Potential Groundwater Contamination Research Articles

A comparison study of DRASTIC methods with various objective methods for groundwater vulnerability assessment

Groundwater vulnerability assessment is a measure of potential groundwater contamination for areas of interest. The main objective of this study is to modify original DRASTIC model using four objective methods, Weights-of-Evidence (WOE), Shannon Entropy (SE), Logistic Model Tree (LMT), and Bootstrap Aggregating (BA) to create a map of groundwater vulnerability for the Sari-Behshahr plain, Iran. The study also investigated impact of addition of eight additional factors (distance to fault, fault density, distance to river, river density, land-use, soil order, geological time scale, and altitude) to improve groundwater vulnerability assessment. A total of 109 nitrate concentration data points were used for modeling and validation purposes. The efficacy of the four methods was evaluated quantitatively using the Area Under the Receiver Operating Characteristic (ROC) Curve (AUC). AUC value for original DRASTIC model without any modification of weights and rates was 0.50. Modification of weights and rates resulted in better performance with AUC values of 0.64, 0.65, 0.75, and 0.81 for BA, SE, LMT, and WOE methods, respectively. This indicates that performance of WOE is the best in assessing groundwater vulnerability for DRASTIC model with 7 factors. The results also show more improvement in predictability of the WOE model by introducing 8 additional factors to the DRASTIC as AUC value increased to 0.91. The most effective contributing factor for ground water vulnerability in the study area is the net recharge. The least effective factors are the impact of vadose zone and hydraulic conductivity.

Modelling groundwater contamination above a potential nuclear waste repository in the Columbia River Basalt, USA

Potential groundwater contamination above the one-time candidate repository for high-level nuclear waste in the Columbia River Basalt (CRB), USA, is evaluated in a flow-transport model with 260,895 elements for a period of 1 million years. The hydrogeologic database originates from the Basalt Waste Isolation Project, which ended in 1987, giving way to the Yucca Mountain project. The CRB data have been scanned recently with the object of finding a storage site for natural gas and a sequestration site for CO2. However, the impact on the nuclear issue in the USA or other countries with similar large flood-basalt provinces has never been evaluated since the suspension of the project. The peak radioactive dose predicted for a potential repository in the CRB is at least eight orders of magnitude lower than the US generic regulatory limit (0.15 mS/a) even for the most pessimistic scenario.

Mapping Groundwater Vulnerability Zones in Eogenetic Karst Catchment Using Particle-tracking Method

Accurate mapping of groundwater vulnerability zones based on robust groundwater model is crucial towards an appropriate development of management strategies. This study aimed at developing groundwater vulnerability zones in a tropical karst area in Rote Island, Indonesia. HGZ method was employed to accommodate the limitation of subsurface data. Using reverse particle-tracking simulation, this study combined the simulation results (travel time and pathline trajectory) with the potential groundwater contamination risk to designate three vulnerability zones. In this study preventive management measures were recommended to ensure provision of safe and good quality water from Oemau Spring and to protect the spring from contamination.

Groundwater Pollution Threats in the Republic of Macedonia due to Uncontrolled Landfills

AbstractWaste management practices are among the most important environmental issues in the Republic of Macedonia. Reusing, recycling, recovery and treatment of municipal solid waste are very limited. Nearly all municipal solid wastes in the country are disposed on landfills, out of which some are sanitary, while most are uncontrolled landfills/dumps and do not comply with the Directive 99/31/EC of 26 April 1999 set by the European Commission. This is a major environmental concern due to pollution of surrounding soil, ground and surface waters, human and wildlife food sources, animal habitat patterns and aesthetic impacts in the countryside. Available data about uncontrolled landfills locations are mapped and compared to the geology, hydrogeology, groundwater vulnerability as well as rainfall maps, upon which appropriate analysis is performed related to the groundwater contamination potential. The uncontrolled landfill sites and surrounding regions are then ranked according to their threats for groundwater contamination and prioritized for sustainable remediation.

