.; Burt, Tim P.; Worrall, Fred; Mathias, Simon; Whelan, Mick J.

2011-06-01

Widespread pollution of groundwater by nutrients due to 20th century agricultural intensification has been of major concern in the developed world for several decades. This paper considers the River Thames catchment (UK), where water-quality monitoring at Hampton (just upstream of London) has produced continuous records for nitrate for the last 140 years, the longest continuous record of water chemistry anywhere in the world. For the same period, data are available to characterize changes in both land use and land management at an annual scale. A modeling approach is used that combines two elements: an estimate of nitrate available for leaching due to land use and land management; and, an algorithm to route this leachable nitrate through to surface or groundwaters. Prior to agricultural intensification at the start of World War II, annual average inputs were around 50 kg ha-1, and river concentrations were stable at 1 to 2 mg l-1, suggesting in-stream denitrification capable of removing 35 (±15) kt N yr-1. Postintensification data suggest an accumulation of 100 (±40) kt N yr-1 in the catchment, most of which is stored in the aquifer. This build up of reactive N species within the catchments means that restoration of surface nitrate concentrations typical of the preintensification period would require massive basin-wide changes in land use and management that would compromise food security and take decades to be effective. Policy solutions need to embrace long-term management strategies as an urgent priority.

Source Areas of Water and Nitrate in a Peatland Catchment, Minnesota, USA

Science.gov (United States)

Sebestyen, S. D.

2017-12-01

In nitrogen polluted forests, stream nitrate concentrations increase and some unprocessed atmospheric nitrate may be transported to streams during stormflow events. This understanding has emerged from forests with upland mineral soils. In contrast, catchments with northern peatlands may have both upland soils and lowlands with deep organic soils, each with unique effects on nitrate transport and processing. While annual budgets show nitrate yields to be relatively lower from peatland than upland-dominated catchments, little is known about particular runoff events when stream nitrate concentrations have been higher (despite long periods with little or no nitrate in outlet streams) or the reasons why. I used site knowledge and expansive/extensive monitoring at the Marcell Experimental Forest in Minnesota, along with a targeted 2-year study to determine landscape areas, water sources, and nitrate sources that affected stream nitrate variation in a peatland catchment. I combined streamflow, upland runoff, snow amount, and frost depth data from long-term monitoring with nitrate concentration, yield, and isotopic data to show that up to 65% of stream nitrate during snowmelt of 2009 and 2010 was unprocessed atmospheric nitrate. Up to 46% of subsurface runoff from upland soils during 2009 was unprocessed atmospheric nitrate, which shows the uplands to be a stream nitrate source during 2009, but not during 2010 when upland runoff concentrations were below the detection limit. Differences are attributable to variations in water and nitrate sources. Little snow (a nitrate source), less upland runoff relative to peatland runoff, and deeper soil frost in the peatland caused a relatively larger input of nitrate from the uplands to the stream during 2009 and the peatland to the stream during 2010. Despite the near-absence of stream nitrate during much of rest of the year, these findings show an important time when nitrate transport affected downstream aquatic ecosystems, reasons

Nuclear techniques to investigate source and origin of groundwater pollutants and their flow path at Indian Rare Earths Ltd., Cochin, Kerala

International Nuclear Information System (INIS)

Tirumalesh, K.; Shivanna, K.; Noble, J.

2007-01-01

Hydrochemical, environmental isotope and injected radiotracer investigations were carried out in order to investigate the possible source of contaminants and their movement in groundwater at Indian Rare Earths (IRE) site. Water samples were collected from piezometers, dug wells and river in and around IRE site for measurement of physical parameters, chemistry and isotopes. Chemical results show high fluoride, nitrate, sulphate and phosphate concentrations in piezometers whereas dug wells and river samples are free from contamination. Isotope data indicate that the contaminated groundwaters are enriched in δ 2 H and δ 18 O compared to dug well and river samples. Radiotracer experiments were carried out using single-well and multi-well techniques (radiotracers: 82 Br and 3 H) for determining groundwater filtration velocity and flow direction, respectively. Groundwater filtration velocity was found to be about 1.3 cm/day and flow direction is from south to north. Based on the investigations it can be concluded that groundwater is getting contamination from southern part of IRE campus and the possible source for these contaminants could be the Fertilizer and Chemical of Travancore (FACT) industry. (author)

Estimating nitrate concentrations in groundwater at selected wells and springs in the surficial aquifer system and Upper Floridan aquifer, Dougherty Plain and Marianna Lowlands, Georgia, Florida, and Alabama, 2002-50

Science.gov (United States)

Crandall, Christy A.; Katz, Brian G.; Berndt, Marian P.

2013-01-01

Groundwater from the surficial aquifer system and Upper Floridan aquifer in the Dougherty Plain and Marianna Lowlands in southwestern Georgia, northwestern Florida, and southeastern Alabama is affected by elevated nitrate concentrations as a result of the vulnerability of the aquifer, irrigation water-supply development, and intensive agricultural land use. The region relies primarily on groundwater from the Upper Floridan aquifer for drinking-water and irrigation supply. Elevated nitrate concentrations in drinking water are a concern because infants under 6 months of age who drink water containing nitrate concentrations above the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter as nitrogen can become seriously ill with blue baby syndrome. In response to concerns about water quality in domestic wells and in springs in the lower Apalachicola–Chattahoochee–Flint River Basin, the Florida Department of Environmental Protection funded a study in cooperation with the U.S. Geological Survey to examine water quality in groundwater and springs that provide base flow to the Chipola River. A three-dimensional, steady-state, regional-scale groundwater-flow model and two local-scale models were used in conjunction with particle tracking to identify travel times and areas contributing recharge to six groundwater sites—three long-term monitor wells (CP-18A, CP-21A, and RF-41) and three springs (Jackson Blue Spring, Baltzell Springs Group, and Sandbag Spring) in the lower Apalachicola–Chattahoochee–Flint River Basin. Estimated nitrate input to groundwater at land surface, based on previous studies of nitrogen fertilizer sales and atmospheric nitrate deposition data, were used in the advective transport models for the period 2002 to 2050. Nitrate concentrations in groundwater samples collected from the six sites during 1993 to 2007 and groundwater age tracer data were used to calibrate the transport aspect of the simulations

Nitrate addition to groundwater impacted by ethanol-blended fuel accelerates ethanol removal and mitigates the associated metabolic flux dilution and inhibition of BTEX biodegradation

Science.gov (United States)

Corseuil, Henry Xavier; Gomez, Diego E.; Schambeck, Cássio Moraes; Ramos, Débora Toledo; Alvarez, Pedro J. J.

2015-03-01

A comparison of two controlled ethanol-blended fuel releases under monitored natural attenuation (MNA) versus nitrate biostimulation (NB) illustrates the potential benefits of augmenting the electron acceptor pool with nitrate to accelerate ethanol removal and thus mitigate its inhibitory effects on BTEX biodegradation. Groundwater concentrations of ethanol and BTEX were measured 2 m downgradient of the source zones. In both field experiments, initial source-zone BTEX concentrations represented less than 5% of the dissolved total organic carbon (TOC) associated with the release, and measurable BTEX degradation occurred only after the ethanol fraction in the multicomponent substrate mixture decreased sharply. However, ethanol removal was faster in the nitrate amended plot (1.4 years) than under natural attenuation conditions (3.0 years), which led to faster BTEX degradation. This reflects, in part, that an abundant substrate (ethanol) can dilute the metabolic flux of target pollutants (BTEX) whose biodegradation rate eventually increases with its relative abundance after ethanol is preferentially consumed. The fate and transport of ethanol and benzene were accurately simulated in both releases using RT3D with our general substrate interaction module (GSIM) that considers metabolic flux dilution. Since source zone benzene concentrations are relatively low compared to those of ethanol (or its degradation byproduct, acetate), our simulations imply that the initial focus of cleanup efforts (after free-product recovery) should be to stimulate the degradation of ethanol (e.g., by nitrate addition) to decrease its fraction in the mixture and speed up BTEX biodegradation.

California GAMA Special Study: Nitrate Fate and Transport in the Salinas Valley

Energy Technology Data Exchange (ETDEWEB)

Moran, Jean E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Esser, Bradley K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hillegonds, Darren [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Holtz, Marianne [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Roberts, Sarah K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Singleton, Michael J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Visser, Ate [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2011-05-13

The Groundwater Ambient Monitoring and Assessment (GAMA) Program is a comprehensive groundwater quality monitoring program managed by the California State Water Resources Control Board (SWRCB). Under the GAMA program, Lawrence Livermore National Laboratory carries out special studies that address groundwater quality issues of statewide relevance. The study described here is one in a series of special studies that address the fate and transport of nitrate in basins where groundwater is the main source of water for both irrigation and public drinking water supply.

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

Science.gov (United States)

Spruill, T.B.; Showers, W.J.; Howe, S.S.

2002-01-01

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 I was constructed by evaluating 32 variables and selecting four primary predictor variables (??15N, nitrate to ammonia ratio, sodium to potassium ratio, and zinc) to identify nitrate sources. A ??15N value of nitrate plus potassium 18.2 indicated inorganic or soil organic N. A nitrate to ammonia ratio 575 indicated nitrate from golf courses. A sodium to potassium ratio 3.2 indicated spray or poultry wastes. A value for zinc 2.8 indicated poultry wastes. Model 2 was devised by using all variables except ??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.

Modeling interactions of agriculture and groundwater nitrate contaminants: application of The STICS-Eau-Dyssée coupled models over the Seine River Basin

Science.gov (United States)

Tavakoly, A. A.; Habets, F.; Saleh, F.; Yang, Z. L.

2017-12-01

Human activities such as the cultivation of N-fixing crops, burning of fossil fuels, discharging of industrial and domestic effluents, and extensive usage of fertilizers have recently accelerated the nitrogen loading to watersheds worldwide. Increasing nitrate concentration in surface water and groundwater is a major concern in watersheds with extensive agricultural activities. Nutrient enrichment is one of the major environmental problems in the French coastal zone. To understand and predict interactions between agriculture, surface water and groundwater nitrate contaminants, this study presents a modeling framework that couples the agronomic STICS model with Eau-Dyssée, a distributed hydrologic modeling system to simulate groundwater-surface water interaction. The coupled system is implemented on the Seine River Basin with an area of 88,000 km2 to compute daily nitrate contaminants. Representing a sophisticated hydrosystem with several aquifers and including the megalopolis of Paris, the Seine River Basin is well-known as one of the most productive agricultural areas in France. The STICS-EauDyssée framework is evaluated for a long-term simulation covering 39 years (1971-2010). Model results show that the simulated nitrate highly depends on the inflow produced by surface and subsurface waters. Daily simulation shows that the model captures the seasonal variation of observations and that the overall long-term simulation of nitrate contaminant is satisfactory at the regional scale.

Open-Source Photometric System for Enzymatic Nitrate Quantification.

Science.gov (United States)

Wittbrodt, B T; Squires, D A; Walbeck, J; Campbell, E; Campbell, W H; Pearce, J M

2015-01-01

Nitrate, the most oxidized form of nitrogen, is regulated to protect people and animals from harmful levels as there is a large over abundance due to anthropogenic factors. Widespread field testing for nitrate could begin to address the nitrate pollution problem, however, the Cadmium Reduction Method, the leading certified method to detect and quantify nitrate, demands the use of a toxic heavy metal. An alternative, the recently proposed Environmental Protection Agency Nitrate Reductase Nitrate-Nitrogen Analysis Method, eliminates this problem but requires an expensive proprietary spectrophotometer. The development of an inexpensive portable, handheld photometer will greatly expedite field nitrate analysis to combat pollution. To accomplish this goal, a methodology for the design, development, and technical validation of an improved open-source water testing platform capable of performing Nitrate Reductase Nitrate-Nitrogen Analysis Method. This approach is evaluated for its potential to i) eliminate the need for toxic chemicals in water testing for nitrate and nitrite, ii) reduce the cost of equipment to perform this method for measurement for water quality, and iii) make the method easier to carryout in the field. The device is able to perform as well as commercial proprietary systems for less than 15% of the cost for materials. This allows for greater access to the technology and the new, safer nitrate testing technique.

Hydrodynamic analysis of the interaction of two operating groundwater sources, case study: Groundwater supply of Bečej

Directory of Open Access Journals (Sweden)

Polomčić Dušan M.

2014-01-01

Full Text Available The existing groundwater source 'Vodokanal' for the public water supply of Bečej city in Serbia tapping groundwater from three water-bearing horizons over 15 wells with summary capacity of 100 l/s. Near the public water source of Bečej exists groundwater source 'Soja Protein' for industry with current capacity of 12 l/s which tapped same horizons. In the coming period is planned to increase summary capacity of this groundwater source up to 57 l/s. Also, the increase of summary city's source capacity is planned for 50 l/s in the next few years. That is means an increase of groundwater abstraction for an additional 84 % from the same water-bearing horizons. Application of hydrodynamic modeling, based on numerical method of finite difference will show the impact of increasing the total capacity of the source 'Soja Protein' on the groundwater level in groundwater source 'Vodokanal' and effects of additional decrease in groundwater levels, in all three water-bearing horizons, on the wells of the 'Vodokanala' groundwater source due to operation of industrial source. It was done 7 variant solutions of the extensions of groundwater sources and are their effects for a period of 10 years with the aim of the sustainable management of groundwater.

The effects of land application of farm dairy effluent on groundwater quality : West Coast 2001

International Nuclear Information System (INIS)

Baker, T.M.; Hawke, R.M.

2007-01-01

Land application of agricultural effluent is becoming a standard farming practice. The application of farm dairy effluent to land, as opposed to direct discharge to waterways, is the preferred method for disposal in New Zealand as regulatory authorities move to protect and enhance water quality and meet Maori spiritual and cultural values. Land application recognises the nutrient value of dairy effluent; however, it is not without risks. Careful management of land application of the effluent is required because of the potential nutrient and bacterial contamination of groundwater. In 2001, 19 groundwater bores were sampled on four occasions to assess the effects of farm dairy effluent on groundwater quality. Elevated (> 1.6 g m -3 nitrate-nitrogen concentrations were found in 14 of these bores (43 of 74 samples). The available long-term data shows statistically significant increasing trends in nitrate-nitrogen and chloride over the period 1998 to 2007. The nitrate-nitrogen and chloride results suggest effluent is the source of the elevated nitrate-nitrogen; however, the nitrogen isotope analysis indicates that the source of the nitrate-nitrogen may be from fertiliser or soil organic matter (average δ 15 N value of 3.5 permille). Spatially isolated occurrences of bacterial contamination were also recorded: in 7 bores and 12% of all samples analysed. Groundwater dating, using chlorofluorocarbons, suggested that the groundwater in the region was young (8 to 12 years). Overall, the spatial and temporal data suggests human influences are affecting groundwater quality on the West Coast. (author). 27 refs., 5 figs., 2 tabs

Quantifying in-stream nitrate reaction rates using continuously-collected water quality data

Science.gov (United States)

Matthew Miller; Anthony Tesoriero; Paul Capel

2016-01-01

High frequency in situ nitrate data from three streams of varying hydrologic condition, land use, and watershed size were used to quantify the mass loading of nitrate to streams from two sources – groundwater discharge and event flow – at a daily time step for one year. These estimated loadings were used to quantify temporally-variable in-stream nitrate processing ...

