Reduce Groundwater Pollution Research Articles

Assessment of well water pollution by sewage contaminants: A case study of Akure South, Ondo State, Nigeria

This study investigated the extent of well water contamination in dry and rainy seasons through infiltration of coliform bacteria from sewage pits in their proximity in Akure. Total and Faecal coliform counts of twenty household wells were investigated between the months of March and July with respect to proximity of wells to sewage pits, orientation of wells to sewage pits, and other well characteristics. All wells studied were assessed to be vulnerable to contamination with observable differences in characteristics, physicochemical parameters, total coliform counts and faecal coliform counts. Asides pH which was higher in the dry season, all other parameters had lower values in the dry season. At an average distance of 17.6 m from the sewage pits, all well water sampled had greater coliform counts than the WHO recommended level for drinking water (< 1 cfu/mL). Correlations between coliform counts of water samples and the distances of the wells to sewage pits was positive and not significant for both total and faecal coliform in dry season, while it was negative and significant for both total and faecal coliform in the rainy season. Topography, and distance between wells and sewage pits were prominent factors responsible for well water contamination. Amounts of coliforms found in wells were significantly affected by seasonal variation. It is thus suggested that wells be sited up-gradient and at safer distances away from sanitary systems in the ultimate bid to reduce groundwater pollution and the occurrence of water borne diseases.

Characterisation of groundwater quality around Soluos dumpsite in Lagos, Nigeria

Groundwater quality in Lagos is susceptible to pollution due to infiltration from dumpsites. This study therefore assessed groundwater quality around Solous dumpsite in Lagos. Groundwater samples collected bimonthly from 20 wells for two years were analysed for pH, acidity, alkalinity, conductivity, total dissolved solids, total hardness, Cl−, SO42−, NO3−,PO43−, Pb, Ni, Cd, Zn, Cu, Fe, Mg, Ca, Na, K and total count of E. coli using standard methods. Multivariate statistical techniques (factor and cluster analyses) and phreeqC software were used to analyse the groundwater quality data. Seven principal components (PCs) extracted 85.3% of the total variance and four clusters of wells with distinct characteristics were revealed. Groundwater was classified as (Na +K) SO42− and (Na +K) Cl−. About 50% of the samples exceeded the WHO (< 1.0) limits for coliform count. The quality of the water investigated is doubtful, implicating the impact of dumpsite. Therefore, there is a need for regulatory measures on the dumpsite activities so as to reduce groundwater pollution.

Characterisation of groundwater quality around Soluos dumpsite in Lagos, Nigeria

Groundwater quality in Lagos is susceptible to pollution due to infiltration from dumpsites. This study therefore assessed groundwater quality around Solous dumpsite in Lagos. Groundwater samples collected bimonthly from 20 wells for two years were analysed for pH, acidity, alkalinity, conductivity, total dissolved solids, total hardness, Cl&minus;, SO42&minus;, NO3&minus;,PO43&minus;, Pb, Ni, Cd, Zn, Cu, Fe, Mg, Ca, Na, K and total count of E. coli using standard methods. Multivariate statistical techniques (factor and cluster analyses) and phreeqC software were used to analyse the groundwater quality data. Seven principal components (PCs) extracted 85.3% of the total variance and four clusters of wells with distinct characteristics were revealed. Groundwater was classified as (Na +K) SO42&minus; and (Na +K) Cl&minus;. About 50% of the samples exceeded the WHO (< 1.0) limits for coliform count. The quality of the water investigated is doubtful, implicating the impact of dumpsite. Therefore, there is a need for regulatory measures on the dumpsite activities so as to reduce groundwater pollution.

Impact of treated wastewater on groundwater quality in the region of Tiznit (Morocco)

The Tiznit region has an arid to semi-arid climate. Rainfall is scarce and the reuse of wastewater for crop irrigation is common, and consequently groundwater can be contaminated by chemical and biological pollutants. A wastewater treatment plant is constructed with the aim of producing water suitable for reuse in agriculture and reducing groundwater pollution. The aim of this study is to assess the impact of factors that may influence groundwater quality, namely wastewater reuse and fertilizer use in the region. Groundwater was collected monthly over 1 year from five shallow wells (P1–P5) and analysed for a range of physicochemical and microbiological parameters. Concentrations frequently exceeded the WHO standards for potable water. The average concentration of nitrate was 98 mg/L. Conductivity varied from 1,930 to 2,500 μS/cm over four of the wells but was 11,703 in P3, which was close to the treatment plant. Bacteriological contamination was also found, with total coliforms varying from 0 at P1 to 9,000 cfu/100 mL at P4 and fecal coliforms (FC) 0 in P1, P2, P3 and P5 but up to 250 FC/100 mL at P4. Fecal streptococci (FS) varied from 0 to 3,500 FS/100 mL at P4. These values widely exceeded the limit for bacteria in water (0 units/100 mL).

