Concentrations Of Various Contaminants Research Articles

THE IMPACT OF SANITATION ON GROUNDWATER NITRATE LEVEL IN BANTUL DISTRICT, BANTUL REGENCY, YOGYAKARTA SPECIAL PROVINCE, INDONESIA

Bantul is one district of Yogyakarta Special Province which residents mostly use on-site sanitation. On-site sanitation is well-known for hot-spot system of nitrate groundwater contamination. It is because the wide-practice of failure of on-site sanitation systems. Besides, the failure of on-site sanitation system, it will depend on the age of settlement, population density, sanitation arrangement and sanitation behavior including water use patterns. Because of this, nitrate has leaked to groundwater and polluted many supply wells surrounding the septic systems.
 
 Since the repeated intake of nitrate could cause various acute and chronic effects to human health, especially the infant’s health under 3 months (blue baby syndrome), it is crucial to undertake the study of impact of sanitation on groundwater nitrate level in Bantul district to acquire a better understanding of the effect of settlement age, population density, sanitation arrangement and sanitation behavior on the concentration of nitrate in groundwater. In order to recognize or achieve the understanding of this issue, a methodology is conducted by observation directly to the field, including the measuring of groundwater table and the distance of septic tank to well, and also make the questionnaires for the mentioned parameters.
 
 Finally, the result of each factors (Sanitation arrangement, Settlement age, House density) are shown a low relationship with nitrate concentration, although water use patterns does not. However, the combination of these three factors can show up to find out a better correlation than one factor with this nitrate concentration. Although it has a good relationship with nitrate concentration (average), the variation of nitrate concentration from high to low shows a low relationship. Therefore, the importance of groundwater vulnerability cannot be overlooked in explaining the variation in contaminant concentrations because the nitrate concentration in the groundwater does not only depend on contaminant loading but also groundwater vulnerability.
 
 Keywords: Groundwater, on-site sanitation, nitrate concentration, contaminant loading

A longitudinal study of ventilation rates in California office buildings and self-reported occupant outcomes including respiratory illness absence

BackgroundLimited evidence has associated lower ventilation rates (VRs) in offices with higher illness-related absence rates. MethodsWe studied spaces in office buildings, selected without knowledge of their VRs, in three California climate zones. In each study space, real-time logging sensors measured carbon dioxide and thermal parameters for one year. Web-based surveys every three months collected data on occupants’ health outcomes. Using multivariate models, relationships were assessed between CO2 concentrations, or VRs estimated from CO2, and adverse occupant outcomes including respiratory infections and illness absences. For all outcomes, positive associations were hypothesized with higher CO2 levels (and negative associations with higher VRs). ResultsLow survey response limited sample size and study power. In the 16 study spaces, CO2 concentrations were uniformly low over the year, and most estimated VRs ranged from twice to nine times the California office minimum VR standard (7 L/s or 15 cfm per person). Primary CO2 and VR metrics had no statistically significant relationships with occupant outcomes. ConclusionsWithin the observed range of uniformly low CO2 and high VRs (mostly 16–42 L/s per person), little variation in contaminant concentrations would be expected, which would explain lack of relationships with occupant outcomes. These high VRs resulted partly from frequently used energy-saving “economizer” cycles in moderate California climates, but VRs at other times also substantially exceeded required VRs. These findings suggest, consistent with theory, that within a higher VR range, increased VRs do not reduce respiratory illness. Further studies are needed to better characterize such relationships.

Impact of consolidation pressure on contaminant migration in clay liner

Consolidation deformation occurs in clay liners under the self-weight of wastes at a simple garbage dump or dredged sediment dump, which leads to a decrease in the porosity. However, the migration of contaminants in clay liners is influenced by the porosity. Thus, the impact of consolidation deformation of clay liners on the migration of contaminants cannot be ignored. Based on Biot's consolidation theory, the contaminant migration theory, and consideration of the three kinds of migration mechanisms of convection, diffusion, and adsorption, a one-dimensional migration model of contaminants in deforming porous media was established, and the finite difference method was adopted to obtain the numerical solutions for an established initial-boundary value problem. The impact of consolidation pressure on the migration law of a contaminant was studied. The results show that, regardless of adsorption modes, different consolidation pressures have similar impacts on the migration law of the contaminant. Namely, over a certain migration time, the greater the consolidation pressure is, the smaller the migration depth of the contaminant. The results also show that, while the migration time increases, the impact of a certain increment of consolidation pressure on the variation of contaminant concentration with the depth increases gradually and, while the migration depth increases, the impact of a certain increment of consolidation pressure on the variation of the contaminant concentration with time increases gradually.