Green Silver Nanoparticles for Enhancing the Phytoremediation of Soil and Water Contaminated by Fipronil and Degradation Products

Fipronil has been associated with neurotoxicity, carcinogenicity, endocrine disruption, persistence in soil, and low uptake by plants and is a potential groundwater contaminant. Fipronil degradation by silver nanoparticles (AgNPs) from medicinal plant extracts was investigated in spiked water. Also, remediation capacity of soil contaminated by fipronil under the combined application of green AgNPs and phytoremediation was investigated. Brassica-AgNps, Ipomoea-AgNps, Camellia-AgNps, and Plantago-AgNps in water solution significantly reduced fipronil residues by 95.45, 90.15, 63.65, and 63.48%) during 2 days of treatment as compared with 18.42% in untreated water without AgNps. Fipronil amide and fipronil-desulfenyl metabolites were detected in water under the influence of AgNps. The contribution of Brassica-AgNps, Plantago-AgNps, Ipomoea-AgNps, and Camellia-AgNps to the dissipation of fipronil in the soil were 68.8, 54.64, 43.75, and 30.99%, respectively, compared with 10.14% by Plantago major alone through 6 days. Low uptake and translocation of fipronil by P. major roots and leaves were seen in flooded soil alone or under the influence of AgNps within 6 days of treatment. However, the resulting fipronil amide product accumulates in large quantities in P. major roots and leaves. These results show that AgNps and P. major play a major role for the remediation of fipronil contaminated water and in flooded soil, while P. major played an important role for remediation the polar break product, fipronil-amide as phytoremediation.

Assessment of groundwater vulnerability and sensitivity to pollution in Aquifers Zanjan Plain, Iran

Groundwater pollution caused by human activity is a serious environmental problem in cities. Pollution vulnerability assessment of groundwater resources provides information on how to protect areas vulnerable to pollution. The present study is a detailed investigation of the potential for groundwater contamination through construction of a vulnerability map for the study aquifer in Zanjan plain. The parameters used in the DRASTIC model are depth-to-water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity. The overlying index, GIS and AHP were used with the modified DRASTIC model to evaluate the vulnerability of the alluvial Zanjan aquifer to nitrates. AHP was used to determine the rate coefficient of each parameter. The correlation coefficients were produced by comparing the vulnerability index with the nitrate concentrations in the groundwater. The results show that the DRASTIC index values for the study area ranged from 82 to 186 and were divided into low, medium, and high vulnerability classes. GIS was found to provide an efficient environment for such analyses. The DRASTIC aquifer vulnerability map indicates the dominance of the medium vulnerability class in the most parts of the study area (49.033%). The high correlation coefficient for the modified DRASTIC index (0.92) and nitrate layer than for the standard DRASTIC model (0.74) suggests that the actual condition in the study area can be better explained by the modified DRASTIC model.Keywords: Groundwater vulnerability, GIS, DRASTIC Model, AHP, Zanjan

Assessing the abilities of intrinsic and specific vulnerability models to indicate groundwater vulnerability to groups of similar pesticides: a comparative study

With continued population growth and increasing use of fresh groundwater resources, protection of this valuable resource is critical. A cost effective means to assess risk of groundwater contamination potential will provide a useful tool to protect these resources. Integrating geospatial methods offers a means to quantify the risk of contaminant potential in cost effective and spatially explicit ways. This research was designed to compare the ability of intrinsic (DRASTIC) and specific (Attenuation Factor; AF) vulnerability models to indicate groundwater vulnerability areas by comparing model results to the presence of pesticides from groundwater sample datasets. A logistic regression was used to assess the relationship between the environmental variables and the presence or absence of pesticides within regions of varying vulnerability. According to the DRASTIC model, more than 20% of the study area is very highly vulnerable. Approximately 30% is very highly vulnerable according to the AF model. When groundwater concentrations of individual pesticides were compared to model predictions, the results were mixed. Model predictability improved when concentrations of the group of similar pesticides were compared to model results. Compared to the DRASTIC model, the AF model more accurately predicts the distribution of the number of contaminated wells within each vulnerability class.

