Nitrate-nitrogen Concentrations In Groundwater Research Articles

Geostatistical estimates of groundwater nitrate-nitrogen concentrations with spatial auxiliary information on DRASTIC-LU-based aquifer contamination vulnerability.

Groundwater nitrate-nitrogen contamination typically involves several natural and anthropogenic factors, including those related to hydrology, hydrogeology, topography, and land use (LU). DRASTIC-LU-based aquifer contamination vulnerability could be used to characterize the pollution potentials of groundwater nitrate-nitrogen and to determine groundwater protection zones. This study used regression kriging (RK) with environmental auxiliary information on DRASTIC-LU-based aquifer contamination vulnerability to investigate groundwater nitrate-nitrogen pollution in the Pingtung Plain of Taiwan. First, the relationship between groundwater nitrate-nitrogen pollution and assessments of aquifer contamination vulnerability was determined using stepwise multivariate linear regression (MLR). Subsequently, the residuals between the nitrate-nitrogen observations and MLR predictions were estimated by kriging techniques. Finally, the groundwater nitrate-nitrogen distributions were spatially analyzed using RK, ordinary kriging (OK), and MLR. The findings indicated that the land used for orchards and the medium- and coarse-sand fractions of vadose zones were associated with groundwater nitrate-nitrogen concentrations. The fertilizer used for orchards was identified as the primary source of groundwater nitrate-nitrogen pollution. The RK estimates could be used to analyze the characteristics of the pollution source for land used for orchards and exhibited high spatial variability and accuracy after residual correction. Moreover, RK had an excellent estimate ability for extreme data compared to MLR and OK. Correctly determining groundwater nitrate-nitrogen distributions using RK was useful for administering environmental resources and preventing public health hazards.

Dynamics of Organic Nitrogen Compound Mineralization in Organic Soils under Grassland, and the Mineral N Concentration in Groundwater (A Case Study of the Mazurian Lake District, Poland)

Peatlands serve numerous functions, with one of the main ones being the retention of nutrients, including mineral nitrogen. A field study in organic soils was carried out in the Mazurian Lake District situated in north-eastern Poland (53°37′50′ N, 20°28′51′ E). In the test peat soils, the rate of organic nitrogen compound mineralization varied significantly depending on the season. The dynamics of the organic matter mineralization process were most strongly influenced by the soil use and the season. The mineral N release was higher in organic soil under intensively used grassland. In this soil, much more mineral nitrogen was released during the summer and spring periods. The dominant form in the organic nitrogen compound mineralization processes was N-NO3. The highest dynamics of the organic nitrogen compound mineralization were noted at a soil moisture content ranging from 57% to 59%. The interdependence of the soil moisture content and the rate of organic nitrogen compound mineralization fluctuated over the study period, with an increase in spring and a decrease in summer. A correlation was demonstrated between the nitrate form content in the peat soils under intensive cultivation and the nitrate-nitrogen concentration in groundwater, while no correlation was demonstrated between the N-NO3 content in the soils under a forest and the N-NO3 concentration in the groundwater of these soils. The results provide the basis for the conclusion that the land use type (forest, grassland), which determines the morphological structure of organic soils, affects the intensity of the infiltration of different mineral nitrogen forms.

Contribution of nitrate-nitrogen concentration in groundwater to stream water in an agricultural head watershed

This study characterized nitrate-nitrogen (NO3–N) concentrations in groundwater and stream water in an agricultural head watershed in South Korea and identified the pollution load of NO3–N as a result of the groundwater entering streams using field surveys, analyses of chemical constituents, and numerical modeling. The mean NO3–N concentration in groundwater was 7.373 mg/L, which is approximately 1.9 times higher than concentrations found in stream water. The groundwater and stream water samples belonged to the Ca–HCO3 type. The concentration of NO3–N in groundwater tended to increase in the lowland areas downstream. There was seasonal variations of NO3–N in both the groundwater and stream water samples, with increases in concentration during the dry season (January–April) and decreases during the wet season (June–October). The NO3–N load in stream water to that in groundwater (R) was higher during the wet season (September) than the dry season (March), with R distinctly increasing in upstream areas relative to downstream areas, indicating that during the wet season, a large amount of NO3–N is introduced into stream water from groundwater. By analyzing the relationship between groundwater and stream water and through NO3–N transport modeling, it was revealed that in the watershed, the nitrate-N load in stream water is greatly augmented by inputs from groundwater, particularly in the middle and downstream areas.