Strategies to Reduce Nitrate Leaching into Groundwater in Potato Grown in Sandy Soils: Case Study from North Central USA

There is increasing public concern to reduce nitrate pollution to groundwater, especially in sandy soils. Strategies to reduce nitrate leaching are developed to increase N use efficiency, reduce groundwater pollution, and increase tuber yield. A growing interest in N management should consider management strategies for N supply, soil moisture for transport, and crop N demand that are economical and compatible with local production systems. We present a review of the literature on conventional and innovative strategies for N, irrigation, and crop management for potato production in reducing N leaching in sandy soils. The amount of fertilizer-N should be decided based on an integrated evaluation of soil organic matter content, soil texture, residual soil N, crop residues, credit to organic N sources, crops to be grown including varieties and crop physiological needs, cropping systems, yield potential, water management, and N concentrations in irrigation water. Research advances have no quick fix for controlling NO3 leaching to groundwater. However, the best combination of proven strategies can reduce leaching potential significantly.

Evaluation of variable‐rate nitrogen recommendation of winter wheat based on SPAD chlorophyll meter measurement

To develop a time‐Specific and time‐critical spatial variable rate nitrogen application (VRN) method and to overcome the limitations of traditional field sampling methods, this study focused on the relationship between SPAD chlorophyll meter readings and nitrogen content in leaves in order to determine the amount of nitrogen fertilisation required for agricultural objectives. Field experiments were conducted in three wheat growth duration stages from 2003 to 2006. Grain yields and soil NO3‐N contents were measured in all plots. Our results indicated that VRN technology reduced wheat yield spatial variability. The benefits of VRN included low soil residual NO3‐N content and NO3‐N leaching potential, suggesting that VRN technology based on SPAD readings can potentially reduce groundwater pollution and therefore protect our limited environmental resources.

Soil N and salinity leaching after the autumn irrigation and its impact on groundwater in Hetao Irrigation District, China

Soil water and salinity are crucial factors influencing crop production in arid regions. An autumn irrigation system employing the application of a large volume of water (2200–2600 m 3 ha −1) is being developed in the Hetao Irrigation District of China, since the 1980s with the goal to reduce salinity levels in the root zone and increase the water availability for the following spring crops. However, the autumn irrigation can cause significant quantities of NO 3 − to leach from the plant root zone into the groundwater. In this study, we investigated the changes in soil water content, NO 3–N and salinity within a 150 cm deep soil profile in four different types of farmlands: spring wheat (F W), maize (F M), spring wheat–maize inter-planting (F W–M) and sunflower (F S). Our results showed that (1) salt losses mainly occurred in the upper 60 cm of the soil and in the upper 40 cm for NO 3–N; (2) the highest losses of salt and NO 3–N could be observed in F W, whereas the lowest losses were found in F W–M. NO 3–N concentration, pH and electrical conductivity (EC) in the groundwater were also monitored before and after the autumn irrigation. We found that the autumn irrigation caused the groundwater concentration of NO 3–N to increase from 1.73 to 21.6 mg L −1, thereby, exceeding the standards of the World Health Organization (WHO). Our results suggest that extensive development of inter-planting tillage might be a viable measure to reduce groundwater pollution, and that the application of optimized minimum amounts of water and nitrogen to meet realistic yield goals, as well as the timely application of N fertilizers and the use of slow release fertilizers can be viable measures to minimize nitrate leaching.

Leaching potential of persistent soil fumigant residues.