Assessment of Mesotrione Leaching Applied Alone and Mixed in Seven Tropical Soils Columns under Laboratory Conditions

Herbicide leaching is influenced by soil physical and chemical properties as well as the prevailing climatic conditions. However, little is known about leaching of mixture of herbicides in the soil, especially in tropical regions like Brazil. The objective of this study is to evaluate the leaching of 14C-mesotrione (cyclohexane-2-14C-mesotrione) alone and in a mixture with S-metolachlor and terbuthylazine in seven tropical soil columns under laboratory conditions. These soils represented a wide range of properties with varying textures, cation exchange capacity (44 to 154 mmolc kg−1), pH (6.0 to 7.7), organic carbon content (0.58 to 27.32 g kg−1) and clay mineral contents (50 to 605 g kg−1), which are typical of tropical soils. Mesotrione residues were observed across all soil column layers (0–30 cm) in all evaluated soils by simulating 200 mm of water for 48 h. The application of mesotrione, alone or in a mixture, does not influence the leaching of this herbicide. Leaching of mesotrione ranged from low (up 15 cm) to very high (up 30 cm and leachate) in the tropical soils and may pose a potential groundwater contamination risk. In sand and loamy sand soil, the mesotrione was quantified in the leachate at all sampling times as above 80% of the amount initially applied. Thus, mesotrione application without the prior knowledge of the soil physical and chemical properties can result in inefficient weed control on field condition due to high leaching potentials.

Evaluating the fate of agrochemical through adsorption and desorption studies of chlorfluazuron in selected agricultural soils

Around two millennia ago agrochemicals were introduced to enhance crop quality and quantity. Later on these pesticides were found to cause undesired environmental effects mainly contamination of water bodies and soil. Therefore it became necessary to study and understand the environmental behavior of pesticides. In the present study adsorption and desorption of benzoylphenylurea insecticide, Chlorfluazuron was investigated for 4 different types of soils (clay, Sandy clay loam, Sandy loam and Sandy clay). These 4 types of soils were collected from 10 different agricultural areas of Pakistan. The physiochemical properties of selected soil samples were analyzed according to standard test method (STM), and then their sorption study was investigated through batch equilibrium method involving UV–Visible spectrophotometer and HPLC techniques. The sorption data was fitted well into the Freundlich and linear equation. The Freundlich adsorption coefficients (Kf ads) ranged from 3.9 to 9.05 µg ml−1 and distribution adsorption coefficients (Kd ads) ranged from 4.7 to 12.0 µg ml−1 suggesting that chlorfluazuron was weakly adsorbed on the tested soils. The Freundlich desorption coefficients (Kf des) varied from 1.23 to 8.9 µg ml−1, and distribution desorption coefficients (Kd des) ranged from 4.09 to 9.2 µg ml−1 indicating that chlorfluazuron tend to be leached from soils thus there is significant potential for surface and groundwater contamination of tested soil samples with chlorfluazuron. These results were further confirmed by leachability/mobility index KOM, which classified chlorfluazuron in highly mobile group of pesticides.

Long‐Term Reaction Characteristics of CO2–Water–Rock Interaction: Insight into the Potential Groundwater Contamination Risk from Underground CO2 Storage

AbstractCO2 sequestration into saline aquifers is considered to be one of the most promising options for reducing industrial CO2 emissions to the atmosphere. However, there are still many uncertainties regarding the storage of CO2 in the subsurface because of a lack of knowledge about CO2–water–rock interaction within CO2 reservoirs and the potential risk of CO2 leakage. In this study, we construct a semi‐open type experimental system that can reproduce the interactions under conditions close to those of actual CO2 reservoirs. Using the system, we conduct CO2–water–rock interaction experiments for 8 months to monitor the long‐term reaction and the mobilization of harmful metal elements. Altered tuffaceous rock is used in the experiment because these tuffaceous rock formations (called “Green Tuff”) are a potential candidate for CO2 storage in Japan. The results show that the major‐element water composition will converge to the point where host rock dissolution and secondary mineral precipitation are balanced; then, the interaction will proceed under a certain groundwater composition. In addition, we found that groundwater contamination by some metal elements (Ni, Ba, and Mn) may reach unsafe levels for drinking water as a result of CO2‐water–rock interaction.