Pollution indicators in groundwater of two agricultural catchments in Lower Silesia (Poland)

Science.gov (United States)

Kasperczyk, Lidia; Modelska, Magdalena; Staśko, Stanisław

2016-12-01

The article discusses the content and source of mineral nitrogen compounds in groundwater, based on the data collected in two river catchments in two series (spring and autumn 2014). The study area comprises two catchments located in Lower Silesia, Poland - Cicha Woda and Sąsiecznica. Both catchments are characterised agricultural character of development. In the both researched areas, the points of State Environmental Monitoring (SEM) are located but only the Cicha Woda area is classified as nitrate vulnerable zone (NVZ). To analyse and compare the contamination of Quaternary and Neogene aquifers, the concentration of nitrates, nitrites, ammonium and potassium ions was measured primarily. Results showed the exceedance of nitrogen mineral forms of shallow groundwater Quaternary aquifer in both basins. The concentration of nitrates range from 0.08 to 142.12 mgNO3 -/dm3 (Cicha Woda) and from 2.6 to 137.65 mg NO3 -/dm3 (Sąsiecznica). The major source of pollution is probably the intensive agriculture activity. It causes a degradation of the shallow groundwater because of nitrate, nitrite, potassium, phosphates and ammonium contents. There was no observed contamination of anthropogenic origin in the deeper Neogene aquifer of Cicha Woda catchment.

Using Nitrate Isotopes to Distinguish Pathways along which Unprocessed Atmospheric Nitrate is Transported through Forests to Streams

Science.gov (United States)

Sebestyen, S. D.

2013-12-01

Evaluation of natural abundance oxygen and nitrogen isotopes in nitrate has revealed that atmospheric deposition of nitrate to forests sometimes has direct effects on the timing and magnitude of stream nitrate concentrations. Large amounts of unprocessed atmospheric nitrate have sometimes been found in streams during snowmelt and stormflow events. Despite increasing evidence that unprocessed atmospheric nitrate may be transported without biological processing to streams at various times and multiple locations, little has been reported about specific hydrological processes. I synthesized research findings from a number of studies in which nitrate isotopes have been measured over the past decade. Unprocessed nitrate may predominate in surficial soil waters after rainfall and snowmelt events relative to nitrate that originated from nitrification. Although transport to deep groundwater may be important in the most nitrogen saturated catchments, the transport of unprocessed atmospheric nitrate along shallow subsurface flowpaths is likely more important in many moderately N-polluted ecosystems, which predominate in the northeastern USA where most of my study sites are located. The presence of unprocessed atmospheric nitrate in surficial soils was linked to stream nitrate concentrations when large amounts of unprocessed nitrate were occasionally routed along lateral, shallow subsurface flowpaths during stormflow events. During these events, water tables rose to saturate shallow-depth soils. When catchments were drying or dryer, atmospheric nitrate was completely consumed by biological processing as flowpaths shifted from lateral to vertical transport through soils. The source areas of unprocessed atmospheric nitrate were usually limited to soils that were adjacent to streams, with little to no near-surface saturation and transport of unprocessed nitrate from more distal hillslope positions. The occasional large amounts of unprocessed atmospheric nitrate in soil water

REMOVAL OF ADDED NITRATE IN THE SINGLE, BINARY, AND TERNARY SYSTEMS OF COTTON BURR COMPOST, ZEROVALENT IRON, AND SEDIMENT: IMPLICATIONS FOR GROUNDWATER NITRATE REMEDIATION USING PERMEABLE REACTIVE BARRIERS

Science.gov (United States)

Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe0) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and ...

Isotopic evidence for the diverse origins of nitrate minerals

International Nuclear Information System (INIS)

Heaton, T.H.E.

1987-01-01

Nitrate minerals are rare and, apart from their occasional value as economic deposits of fertilizer, not of general importance in geology. The mechanisms by which they are formed, however, are still the subject of considerable debate. This brief discussion indicates that the study of the 15 N/ 14 N ratios of nitrate minerals can yield useful information on their origins. The low 15 N/ 14 N ratios for nitrate in desert environments indicate that soil or animal waste sources of nitrogen are unlikely. Derivation from atmospheric precipitation is consistent with the presently limited knowledge of the isotopic characteristics of atmospheric compounds, but can only be confirmed when data for these compounds in desert areas become available. For nitrates in wetter environments the 15 N/ 14 N ratios indicate that atmospheric sources are not important, and that the formation of nitrate from gaseous ammonia emanating from animal waste is probably not a significant mechanism. The nitrate appears to be chiefly derived either by direct solution of animal waste nitrate (Lydenburg cave and Prieskapoort) or from soil-derived nitrate brought in by groundwater (Autana and possibly Abjaterskop caves). In the case of Sveite special conditions involving bacterial processes are also implied

Herbicides and nitrates in groundwater of Maryland and childhood cancers: a geographic information systems approach.

Science.gov (United States)

Thorpe, Nancy; Shirmohammadi, Adel

2005-01-01

This hypothesis-generating study explores spatial patterns of childhood cancers in Maryland and investigates their potential associations with herbicides and nitrates in groundwater. The Maryland Cancer Registry (MCR) provided data for bone and brain cancers, leukemia, and lymphoma, for ages 0-17, during the years 1992-1998. Cancer clusters and relative risks generated in the study indicate higher relative risk areas and potential clusters in several counties. Contingency table analysis indicates a potential association with several herbicides and nitrates. Cancer rates for the four types have a crude odds ratio (OR) = 1.10 (0.78-1.56) in relationship to atrazine, and an OR = 1.54 (1.14-2.07) for metolachlor. Potential association to mixtures of three compounds give an OR = 7.56 (4.16-13.73). A potential association is indicated between leukemia and nitrates, OR = 1.81 (1.35-2.42), and bone cancer with metolachlor, OR = 2.26 (0.97-5.24). These results give insight to generate a hypothesis of the potential association between exposure to these herbicides and nitrates and specific types of childhood cancer.

Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion

Science.gov (United States)

Xiaobo Zhou; Matthew J. Helmers; Heidi Asbjornsen; Randy Kolka; Mark D. Tomer

2010-01-01

Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to...

Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

Science.gov (United States)

Mills, Taylor J.; Mast, M. Alisa; Thomas, Judith C.; Keith, Gabrielle L.

2016-01-01

Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO3 inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO3 application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential source of Se in the future as soluble salts are progressively depleted.

Nitrate pollution of a karstic groundwater system in Svaty Jan Pod Skalou, Czech Republic

International Nuclear Information System (INIS)

Buzek, F.; Kadlecova, R.; Zak, K.

1998-01-01

Due to increasing agricultural activity after the 1960's both shallow and deep water resources in the Czech Republic including karstic systems have been contaminated by infiltrating nitrate. Nitrate content of one of the largest spring (19L/s) now varies from 50 to 60 mg/L. To specify the sources of nitrate pollution and collect sufficient data for the prediction of possible future development, flow dynamics, chemical and isotopic composition (δ 18 O in water, δ 15 N in nitrate) were monitored in the spring and precipitation together with potential sources of pollution (fertilizers, solutes in soil profile). Observed data were modelled by a simple mixing cell model to specify system parameters (volume and mean residence time). (author)

Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

Energy Technology Data Exchange (ETDEWEB)

Mills, Taylor J.; Mast, M. Alisa; Thomas, Judith; Keith, Gabrielle

2016-10-01

Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (< 0.5 μg L{sup −1}) to 4070 μg L{sup −1}, and primarily are controlled by high groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO{sub 3} inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO{sub 3} application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential

Nitrate distribution and potential attenuation mechanisms of a municipal water supply bedrock aquifer

International Nuclear Information System (INIS)

Opazo, Tomás; Aravena, Ramón; Parker, Beth

2016-01-01

The Silurian bedrock aquifer constitutes a major aquifer system for groundwater supply across the Ontario province in Canada. The application of natural and industrial fertilizers near urban centers has led to groundwater NO_3"−-N concentrations that sometimes have exceeded the drinking water limit, posing a threat to the usage of groundwater for the human consumption. Therefore, there is a growing interest and concern about how nitrate is being leached, transported and potentially attenuated in bedrock aquifers. This study assesses the local distribution of groundwater NO_3"− in the up-gradient area of two historically impacted municipal wells, called Carter Wells, in the City of Guelph, Canada, in order to evaluate the potential nitrate attenuation mechanisms, using both groundwater geochemical and isotopic analysis ("3H, δ"1"5N-NO_3, δ"1"8O-NO_3, δ"1"8O-SO_4, δ"3"4S-SO_4) and a detailed vertical hydrogeological and geochemical bedrock characterization. The results indicate that probably the main source of nitrate to the Carter Wells is the up-gradient Arkell Research Station (ARS), an agricultural research facility where manure has been historically applied. The overburden and bedrock groundwater with high NO_3 concentrations at the ARS exhibits a manure-related δ"1"5N and δ"1"8O signature, isotopically similar to the high nitrate in the down-gradient groundwater from domestic wells and from the Carter Wells. The nitrate spatial distribution appears to be influenced and controlled by the geology, in which more permeable rock is found in the Guelph Formation which in turn is related to most of the high NO_3"− groundwater. The presence of an underlying low permeability Eramosa Formation favors the development of oxygen-depleted conditions, a key factor for the occurrence of denitrification. Groundwater with low NO_3"−-N concentrations associated with more oxygen-limited conditions and coincident with high SO_4"2"− concentrations are related to more

Nitrate reduction in an unconfined sandy aquifer

DEFF Research Database (Denmark)

Postma, Diederik Jan; Boesen, Carsten; Kristiansen, Henning

1991-01-01

of total dissolved ions in the NO3- free anoxic zone indicates the downward migration of contaminants and that active nitrate reduction is taking place. Nitrate is apparently reduced to N2 because both nitrite and ammonia are absent or found at very low concentrations. Possible electron donors......Nitrate distribution and reduction processes were investigated in an unconfined sandy aquifer of Quaternary age. Groundwater chemistry was studied in a series of eight multilevel samplers along a flow line, deriving water from both arable and forested land. Results show that plumes of nitrate...... processes of O2 and NO3- occur at rates that are fast compared to the rate of downward water transport. Nitrate-contaminated groundwater contains total contents of dissolved ions that are two to four times higher than in groundwater derived from the forested area. The persistence of the high content...

Forensic applications of nitrogen and oxygen isotopes in tracing nitrate sources in urban environments

Science.gov (United States)

Silva, S.R.; Ging, P.B.; Lee, R.W.; Ebbert, J.C.; Tesoriero, A.J.; Inkpen, E.L.

2002-01-01

Ground and surface waters in urban areas are susceptible to nitrate contamination from septic systems, leaking sewer lines, and fertilizer applications. Source identification is a primary step toward a successful remediation plan in affected areas. In this respect, nitrogen and oxygen isotope ratios of nitrate, in conjunction with hydrologic data and water chemistry, have proven valuable in urban studies from Austin, Texas, and Tacoma, Washington. In Austin, stream water was sampled during stremflow and baseflow conditions to assess surface and subsurface sources of nitrate, respectively. In Tacoma, well waters were sampled in adjacent sewered and un-sewered areas to determine if locally high nitrate concentrations were caused by septic systems in the un-sewered areas. In both studies, sewage was identified as a nitrate source and mixing between sewage and other sources of nitrate was apparent. In addition to source identification, combined nitrogen and oxygen isotopes were important in determining the significance of denitrification, which can complicate source assessment by reducing nitrate concentrations and increasing ??15N values. The two studies illustrate the value of nitrogen and oxygen isotopes of nitrate for forensic applications in urban areas. ?? Published by Elsevier Science Ltd. on behalf of AEHS.

Reexamining the risks of drinking-water nitrates on public health.

Science.gov (United States)

Richard, Alyce M; Diaz, James H; Kaye, Alan David

2014-01-01

Nitrates in drinking water are generally considered the sole source of nitrite poisoning with methemoglobinemia in infantile methomoglobinemia (IM). However, IM, which occurs during the first 4 months of life, is actually a constellation of cyanosis and hypoxia associated with methemoglobinemia that can result from several other causes. This review reexamines the role of nitrate levels in drinking water as a cause of IM and identifies other sources of nitrates that can affect public health and cause chronic diseases. Causes of IM include nitrites in foods, environmental chemical exposures, commonly prescribed pharmaceuticals, and the endogenous generation of oxides of nitrogen. Infants with congenital enzyme deficiencies in glucose-6-phosphate dehydrogenase and methemoglobin reductase are at greater risk of nitrite-induced methemoglobinemia from nitrates in water and food and from exposures to hemoglobin oxidizers. Early epidemiological studies demonstrated significant associations between high groundwater nitrate levels and elevated methemoglobin levels in infants fed drinking water-diluted formulas. However, more recent epidemiological investigations suggest other sources of nitrogenous substance exposures in infants, including protein-based formulas and foods and the production of nitrate precursors (nitric acid) by bacterial action in the infant gut in response to inflammation and infection.

Evaluation of Nitrate Contaminaion of Drinking Water Wells in the City of Qom

Directory of Open Access Journals (Sweden)

Mohammadhossein Rahimi

2017-09-01

Full Text Available Groundwater is the only vital source of water for millions of people around the world and its contamination has dire impacts on human health, industrial activities, agriculture, and the environment. The drinking water in the City of Qom is supplied from neighboring water basins transferred by interbasin water transimission facilities and from water wells within the city. The growing demands and the consequent increasing water scarcity have augmented and foregrounded the significant role played by the water wells in this city. Nitrate as a widespread pollutant originates from human activities and the dumped wastes that lead to the gradual degradation of groundwater resources, which might go undetected for years. On the other hand, remediation of polluted aquifers is a formidable, cost-intensive, and, at times, impossible endeavor. In this study, groundwater resources in the city of Qom were investigated in terms of their nitrate concentration. For this purpose, 600 groundwater samples collected from 2006 to 2013 by the Qom Water and Sewage Company were used, 136 of which were found to be polluted with nitrate. In order to validate the data thus obtained and to identify the contaminated areas, additional samples were collected from 27 wells in December 2013 and subjected to the relevant analysis. The latter analysis revealed a mean nitrate concentration of 74 mg/L and a standard deviation of 37 mg/L, with nitrate contamination detected in 19 wells accounting for 70% of the sampling sites. Generally, the results indicate that the aquifers within the city of Qom suffer from nitrate contamination.

A new method for in situ nitrate removal from groundwater using submerged microbial desalination-denitrification cell (SMDDC)

DEFF Research Database (Denmark)

Zhang, Yifeng; Angelidaki, Irini

2013-01-01

, which was composed of an anode and a cathode chamber, can be easily applied to subsurface environments. When current was produced by bacteria on the anode, NO3- and Na+ were transferred into the anode and cathode through anion and cation exchange membrane, respectively; the anode effluent was directed...... groundwater with 12 h wastewater hydraulic retention time (HRT) and 10 Ω of external resistance. The nitrate concentration and ionic strength of groundwater were the main limiting factors to the system performance. Besides, the external resistance and HRT were also affecting the system performance...

Natural radioactivity in groundwater sources in Ireland

Energy Technology Data Exchange (ETDEWEB)

Currivan, L.; Dowdall, A.; Mcginnity, P.; Ciara, M. [Radiological Protection Institute of Ireland (Ireland); Craig, M. [Environmental Protection Agency (Ireland)

2014-07-01

The Radiological Protection Institute of Ireland (RPII) in collaboration with the Irish Environmental Protection Agency (EPA) undertook a national survey of radioactivity in groundwater sources for compliance with parameters set out in the European Communities Drinking Water Directive. The Directive outlines the minimum requirements for the quality of drinking water and water intended for human consumption. Over two hundred samples were screened for radioactivity. Where indicated, analysis for individual radionuclide activity was undertaken and the radiation dose arising calculated. Furthermore, samples were analysed for radon concentration. This survey is the first comprehensive national survey of radioactivity in groundwater sources in Ireland. Approximately 18 per cent of drinking water in Ireland originates from groundwater and springs with the remainder from surface water. Between 2007 and 2011, water samples from a representative network of groundwater sources were analysed and assessed for compliance with the radioactivity parameters set out in the Drinking Water Directive. The assessment was carried out using the methodology for screening drinking water set out by the WHO. For practical purposes the WHO recommended screening levels for drinking water below which no further action is required of 100 mBq/l for gross alpha activity and 1000 mBq/l for gross beta activity were applied. Of the 203 groundwater sources screened for gross alpha and gross beta all met the gross beta activity criteria of less than 1000 mBq/l and 175 supplies had gross alpha activity concentrations of less than 100 mBq/l. For these sources no further analysis was required. The remaining 28 sources required further (radionuclide-specific) analysis from an alpha activity perspective. Results on ranges and distributions of radionuclide concentrations in groundwater as well as ingestion doses estimated for consumers of these water supplies will be presented. Document available in abstract

Probability distribution functions of δ15N and δ18O in groundwater nitrate to probabilistically solve complex mixing scenarios

Science.gov (United States)

Chrystal, A.; Heikoop, J. M.; Davis, P.; Syme, J.; Hagerty, S.; Perkins, G.; Larson, T. E.; Longmire, P.; Fessenden, J. E.