Comparison of the nutritional composition and the concentrations of various contaminants in branded and private label yogurts

This study was aimed at comparing the nutritional and contaminant profiles among several of the most consumed trademarks of yogurts in Catalonia (Spain). The nutritional composition, the levels of aflatoxin M1 (AFM1), as well as the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and various heavy metals were determined in six of the main trademarks of yogurts in Catalonia. To assess potential quantitative differences, a critical comparison between “private label” yogurts and branded yogurts was performed. AFM1 was detected in six samples (33%), while the most detected heavy metals were As, Cd, and Pb. Slight differences were found between yogurt samples in some minerals and trace elements including Ba, Ca, Cu, Cr, Fe, K, and Mg. The WHO-TEQ values ranged between 0.006–0.008 and 0.003–0.012ng/kg, for PCDD/Fs and PCBs, respectively. To the best of our knowledge, this is the first study providing a transversal approach on the occurrence and co-occurrence of the major chemical contaminants in yogurt with a critical comparison between trademarks. The results do not show relevant differences on the nutritional composition, or on the levels of the assessed contaminants (chemicals and AFM1) between “private label” and branded plain yogurts.

Biologic risk and source diagnose of 16 PAHs from Haihe River Basin, China

Surface sediments of rivers can exhibit spatial and temporal variations in contaminant concentrations that may significantly affect risk evaluations. As to pollution control and remediation of watershed, large-scale and further background data on PAHs in China were required urgently. Spatial distribution and compositional characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments from Haihe River Basin were investigated. A method based on effects range (ER) was used to assess ecosystem risk of ΣPAHs (the total of 16 PAH) sensitively and accurately. The results indicated that ΣPAHs content levels ranged from 257 to 16901 μg·kg−1 dry weight. The lower rings predominated in the samples, and 2-, 3-, 4-, 5- and 6-ring PAHs accounted for 12%, 21%, 30%, 30%, and 7% respectively in total PAHs. The ratio of Fl / (Fl + Py) uniformly distributed in the interval 0.20–0.80, indicating that it may be affected by petroleum origin, oil combustion, biomass and coal combustion jointly. ΣPAHs in Cetian (S6), Dongwushi (S19), Handan (S20), Aixinzhuang (S21) and Tianjin (S37) exceeded effects range low (ERL), in which biologic effects were in a medium level with an adverse effect on biologic organisms. Thus, it is necessary to strengthen the PAHs monitoring and research of the Haihe River Basin.

Effects of Seasonal Operation on the Quality of Water Produced by Public‐Supply Wells

Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin.

Reducing monitoring costs in industrially contaminated rivers: cluster and regression analysis approach.

Monitoring contamination in river water is an expensive procedure, particularly for developing countries where pollution is a significant problem. This study was conducted to provide a pollution monitoring strategy that reduces the cost of laboratory analysis. The new monitoring strategy was designed as a result of cluster and regression analysis on field data collected from an industrially influenced river. Pollution sources in the study site were coal mining, metallurgy, chemical industry, and metropolitan sewage. This river resembles those in other areas of the world, including developing countries where environmental monitoring is financially constrained. Data were collected on variability of contaminant concentrations during four seasons at the same points on tributaries of the river. The variables described in the study are pH, electrical conductivity, inorganic ions, trace elements, and selected organic pollutants. These variables were divided into groups using cluster analysis. These groups were then tested using regression models to identify how the behavior of one variable changes in relation to another. It was found that up to 86.8% of variability of one parameter could be determined by another in the dataset. We adopted 60, 65, and 70% determination levels () for accepting a regression model. As a result, monitoring could be reduced by 15 (60% level) and 10 variables (65 and 70%) out of 43, which comprises 35 and 23% of the monitored variable total. Cost reduction would be most effective if trace elements or organic pollutants were excluded from monitoring because these are the constituents most expensive to analyze.