The Nitrate Nitrogen in Groundwater of Intensive Agricultural Region in Pinggu District by Sampling and Monitoring for 12 Years

The nitrate nitrogen of groundwater samples which sampled 24 times from 2006 to 2017 in the intensive agricultural region of Pinggu district in Beijing were analyzed in this study, in order to investigate its dynamic change and important influence factors of this region. The results indicated that the mean value of nitrate nitrogen in groundwater of this region was 6.23 mg/L, which had reached the third level of the national groundwater quality standard, and the annual nitrate nitrogen concentration in groundwater of the region tended to increase. The significant positive correlations between the annual average concentrations of nitrate nitrogen in groundwater and the statistical data of livestock and poultry products from 2006 to 2015 implied that the impact of livestock and poultry industry on the nitrate in groundwater should not be ignored in the region. The increase of precipitation has a trend of increasing the difference of nitrate in groundwater in Pinggu district. The nitrate nitrogen in groundwater sampled from orchard was markedly higher than which from grain field and vegetable field. Samples from deeper well (WD3) always locatd in mountainous area, their nitrate nitrogen was significantly higher than which from spring well (WD1) and well with 30 to 100 m depth (WD2).

Groundwater Nitrate in Three Hydrogeologic Settings within Southwestern Ontario

Groundwater nitrate concentrations, along with other hydrogeochemical parameters (e.g. oxidation-reduction potential, dissolved organic carbon, sulfate, isotopes: nitrogen-15 and oxygen-18 in nitrate) were measured at 25 different monitoring wells located at three research sites (Norfolk, Guelph, and Acton), once every two months from June 2014 to July 2016. To identify trends in groundwater nitrate-nitrogen concentrations and to attempt to understand them, the hydrogeologic settings of these three unique sites were characterized by their climate, land use, soil, hydrochemistry, and hydrogeology. The research sites are comprised of; a thick sand and gravel unconfined aquifer; a fractured limestone/dolostone bedrock aquifer; overlain by sand and gravel; and a fractured limestone/dolostone aquifer, overlain by thin diamict. Evidence from groundwater hydrochemical analyses suggests that denitrification may be occurring at some of the deeper monitoring wells while evidence for nitrification was found at shallower depths. By determining which environmental and anthropogenic factors impact nitrate contamination in groundwater land managers can be informed to avoid further contamination of underlying groundwater resources.

Sustainable Optimization for Wastewater Treatment System Using PSF-HS

The sustainability in a river with respect to water quality is critical because it is highly related with environmental pollution, economic expenditure, and public health. This study proposes a sustainability problem of wastewater treatment system for river ecosystem conservation which helps the healthy survival of the aquatic biota and human beings. This study optimizes the design of a wastewater treatment system using the parameter-setting-free harmony search algorithm, which does not require the existing tedious value-setting process for algorithm parameters. The real-scale system has three different options of wastewater treatment, such as filtration, nitrification, and diverted irrigation (fertilization), as well as two existing treatment processes (settling and biological oxidation). The objective of this system design is to minimize life cycle costs, including initial construction costs of those treatment options, while satisfying minimal dissolved oxygen requirements in the river, maximal nitrate-nitrogen concentration in groundwater, and a minimal nitrogen requirement for crop farming. Results show that the proposed technique could successfully find solutions without requiring a tedious setting process.

Removal of NO3– from groundwater by PP-g-AA-Am non-woven fabric using fixed-bed column reactors

This study investigated the effect of PP-g-AA-AM non-woven fabric on the removal of nitrate nitrogen from groundwater. The breakthrough time was 1.5–2.6, 2.5–5.5, and 6.2–12.2 h for a superficial velocity of 2.0, 1.0, and 0.5 cm/s, respectively, for the nitrate nitrogen concentration in groundwater to satisfy the safe standard for drinking of 10 mg/L (as per the Ministry of Environment in Korea's 2011 Management of Drinking Water Act); the slower the superficial velocity, the longer is the breakthrough time. The ion exchange amount was a maximum of 28.37 mg/g for a superficial velocity of 2.0 cm/s, and the ion exchange amount decreased with slower or faster superficial velocities. The ratio of adsorbent used shows a linear relationship with the column diameter to length ratio and an inverse one with the superficial velocity. It is a maximum of 79% for a superficial velocity of 0.5 cm/s and a column diameter to length ratio of 1:10. Multiple regression analysis with the superficial velocity, nitrate nitrogen concentration in groundwater, and column diameter to length ratio showed that the initial nitrate nitrogen concentration has the strongest influence on the ion exchange amount. A 10% NaCl regenerant solution of 20 times the reactor volume is required to accomplish >99% of ion exchange bed regeneration in a groundwater treatment facility when applied to a packed column filled with PP-g-AA-Am.