2010-12-01

Elevated nitrate (NO3-) concentrations in drinking water pose a health risk to the public. The dual stable isotopic signatures of δ15N and δ18O in NO3- in surface- and groundwater are often used to identify and distinguish among sources of NO3- (e.g., sewage, fertilizer, atmospheric deposition). In oxic groundwaters where no denitrification is occurring, direct calculations of mixing fractions using a mass balance approach can be performed if three or fewer sources of NO3- are present, and if the stable isotope ratios of the source terms are defined. There are several limitations to this approach. First, direct calculations of mixing fractions are not possible when four or more NO3- sources may be present. Simple mixing calculations also rely upon treating source isotopic compositions as a single value; however these sources themselves exhibit ranges in stable isotope ratios. More information can be gained by using a probabilistic approach to account for the range and distribution of stable isotope ratios in each source. Fitting probability density functions (PDFs) to the isotopic compositions for each source term reveals that some values within a given isotopic range are more likely to occur than others. We compiled a data set of dual isotopes in NO3- sources by combining our measurements with data collected through extensive literature review. We fit each source term with a PDF, and show a new method to probabilistically solve multiple component mixing scenarios with source isotopic composition uncertainty. This method is based on a modified use of a tri-linear diagram. First, source term PDFs are sampled numerous times using a variation of stratified random sampling, Latin Hypercube Sampling. For each set of sampled source isotopic compositions, a reference point is generated close to the measured groundwater sample isotopic composition. This point is used as a vertex to form all possible triangles between all pairs of sampled source isotopic compositions

Nitrate Leaching under Vegetable Fields above a Shallow Aquifer in Slovenia

International Nuclear Information System (INIS)

Zupanc, V.; Sturm, M.; Lojen, S.; Marsic-Kacjana, N.; Pintar, M.; Adu-Gyamfi, J.; Bracic-Zeleznik, B.; Urbanc, J.

2012-01-01

Shallow aquifers can be prone to nitrate pollution, especially in rural, high rainfall zones under intensive vegetable production, as well as in areas with urban and industrial pollution. Due to its mobility in the soil, nitrate is the most problematic pollutant in intensive agricultural production areas. The risk of nitrate leaching is closely related to the excessive application of organic and inorganic nitrogen (N) fertilizers and can occur at and after harvest, as well as during the crop cycle, because of excessive irrigation or heavy precipitation. The impact of agriculture on groundwater quality can be minimized through improved nitrogen and water management (irrigation) practices, which should be evaluated with regard to their production, polluting effects and cost effectiveness. Most of the Slovenian highly fertile arable lands occur on plains in the shallow groundwater recharge zones, and are used for intensive fresh vegetable production, an important source of income generation for the farmers. These shallow alluvial aquifers are, however, one of the country's most important sources of drinking water. This leads to a conflict of interest between drinking water resource protection and agricultural production. The common farming practice in Slovenia is to broadcast fertilizer applications which often results in extensive nitrate leaching. Thus nitrate management in agriculture is a contentious issue, as adequate nitrogen fertilization is required to ensure reasonable crop yields, yet excessive N fertilization can lead to groundwater pollution. Through an IAEA technical cooperation project SLO 5002 Protecting Groundwater and Soil Pollutants using Nuclear echniques, various irrigation, nitrogen and cropping system management strategies for the production of vegetables with a shorter growing period were assessed at a benchmark site in Slovenia during the years 2006 and 2007. Four irrigation and fertilization treatments were applied: (1) 50% drip irrigation of

A Unified Experimental Approach for Estimation of Irrigationwater and Nitrate Leaching in Tree Crops

Science.gov (United States)

Hopmans, J. W.; Kandelous, M. M.; Moradi, A. B.

2014-12-01

Groundwater quality is specifically vulnerable in irrigated agricultural lands in California and many other(semi-)arid regions of the world. The routine application of nitrogen fertilizers with irrigation water in California is likely responsible for the high nitrate concentrations in groundwater, underlying much of its main agricultural areas. To optimize irrigation/fertigation practices, it is essential that irrigation and fertilizers are applied at the optimal concentration, place, and time to ensure maximum root uptake and minimize leaching losses to the groundwater. The applied irrigation water and dissolved fertilizer, as well as root growth and associated nitrate and water uptake, interact with soil properties and fertilizer source(s) in a complex manner that cannot easily be resolved. It is therefore that coupled experimental-modeling studies are required to allow for unraveling of the relevant complexities that result from typical field-wide spatial variations of soil texture and layering across farmer-managed fields. We present experimental approaches across a network of tree crop orchards in the San Joaquin Valley, that provide the necessary soil data of soil moisture, water potential and nitrate concentration to evaluate and optimize irrigation water management practices. Specifically, deep tensiometers were used to monitor in-situ continuous soil water potential gradients, for the purpose to compute leaching fluxes of water and nitrate at both the individual tree and field scale.

Tracing the Atmospheric Source of Desert Nitrates Using Δ 17O

Science.gov (United States)

Michalski, G. M.; Holve, M.; Feldmeier, J.; Bao, H.; Reheis, M.; Bockheim, J. G.; Thiemens, M. H.

2001-05-01

Mineral, caliche, and soil nitrates are found throughout the worlds deserts, including the cold dry Wright Valley of Antarctica, the Atacama desert in Chile and the Mojave desert in the southwest United States. Several authors have suggested biologic sources of these nitrates while others have postulated atmospheric deposition. A recent study utilizing 18O indicated that 30%, and perhaps 100%, of nitrates found in the Atacama and Mojave were of atmospheric origin [1]. A more quantitative assessment of the source strength of atmospheric nitrates was impossible because of the high variability of δ 18 18O of atmospheric nitrates and uncertainties in conditions of biologic production. Mass independently fractionated (MIF) processes are defined and quantified by the equation Δ 17O = δ 17O - .52x δ 18O. MIF processes are associated with the photochemistry of trace gases in the atmosphere and have been found in O3, N2O, CO, and sulfate aerosols . A large MIF (Δ 17O ~ 28 ‰ ) in nitrate aerosols collected in polluted regions was recently reported [2]. Here we extend measurements of MIF in nitrate to the dry deposition of nitrate in less polluted areas (Mojave desert). In addition we trace the MIF signal as it accumulates in the regolith as nitrate salts and minerals and is mixed with biologically produced nitrate (nitrification). Also examined were the isotopic composition of soil nitrates from Antarctic dry valleys. Dust samples were collected as part of the NADP program and soils were collected throughout the Mojave and Death Valley regions of California. Isotope analysis was done in addition to soluble ion content (Cl, NO3, SO4). Dust samples collected by dry deposition samplers showed a large MIF > 20‰ approaching values measured in urban nitrate aerosol. Soils collected throughout the region showed large variations in Δ 17O from ~ 0 to 18 ‰ . The low Δ 17O values are nitrates dominated by biologic nitrification and higher values are nitrates derived by

Isotope chemistry of an extensively nitrate-contaminated urban aquifer

Science.gov (United States)

Kracht, O.; de Souza, L. C.; de Queiros, M. A.; Stegemann, C.; Hunziker, J.

2003-04-01

The supply of drinking water for the approximately 800.000 inhabitants of the city of Natal (Rio Grande do Norte, Brazil) is strongly dependent on the use of local groundwater from the Barreiras Aquifer. Over 70 % of the public production are served by a system of about 130 tubular wells, that are distributed all over the urban area. Yet, no groundwater protection zones have been declared. In addition, a comparable number of private wells also depend on the cities underground water resources. Depending on the local topography, the groundwater table is located several tens of meters below surface. Useable groundwater occurrences are bound to an up to hundred meters thick series of unconsolidated clastic sediments from the younger tertiary (Barreiras Formation), that is underlain by less permeable cretaceous carbonates. Natals topography is dominated by impressive quaternary dunes formations, that play an important role for the infiltration of rain as the only source of recharge for the local groundwater. During the last decades, an extensive and rapidly growing groundwater-contamination with up to over 100 mg/l nitrate was observed by the local authorities. Hydrochemical data indicate this deterioration to be due to a massive spill of sanitary effluents over septic pits, as only 20 % of the city is yet served by a sewer system. The isotopic composition of Natals groundwater shows only small variations, with an average δ18O value of -2,3 per mill and δ2H value of -10,5 per mill vs. SMOW. Its origin from recent local precipitation is revealed by a good correspondence with the annual weighted means for precipitation in Ceara Mirim (nearest GNIP station, situated 45 km NE of Natal). In contrast, a set of samples from different regional surface waters indicated a strong evaporation trend with systematic enrichment in the oxygen and hydrogen isotopic composition. Samples from 33 production wells with a wide variation of nitrate concentrations were investigated for their

The unintended energy impacts of increased nitrate contamination from biofuels production.

Science.gov (United States)

Twomey, Kelly M; Stillwell, Ashlynn S; Webber, Michael E

2010-01-01

Increases in corn cultivation for biofuels production, due to the Energy Independence and Security Act of 2007, are likely to lead to increases in nitrate concentrations in both surface and groundwater resources in the United States. These increases might trigger the requirement for additional energy consumption for water treatment to remove the nitrates. While these increasing concentrations of nitrate might pose a human health concern, most water resources were found to be within current maximum contaminant level (MCL) limits of 10 mg L(-1) NO(3)-N. When water resources exceed this MCL, energy-intensive drinking water treatment is required to reduce nitrate levels below 10 mg L(-1). Based on prior estimates of water supplies currently exceeding the nitrate MCL, we calculate that advanced drinking water treatment might require an additional 2360 million kWh annually (for nitrate affected areas only)--a 2100% increase in energy requirements for water treatment in those same areas--to mitigate nitrate contamination and meet the MCL requirement. We predict that projected increases in nitrate contamination in water may impact the energy consumed in the water treatment sector, because of the convergence of several related trends: (1) increasing cornstarch-based ethanol production, (2) increasing nutrient loading in surface water and groundwater resources as a consequence of increased corn-based ethanol production, (3) additional drinking water sources that exceed the MCL for nitrate, and (4) potentially more stringent drinking water standards for nitrate.

Food sources of nitrates and nitrites: the physiologic context for potential health benefits.

Science.gov (United States)

Hord, Norman G; Tang, Yaoping; Bryan, Nathan S

2009-07-01

The presence of nitrates and nitrites in food is associated with an increased risk of gastrointestinal cancer and, in infants, methemoglobinemia. Despite the physiologic roles for nitrate and nitrite in vascular and immune function, consideration of food sources of nitrates and nitrites as healthful dietary components has received little attention. Approximately 80% of dietary nitrates are derived from vegetable consumption; sources of nitrites include vegetables, fruit, and processed meats. Nitrites are produced endogenously through the oxidation of nitric oxide and through a reduction of nitrate by commensal bacteria in the mouth and gastrointestinal tract. As such, the dietary provision of nitrates and nitrites from vegetables and fruit may contribute to the blood pressure-lowering effects of the Dietary Approaches to Stop Hypertension (DASH) diet. We quantified nitrate and nitrite concentrations by HPLC in a convenience sample of foods. Incorporating these values into 2 hypothetical dietary patterns that emphasize high-nitrate or low-nitrate vegetable and fruit choices based on the DASH diet, we found that nitrate concentrations in these 2 patterns vary from 174 to 1222 mg. The hypothetical high-nitrate DASH diet pattern exceeds the World Health Organization's Acceptable Daily Intake for nitrate by 550% for a 60-kg adult. These data call into question the rationale for recommendations to limit nitrate and nitrite consumption from plant foods; a comprehensive reevaluation of the health effects of food sources of nitrates and nitrites is appropriate. The strength of the evidence linking the consumption of nitrate- and nitrite-containing plant foods to beneficial health effects supports the consideration of these compounds as nutrients.

Autotrophic denitrification of synthetic nitrate-contaminated groundwater in up-flow fixed-bed bioreactor by pumice as porous media

Directory of Open Access Journals (Sweden)

Masoud Tourang1

2018-05-01

Full Text Available Background: Background: Increasing nitrate concentrations in groundwater resources is considered a common environmental and public health problem worldwide. In this research, an autotrophic up-flow bioreactor with pumice as media was used to study the effects of the sulfur-to-nitrogen (S/N ratio and empty bed contact time (EBCT on nitrate removal efficiency and byproducts. Methods: Experiments were carried out in a 3.47 L up-flow, fixed-bed reactor with 3 sampling ports. To evaluate the overall impact of S/N ratio and EBCT on the performance of the bioreactor, several phases with different S/N ratios and EBCTs were applied. Results: At a constant S/N ratio of 3.85 g/g, as EBCT decreased from 24 hours to 2 hours, the nitrate removal efficiency decreased from 98% to 64%. On the other hand, at the desired EBCT of 4 hr, as S/N ratio decreased from 3.85 to 1.51 g/g, nitrate removal efficiency was reduced from 85% to 32%. Changing the EBCT and S/N ratio also affected the effluent nitrite and sulfate concentrations as byproducts. At the S/N ratio of 3.85 g/g and EBCT of 24 hours, effluent nitrite and sulfate concentrations were 0.1 mg NO2--N/L and 463 mg SO4 2-/L, respectively. Decreasing the S/N ratio to 1.51 g/g and the EBCT to 4 hours caused drastic changes in effluent nitrite and sulfate concentrations. Conclusion: The results indicated that the autotrophic denitrification with thiosulfate as electron donor and pumice as media was feasible and applicable for nitrate contaminated groundwater.

The nitrate response of a lowland catchment and groundwater travel times

Science.gov (United States)

van der Velde, Ype; Rozemeijer, Joachim; de Rooij, Gerrit; van Geer, Frans

2010-05-01

Intensive agriculture in lowland catchments causes eutrophication of downstream waters. To determine effective measures to reduce the nutrient loads from upstream lowland catchments, we need to understand the origin of long-term and daily variations in surface water nutrient concentrations. Surface water concentrations are often linked to travel time distributions of water passing through the saturated and unsaturated soil of the contributing catchment. This distribution represents the contact time over which sorption, desorption and degradation takes place. However, travel time distributions are strongly influenced by processes like tube drain flow, overland flow and the dynamics of draining ditches and streams and therefore exhibit strong daily and seasonal variations. The study we will present is situated in the 6.6 km2 Hupsel brook catchment in The Netherlands. In this catchment nitrate and chloride concentrations have been intensively monitored for the past 26 years under steadily decreasing agricultural inputs. We described the complicated dynamics of subsurface water fluxes as streams, ditches and tube drains locally switch between active or passive depending on the ambient groundwater level by a groundwater model with high spatial and temporal resolutions. A transient particle tracking approach is used to derive a unique catchment-scale travel time distribution for each day during the 26 year model period. These transient travel time distributions are not smooth distributions, but distributions that are strongly spiked reflecting the contribution of past rainfall events to the current discharge. We will show that a catchment-scale mass response function approach that only describes catchment-scale mixing and degradation suffices to accurately reproduce observed chloride and nitrate surface water concentrations as long as the mass response functions include the dynamics of travel time distributions caused by the highly variable connectivity of the surface

Stable isotope and groundwater flow dynamics of agricultural irrigation recharge into groundwater resources of the Central Valley, California

International Nuclear Information System (INIS)

Davisson, M.L.; Criss, R.E.