The porifera Hymeniacidon perlevis (Montagu, 1818) as a bioindicator for water quality monitoring

Because sponges are promising bioindicators, we present here a multispecies comparison of the bioconcentration capacity for copper, zinc and the hydrocarbon fluoranthene. The spatial distribution of sponge populations was studied in 17 areas in intertidal zones on the Lower Normandy coast (France) to determine the most common species with the highest bioaccumulation capacity. Results are compared with published data on blue mussels Mytilus edulis from the Réseau d'Observation de la Contamination Chimique biomonitoring network. A total of 720 sponge samples were collected to assess species richness. Samples were analysed for metal concentrations by flame-mode atomic absorption spectrometry. Analyses of polycyclic aromatic hydrocarbon were sub-contracted. Species richness varies according to the water mass concerned. The most common species in the study area showing the highest bioconcentration in its soft tissues is Hymeniacidon perlevis, which contains about 20 times the zinc, 44 times the copper and 16 times the fluoranthene levels found in mussels. The variability of contaminant concentrations in H. perlevis is also systematically higher than those in mussels. The results obtained for this sponge closely reflect the heterogeneous distribution of contaminants. This study demonstrates that H. perlevis has a much higher capacity to accumulate in situ contaminants than the blue mussel M. edulis. H. perlevis meets all the requirements of a good bioindicator suitable for use in an integrated monitoring programme. In the near future, controlled cultivation of H. perlevis will allow us to produce sufficient quantities of this species to carry out ecotoxicological tests and in situ biomonitoring by caging.

Factors Influencing Legacy Pollutant Accumulation in Alpine Osprey: Biology, Topography, Or Melting Glaciers?

Persistent organic pollutants (POPs) can be transported long distances and deposited into alpine environments via cold trapping and snow scavenging processes. Here we examined biotic and abiotic factors determining contaminant variability of wildlife in alpine ecosystems. We measured POPs in eggs and plasma of an apex predator, the osprey (Pandion haliaetus) breeding in 15 mountainous watersheds across a broad latitudinal, longitudinal and altitudinal range in western Canada. After accounting for proximate biotic factors such as trophic level (δ(15)N) and carbon source (δ(13)C), variability in contaminant concentrations, including ΣDDT (sum of trichlorodiphenylethane-related compounds), toxaphene, hexachlorobenzene (HCB), total chlordane, and ΣPCBs (polychlorinated biphenyls) in osprey tissues was explained by interactions among relative size of watersheds, water bodies, elevation, and glacial input. ΣDDT in nestling plasma, for example, decreased with lake elevation, probably as a result of local past inputs from agricultural or public health usage at lower altitude sites. In contrast, toxaphene, never used as an insecticide in western Canada, increased with elevation and year-round snow and ice cover in both plasma and eggs, indicating long-range atmospheric sources as dominant for toxaphene. Lower chlorinated PCBs in plasma tended to decrease with elevation and ice cover consistent with published data and model outcomes. Temporal trends of POPs in osprey eggs are coincident with some modeled predictions of release from melting glaciers due to climate change. Currently we suggest that contaminants largely are released through annual snowpack melt and deposited in large lower elevation lakes, or some smaller lakes with poor drainage. Our study highlights the importance of understanding how biological processes integrate physical when studying the environmental chemistry of wildlife.

Indicators of environmental stress: cellular biomarkers and reproductive responses in the Sydney rock oyster (Saccostrea glomerata)