Persistent fumigant residues in soil resulting from agricultural pest-control practices may be released into water and leached to groundwater. In this study, the leaching potential of persistent soil fumigant residues was evaluated, and the effect of dissolved organic matter (DOM) and ammonium thiosulfate (ATS) amendment was investigated. A silt loam soil was incubated separately with the fumigants 1,3-dichloropropene (1,3-D), chloropicrin (CP), and methyl isothiocyanate (MITC) at 240-990 mg kg(-1) for 35 d, followed by 48 h of evaporation. The soil was packed into stainless steel columns (1.4 cm x 10 cm) and leached with water, 5 mM ATS, and DOM solution (DOC 250 mg L(-1)) by gravity. Residues of 1,3-D, CP, and MITC in the evaporated soil were 5.61, 11.38, and 1.83 mg kg(-1), respectively. Concentrations of 1,3-D, CP, and MITC in column effluents ranged from 0.05 to 0.73, 0.16 to 0.81, and 0.05 to 0.27 mg L(-1), respectively, when the soil was leached with 10 pore volumes of water. DOM did not promote the leaching of persistent fumigant residues, and ATS remarkably reduced the amount of 1,3-D and CP yet notably increased MITC recovered in the effluents. The results suggest that the leaching of persistent fumigant residues through soil to water is significant, and movement of fumigants in soil is not facilitated by DOM. Amending soil with ATS through irrigation is an effective method to remove persistent residues of halogenated fumigants. To reduce groundwater pollution risks posed by fumigation, persistent soil fumigant residues have to be considered.

Nitrate Reductase Activity of Diverse Grain Sorghum Genotypes and Its Relationship to Nitrogen Use Efficiency

High crop N use efficiency is desirable for reducing the cost and reliance on fertilizer N, and it may help reduce ground water pollution. The objectives of this study were to (i) characterize and compare the seasonal trends in nitrate reductase activity (NRA) of seven grain sorghum [Sorghum bicolor (L.) Moench] genotypes of tropical and U.S. origin, (ii) determine how NRA is related to total plant N, dry matter, grain yield, and N use efficiency, and (iii) examine how NRA and plant N accumulation affect N use efficiency for biomass (NUE1) and grain production (NUE2). The genotypes were evaluated in field trials in 1994 and 1996 at applied N levels of 0 and 100 N kg ha−1 on a Sharpsburg silty clay loam soil (fine, smectitic, mesic Typic Argiudoll). Plant biomass, reduced N, NRA, NUE1, and NUE2 were determined at three growth stages (vegetative, anthesis, and physiological maturity). Genotypes did not differ for NRA at either N level; however, there was a definite tendency for the four tropical lines and two U.S. adapted lines to have greater NRA values at all growth stages than the one hybrid. Nitrate reductase activity decreased throughout the growing season, with the sharpest decline from anthesis to maturity. Nitrate reductase activity did not correlate with grain yield or shoot biomass, but did correlate with grain N concentration. Shoot and grain N concentration correlated with NUE1, while grain and shoot N contents and shoot N concentration were correlated with NUE2. Neither NUE1 nor NUE2 were significantly affected by the NRA level. Tropical lines had greater preanthesis N uptake accumulation (1.45 g plant−1) and greater NUE1 than the hybrid (0.90 g plant−1) and U.S. adapted lines (0.73 g plant−1). In terms of grain N use efficiency, the hybrid had a 14% greater value than U.S. adapted lines and a 17% greater value than the tropical lines. It appears that NRA is not a factor that limited N accumulation and use efficiency in grain sorghum.

Best management practices for automobile salvage yards

This paper collects a group of best management practices (BMPs) that outline the techniques needed to establish an environmentally friendly automobile recycling facility. Using common as well as unique BMPs from several different states, a full but not detailed set of management practices has been established. Since every facility is different, each facility will need a set of BMPs that meets its specific needs. However, the integrity behind the BMPs must remain the same. Its main purpose is to reduce the amount of pollutants seeping into and contaminating the underground water supply. If these BMPs are properly applied to every automobile salvage yard it will greatly reduce groundwater pollution and create a safer working environment for all employees.

Uptake and agronomic efficiency of nitrogen in winter barley and winter wheat

Nitrogen (N) uptake and utilization efficiency ( N UtE) of the high-yielding cultivars `Gemini' of wheat and `Jaidor' of barley were tested with N rates of 0, 140 and 210 kg ha −1 and 0, 80 and 140 kg ha −1, respectively. The different grain yield response was linked to their difference in nitrogen uptake and utilization efficiency. The highest yield in barley was recorded with 80 kg N ha −1 and in wheat with 210 kg N ha −1. Nitrogen application affected the accumulation of biomass up to heading in wheat and barley. While N uptake during grain filling did not show any correlation to N applied in barley, it was markedly correlated in wheat. At N 0 and N 140 N applied, barley exhibited a 32 and 8% higher N UtE than wheat. N agronomic efficiency, a parameter representing the ability of the plant to increase yield in response to N applied, was similar in barley and wheat (8.7 and 9.2 kg kg −1 of N applied, respectively), suggesting that both species respond equally to nitrogen fertilization. Nevertheless, due to its lower N UtE, wheat requires high N fertilization to optimize yields; by contrast, in barley the lower N rate needed to achieve highest yields enables this crop to perform better in low-input conditions. As a results, the reduced N requirements for barley highest yield associated with a better R F value (apparent N fertilizer recovery of 63% in barley and 49% in wheat at N 140) makes barley crop a better choice to reduce ground-water pollution due to nitrate leaching in winter and early spring.