1995-01-01

Intensive agricultural irrigation and overdraft of groundwater in the Central Valley of California profoundly affect the regional quality and availability of shallow groundwater resources. In the natural state, the δ 18 O values of groundwater were relatively homogeneous (mostly -7.0 ± 0.5 per-thousand), reflecting local meteoric recharge that slowly (1-3m/yr) flowed toward the valley axis. Today, on the west side of the valley, the isotope distribution is dominated by high 18 O enclosures formed by recharge of evaporated irrigation waters, while the east side has bands of low 18 O groundwater indicating induced recharge from rivers draining the Sierra Nevada mountains. Changes in δ 18 O values caused by the agricultural recharge strongly correlate with elevated nitrate concentrations (5 to >100 mg/L) that form pervasive, non-point source pollutants. Small, west-side cities dependent solely on groundwater resources have experienced increases of >1.0 mg/L per year of nitrate for 10-30 years. The resultant high nitrates threaten the economical use of the groundwater for domestic purposes, and have forced some well shut-downs. Furthermore, since >80% of modern recharge is now derived from agricultural irrigation, and because modern recharge rates are ∼10 times those of the natural state, agricultural land retirement by urbanization will severely curtail the current safe-yields and promote overdraft pumping. Such overdrafting has occurred in the Sacramento metropolitan area for ∼40 years, creating cones of depression ∼25m deep. Today, groundwater withdrawal in Sacramento is approximately matched by infiltration of low 18 O water (-11.0 per-thousand) away from the Sacramento and American Rivers, which is estimated to occur at 100-300m/year from the sharp 18 O gradients in our groundwater isotope map

Iodate and nitrate transformation by Agrobacterium/Rhizobium related strain DVZ35 isolated from contaminated Hanford groundwater.

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Lee, Brady D; Ellis, Joshua T; Dodwell, Alex; Eisenhauer, Emalee E R; Saunders, Danielle L; Lee, M Hope

2018-05-15

Nitrate and radioiodine ( 129 I) contamination is widespread in groundwater underneath the Central Plateau of the Hanford Site. 129 I, a byproduct of nuclear fission, is of concern due to a 15.7 million year half-life, and toxicity. The Hanford 200 West Area contains plumes covering 4.3 km 2 with average 129 I concentrations of 3.5 pCi/L. Iodate accounts for 70.6% of the iodine present and organo-iodine and iodide make up 25.8% and 3.6%, respectively. Nitrate plumes encompassing the 129 I plumes have a surface area of 16 km 2 averaging 130 mg/L. A nitrate and iodate reducing bacterium closely related to Agrobacterium, strain DVZ35, was isolated from sediment incubated in a 129 I plume. Iodate removal efficiency was 36.3% in transition cultures, and 47.8% in anaerobic cultures. Nitrate (10 mM) was also reduced in the microcosm. When nitrate was spiked into the microcosms, iodate removal efficiency was 84.0% and 69.2% in transition and anaerobic cultures, respectively. Iodate reduction was lacking when nitrate was absent from the growth medium. These data indicate there is simultaneous reduction of nitrate and iodate by DVZ35, and iodate is reduced to iodide. Results provide the scientific basis for combined nitrogen and iodine cycling throughout the Hanford Site. Copyright © 2018. Published by Elsevier B.V.

Compositional cokriging for mapping the probability risk of groundwater contamination by nitrates.

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Pardo-Igúzquiza, Eulogio; Chica-Olmo, Mario; Luque-Espinar, Juan A; Rodríguez-Galiano, Víctor

2015-11-01

Contamination by nitrates is an important cause of groundwater pollution and represents a potential risk to human health. Management decisions must be made using probability maps that assess the nitrate concentration potential of exceeding regulatory thresholds. However these maps are obtained with only a small number of sparse monitoring locations where the nitrate concentrations have been measured. It is therefore of great interest to have an efficient methodology for obtaining those probability maps. In this paper, we make use of the fact that the discrete probability density function is a compositional variable. The spatial discrete probability density function is estimated by compositional cokriging. There are several advantages in using this approach: (i) problems of classical indicator cokriging, like estimates outside the interval (0,1) and order relations, are avoided; (ii) secondary variables (e.g. aquifer parameters) can be included in the estimation of the probability maps; (iii) uncertainty maps of the probability maps can be obtained; (iv) finally there are modelling advantages because the variograms and cross-variograms of real variables that do not have the restrictions of indicator variograms and indicator cross-variograms. The methodology was applied to the Vega de Granada aquifer in Southern Spain and the advantages of the compositional cokriging approach were demonstrated. Copyright © 2015 Elsevier B.V. All rights reserved.

Predicting redox conditions in groundwater at a regional scale

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Tesoriero, Anthony J.; Terziotti, Silvia; Abrams, Daniel B.

2015-01-01

Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the Chesapeake Bay watershed was predicted by relating dissolved O2 concentrations in groundwater samples to indicators of residence time and/or electron donor availability using logistic regression. Variables that describe surficial geology, position in the flow system, and soil drainage were important predictors of oxic water. The probability of encountering oxic groundwater at a 30 m depth and the depth to the bottom of the oxic layer were predicted for the Chesapeake Bay watershed. The influence of depth to the bottom of the oxic layer on stream nitrate concentrations and time lags (i.e., time period between land application of nitrogen and its effect on streams) are illustrated using model simulations for hypothetical basins. Regional maps of the probability of oxic groundwater should prove useful as indicators of groundwater susceptibility and stream susceptibility to contaminant sources derived from groundwater.

Evaluating vertical concentration profile of carbon source released from slow-releasing carbon source tablets and in situ biological nitrate denitrification activity

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Yeum, Y.; HAN, K.; Yoon, J.; Lee, J. H.; Song, K.; Kang, J. H.; Park, C. W.; Kwon, S.; Kim, Y.

2017-12-01

Slow-releasing carbon source tablets were manufactured during the design of a small-scale in situ biological denitrification system to reduce high-strength nitrate (> 30 mg N/L) from a point source such as livestock complexes. Two types of slow-releasing tablets, precipitating tablet (PT, apparent density of 2.0 g/mL) and floating tablet (FT), were prepared to achieve a vertically even distribution of carbon source (CS) in a well and an aquifer. Hydroxypropyl methylcellulose (HPMC) was used to control the release rate, and microcrystalline cellulose pH 101 (MCC 101) was added as a binder. The #8 sand was used as a precipitation agent for the PTs, and the floating agents for the FTs were calcium carbonate and citric acid. FTs floated within 30 min. and remained in water because of the buoyance from carbon dioxide, which formed during the acid-base reaction between citric acid and calcium carbonate. The longevities of PTs with 300 mg of HPMC and FTs with 400 mg of HPMC were 25.4 days and 37.3 days, respectively. We assessed vertical CS profile in a continuous flowing physical aquifer model (release test, RT) and its efficiency on biological nitrate denitrification (denitrification test, DT). During the RT, PTs, FTs and a tracer (as 1 mg rhodamine B/L) were initially injected into a well of physical aquifer model (PAM). Concentrations of CS and the tracer were monitored along the streamline in the PAM to evaluate vertical profile of CS. During the DT, the same experiment was performed as RT, except continuous injection of solution containing 30 mg N/L into the PAM to evaluate biological denitrification activity. As a result of RT, temporal profiles of CS were similar at 3 different depths of monitoring wells. These results suggest that simultaneous addition of PT and FT be suitable for achieving a vertically even distribution of the CS in the injection well and an aquifer. In DT, similar profile of CS was detected in the injection well, and nitrate was biologically

Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: Influence of legacy land use

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Kent, Robert; Landon, Matthew K.

2013-01-01

Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area.

Nitrates in Groundwater Discharges from the Azores Archipelago: Occurrence and Fluxes to Coastal Waters

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J. Virgílio Cruz

2017-02-01

Full Text Available Groundwater discharge is an important vector of chemical fluxes to the ocean environment, and as the concentration of nutrients is often higher in discharging groundwater, the deterioration of water quality in the receiving environment can be the result. The main objective of the present paper is to estimate the total NO3 flux to coastal water bodies due to groundwater discharge in the volcanic Azores archipelago (Portugal. Therefore, 78 springs discharging from perched-water bodies have been monitored since 2003, corresponding to cold (mean = 14.9 °C and low mineralized (47.2–583 µS/cm groundwater from the sodium-bicarbonate to sodium-chloride water types. A set of 36 wells was also monitored, presenting groundwater with a higher mineralization. The nitrate content in springs range between 0.02 and 37.4 mg/L, and the most enriched samples are associated to the impact of agricultural activities. The total groundwater NO3 flux to the ocean is estimated in the range of 5.23 × 103 to 190.6 × 103 mol/km2/a (∑ = ~523 × 103 mol/km2/a, exceeding the total flux associated to surface runoff (∑ = ~281 × 103 mol/km2/a. In the majority of the islands, the estimated fluxes are higher than runoff fluxes, with the exception of Pico (47.2%, Corvo (46% and Faial (7.2%. The total N-NO3 flux estimated in the Azores (~118.9 × 103 mol/km2/a is in the lower range of estimates made in other volcanic islands.

Evaluating the source of streamwater nitrate using d15N and d18O in nitrate in two watersheds in New Hampshire, USA

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Linda H. Pardo; Carol Kendall; Jennifer Pett-Ridge; Cecily C.Y. Chang; Cecily C.Y. Chang

2004-01-01

The natural abundance of nitrogen and oxygen isotopes in nitrate can be a powerful tool for identifying the source of nitrate in streamwater in forested watersheds, because the two main sources of nitrate, atmospheric deposition and microbial nitrification, have distinct d18O values. Using a simple mixing model, we estimated the relative fractions in streamwater...

Assessment of variables controlling nitrate dynamics in groundwater: is it a threat to surface aquatic ecosystems?

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Rasiah, V; Armour, J D; Cogle, A L

2005-01-01

The impact of fertilised cropping on nitrate-N dynamics in groundwater (GW) was assessed in a catchment from piezometers installed: (i) to different depths, (ii) in different soil types, (iii) on different positions on landscape, and (iv) compared with the Australian and New Zealand Environmental and Conservation Council guideline values provided for different aquatic ecosystems. The GW and NO(3)-N concentration dynamics were monitored in 39 piezometer wells, installed to 5-90 m depth, under fertilized sugarcane (Saccharum officinarum-S) in the Johnstone River Catchment, Australia, from 1999 January through September 2002. The median nitrate-N concentration ranged from 14 to 1511 microg L(-1), and the 80th percentile from 0 to 1341 microg L(-1). In 34 out of the 39 piezometer wells the 80th percentile or 80% of the nitrate-N values were higher than 30 microg L(-1), which is the maximum trigger value provided in the ANZECC table for sustainable health of different aquatic ecosystems. Nitrate-N concentration decreased with increasing well depth, increasing depth of water in wells, and with decreasing relief on landscape. Nitrate-N was higher in alluvial soil profiles than on those formed in-situ. Nitrate-N increased with increasing rainfall at the beginning of the rainy season, fluctuated during the peak rainy period, and then decreased when the rain ceased. The rapid decrease in GW after the rains ceased suggested potential existed for nitrate-N to be discharged as lateral-flow into streams. This may contribute towards the deterioration in the health of down-stream aquatic ecosystems.

Assessment of well vulnerability for groundwater source protection based on a solute transport model: a case study from Jilin City, northeast China

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Huan, Huan; Wang, Jinsheng; Lai, Desheng; Teng, Yanguo; Zhai, Yuanzheng

2015-05-01

Well vulnerability assessment is essential for groundwater source protection. A quantitative approach to assess well vulnerability in a well capture zone is presented, based on forward solute transport modeling. This method was applied to three groundwater source areas (Jiuzhan, Hadawan and Songyuanhada) in Jilin City, northeast China. The ratio of the maximum contaminant concentration at the well to the released concentration at the contamination source ( c max/ c 0) was determined as the well vulnerability indicator. The results indicated that well vulnerability was higher close to the pumping well. The well vulnerability in each groundwater source area was low. Compared with the other two source areas, the cone of depression at Jiuzhan resulted in higher spatial variability of c max/ c 0 and lower minimum c max/ c 0 by three orders of magnitude. Furthermore, a sensitivity analysis indicated that the denitrification rate in the aquifer was the most sensitive with respect to well vulnerability. A process to derive a NO3-N concentration at the pumping well is presented, based on determining the maximum nitrate loading limit to satisfy China's drinking-water quality standards. Finally, the advantages, disadvantages and prospects for improving the precision of this well vulnerability assessment approach are discussed.

A California Statewide App to Simulate Fate of Nitrate in Irrigated Agricultural System

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Diamantopoulos, E.; Walkinshaw, M.; Harter, T.; O'Geen, A. T.

2017-12-01

Groundwater resources are very important for California's economic development and environmental sustainability. Nitrate is by far the most widespread anthropogenic groundwater pollutant in California's mostly alluvial groundwater basins. Major sources are synthetic fertilizer and dairy manure, but also septic systems and urban wastewater effluent. Here, we evaluate agricultural soils in California according to their risk for nitrate leaching. We conducted over 1 million numerical simulations taking into account the effect of climate, crop type, irrigation and fertilization management scenarios across all 4,568 agricultural soil profiles occurring in California. The assessment was done solving 1-D Richards equation and the advection-dispersion equation numerically. This study is focused on the complex water and nitrate dynamics occurring at the shallow vadose zone (rootzone). The results of this study allow the construction of state-wide maps which can be used for the identification of high-risk regions and the design of agricultural nutrient management policy. We investigate how pollution risk can be minimized by adopting simple irrigation and fertilization methods. Furthermore, we show that these methods are more effective for the most permeable soil profiles along with high demanding crops in terms of fertilization amount and irrigation water. We also present how seasonal (winter) climate conditions contribute on nitrate leaching.

Effect of Co-Contaminant on Denitrification Removal of Nitrate in Drinking Water

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Arzu KILIÇ

2012-12-01

Full Text Available In recent years, nitrogenous fertilizers used in agriculture, unconscious and without treatment wastewater is discharged led to an increase in groundwater nitrate pollution. In many countries, nitrate concentration in the ground waters used as drinking water source exceeded the maximum allowable concentration of 10 mg/L NO3-N. According to a study, some wells in the Harran Plain contain nitrate as high as 180 mg/L NO3--N and the average concentration for whole plain is 35 mg/L NO3--N (Yesilnacar et al., 2008. Additionally, increased water consumption, unconscious use of fertilizers and pesticides has led to the emergence of co-contaminant in drinking water. Recently, hazardous to human health co-contaminant such as arsenic, pesticides, perchlorate, selenate, chromate, uranium are observed in the nitrate pollution drinking water. There are many processes used for the removal of nitrate. The physical–chemical technologies that can be used for nitrate removal are reverse osmosis, ion exchange and electrodialysis (Alvarez et al., 2007. Important disadvantages of these processes are their poor selectivity, high operation and maintenance costs and the generation of brine wastes after treatment. Consequently, biological treatment processes to convert nitrates to benign dinitrogen gas, could be an interesting alternative for the remediation of groundwater contaminated with nitrates. The aim of this article, effective and cheap method for the removal of nitrate from drinking water biological denitrification is to examine the usability of contaminated drinking water with co-contaminant pollutions.

Groundwater quality, age, and susceptibility and vulnerability to nitrate contamination with linkages to land use and groundwater flow, Upper Black Squirrel Creek Basin, Colorado, 2013

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Wellman, Tristan P.; Rupert, Michael G.