We measured a suite of common biomarker responses for the first time in the Sydney rock oyster Saccostrea glomerata to evaluate their utility as biological effects measures for pollution monitoring. To examine the relationship between biomarker responses and population level effects, fertilisation and embryo development assays were also conducted. Adult oysters were deployed in two contaminated estuaries and a reference estuary in Sydney, Australia. The concentrations of various contaminants (metals and polycyclic aromatic hydrocarbon, PAHs) were quantified in oyster's tissue from each site and both metals and total PAHs were significantly elevated in contaminated estuaries relative to the reference estuary. Lysosomal membrane destabilisation, lipid peroxidation levels and glutathione (GSH) concentrations were measured in the digestive gland of oysters. Of all biomarkers measured, lysosomal membrane destabilisation proved to be the most useful indicator of oysters facing anthropogenic stress and we suggest this may be an especially useful biomarker for incorporation into local environmental monitoring programs. Moreover, lysosomal membrane destabilisation showed good correlations with fertilisation, normal embryo development and estuary status. GSH and lipid peroxidation were not as valuable for distinguishing between estuaries exposed to differing levels of anthropogenic stress, but did provide additional valuable information regarding overall health status of the oysters.

Factors Influencing Variability in Groundwater Monitoring Data Sets

“Random” variability in groundwater monitoring data sets reduces the ability to identify long‐term concentration trends. This, in turn, increases the time and cost required to evaluate the effectiveness of natural attenuation and other groundwater remedies. To better understand the factors influencing variability in groundwater monitoring results, we have analyzed three large groundwater monitoring data sets. For the three data sets, the long‐term trend in contaminant concentration in each well accounted for an average of 30% to 40% of the overall variation in contaminant concentration. Understanding the causes of the remaining variability would support the development of improved groundwater monitoring methods. All three data sets show large differences in the temporal monitoring records between individual wells (e.g., coefficient of variation for monitoring results from individual wells ranges from 0.08 to 4.6) indicating that well and aquifer factors are more important contributors to variability than sample collection and analysis factors. However, the depth to groundwater (R2 = 0.020) and distance between water level and screened interval (R2 = 0.049) accounted for only a portion of the differences in variability between wells and other aquifer characteristics evaluated and were not correlated with the observed variability in monitoring results. Unidentified factors were apparently much more important contributors to variability than these factors. The monitoring data sets exhibited two distinct timescales for variability: Time‐independent variability that was apparent even when wells were re‐sampled within a few days and a long‐term variability likely associated with the long‐term concentration trend. The observation of time‐independent variability suggests that frequent monitoring of contaminated monitoring wells serves primarily to characterize sources of variability unrelated to the long‐term trend of primary interest.

Metals, nutrients and total suspended solids discharged during different flow conditions in highly urbanised catchments

Stormwater discharged from highly urbanised catchments on the southern shore of Sydney estuary, Australia, has been identified as the primary source of contaminants responsible for ecological degradation and reduction in recreational value of the waterway. Effective management of this pollution requires knowledge of contaminant loads associated with various stormwater flow conditions in three highly urbanised catchments in Sydney estuary catchment. The majority (>90%) of metal (Cu, Pb and Zn) and total suspended solid annual loads were contributed during high-flow conditions (>50 mm rainfall day(t1)), whereas ≤55% of TN and ≤21% of total phosphorus were contributed to annual loading by dry weather base-flow conditions. All flow conditions posed an in-stream ecological threat because contaminant concentrations exceeded water quality guidelines for all analytes measured, except Pb. Irregular, temporal variability in contaminant concentrations associated with base-flow (within day and amongst days), high-flow (amongst events) and irregular discharges indicated that contaminant contributions in stormwater were strongly controlled by human activity in the three catchments. Significant variation in contaminant concentrations under all flow conditions revealed unique chemical signatures for each catchment despite similarities in land uses, location and geology amongst catchments. These characteristics indicate that assessment and management of stormwater pollution needs to be conducted on an individual-catchment basis for highly urbanised regions of Sydney estuary catchment.

Natural Variations in Flow Are Critical in Determining Concentrations of Point Source Contaminants in Rivers: An Estrogen Example