Efficiency of controlled drainage and subirrigation in reducing nitrogen losses from agricultural fields

In northeast Italy, a regimen of controlled drainage in winter and subirrigation in summer was tested as a strategy for continuous water table management with the benefits of optimizing water use and reducing unnecessary drainage and nitrogen losses from agricultural fields. To study the feasibility and performance of water table management, an experimental facility was set up in 1996 to reproduce a hypothetical 6-ha agricultural basin with different land drainage systems existing in the region. Four treatments were compared: open ditches with free drainage and no irrigation (O), open ditches with controlled drainage and subirrigation (O-CI), subsurface corrugated drains with free drainage and no irrigation (S), subsurface corrugated drains with controlled drainage and subirrigation (S-CI). As typically in the region free drainage ditches were spaced 30 m apart, and subsurface corrugated drains were spaced 8 m apart. Data were collected from 1997 to 2003 on water table depth, drained volume, nitrate-nitrogen concentration in the drainage water, and nitrate-nitrogen concentration in the groundwater at various depths up to 3 m. Subsurface corrugated drains with free drainage (S) gave the highest measured drainage volume of the four regimes, discharging, on average, more than 50% of annual rainfall, the second-highest concentration of nitrate-nitrogen in the drainage water, and the highest nitrate-nitrogen losses at 236 k ha−1. Open ditches with free drainage (O) showed 18% drainage return of rainfall, relatively low concentration of nitrate-nitrogen in the drainage water, the highest nitrate-nitrogen concentration in the shallow groundwater, and 51 kg ha−1 nitrate-nitrogen losses. Both treatments with controlled drainage and subirrigation (O-CI and S-CI) showed annual rainfall drainage of approximately 10%. O-CI showed the lowest nitrate-nitrogen concentration in the drainage water, and the lowest nitrogen losses (15 kg ha−1). S-CI showed the highest nitrate-nitrogen concentration in the drainage water, and 70 kg ha−1 nitrate-nitrogen losses. Reduced drained volumes resulted from the combined effects of reduced peak flow and reduced number of days with drainage. A linear relationship between daily cumulative nitrate-nitrogen losses and daily cumulative drainage volumes was found, with slopes of 0.16, 0.12, 0.07, and 0.04 kg ha−1 of nitrate-nitrogen lost per mm of drained water in S-CI, S, O, and O-CI respectively. These data suggest that controlled drainage and subirrigation can be applied at farm scale in northeast Italy, with advantages for water conservation.

Effects of Temperature on Measurements of Nitrate-Nitrogen Concentration in Groundwater Using Portable Reflection Photometer

Effects of Temperature on Measurements of Nitrate-Nitrogen Concentration in Groundwater Using Portable Reflection Photometer

IMPACT OF ALTERNATIVE CITRUS MANAGEMENT PRACTICES ON GROUNDWATER NITRATE IN THE CENTRAL FLORIDA RIDGE: II. NUMERICAL MODELING