2016-03-03

The Upper Black Squirrel Creek Basin is located about 25 kilometers east of Colorado Springs, Colorado. The primary aquifer is a productive section of unconsolidated deposits that overlies bedrock units of the Denver Basin and is a critical resource for local water needs, including irrigation, domestic, and commercial use. The primary aquifer also serves an important regional role by the export of water to nearby communities in the Colorado Springs area. Changes in land use and development over the last decade, which includes substantial growth of subdivisions in the Upper Black Squirrel Creek Basin, have led to uncertainty regarding the potential effects to water quality throughout the basin. In response, the U.S. Geological Survey, in cooperation with Cherokee Metropolitan District, El Paso County, Meridian Service Metropolitan District, Mountain View Electric Association, Upper Black Squirrel Creek Groundwater Management District, Woodmen Hills Metropolitan District, Colorado State Land Board, and Colorado Water Conservation Board, and the stakeholders represented in the Groundwater Quality Study Committee of El Paso County conducted an assessment of groundwater quality and groundwater age with an emphasis on characterizing nitrate in the groundwater.

Nitrogen balance and groundwater nitrate contamination: Comparison among three intensive cropping systems on the North China Plain

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Ju, X.T. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Kou, C.L. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Institute of Soils and Fertilizers, Henan Academy of Agricultural Sciences, Zhengzhou 450002 (China); Zhang, F.S. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China)]. E-mail: zfs@cau.edu.cn; Christie, P. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Agricultural and Environmental Science Department, Queen' s University Belfast, Belfast BT9 5PX (United Kingdom)

2006-09-15

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha{sup -1} on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha{sup -1}, with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha{sup -1} in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha{sup -1} at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs. - Intensive greenhouse vegetable production systems may pose a greater nitrogen pollution threat than apple orchards or cereal rotations to soil and water quality in north China.

Nitrogen balance and groundwater nitrate contamination: Comparison among three intensive cropping systems on the North China Plain

International Nuclear Information System (INIS)

Ju, X.T.; Kou, C.L.; Zhang, F.S.; Christie, P.

2006-01-01

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha -1 on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha -1 , with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha -1 in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha -1 at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs. - Intensive greenhouse vegetable production systems may pose a greater nitrogen pollution threat than apple orchards or cereal rotations to soil and water quality in north China

Using Dual Isotopes and a Bayesian Isotope Mixing Model to Evaluate Nitrate Sources of Surface Water in a Drinking Water Source Watershed, East China

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Meng Wang

2016-08-01

Full Text Available A high concentration of nitrate (NO3− in surface water threatens aquatic systems and human health. Revealing nitrate characteristics and identifying its sources are fundamental to making effective water management strategies. However, nitrate sources in multi-tributaries and mix land use watersheds remain unclear. In this study, based on 20 surface water sampling sites for more than two years’ monitoring from April 2012 to December 2014, water chemical and dual isotopic approaches (δ15N-NO3− and δ18O-NO3− were integrated for the first time to evaluate nitrate characteristics and sources in the Huashan watershed, Jianghuai hilly region, China. Nitrate-nitrogen concentrations (ranging from 0.02 to 8.57 mg/L were spatially heterogeneous that were influenced by hydrogeological and land use conditions. Proportional contributions of five potential nitrate sources (i.e., precipitation; manure and sewage, M & S; soil nitrogen, NS; nitrate fertilizer; nitrate derived from ammonia fertilizer and rainfall were estimated by using a Bayesian isotope mixing model. The results showed that nitrate sources contributions varied significantly among different rainfall conditions and land use types. As for the whole watershed, M & S (manure and sewage and NS (soil nitrogen were major nitrate sources in both wet and dry seasons (from 28% to 36% for manure and sewage and from 24% to 27% for soil nitrogen, respectively. Overall, combining a dual isotopes method with a Bayesian isotope mixing model offered a useful and practical way to qualitatively analyze nitrate sources and transformations as well as quantitatively estimate the contributions of potential nitrate sources in drinking water source watersheds, Jianghuai hilly region, eastern China.

Probability of Elevated Nitrate Concentrations in Groundwater in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

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Rupert, Michael G.; Plummer, Niel

2009-01-01

This raster data set delineates the predicted probability of elevated nitrate concentrations in groundwater in the Eagle River watershed valley-fill aquifer, Eagle County, North-Central Colorado, 2006-2007. This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. This groundwater probability map and its associated probability maps was developed as follows: (1) A point data set of wells with groundwater quality and groundwater age data was overlaid with thematic layers of anthropogenic (related to human activities) and hydrogeologic data by using a geographic information system to assign each well values for depth to groundwater, distance to major streams and canals, distance to gypsum beds, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Statistical models predicting the probability of elevated nitrate concentrations, the probability of unmixed young water (using chlorofluorocarbon-11 concentrations and tritium activities), and the probability of elevated volatile organic compound concentrations were developed using logistic regression techniques. (3) The statistical models were entered into a GIS and the probability map was constructed.

Hydrodynamic analysis of potential groundwater extraction capacity increase: case study of 'Nelt' groundwater source at Dobanovci

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Bajić Dragoljub I.

2017-01-01

Full Text Available A comprehensive hydrodynamic analysis of the groundwater regime undertaken to assess the potential for expanding the 'Nelt' groundwater source at Dobanovci, or developing a new groundwater source for a future baby food factory, including the quantification of the impact on the production wells of the nearby 'Pepsi' groundwater source, is presented in the paper. The existing Nelt source is comprised of three active production wells that tap a subartesian aquifer formed in sands and gravelly sands; however, the analysis considers only the two nearest wells. A long-term group pumping test was con-ducted of production wells N-1 and N2 (Nelt source and production wells B-1 and B-2 (Pepsi source, while the piezometric head in the vicinity of these wells was monitored at observation well P-1, which is located in the area considered for Nelt source expansion. Data were collected at maximum pumping capacity of all the production wells. A hydrodynamic model of groundwater flow in the extended area of the Nelt source was generated for the purposes of the comprehensive hydrodynamic analysis. Hydrodynamic prognostic calculations addressed two solution alternatives for the capacity increase over a period of ten years. Licensed Visual MODFLOW Pro software, deemed to be at the very top in this field, was used for the calculations.

Nitrate fluxes to groundwater under citrus orchards in a Mediterranean climate: Observations, calibrated models, simulations and agro-hydrological conclusions

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Kurtzman, Daniel; Shapira, Roi H.; Bar-Tal, Asher; Fine, Pinchas; Russo, David

2013-08-01

Nitrate contamination of groundwater under land used for intensive-agriculture is probably the most worrisome agro-hydrological sustainability problem worldwide. Vadose-zone samples from 0 to 9 m depth under citrus orchards overlying an unconfined aquifer were analyzed for variables controlling water flow and the fate and transport of nitrogen fertilizers. Steady-state estimates of water and NO3-N fluxes to groundwater were found to vary spatially in the ranges of 90-330 mm yr- 1 and 50-220 kg ha- 1 yr- 1, respectively. Calibration of transient models to two selected vadose-zone profiles required limiting the concentration of NO3-N in the solution that is taken up by the roots to 30 mg L- 1. Results of an independent lysimeter experiment showed a similar nitrogen-uptake regime. Simulations of past conditions revealed a significant correlation between NO3-N flux to groundwater and the previous year's precipitation. Simulations of different nitrogen-application rates showed that using half of the nitrogen fertilizer added to the irrigation water by farmers would reduce average NO3-N flux to groundwater by 70%, decrease root nitrogen uptake by 20% and reduce the average pore water NO3-N concentration in the deep vadose zone to below the Israeli drinking water standard; hence this rate of nitrogen application was found to be agro-hydrologically sustainable. Beyond the investigation of nitrate fluxes to groundwater under citrus orchards and the interesting case-study aspects, this work demonstrates a methodology that enables skillful decisions concerning joint sustainability of both the water resource and agricultural production in a common environmental setting.

Quantitative identification of nitrate pollution sources and uncertainty analysis based on dual isotope approach in an agricultural watershed.

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Ji, Xiaoliang; Xie, Runting; Hao, Yun; Lu, Jun

2017-10-01

Quantitative identification of nitrate (NO 3 - -N) sources is critical to the control of nonpoint source nitrogen pollution in an agricultural watershed. Combined with water quality monitoring, we adopted the environmental isotope (δD-H 2 O, δ 18 O-H 2 O, δ 15 N-NO 3 - , and δ 18 O-NO 3 - ) analysis and the Markov Chain Monte Carlo (MCMC) mixing model to determine the proportions of riverine NO 3 - -N inputs from four potential NO 3 - -N sources, namely, atmospheric deposition (AD), chemical nitrogen fertilizer (NF), soil nitrogen (SN), and manure and sewage (M&S), in the ChangLe River watershed of eastern China. Results showed that NO 3 - -N was the main form of nitrogen in this watershed, accounting for approximately 74% of the total nitrogen concentration. A strong hydraulic interaction existed between the surface and groundwater for NO 3 - -N pollution. The variations of the isotopic composition in NO 3 - -N suggested that microbial nitrification was the dominant nitrogen transformation process in surface water, whereas significant denitrification was observed in groundwater. MCMC mixing model outputs revealed that M&S was the predominant contributor to riverine NO 3 - -N pollution (contributing 41.8% on average), followed by SN (34.0%), NF (21.9%), and AD (2.3%) sources. Finally, we constructed an uncertainty index, UI 90 , to quantitatively characterize the uncertainties inherent in NO 3 - -N source apportionment and discussed the reasons behind the uncertainties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uranium in groundwater--Fertilizers versus geogenic sources.

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Liesch, Tanja; Hinrichsen, Sören; Goldscheider, Nico

2015-12-01

Due to its radiological and toxicological properties even at low concentration levels, uranium is increasingly recognized as relevant contaminant in drinking water from aquifers. Uranium originates from different sources, including natural or geogenic, mining and industrial activities, and fertilizers in agriculture. The goal of this study was to obtain insights into the origin of uranium in groundwater while differentiating between geogenic sources and fertilizers. A literature review concerning the sources and geochemical processes affecting the occurrence and distribution of uranium in the lithosphere, pedosphere and hydrosphere provided the background for the evaluation of data on uranium in groundwater at regional scale. The state of Baden-Württemberg, Germany, was selected for this study, because of its hydrogeological and land-use diversity, and for reasons of data availability. Uranium and other parameters from N=1935 groundwater monitoring sites were analyzed statistically and geospatially. Results show that (i) 1.6% of all water samples exceed the German legal limit for drinking water (10 μg/L); (ii) The range and spatial distribution of uranium and occasional peak values seem to be related to geogenic sources; (iii) There is a clear relation between agricultural land-use and low-level uranium concentrations, indicating that fertilizers generate a measurable but low background of uranium in groundwater. Copyright © 2015 Elsevier B.V. All rights reserved.

Assessing regional groundwater stress for nations using multiple data sources with the groundwater footprint

International Nuclear Information System (INIS)

Gleeson, Tom; Wada, Yoshihide

2013-01-01

Groundwater is a critical resource for agricultural production, ecosystems, drinking water and industry, yet groundwater depletion is accelerating, especially in a number of agriculturally important regions. Assessing the stress of groundwater resources is crucial for science-based policy and management, yet water stress assessments have often neglected groundwater and used single data sources, which may underestimate the uncertainty of the assessment. We consistently analyze and interpret groundwater stress across whole nations using multiple data sources for the first time. We focus on two nations with the highest national groundwater abstraction rates in the world, the United States and India, and use the recently developed groundwater footprint and multiple datasets of groundwater recharge and withdrawal derived from hydrologic models and data synthesis. A minority of aquifers, mostly with known groundwater depletion, show groundwater stress regardless of the input dataset. The majority of aquifers are not stressed with any input data while less than a third are stressed for some input data. In both countries groundwater stress affects agriculturally important regions. In the United States, groundwater stress impacts a lower proportion of the national area and population, and is focused in regions with lower population and water well density compared to India. Importantly, the results indicate that the uncertainty is generally greater between datasets than within datasets and that much of the uncertainty is due to recharge estimates. Assessment of groundwater stress consistently across a nation and assessment of uncertainty using multiple datasets are critical for the development of a science-based rationale for policy and management, especially with regard to where and to what extent to focus limited research and management resources. (letter)

Groundwater vulnerability and risk mapping using GIS, modeling and a fuzzy logic tool.

Science.gov (United States)

Nobre, R C M; Rotunno Filho, O C; Mansur, W J; Nobre, M M M; Cosenza, C A N

2007-12-07

A groundwater vulnerability and risk mapping assessment, based on a source-pathway-receptor approach, is presented for an urban coastal aquifer in northeastern Brazil. A modified version of the DRASTIC methodology was used to map the intrinsic and specific groundwater vulnerability of a 292 km(2) study area. A fuzzy hierarchy methodology was adopted to evaluate the potential contaminant source index, including diffuse and point sources. Numerical modeling was performed for delineation of well capture zones, using MODFLOW and MODPATH. The integration of these elements provided the mechanism to assess groundwater pollution risks and identify areas that must be prioritized in terms of groundwater monitoring and restriction on use. A groundwater quality index based on nitrate and chloride concentrations was calculated, which had a positive correlation with the specific vulnerability index.

Fertilizer Induced Nitrate Pollution in RCW: Calibration of the DNDC Model

Science.gov (United States)

El Hailouch, E.; Hornberger, G.; Crane, J. W.

2012-12-01

Fertilizer is widely used among urban and suburban households due to the socially driven attention of homeowners to lawn appearance. With high nitrogen content, fertilizer considerably impacts the environment through the emission of the highly potent greenhouse gas nitrous oxide and the leaching of nitrate. Nitrate leaching is significantly important because fertilizer sourced nitrate that is partially leached into soil causes groundwater pollution. In an effort to model the effect of fertilizer application on the environment, the geochemical DeNitrification-DeComposition model (DNDC) was previously developed to quantitatively measure the effects of fertilizer use. The purpose of this study is to use this model more effectively on a large scale through a measurement based calibration. For this reason, leaching was measured and studied on 12 sites in the Richland Creek Watershed (RCW). Information about the fertilization and irrigation regimes of these sites was collected, along with lysimeter readings that gave nitrate fluxes in the soil. A study of the amount and variation in nitrate leaching with respect to the varying geographical locations, time of the year, and fertilization and irrigation regimes has lead to a better understanding of the driving forces behind nitrate leaching. Quantifying the influence of each of these parameters allows for a more accurate calibration of the model thus permitting use that extends beyond the RCW. Measurement of nitrate leaching on a statewide or nationwide level in turn will help guide efforts in the reduction of groundwater pollution caused by fertilizer.

Relations that affect the probability and prediction of nitrate concentration in private wells in the glacial aquifer system in the United States

Science.gov (United States)

Warner, Kelly L.; Arnold, Terri L.