Daily steroid estrogen concentrations as 17β-estradiol equivalents (E2 equiv.) were modeled from 1992 to 2008 for single locations on the well populated Thames and Soar rivers in England. The historic daily mean flow values which were the basis of this exercise came from a selected gauging site on each river. The natural variation in flow from winter to summer typically produced a 20- to 30-fold difference in predicted estrogen concentration over the course of a year. Based on all the predicted values from minimum to maximum over the 1992 to 2008 period there was a 98-fold difference in estrogen concentrations on the basis of flow alone for the Thames (0.1-12.7 ng/L E2 equiv.) and 67-fold for the Soar (0.2-13.3 ng/L E2 equiv.). This compares to a predicted 0.5-fold difference that could arise from differences in sewage treatment and 0.1-fold difference due to differences in in-stream biodegradation. The seasonal variation in flow generated a repeating "roller coaster" in predicted estrogen concentrations. Regularly measured phosphate data for the river Avon over the period 1993 to 1996, where point sources also dominate, was compared against flow and predicted estrogen concentrations. The pattern of predicted estrogen and measured total phosphate concentration were very closely related. This dramatic variation in contaminant concentration over the year due to flow poses questions over what we mean by environmental relevance and the representation of the real environment in aquatic ecotoxicity tests.

Concentrations of Polychlorinated Biphenyls (PCBs), Polychlorinated Dibenzo-pdioxins and Furans (PCDD/Fs), and Polybrominated Diphenyl Ethers (PBDEs) as Functions of Sample Depth in Killer Whale (Orcinus orca) Blubber

Concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs) were examined as a function of depth in killer whale (Orcinus orca) blubber samples. Lipid-normalized concentrations of PCBs, PCDD/Fs, and PBDEs did not display significant variation with depth in three distinct blubber layers (outer, central, and inner). Significantly more variation in contaminant concentrations were observed with depth on a wet weight basis for the killer whale sample. The current study indicates that non-invasive microdart biopsy sampling methods commonly used for monitoring contaminants in marine mammals yield representative details on contaminant burdens for chlorinated and brominated aromatic compounds in marine mammal blubber, regardless of the quantity and type of blubber sampled, provided that lipid normalization is performed on resulting analytical determinations

Assessment of uncertainty sources in water quality modeling in the Niagara River

This paper presents a framework to quantify the overall variability of the model estimations of Total Polychlorinated Biphenyls (Total PCBs) concentrations in the Niagara River on the basis of the uncertainty of few model parameters and the natural variability embedded in some of the model input variables. The results of the uncertainty analysis are used to understand the importance of stochastic model components and their effect on the overall reliability of the model output and to evaluate multiple sources of uncertainty that might need to be further studied. The uncertainty analysis is performed using a newly developed point estimate method, the Modified Rosenblueth method. The water quality along the Niagara River is simulated by coupling two numerical models the Environmental Fluid Dynamic Code (EFDC) – for the hydrodynamic portion of the study and the Water Quality Analysis and Simulation Program (WASP) – for the fate and transport of contaminants. For the monitoring period from May 1995 to March 1997, the inflow Total PCBs concentration from Lake Erie is the stochastic component that most influences the variability of the modeling results for the simulated concentrations at the exit of the Niagara River. Other significant stochastic components in order are as follows: the suspended sediments concentration, the point source loadings and to a minor degree the atmospheric deposition, the flow and the non-point source loadings. Model results that include estimates of uncertainty provide more comprehensive information about the variability of contaminant concentrations, such as confidence intervals, and, in general offer a better approach to compare model results with measured data.

Distributions of typical contaminant species in urban short-term storm runoff and their fates during rain events: A case of Xiamen City

The pollutants in urban storm runoff, which lead to an non-point source contamination of water environment around cities, are of great concerns. The distributions of typical contaminants and the variations of their species in short term storm runoff from different land surfaces in Xiamen City were investigated. The concentrations of various contaminants, including organic matter, nutrients (i.e., N and P) and heavy metals, were significantly higher in parking lot and road runoff than those in roof and lawn runoff. The early runoff samples from traffic road and parking lot contained much high total nitrogen (TN 6–19 mg/L) and total phosphorus (TP 1–3 mg/L). A large proportion (around 60%) of TN existed as total dissolved nitrogen (TDN) species in most runoff. The percentage of TDN and the percentage of total dissolved phosphorus remained relatively stable during the rain events and did not decrease as dramatically as TN and TP. In addition, only parking lot and road runoff were contaminated by heavy metals, and both Pb (25–120 μg/L) and Zn (0.1–1.2 mg/L) were major heavy metals contaminating both runoff. Soluble Pb and Zn were predominantly existed as labile complex species (50%–99%), which may be adsorbed onto the surfaces of suspended particles and could be easily released out when pH decreased. This would have the great impact to the environment.