ROLE OF SOIL MOISTURE CONTENT IN REDUCING ENVIRONMENTAL POLLUTION FROM PESTICIDES

The role of soil moisture content in reducing groundwater pollution from agricultural chemicals was investigated under laboratory conditions. Specifically, the effects of different soil moisture content levels on the dissipation rates of three commonly-used herbicides: atrazine, metolachlor, and metribuzin, were analyzed using a batch degradation study in the laboratory. The soil samples were taken from a sand field in southern Quebec, where no herbicides had previously been applied in the past two years. Four soil moisture content treatments: 20%, 35%, 50% and a slurried condition, were simulated to represent different moisture regimes that might occur in humid regions. Our results indicate that the degradation rates of atrazine and metribuzin were higher at 35% and 50% soil moisture content than at 20% moisture content, whereas that for metolachlor remained unaffected. The half life of atrazine was found to be one week at 50% moisture content, and two weeks at 20% and 35% moisture content. In the slurri...

Nonpoint sources

Nonpoint sources

The On‐Farm Costs of Reducing Groundwater Pollution

AbstractAgricultural chemicals ate a source of groundwater pollution in some areas. Regulatory options to reduce such nonpoint pollution imply costs to producers. By integrating plant simulation, hydrologic, and economic models of farm‐level processes, this study evaluates on‐farna costs of strategies to reduce nitrate groundwater pollution. The empirical focus is on intensively managed, irrigated farms in the Columbia Basin of Oregon. Results suggest that changes in timing and application rates of nitrogen and water reduce nitrate pollution with little loss in profits. Once such practices are adopted, further reductions in nitrates can be achieved only at increasing costs to producers.

Evaluating Pesticide Migration in Tile‐Drained Soils with a Transfer Function Model

AbstractThe interpretation and prediction of chemical outflow in tile drains as a result of solute migration through both unsaturated and saturated soil can be an important tool for understanding and reducing groundwater pollution risk. A simple analytical solution for predicting pesticide transport in tile‐drained soils, based on the transfer‐function concept, is presented and tested in screening scenarios for chemicals with widely varying fate properties under different hypothetical transport characteristics for the individual soil layers. The inherent soil travel time variability of the two layers is embodied in probability density functions (pdf). The unsaturated zone is represented by either a unimodal or a bimodal pdf, the latter describing both preferential and matrix flow of solutes at the field scale. The saturated travel time pdf is derived from cumulative travel time distributions calculated by streamline functions. Sensitivity analysis focused on chemical outflow in tile drains as a function of travel time variability in the unsaturated and saturated soil, assuming linear equilibrium adsorption and first order decay in either the entire soil or the preferential and/or slow flow regions of the unsaturated soil, respectively. The tile drain outflow clearly reflects the time‐delayed travel time characteristics of the unsaturated soil. Compared with a Gaussian‐like pdf, a bimodal pdf for the unsaturated zone affects primarily the shortest travel times of highly retarded and short‐lived chemicals. Screening scenarios with 10 different pesticides exhibit a strong influence of preferential flow on both the early arrival time in the tile and the total residual mass fraction, whereas the total residence time is nearly independent of travel time characteristics of the unsaturated soil.

Reducing groundwater pollution by toxic substances: Procedures and policies

One major source of water-related health problems is the improper disposal of toxic substances in the environment. Toxic materials leaching from unregulated and unlined pits, ponds, lagoons, and landfills have created a widespread environmental nightmare in the United States and many other parts of the world. At present, there are two major and interrelated components of this problem in the United States. The first is the issue of cleaning up abandoned disposal sites that pose actual or potential threats to water supplies. The second aspect of the problem concerns the necessity of siting proper management, treatment, or disposal facilities in the future. Priorities must be set to allow efficient, effective, and equitable allocation of the scarce resources that are available for accomplishing these tasks.