2010-01-01

Nitrate in private wells in the glacial aquifer system is a concern for an estimated 17 million people using private wells because of the proximity of many private wells to nitrogen sources. Yet, less than 5 percent of private wells sampled in this study contained nitrate in concentrations that exceeded the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL) of 10 mg/L (milligrams per liter) as N (nitrogen). However, this small group with nitrate concentrations above the USEPA MCL includes some of the highest nitrate concentrations detected in groundwater from private wells (77 mg/L). Median nitrate concentration measured in groundwater from private wells in the glacial aquifer system (0.11 mg/L as N) is lower than that in water from other unconsolidated aquifers and is not strongly related to surface sources of nitrate. Background concentration of nitrate is less than 1 mg/L as N. Although overall nitrate concentration in private wells was low relative to the MCL, concentrations were highly variable over short distances and at various depths below land surface. Groundwater from wells in the glacial aquifer system at all depths was a mixture of old and young water. Oxidation and reduction potential changes with depth and groundwater age were important influences on nitrate concentrations in private wells. A series of 10 logistic regression models was developed to estimate the probability of nitrate concentration above various thresholds. The threshold concentration (1 to 10 mg/L) affected the number of variables in the model. Fewer explanatory variables are needed to predict nitrate at higher threshold concentrations. The variables that were identified as significant predictors for nitrate concentration above 4 mg/L as N included well characteristics such as open-interval diameter, open-interval length, and depth to top of open interval. Environmental variables in the models were mean percent silt in soil, soil type, and mean depth to

Nitrate source apportionment in a subtropical watershed using Bayesian model

International Nuclear Information System (INIS)

Yang, Liping; Han, Jiangpei; Xue, Jianlong; Zeng, Lingzao; Shi, Jiachun; Wu, Laosheng; Jiang, Yonghai

2013-01-01

Nitrate (NO 3 − ) pollution in aquatic system is a worldwide problem. The temporal distribution pattern and sources of nitrate are of great concern for water quality. The nitrogen (N) cycling processes in a subtropical watershed located in Changxing County, Zhejiang Province, China were greatly influenced by the temporal variations of precipitation and temperature during the study period (September 2011 to July 2012). The highest NO 3 − concentration in water was in May (wet season, mean ± SD = 17.45 ± 9.50 mg L −1 ) and the lowest concentration occurred in December (dry season, mean ± SD = 10.54 ± 6.28 mg L −1 ). Nevertheless, no water sample in the study area exceeds the WHO drinking water limit of 50 mg L −1 NO 3 − . Four sources of NO 3 − (atmospheric deposition, AD; soil N, SN; synthetic fertilizer, SF; manure and sewage, M and S) were identified using both hydrochemical characteristics [Cl − , NO 3 − , HCO 3 − , SO 4 2− , Ca 2+ , K + , Mg 2+ , Na + , dissolved oxygen (DO)] and dual isotope approach (δ 15 N–NO 3 − and δ 18 O–NO 3 − ). Both chemical and isotopic characteristics indicated that denitrification was not the main N cycling process in the study area. Using a Bayesian model (stable isotope analysis in R, SIAR), the contribution of each source was apportioned. Source apportionment results showed that source contributions differed significantly between the dry and wet season, AD and M and S contributed more in December than in May. In contrast, SN and SF contributed more NO 3 − to water in May than that in December. M and S and SF were the major contributors in December and May, respectively. Moreover, the shortcomings and uncertainties of SIAR were discussed to provide implications for future works. With the assessment of temporal variation and sources of NO 3 − , better agricultural management practices and sewage disposal programs can be implemented to sustain water quality in subtropical watersheds

Identifying nitrate sources and transformations in surface water by combining dual isotopes of nitrate and stable isotope mixing model in a watershed with different land uses and multi-tributaries

Science.gov (United States)

Wang, Meng; Lu, Baohong

2017-04-01

Nitrate is essential for the growth and survival of plants, animals and humans. However, excess nitrate in drinking water is regarded as a health hazard as it is linked to infant methemoglobinemia and esophageal cancer. Revealing nitrate characteristics and identifying its sources are fundamental for making effective water management strategies, but nitrate sources in multi-tributaries and mixed land covered watersheds remain unclear. It is difficult to determine the predominant NO3- sources using conventional water quality monitoring techniques. In our study, based on 20 surface water sampling sites for more than two years' monitoring from April 2012 to December 2014, water chemical and dual isotopic approaches (δ15N-NO3- and δ18O-NO3-) were integrated for the first time to evaluate nitrate characteristics and sources in the Huashan watershed, Jianghuai hilly region, East China. The results demonstrated that nitrate content in surface water was relatively low in the downstream (nitrate was observed at the source of the river in one of the sub-watersheds, which exhibited an exponential decline along the stream due to dilution, absorption by aquatic plants, and high forest cover. Although dramatically decline of nitrate occurred along the stream, denitrification was not found in surface water by analyzing δ15N-NO3- and δ18O-NO3- relationship. Proportional contributions of five potential nitrate sources (i.e., precipitation; manure and sewage; soil nitrogen; nitrate fertilizer; nitrate derived from ammonia fertilizer and rainfall) were estimated using a Bayesian isotope mixing model. Model results indicated nitrate sources varied significantly among different rainfall conditions, land use types, as well as anthropologic activities. In summary, coupling dual isotopes of nitrate (δ15N-NO3- and δ18O-NO3-, simultaneously) with a Bayesian isotope mixing model offers a useful and practical way to qualitatively analyze nitrate sources and transformations as well as

Sustainability of natural attenuation of nitrate in agricultural aquifers

Science.gov (United States)

Green, Christopher T.; Bekins, Barbara A.

2010-01-01

Increased concentrations of nitrate in groundwater in agricultural areas, coinciding with increased use of chemical and organic fertilizers, have raised concern because of risks to environmental and human health. At some sites, these problems are mitigated by natural attenuation of nitrate as a result of microbially mediated reactions. Results from U.S. Geological Survey (USGS) research under the National Water-Quality Assessment (NAWQA) program show that reactions of dissolved nitrate with solid aquifer minerals and organic carbon help lower nitrate concentrations in groundwater beneath agricultural fields. However, increased fluxes of nitrate cause ongoing depletion of the finite pool of solid reactants. Consumption of the solid reactants diminishes the capacity of the aquifer to remove nitrate, calling into question the long-term sustainability of these natural attenuation processes.

Riverscape and Groundwater Preservation: A Choice Experiment

Science.gov (United States)

Tempesta, T.; Vecchiato, D.

2013-12-01

This study presents a quantitative approach to support policy decision making for the preservation of riverscapes, taking into account the EC Water Framework Directive (2000/60/EC) and the EC Nitrates Directive (91/676/EEC) concerning the protection of waters against nitrate pollution from agricultural sources. A choice experiment was applied to evaluate the benefits, as perceived by inhabitants, of the implementation of policies aiming to reduce the concentration of nitrates in groundwater, preserve the riverscape by maintaining a minimum water flow and increasing hedges and woods along the Serio River in central northern Italy. Findings suggested that people were particularly concerned about groundwater quality, probably because it is strongly linked to human health. Nevertheless, it was interesting to observe that people expressed a high willingness to pay for actions that affect the riverscape as a whole (such as the minimum water flow maintenance plus reforestation). This is probably due to the close connection between the riverscape and the functions of the river area for recreation, health purposes, and biodiversity preservation.

Nitrate concentration in spring water at the Nogawa basin and its possible source

International Nuclear Information System (INIS)

Yoshida, Kazuhiro; Ogura, Norio

1978-01-01

Fluctuation of nitrate concentration in spring water at the Nogawa basin was studied during 1976 - 1977, and the possible source of nitrate nitrogen was discussed. Nitrate concentration in spring water at the station N-O in Kokubunji, Tokyo ranged from 360 to 574 μg at/l with an average value of 502 μg at/l. It seemed that the effluent of spring water at N-O was influenced by rainfall within a short period. A laboratory experiment on production of nitrate in soil showed that ammonium nitrogen added to fresh soil was transformed quantitatively to nitrate nitrogen during 23 days incubation. Thd sup(delta15)N value of nitrate nitrogen in spring water (+0.89%) was similar to that of ammonium nitrogen in sewage (+0.82%) discharging into the Nogawa River. In the area near N-O, domestic wastes have been discharged into the Nogawa River by simple sewers or percolated downward through the soil. These results suggest that one of the main source of nitrate nitrogen in spring water is ammonium and organic nitrogen in domestic wastes. (author)

Burn site groundwater interim measures work plan.

Energy Technology Data Exchange (ETDEWEB)

Witt, Jonathan L. (North Wind, Inc., Idaho Falls, ID); Hall, Kevin A. (North Wind, Inc., Idaho Falls, ID)

2005-05-01

This Work Plan identifies and outlines interim measures to address nitrate contamination in groundwater at the Burn Site, Sandia National Laboratories/New Mexico. The New Mexico Environment Department has required implementation of interim measures for nitrate-contaminated groundwater at the Burn Site. The purpose of interim measures is to prevent human or environmental exposure to nitrate-contaminated groundwater originating from the Burn Site. This Work Plan details a summary of current information about the Burn Site, interim measures activities for stabilization, and project management responsibilities to accomplish this purpose.

Nitrate-N movement in groundwater from the land application of treated municipal wastewater and other sources in the Wakulla Springs springshed, Leon and Wakulla Counties, Florida, 1966-2018

Science.gov (United States)

Davis, J. Hal; Katz, Brian G.; Griffin, Dale W.

2010-01-01

The City of Tallahassee began a pilot study in 1966 at the Southwest Farm sprayfield to determine whether disposal of treated municipal wastewater using center pivot irrigation techniques to uptake nitrate-nitrogen (nitrate-N) is feasible. Based on the early success of this project, a new, larger Southeast Farm sprayfield was opened in November 1980. However, a recent 2002 study indicated that nitrate-N from these operations may be moving through the Upper Floridan aquifer to Wakulla Springs, thus causing nitrate-N concentrations to increase in the spring water. The increase in nitrate-N combined with the generally clear spring water and abundant sunshine may be encouraging invasive plant species growth. Determining the link between the nitrate-N application at the sprayfields and increased nitrate-N levels is complicated because there are other sources of nitrate-N in the Wakulla Springs springshed, including atmospheric deposition, onsite sewage disposal systems, disposal of biosolids by land spreading, creeks discharging into sinks, domestic fertilizer application, and livestock wastes.

Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: influence of legacy land use.

Science.gov (United States)

Kent, Robert; Landon, Matthew K

2013-05-01

Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p<0.10) increase in nitrate and 14 wells (11%) had a significant decrease in nitrate. For TDS, 46 wells (35%) had a significant increase and 8 wells (6%) had a significant decrease. Slopes for the observed significant trends ranged from -0.44 to 0.91 mg/L/yr for nitrate (as N) and -8 to 13 mg/L/yr for TDS. Increasing nitrate trends were associated with greater well depth, higher percentage of agricultural land use, and being closer to the distal end of the flow system. Decreasing nitrate trends were associated with the occurrence of volatile organic compounds (VOCs); VOC occurrence decreases with increasing depth. The relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area. Published by Elsevier B.V.

18O isotopic characterisation of non-point source contributed heavy metals (Zn and Cu) contamination of groundwater

International Nuclear Information System (INIS)

Datta, P.S.; Manjaiah, K.M.; Tyagi, S.K.

1999-01-01

In many urbanised areas, fast depletion and severe degradation of the of groundwater resource with contaminants such as nitrate, fluoride, and heavy metals is a common phenomenon, resulting in zonal disparity in fresh water availability. Therefore, for protection of groundwater from pollution and depletion, it is a matter of concern for the planners and decision makers to clearly characterise the sources of contamination and to search for an alternative approach for groundwater development and management. In this context, a new approach is presented here, based on monitoring of 18 O stable isotopic and heavy metals composition of groundwater, to clearly characterise non-point source contributed heavy metals pollution of groundwater in northern parts of Delhi area. In the investigated area, the Cu content in the groundwater ranges from 3-41 μg/l and Zn content ranges from 5-182 μg/l, showing considerable variation from location to location as well as within the small parts of a location. Wide variation in the 18 O stable isotope content of groundwater (δ value of -5.7 per mille to -8.5 per mille) is due to significant variation in the δ 18 O-contents of rainfall with space and time, as well as intensity and distribution of rainfall. Enrichment in 18 O composition with increasing Cu and Zn levels in groundwater suggest that infiltration of rain water, irrigation water and surface run-off water from the surrounding farm lands, along with agrochemicals and other salts present in the soil, to be the main processes causing groundwater contamination. The concentration of Cu and Zn in groundwater vary spatially, due to different degrees of evaporation/recharge, amounts of fertiliser applied and wastes disposed, adsorption/dispersion of species in the soils and lateral mixing of groundwater. Two opposite mechanisms adsorption and redistribution of infiltrating water along with Zn and Cu species in the soil zone are likely to affect the movement of the Zn and Cu species

Groundwater Pollution Source Identification using Linked ANN-Optimization Model

Science.gov (United States)

Ayaz, Md; Srivastava, Rajesh; Jain, Ashu

2014-05-01

Groundwater is the principal source of drinking water in several parts of the world. Contamination of groundwater has become a serious health and environmental problem today. Human activities including industrial and agricultural activities are generally responsible for this contamination. Identification of groundwater pollution source is a major step in groundwater pollution remediation. Complete knowledge of pollution source in terms of its source characteristics is essential to adopt an effective remediation strategy. Groundwater pollution source is said to be identified completely when the source characteristics - location, strength and release period - are known. Identification of unknown groundwater pollution source is an ill-posed inverse problem. It becomes more difficult for real field conditions, when the lag time between the first reading at observation well and the time at which the source becomes active is not known. We developed a linked ANN-Optimization model for complete identification of an unknown groundwater pollution source. The model comprises two parts- an optimization model and an ANN model. Decision variables of linked ANN-Optimization model contain source location and release period of pollution source. An objective function is formulated using the spatial and temporal data of observed and simulated concentrations, and then minimized to identify the pollution source parameters. In the formulation of the objective function, we require the lag time which is not known. An ANN model with one hidden layer is trained using Levenberg-Marquardt algorithm to find the lag time. Different combinations of source locations and release periods are used as inputs and lag time is obtained as the output. Performance of the proposed model is evaluated for two and three dimensional case with error-free and erroneous data. Erroneous data was generated by adding uniformly distributed random error (error level 0-10%) to the analytically computed concentration

Combining stable isotopes with contamination indicators: A method for improved investigation of nitrate sources and dynamics in aquifers with mixed nitrogen inputs.

Science.gov (United States)

Minet, E P; Goodhue, R; Meier-Augenstein, W; Kalin, R M; Fenton, O; Richards, K G; Coxon, C E

2017-11-01

Excessive nitrate (NO 3 - ) concentration in groundwater raises health and environmental issues that must be addressed by all European Union (EU) member states under the Nitrates Directive and the Water Framework Directive. The identification of NO 3 - sources is critical to efficiently control or reverse NO 3 - contamination that affects many aquifers. In that respect, the use of stable isotope ratios 15 N/ 14 N and 18 O/ 16 O in NO 3 - (expressed as δ 15 N-NO 3 - and δ 18 O-NO 3 - , respectively) has long shown its value. However, limitations exist in complex environments where multiple nitrogen (N) sources coexist. This two-year study explores a method for improved NO 3 - source investigation in a shallow unconfined aquifer with mixed N inputs and a long established NO 3 - problem. In this tillage-dominated area of free-draining soil and subsoil, suspected NO 3 - sources were diffuse applications of artificial fertiliser and organic point sources (septic tanks and farmyards). Bearing in mind that artificial diffuse sources were ubiquitous, groundwater samples were first classified according to a combination of two indicators relevant of point source contamination: presence/absence of organic point sources (i.e. septic tank and/or farmyard) near sampling wells and exceedance/non-exceedance of a contamination threshold value for sodium (Na + ) in groundwater. This classification identified three contamination groups: agricultural diffuse source but no point source (D+P-), agricultural diffuse and point source (D+P+) and agricultural diffuse but point source occurrence ambiguous (D+P±). Thereafter δ 15 N-NO 3 - and δ 18 O-NO 3 - data were superimposed on the classification. As δ 15 N-NO 3 - was plotted against δ 18 O-NO 3 - , comparisons were made between the different contamination groups. Overall, both δ variables were significantly and positively correlated (p contamination groups revealed that denitrification did not occur in the absence of point

Predicting redox-sensitive contaminant concentrations in groundwater using random forest classification

Science.gov (United States)

Tesoriero, Anthony J.; Gronberg, Jo Ann; Juckem, Paul F.; Miller, Matthew P.; Austin, Brian P.