Analytical Solution for Conservative Solute Transport in One-Dimensional Homogeneous Porous Formations with Time-Dependent Velocity

The space-time variation in contaminant concentration in unsteady flow in a homogeneous finite aquifer subjected to point source contamination is analytically derived under two conditions: (1) the flow velocity in the aquifer is of sinusoidal form; and (2) the flow velocity is an exponentially decreasing function. The analytical solution is illustrated using an example. Analytical solutions are perhaps most useful for benchmarking numerical codes and solutions.

Spatial and Temporal Variation of Freely Dissolved Polycyclic Aromatic Hydrocarbons in an Urban River Undergoing Superfund Remediation

Urban rivers with a history of industrial use can exhibit spatial and temporal variations in contaminant concentrations that may significantly affect risk evaluations and even the assessment of remediation efforts. Concentrations of 15 biologically available priority pollutant polycyclic aromatic hydrocarbons (PAHs) were measured over five years along 18.5 miles of the lower Willamette River using passive sampling devices and HPLC. The study area includes the Portland Harbor Superfund megasite with several PAH sources including remediation operations for coal tar at RM 6.3 west and an additional Superfund site, McCormick and Baxter, at RM 7 east consisting largely of creosote contamination. Study results show that organoclay capping at the McCormick and Baxter Superfund Site reduced PAHs from a precap average of 440 +/- 422 ng/L to 8 +/- 3 ng/L postcapping. Results also reveal that dredging of submerged coal tar nearly tripled nearby freely dissolved PAH concentrations. For apportioning sources, fluoranthene/pyrene and phenanthrene/anthracene diagnostic ratios from passive sampling devices were established for creosote and coal tar contamination and compared to published sediment values.

Reproduction and survival of tawny owls in relation to persistent organic pollutants

The potential effects of organochlorines (OCs) and brominated flame retardants on reproduction and survival were studied in tawny owls ( Strix aluco) in Central Norway over a period of 19 years (1986–2004). Concentrations of 14 OCs and five polybrominated diphenyl ethers (PBDEs) were measured in eggs ( n = 104), and Principal Component Analysis was used to produce composite measurements of pollutants; i.e. PC1 and PC2, which accounted for 85% of the variation in contaminant concentrations. There was no evidence for adverse associations between pollutants (PC scores) and life-history traits such as clutch size, probability of producing fledglings and survival, when controlling for potentially confounding variables. Moreover, there was no evidence for interactions between pollutants and vole abundance suggesting no synergistic effects of food stress and pollutants on these life-history traits. There was, however, some evidence for a non-linear negative association between p,p′-DDE (1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene) and eggshell thickness. This suggests that the concentrations of pollutants in this ecosystem were too low to affect reproduction and survival in an owl predominantly consuming prey at low trophic levels, but may be sufficient to cause eggshell thinning at the highest concentrations.

Aquifer contamination by chlorinated-VOCs: the case of an urban metropolis megasite overlying the Coastal Plain aquifer in Israel

The Tel Aviv metropolitan region (200 km2), located on the sandy and phreatic Mediterranean Coastal Plain aquifer in Israel, is an example of a contaminated megasite that is additionally complicated by being part of a densely populated urban environment. Despite being a major source of fresh potable water, no dedicated aquifer monitoring systems exist. The vast majority of tested water supply wells (82% of 90 wells) were found to be contaminated with one or more chlorinated volatile organic compounds (Cl-VOCs) such as trichloroethene and tetrachloroethene, originating from multiple sources, including former industrial sites. Temporal variations in Cl-VOC concentrations in water supply wells were large and unpredictable. Such aquifer contamination requires immediate action in terms of aquifer management and municipal water distribution. To cope with temporal and spatial variations in contaminant concentrations in water supply wells in an area where monitoring wells are absent, aquifer impact areas were defined based on the concentration of the Cl-VOC contaminant in pumping wells that was greatest in relation to its drinking water standard over a 3-year period. Such a map can be used to define water supply treatment and municipal well monitoring requirements, until an adequate monitoring system is established.