Long-term impacts of alternative citrus nitrogen and water management practices implemented at growercooperator sites on the Central Florida Ridge were modeled using the nitrogen component of the Leaching Estimationand Chemistry Model (LEACHN). A bromide tracer test was conducted at one representative cooperator site toparameterize and validate the model. Following validation, 50-year simulations of the historic management practices ateach site were conducted. These simulations confirmed field observations that groundwater nitrate-nitrogenconcentrations below mature citrus groves that receive 246 kg/ha/yr nitrogen (N) as three split applications of dry solublefertilizer can be expected to exceed the Environmental Protection Agencys (EPAs) Maximum Contaminant Level (MCL)of 10 mg/L a majority of the time. Fifty-year simulations of alternative nitrogen and water management practicesimplemented in the field study predicted that in all cases reducing the rate and increasing the frequency of N application,and improving irrigation management, will increase N uptake by plants and reduce average groundwater nitrate-nitrogenconcentrations to within EPA standards. Modeling results support conclusions of the field study that showed that, of theBMPs tested on mature citrus, applying 142 kg N/ha/yr as fertigation/foliar spray should be the most effective, whileapplying 180 kg N/ha/year as slow release/dry soluble BMP should be the least effective at reducing groundwater nitratenitrogenconcentrations. Modeling results further suggest that, to maintain the average groundwater nitrate-nitrogenconcentration below the EPA MCL in this region, the N rate should not exceed 172 kg/ha/yr if the fertilizer is to beapplied in three split applications of dry soluble fertilizer; 208 kg/ha/yr if the fertilizer is applied in three applications ofslow release/dry soluble fertilizer; or 231 kg/ha/yr if the N is to be applied in 18 split fertigation applications. If 64 kg N/ha/yr is applied as foliar spray, modeling results suggest that an additional 187 kg/ha/year may be applied in 18 splitfertigation applications (for a total N application rate of 251 kg/ha/yr) while maintaining the average concentration ofthe leachate below the EPA MCL.

IMPACT OF ALTERNATIVE CITRUS MANAGEMENT PRACTICES ON GROUNDWATER NITRATE IN THE CENTRAL FLORIDA RIDGE I. FIELD INVESTIGATION

A research project was conducted to evaluate the impact of alternative citrus nitrogen and water management practices on groundwater nitrate concentrations beneath the vulnerable sandy soils in the ridge citrus region of Central Florida. Fifteen months of baseline data indicated that groundwater nitrate-nitrogen concentrations were above the Environmental Protection Agency’s Maximum Contaminant Level (MCL) beneath mature groves on the Central Florida Ridge. Data from beneath a flatwoods grove off the ridge showed groundwater nitrate-nitrogen levels well below the MCL, and data from beneath a native vegetation site on the Central Florida ridge showed virtually no detectable nitratenitrogen in groundwater. After the baseline monitoring period the following site-specific best management practices (BMPs) were implemented: (1) application of a combination of slow release and dry soluble fertilizer at a rate of 180 kg N/ha/yr split into three applications; (2) application of 18 doses of liquid fertilizer at a rate of 180 kg N/ha/yr applied through a fertigation system; (3) application of 18 doses of liquid fertilizer at a rate of 168 kg N/ha/yr applied through a fertigation system; (4) application of a combination of 18 doses of liquid fertilizer at a rate of 78 N kg/ha/yr through a fertigation system and three applications of foliar spray fertilizer at a rate of 64 kg N/ha/yr (total 142 kg N/ha/yr); and (5) use of irrigation scheduling based on tensiometer measurements to minimize excess leaching. Analysis of 52 months of post-BMP monitoring data indicated that all of these BMPs produced statistically significant downward trends in nitratenitrogen concentration, and all have the potential to meet the EPA MCL for groundwater. The average downward trends ranged from –0.4 to –4.6 mg NO3-N/L-yr, and were greatest for the fertigation/foliar spray BMP, which represented the largest reduction in total N applied.

Nitrate Leaching to a Shallow Mid-Atlantic Coastal Plain Aquifer as Influenced by Conventional No-Till and Low-Input Sustainable Grain Production Systems

In December, 1987, the states in the Chesapeake Bay region, along with the federal government, signed an agreement which called for a 40% reduction in nitrogen and phosphorus loadings to the Bay by the year 2000. To accomplish this goal, major reductions in nutrient loadings associated with agricultural management practices were deemed necessary. The objective of this study was to determine if reducing fertilizer inputs to the NT system would result in a reduction in nitrogen contamination of groundwater. In this study, groundwater, soil, and percolate samples were collected from two cropping systems. The first system was a conventional no-till (NT) grain production system with a two-year rotation of corn/winter wheat/double crop soybean. The second system, denoted low-input sustainable agriculture (LISA), produced the same crops using a winter legume and relay-cropped soybeans into standing wheat to reduce nitrogen and herbicide inputs. Nitrate-nitrogen concentrations in groundwater were significantly lower under the LISA system. Over 80% of the NT groundwater samples had NO3-N concentrations greater than 10 mgl-1, compared to only 4% for the LISA cropping system. Significantly lower soil mineral N to a depth of 180 cm was also observed. The NT soil had nearly twice as much mineral N present in the 90-180 cm portion than the LISA cropping system.