2017-08-01

Machine learning techniques were applied to a large (n > 10,000) compliance monitoring database to predict the occurrence of several redox-active constituents in groundwater across a large watershed. Specifically, random forest classification was used to determine the probabilities of detecting elevated concentrations of nitrate, iron, and arsenic in the Fox, Wolf, Peshtigo, and surrounding watersheds in northeastern Wisconsin. Random forest classification is well suited to describe the nonlinear relationships observed among several explanatory variables and the predicted probabilities of elevated concentrations of nitrate, iron, and arsenic. Maps of the probability of elevated nitrate, iron, and arsenic can be used to assess groundwater vulnerability and the vulnerability of streams to contaminants derived from groundwater. Processes responsible for elevated concentrations are elucidated using partial dependence plots. For example, an increase in the probability of elevated iron and arsenic occurred when well depths coincided with the glacial/bedrock interface, suggesting a bedrock source for these constituents. Furthermore, groundwater in contact with Ordovician bedrock has a higher likelihood of elevated iron concentrations, which supports the hypothesis that groundwater liberates iron from a sulfide-bearing secondary cement horizon of Ordovician age. Application of machine learning techniques to existing compliance monitoring data offers an opportunity to broadly assess aquifer and stream vulnerability at regional and national scales and to better understand geochemical processes responsible for observed conditions.

Relationship of nitrate isotopic character to population density in the Loess Plateau of Northwest China

International Nuclear Information System (INIS)

Xing, Meng; Liu, Weiguo; Wang, Zhoufeng; Hu, Jing

2013-01-01

Highlights: • Investigated nitrate isotopic composition in Xi’an. • δ 15 N–NO 3 - enrich process is mainly caused by the anthropogenic activity. • δ 15 N–NO 3 - value useful for tracing nitrate source. • δ 15 N–NO 3 - value and population density show a significant logarithmic correlation. - Abstract: Nitrate pollution of groundwater is an increasingly serious anthropogenic problem. In this study, the hydrogeochemistry of major ions and stable isotope ratios of NO 3 - in groundwater were determined to identify the contamination sources and chemical transformation processes occurring in the shallow groundwater of Xi’an, the capital of Shaanxi province, NW China. Of a total of 32 groundwater samples, 31% had NO 3 - –N concentrations exceeding the accepted drinking water limit of 10 mg-N L −1 . Most of these samples were from the urban center of the study area, while samples with <10 mg-N L −1 were mainly from suburban areas. Combined with information on NO 3 - and Cl − , the variation in isotopes of NO 3 - in the groundwater suggest a mixing of multiple NO 3 - sources in areas on the urban/suburban border. By determining rainwater and river water NO 3 - isotopic values, the groundwater recharge mode can be deduced for Xi’an city. Chemical fertilizers and nitrification of N-containing organic materials contribute NO 3 - to suburban groundwater, while sewage effluent and nitrification dominate NO 3 - distribution in urban groundwater. Nitrification from organic soil N, manure and sewage was significant in some sampling areas, and NO 3 - isotopic values from groundwater in Xi’an indicated that the effects of denitrification were not an obvious contributor. Thus, the δ 15 N–NO 3 - enrichment process is mainly caused by the intense anthropogenic activity in the city center. From the urban center to suburban areas, the mean δ 15 N–NO 3 - values varied from +16.4‰ to +5.4‰, and the mean NO 3 - –N concentrations varied from 28

Nitrate source apportionment in a subtropical watershed using Bayesian model

Energy Technology Data Exchange (ETDEWEB)

Yang, Liping; Han, Jiangpei; Xue, Jianlong; Zeng, Lingzao [College of Environmental and Natural Resource Sciences, Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, Zhejiang University, Hangzhou, 310058 (China); Shi, Jiachun, E-mail: jcshi@zju.edu.cn [College of Environmental and Natural Resource Sciences, Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, Zhejiang University, Hangzhou, 310058 (China); Wu, Laosheng, E-mail: laowu@zju.edu.cn [College of Environmental and Natural Resource Sciences, Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, Zhejiang University, Hangzhou, 310058 (China); Jiang, Yonghai [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012 (China)

2013-10-01

Nitrate (NO{sub 3}{sup −}) pollution in aquatic system is a worldwide problem. The temporal distribution pattern and sources of nitrate are of great concern for water quality. The nitrogen (N) cycling processes in a subtropical watershed located in Changxing County, Zhejiang Province, China were greatly influenced by the temporal variations of precipitation and temperature during the study period (September 2011 to July 2012). The highest NO{sub 3}{sup −} concentration in water was in May (wet season, mean ± SD = 17.45 ± 9.50 mg L{sup −1}) and the lowest concentration occurred in December (dry season, mean ± SD = 10.54 ± 6.28 mg L{sup −1}). Nevertheless, no water sample in the study area exceeds the WHO drinking water limit of 50 mg L{sup −1} NO{sub 3}{sup −}. Four sources of NO{sub 3}{sup −} (atmospheric deposition, AD; soil N, SN; synthetic fertilizer, SF; manure and sewage, M and S) were identified using both hydrochemical characteristics [Cl{sup −}, NO{sub 3}{sup −}, HCO{sub 3}{sup −}, SO{sub 4}{sup 2−}, Ca{sup 2+}, K{sup +}, Mg{sup 2+}, Na{sup +}, dissolved oxygen (DO)] and dual isotope approach (δ{sup 15}N–NO{sub 3}{sup −} and δ{sup 18}O–NO{sub 3}{sup −}). Both chemical and isotopic characteristics indicated that denitrification was not the main N cycling process in the study area. Using a Bayesian model (stable isotope analysis in R, SIAR), the contribution of each source was apportioned. Source apportionment results showed that source contributions differed significantly between the dry and wet season, AD and M and S contributed more in December than in May. In contrast, SN and SF contributed more NO{sub 3}{sup −} to water in May than that in December. M and S and SF were the major contributors in December and May, respectively. Moreover, the shortcomings and uncertainties of SIAR were discussed to provide implications for future works. With the assessment of temporal variation and sources of NO{sub 3}{sup −}, better

Dynamic surface water-groundwater exchange and nitrogen transport in the riparian aquifer of a tidal river

Science.gov (United States)

Sawyer, A. H.; Barnes, R.; Wallace, C.; Knights, D.; Tight, D.; Bayer, M.

2017-12-01

Tides in coastal rivers can propagate tens to hundreds of kilometers inland and drive large daily changes in water and nitrogen exchange across the sediment-water interface. We use field observations and numerical models to illuminate hydrodynamic controls on nitrogen export from the riparian aquifer to a fresh, tidal reach of White Clay Creek (Delaware, USA). In the banks, an aerobic zone with high groundwater nitrate concentrations occurs near the fluctuating water table. Continuous depth-resolved measurements of redox potential suggest that this zone is relatively stable over tidal timescales but moves up or down in response to storms. The main source of dissolved oxygen is soil air that is imbibed in the zone of water table fluctuations, and the source of nitrate is likely nitrification of ammonium produced locally from the mineralization of organic matter in floodplain soils. Much of the nitrate is removed by denitrification along oscillating flow paths towards the channel. Within centimeters of the sediment-water interface, denitrification is limited by the mixing of groundwater with oxygen-rich river water. Our models predict that the benthic zones of tidal rivers play an important role in removing new nitrate inputs from discharging groundwater but may be less effective at removing nitrate from river water. Nitrate removal and production rates are expected to vary significantly along tidal rivers as permeability, organic matter content, tidal range vary. It is imperative that we understand nitrogen dynamics along tidal rivers and their role in nitrogen export to the coast.

[Research advances in identifying nitrate pollution sources of water environment by using nitrogen and oxygen stable isotopes].

Science.gov (United States)

Mao, Wei; Liang, Zhi-wei; Li, Wei; Zhu, Yao; Yanng, Mu-yi; Jia, Chao-jie

2013-04-01

Water body' s nitrate pollution has become a common and severe environmental problem. In order to ensure human health and water environment benign evolution, it is of great importance to effectively identify the nitrate pollution sources of water body. Because of the discrepant composition of nitrogen and oxygen stable isotopes in different sources of nitrate in water body, nitrogen and oxygen stable isotopes can be used to identify the nitrate pollution sources of water environment. This paper introduced the fractionation factors of nitrogen and oxygen stable isotopes in the main processes of nitrogen cycling and the composition of these stable isotopes in main nitrate sources, compared the advantages and disadvantages of five pre-treatment methods for analyzing the nitrogen and oxygen isotopes in nitrate, and summarized the research advances in this aspect into three stages, i. e. , using nitrogen stable isotope alone, using nitrogen and oxygen stable isotopes simultaneously, and combining with mathematical models. The future research directions regarding the nitrate pollution sources identification of water environment were also discussed.

Screening of sustainable groundwater sources for integration into a regional drought-prone water supply system

Directory of Open Access Journals (Sweden)

H. Lucas

2009-07-01

Full Text Available This paper reports on the qualitative and quantitative screening of groundwater sources for integration into the public water supply system of the Algarve, Portugal. The results are employed in a decision support system currently under development for an integrated water resources management scheme in the region. Such a scheme is crucial for several reasons, including the extreme seasonal and annual variations in rainfall, the effect of climate change on more frequent and long-lasting droughts, the continuously increasing water demand and the high risk of a single-source water supply policy. The latter was revealed during the severe drought of 2004 and 2005, when surface reservoirs were depleted and the regional water demand could not be met, despite the drilling of emergency wells.

For screening and selection, quantitative criteria are based on aquifer properties and well yields, whereas qualitative criteria are defined by water quality indices. These reflect the well's degree of violation of drinking water standards for different sets of variables, including toxicity parameters, nitrate and chloride, iron and manganese and microbiological parameters. Results indicate the current availability of at least 1100 l s⁻¹ of high quality groundwater (55% of the regional demand, requiring only disinfection (900 l s⁻¹ or basic treatment, prior to human consumption. These groundwater withdrawals are sustainable when compared to mean annual recharge, considering that at least 40% is preserved for ecological demands. A more accurate and comprehensive analysis of sustainability is performed with the help of steady-state and transient groundwater flow simulations, which account for aquifer geometry, boundary conditions, recharge and discharge rates, pumping activity and seasonality. They permit an advanced analysis of present and future scenarios and show that increasing water demands and decreasing rainfall will make

Terrestrial sedimentary pyrites as a potential source of trace metal release to groundwater – A case study from the Emsland, Germany

International Nuclear Information System (INIS)

Houben, Georg J.; Sitnikova, Maria A.; Post, Vincent E.A.

2017-01-01

Pyrite is a common minor constituent of terrestrial freshwater sediments and a sink for trace elements. Different amounts and morphological types (framboids and euhedral crystals) of sedimentary pyrites were found in the heavy mineral fraction of cores obtained from several drillholes located in the Emsland region, NW Germany. Their trace element contents were investigated to assess their potential for groundwater contamination after oxidation, e.g. induced by dewatering or autotrophic denitrification. Nickel, arsenic and cadmium were found in significant concentrations in pyrite. Geochemical modeling showed that elevated trace metal concentrations in groundwater, potentially exceeding drinking water standards, should preferentially occur in a less than 1 m thick zone situated around the depth of the redoxcline, where nitrate is reduced by pyrite. This was confirmed by depth-specific groundwater sampling in the Emsland and by previously published studies. The absolute concentration of released trace metals depends on their content in the pyrite but also strongly on the nitrate load of groundwater. - Highlights: • Pyrite from heavy mineral fraction of aquifer sediment analyzed for trace metal content. • Pyrites contain significant concentration of trace metals, such as nickel, arsenic, cadmium. • Trace elements are released by autotrophic denitrification. • Reactive transport model predicts small zone of trace element accumulation. • Release of trace elements strongly dependent on nitrate content of groundwater.

Optimization of DRASTIC method by artificial neural network, nitrate vulnerability index, and composite DRASTIC models to assess groundwater vulnerability for unconfined aquifer of Shiraz Plain, Iran.

Science.gov (United States)

Baghapour, Mohammad Ali; Fadaei Nobandegani, Amir; Talebbeydokhti, Nasser; Bagherzadeh, Somayeh; Nadiri, Ata Allah; Gharekhani, Maryam; Chitsazan, Nima

2016-01-01

Extensive human activities and unplanned land uses have put groundwater resources of Shiraz plain at a high risk of nitrate pollution, causing several environmental and human health issues. To address these issues, water resources managers utilize groundwater vulnerability assessment and determination of protection. This study aimed to prepare the vulnerability maps of Shiraz aquifer by using Composite DRASTIC index, Nitrate Vulnerability index, and artificial neural network and also to compare their efficiency. The parameters of the indexes that were employed in this study are: depth to water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone, hydraulic conductivity, and land use. These parameters were rated, weighted, and integrated using GIS, and then, used to develop the risk maps of Shiraz aquifer. The results indicated that the southeastern part of the aquifer was at the highest potential risk. Given the distribution of groundwater nitrate concentrations from the wells in the underlying aquifer, the artificial neural network model offered greater accuracy compared to the other two indexes. The study concluded that the artificial neural network model is an effective model to improve the DRASTIC index and provides a confident estimate of the pollution risk. As intensive agricultural activities are the dominant land use and water table is shallow in the vulnerable zones, optimized irrigation techniques and a lower rate of fertilizers are suggested. The findings of our study could be used as a scientific basis in future for sustainable groundwater management in Shiraz plain.

Microbially catalyzed nitrate-dependent metal/radionuclide oxidation in shallow subsurface sediments

Science.gov (United States)

Weber, K.; Healy, O.; Spanbauer, T. L.; Snow, D. D.

2011-12-01

Anaerobic, microbially catalyzed nitrate-dependent metal/radionuclide oxidation has been demonstrated in a variety of sediments, soils, and groundwater. To date, studies evaluating U bio-oxidation and mobilization have primarily focused on anthropogenically U contaminated sites. In the Platte River Basin U originating from weathering of uranium-rich igneous rocks in the Rocky Mountains was deposited in shallow alluvial sediments as insoluble reduced uranium minerals. These reduced U minerals are subject to reoxidation by available oxidants, such nitrate, in situ. Soluble uranium (U) from natural sources is a recognized contaminant in public water supplies throughout the state of Nebraska and Colorado. Here we evaluate the potential of anaerobic, nitrate-dependent microbially catalyzed metal/radionuclide oxidation in subsurface sediments near Alda, NE. Subsurface sediments and groundwater (20-64ft.) were collected from a shallow aquifer containing nitrate (from fertilizer) and natural iron and uranium. The reduction potential revealed a reduced environment and was confirmed by the presence of Fe(II) and U(IV) in sediments. Although sediments were reduced, nitrate persisted in the groundwater. Nitrate concentrations decreased, 38 mg/L to 30 mg/L, with increasing concentrations of Fe(II) and U(IV). Dissolved U, primarily as U(VI), increased with depth, 30.3 μg/L to 302 μg/L. Analysis of sequentially extracted U(VI) and U(IV) revealed that virtually all U in sediments existed as U(IV). The presence of U(IV) is consistent with reduced Fe (Fe(II)) and low reduction potential. The increase in aqueous U concentrations with depth suggests active U cycling may occur at this site. Tetravalent U (U(IV)) phases are stable in reduced environments, however the input of an oxidant such as oxygen or nitrate into these systems would result in oxidation. Thus co-occurrence of nitrate suggests that nitrate could be used by bacteria as a U(IV) oxidant. Most probable number

Mechanism and rate of denitrification in an agricultural watershed: Electron and mass balance along groundwater flow paths

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Tesoriero, Anthony J.; Liebscher, Hugh; Cox, Stephen E.

2000-01-01

The rate and mechanism of nitrate removal along and between groundwater flow paths were investigated using a series of well nests screened in an unconfined sand and gravel aquifer. Intensive agricultural activity in this area has resulted in nitrate concentrations in groundwater often exceeding drinking water standards. Both the extent and rate of denitrification varied depending on the groundwater flow path. While little or no denitrification occurred in much of the upland portions of the aquifer, a gradual redox gradient is observed as aerobic upland groundwater moves deeper in the aquifer. In contrast, a sharp shallow redox gradient is observed adjacent to a third‐order stream as aerobic groundwater enters reduced sediments. An essentially complete loss of nitrate concurrent with increases in excess N2 provide evidence that denitrification occurs as groundwater enters this zone. Electron and mass balance calculations suggest that iron sulfide (e.g., pyrite) oxidation is the primary source of electrons for denitrification. Denitrification rate estimates were based on mass balance calculations using nitrate and excess N2 coupled with groundwater travel times. Travel times were determined using a groundwater flow model and were constrained by chlorofluorocarbon‐based age dates. Denitrification rates were found to vary considerably between the two areas where denitrification occurs. Denitrification rates in the deep, upland portions of the aquifer were found to range from from 1.0 to 2.7 mM of N per year. Potential denitrification rates in groundwater adjacent to the stream may be much faster, with rates up to 140 mM per year based on an in situ experiment conducted in this zone.

Assessing submarine groundwater discharge (SGD) and nitrate fluxes in highly heterogeneous coastal karst aquifers: Challenges and solutions

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Montiel, Daniel; Dimova, Natasha; Andreo, Bartolomé; Prieto, Jorge; García-Orellana, Jordi; Rodellas, Valentí

2018-02-01

Groundwater discharge in coastal karst aquifers worldwide represents a substantial part of the water budget and is a main pathway for nutrient transport to the sea. Groundwater discharge to the sea manifests under different forms, making its assessment very challenging particularly in highly heterogeneous coastal systems karst systems. In this study, we present a methodology approach to identify and quantify four forms of groundwater discharge in a mixed lithology system in southern Spain (Maro-Cerro Gordo) that includes an ecologically protected coastal area comprised of karstic marble. We found that groundwater discharge to the sea occurs via: (1) groundwater-fed creeks, (2) coastal springs, (3) diffuse groundwater seepage through seabed sediments, and (4) submarine springs. We used a multi-method approach combining tracer techniques (salinity, 224Ra, and 222Rn) and direct measurements (seepage meters and flowmeters) to evaluate the discharge. Groundwater discharge via submarine springs was the most difficult to assess due to their depth (up to 15 m) and extensive development of the springs conduits. We determined that the total groundwater discharge over the 16 km of shoreline of the study area was at least 11 ± 3 × 103 m3 d-1 for the four types of discharge assessed. Groundwater-derived nitrate (NO3-) fluxes to coastal waters over ∼3 km (or 20%) in a highly populated and farmed section of Maro-Cerro Gordo was 641 ± 166 mol d-1, or ∼75% of the total NO3- loading in the study area. We demonstrate in this study that a multi-method approach must be applied to assess all forms of SGD and derived nutrient fluxes to the sea in highly heterogeneous karst aquifer systems.

A methodology for assessing public health risk associated with groundwater nitrate contamination: a case study in an agricultural setting (southern Spain).

Science.gov (United States)

Chica-Olmo, Mario; Peluso, Fabio; Luque-Espinar, Juan Antonio; Rodriguez-Galiano, Victor; Pardo-Igúzquiza, Eulogio; Chica-Rivas, Lucía

2017-10-01

Groundwater nitrate contamination from agriculture is of paramount environmental interest. A continuous consumption of polluted water as drinking water or for culinary purposes is by no means a minor hazard for people's health that must be studied. This research presents a new methodology for the spatial analysis of health risk rate from intake of nitrate-polluted groundwater. The method is illustrated through its application to a water quality sampling campaign performed in the south of Spain in 2003. The probability risk model used by the US Environmental Protection Agency has been applied, considering a residential intake framework and three representative population age groups (10, 40 and 65 years).The method was based upon coupling Monte Carlo simulations and geostatistics, which allowed mapping of the health risk coefficient (RC). The maps obtained were interpreted in the framework of water resources management and user's health protection (municipalities). The results showed waterborne health risk caused by nitrate-polluted water is moderately low for the region. The observed risk was larger for the elderly and children, although no significant differences were found among the three age groups (RC average values of 95th percentile for age of 0.37, 0.33 and 0.37, respectively). Significant risk values of RC > 1 were obtained for 10 % of the surface in the NW site of the study area, where the municipalities with the highest contamination thresholds are located (agricultural activity). Nitrate concentration and intake rate stood out as the main explanatory variables of the RC.

Determination of 15N nitrates in water samples using mass spectrometry

International Nuclear Information System (INIS)

Moya, P.; Aguirre, E.; Gallardo, P.

2000-01-01

The nitrogen element (Z = 7) has two stable isotopes, whose relative quantities are 99.64% for 14 N and 0.36% for 15 N. Nitrogen is part of many processes and reactions that are important to life and that affect the quality of the water. Within the nitrogen cycle there are kinetic and thermodynamic fractionation processes, which are potentially important for tracing its sources and demands. Water contamination due to nitrates is a serious problem that is affecting large parts of the biosphere. Surface water contamination can be remedied by prevention and control measures, but the problem becomes acute when the contamination penetrates to groundwater water. Contaminated groundwater can remain in the aquifers for centuries, even milleniums, and decontamination is very difficult, if not impossible. Isotopic techniques can help to evaluate how vulnerable the groundwater is to contamination from the surface when its displacement speed and extra load area are determined. Then the sources of surface contamination (natural, industrial, agricultural, domestic) can be identified. Isotopic techniques can also describe an incipient contamination, and they can provide an early alert when chemical or biological indicators do not reveal any signs for concern. The isotopic fractionation of several nitrogen compounds provide the basis for using 15 N as a hydrological isotope tool. There are three main sources of nitrogen contamination in water, these are: organic nitrogen in the soil, nitrogenized fertilizers, domestic, industrial and animal wastes. The following technical procedure describes the method for determining the isotopic ration 15 N/ 14 N in nitrates in water. The nitrate is separated from the water using ion exchange columns through a resin, which is eluded with HCI and with the addition of silver oxide becomes silver nitrate. This solution is freeze-dried and submitted to combustion at 850 in a sealed quartz tube, using copper/copper oxide for the nitrogen reduction

A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells

Science.gov (United States)

Jurgens, Bryant; Böhlke, John Karl; Kauffman, Leon J.; Belitz, Kenneth; Esser, Bradley K.

2016-01-01

A partial exponential lumped parameter model (PEM) was derived to determine age distributions and nitrate trends in long-screened production wells. The PEM can simulate age distributions for wells screened over any finite interval of an aquifer that has an exponential distribution of age with depth. The PEM has 3 parameters – the ratio of saturated thickness to the top and bottom of the screen and mean age, but these can be reduced to 1 parameter (mean age) by using well construction information and estimates of the saturated thickness. The PEM was tested with data from 30 production wells in a heterogeneous alluvial fan aquifer in California, USA. Well construction data were used to guide parameterization of a PEM for each well and mean age was calibrated to measured environmental tracer data (3H, 3He, CFC-113, and 14C). Results were compared to age distributions generated for individual wells using advective particle tracking models (PTMs). Age distributions from PTMs were more complex than PEM distributions, but PEMs provided better fits to tracer data, partly because the PTMs did not simulate 14C accurately in wells that captured varying amounts of old groundwater recharged at lower rates prior to groundwater development and irrigation. Nitrate trends were simulated independently of the calibration process and the PEM provided good fits for at least 11 of 24 wells. This work shows that the PEM, and lumped parameter models (LPMs) in general, can often identify critical features of the age distributions in wells that are needed to explain observed tracer data and nonpoint source contaminant trends, even in systems where aquifer heterogeneity and water-use complicate distributions of age. While accurate PTMs are preferable for understanding and predicting aquifer-scale responses to water use and contaminant transport, LPMs can be sensitive to local conditions near individual wells that may be inaccurately represented or missing in an aquifer-scale flow model.

Identifying sources of groundwater pollution using trace element signatures

International Nuclear Information System (INIS)

Olmez, I.; Hayes, M.J.

1990-01-01

A simple receptor modeling approach has been applied to groundwater pollution studies and has shown that marker trace elements can be used effectively in source identification and apportionment. Groundwater and source materials from one coal-fired and five oil-fired power plants, and one coal-tar deposit site have been analyzed by instrumental neutron activation analysis for more than 20 minor and trace elements. In one of the oil-fired power plants, trace element patterns indicated a leak from the hazardous waste surface impoundments owing to the failure of a hypolon liner. Also, the extent and spatial distribution of groundwater contamination have been determined in a coal-tar deposit site

Global Patterns of Legacy Nitrate Storage in the Vadose Zone

Science.gov (United States)

Ascott, M.; Gooddy, D.; Wang, L.; Stuart, M.; Lewis, M.; Ward, R.; Binley, A. M.

2017-12-01

Global-scale nitrogen (N) budgets have been developed to quantify the impact of man's influence on the nitrogen cycle. However, these budgets often do not consider legacy effects such as accumulation of nitrate in the deep vadose zone. In this presentation we show that the vadose zone is an important store of nitrate which should be considered in future nitrogen budgets for effective policymaking. Using estimates of depth to groundwater and nitrate leaching for 1900-2000, we quantify for the first time the peak global storage of nitrate in the vadose zone, estimated as 605 - 1814 Teragrams (Tg). Estimates of nitrate storage are validated using previous national and basin scale estimates of N storage and observed groundwater nitrate data for North America and Europe. Nitrate accumulation per unit area is greatest in North America, China and Central and Eastern Europe where thick vadose zones are present and there is an extensive history of agriculture. In these areas the long solute travel time in the vadose zone means that the anticipated impact of changes in agricultural practices on groundwater quality may be substantially delayed. We argue that in these areas use of conventional nitrogen budget approaches is inappropriate and their continued use will lead to significant errors.

Nitrogen concentrations in a small Mediterranean stream: 1. Nitrate 2. Ammonium

Directory of Open Access Journals (Sweden)

A. Butturini

2002-01-01

Full Text Available The importance of storm frequency as well as the groundwater and hyporheic inputs on nitrate (NO3-N and ammonium (NH4-N levels in stream water were studied in a small perennial Mediterranean catchment, Riera Major, in northeast Spain. NO3-N concentrations ranged from 0.15 to 1.9 mg l-1. Discharge explained 47% of the annual NO3-N concentration variance, but this percentage increased to 97% when single floods were analysed. The rate of change in nitrate concentration with respect to flow, ΔNO3-N/ΔQ, ranged widely from 0 to 20 μg NO3-N s l-2. The ΔNO3-N/ΔQ values fitted to a non linear model with respect to the storm flow magnitude (ΔQ (r2=0.48, d.f.=22, P3-N/ΔQ occurred at intermediate ΔQ values, whereas low ΔNO3-N/ΔQ values occurred during severe storms (ΔQ > 400 l s-1. N3-N concentrations exhibit anticlockwise hysteresis patterns with changing flow and the patterns observed for autumnal and winter storms indicated that groundwater was the main N3-N source for stream and hyporheic water. At baseflow, NO3-N concentration in groundwater was higher (t=4.75, d.f.=29, P>0.001 and co-varied with concentrations in the stream (r=0.91, d.f.=28, P3-N concentration in hyporheic water was identical to that in stream water. The role of the hyporheic zone as source or sink for ammonium was studied hyporheic was studied comparing its concentrations in stream and hyporheic zone before and after a major storm occurred in October 1994 that removed particulate organic matter stored in sediments. Results showed high ammonium concentrations (75±28 s.d. μg NH4-N l-1 before the storm flow in the hyporheic zone. After the storm, the ammonium concentration in the hyporheic dropped by 80% (13.6±8 μg N4-N l-1 and approached to the level found in stream water (11±8 μg NH4-N l-1 indicating that indisturbed hyporheic sediments act as a source for ammonium. After the storm, the ammonium concentrations in the stream, hyporheic and groundwater zones were very

Nitrate concentrations in drainage water in marine clay areas : exploratory research of the causes of increased nitrate concentrations

NARCIS (Netherlands)

Boekel, van E.M.P.M.; Roelsma, J.; Massop, H.T.L.; Hendriks, R.F.A.; Goedhart, P.W.; Jansen, P.C.

2013-01-01

The nitrate concentrations measured in drainage water and groundwater at LMM farms (farms participating in the National Manure Policy Effects Measurement Network (LLM)) in marine clay areas have decreased with 50% since the mid-nineties. The nitrate concentrations in marine clay areas are on average

Multiscale effects of management, environmental conditions, and land use on nitrate leaching in dairy farms.

Science.gov (United States)

Oenema, Jouke; Burgers, Saskia; Verloop, Koos; Hooijboer, Arno; Boumans, Leo; ten Berge, Hein

2010-01-01

Nitrate leaching in intensive grassland- and silage maize-based dairy farming systems on sandy soil is a main environmental concern. Here, statistical relationships are presented between management practices and environmental conditions and nitrate concentration in shallow groundwater (0.8 m depth) at farm, field, and point scales in The Netherlands, based on data collected in a participatory approach over a 7-yr period at one experimental and eight pilot commercial dairy farms on sandy soil. Farm milk production ranged from 10 to 24 Mg ha(-1). Soil and hydrological characteristics were derived from surveys and weather conditions from meteorological stations. Statistical analyses were performed with multiple regression models. Mean nitrate concentration at farm scale decreased from 79 mg L(-1) in 1999 to 63 in 2006, with average nitrate concentration in groundwater decreasing under grassland but increasing under maize land over the monitoring period. The effects of management practices on nitrate concentration varied with spatial scale. At farm scale, nitrogen surplus, grazing intensity, and the relative areas of grassland and maize land significantly contributed to explaining the variance in nitrate concentration in groundwater. Mean nitrate concentration was negatively correlated to the concentration of dissolved organic carbon in the shallow groundwater. At field scale, management practices and soil, hydrological, and climatic conditions significantly contributed to explaining the variance in nitrate concentration in groundwater under grassland and maize land. We conclude that, on these intensive dairy farms, additional measures are needed to comply with the European Union water quality standard in groundwater of 50 mg nitrate L(-1). The most promising measures are omitting fertilization of catch crops and reducing fertilization levels of first-year maize in the rotation.

Evaluation of Approaches for Managing Nitrate Loading from On-Site Wastewater Systems near La Pine, Oregon

Science.gov (United States)

Morgan, David S.; Hinkle, Stephen R.; Weick, Rodney J.

2007-01-01

This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the Oregon Department of Environmental Quality and Deschutes County, to develop a better understanding of the effects of nitrogen from on-site wastewater disposal systems on the quality of ground water near La Pine in southern Deschutes County and northern Klamath County, Oregon. Simulation models were used to test the conceptual understanding of the system and were coupled with optimization methods to develop the Nitrate Loading Management Model, a decision-support tool that can be used to efficiently evaluate alternative approaches for managing nitrate loading from on-site wastewater systems. The conceptual model of the system is based on geologic, hydrologic, and geochemical data collected for this study, as well as previous hydrogeologic and water quality studies and field testing of on-site wastewater systems in the area by other agencies. On-site wastewater systems are the only significant source of anthropogenic nitrogen to shallow ground water in the study area. Between 1960 and 2005 estimated nitrate loading from on-site wastewater systems increased from 3,900 to 91,000 pounds of nitrogen per year. When all remaining lots are developed (in 2019 at current building rates), nitrate loading is projected to reach nearly 150,000 pounds of nitrogen per year. Low recharge rates (2-3 inches per year) and ground-water flow velocities generally have limited the extent of nitrate occurrence to discrete plumes within 20-30 feet of the water table; however, hydraulic-gradient and age data indicate that, given sufficient time and additional loading, nitrate will migrate to depths where many domestic wells currently obtain water. In 2000, nitrate concentrations greater than 4 milligrams nitrogen per liter (mg N/L) were detected in 10 percent of domestic wells sampled by Oregon Department of Environmental Quality. Numerical simulation models were constructed at transect (2