Multi-criteria potential groundwater contamination and human activities: Araras watershed, Brazil

ABSTRACT Assessment of groundwater contamination potential using geological, hydrological and hydrogeological attributes, is an efficient mechanism of sub-surface water resources protection and conservation. However, usually this method does not take into consideration the potentially polluting human activities, either in punctual or diffuse sources, or because the relative importance of the attributes are not considered. The paper proposes a multi-criteria approach as a way of solving this gap, reducing subjectivity and considering land use/cover due human actions influence in the process. The study was developed in Araras river watershed (Paraná Basin, Brazil) using rock, groundwater, relief, soils, and land use/land cover classification, employing multi-criteria analysis and data of contamination sources. The potential contamination classification showed the predominance (54% of the area) of very high and high potential, especially due to geological environment conditions (exploitation areas and groundwater recharge of the Itararé Aquifer - clastic sedimentary and free flow). The contaminant sources analyzed are located mainly in higher potential contamination areas.

Dynamics of Ions in Soils Irrigated with Saline Reject

The objective of this work was to evaluate the variation in the electrical conductivity and the mobilization of ions present in reject brine from desalination plant of brackish well water in three types of soil. The mobilization of the contaminant ions in the reject brine was studied in glass percolation columns, which were filled with soil of contrasting textures (eutrophic CAMBISOL, typic dystrophic Red OXISOL, ENTISOL Quartzipsamment). Experiments ware repeated three times each, and the initial and final concentrations of the ion contaminants were analyzed. The pollution potential of this residue was determined by the retardation factor and dispersion-diffusion coefficient of Ca2+ and Mg2+, besides the variation of electrical conductivity along the profile of each soil studied. In the Red Oxisol, Ca2+ and Mg2+ ions move with greater ease resulting in possibility largest of potential of ground water contamination. In Entisol Quartzipsamment presented higher Mg2+ (R) ion advancement speed, that is, higher subsurface contamination power for these ions. The eutrophic Cambisol presented low diffusion-dispersion coefficient in all the evaluated ions and, therefore, lower mobility of the ions in the soil profile, and consequently, a greater possibility of contamination when irrigated with reject brine.

A review of using porous asphalt pavement as an alternative to conventional pavement in stormwater treatment

PurposePorous asphalt has been used for than 50 years, but it was originally developed in 1970 at Franklin institute in Philadelphia, Pennsylvania. By 1974 the first formalized procedure was created by the federal highway administration to design mixtures. Many researches on porous asphalt mixture have been conducted for the past two decades. However, there remains some concern about the potential adverse impacts of infiltrated surface water on the underlying groundwater. The purpose of this paper is to presents a short review on the application of porous asphalt pavement stormwater treatment.Design/methodology/approachIn this paper, a critical review on history and benefits is presented followed by review of general studies of using porous asphalt pavement, and some recent scientific studies that examine potential contamination of soil and groundwater because of infiltration systems.FindingsThis paper indicates that porous asphalt pavement is more efficient than conventional pavements in terms of retaining pollutants, improving the quality of water and runoff while maintaining infiltration.Originality/valueThis paper may also help reduce land consumption by reducing the need for traditional storm-water management structures. However, on the other hand, the priority objectives which is minimizing increased flooding and pollution risks while increasing performance efficiency and enhancing local environmental quality-of-life is achieved.

Modeling the potential impacts of CO2 sequestration on shallow groundwater: The fate of trace metals and organic compounds before and after leakage stops

AbstractLarge‐scale deployment of CO2 geological sequestration requires understanding and assessing the risks of such an operation. One of these risks is the potential contamination of groundwater by CO2/brine leakage into shallow aquifers. Although our understanding of this issue has improved significantly over the last decade, several questions still need to be better addressed, including the fate of organic constituents, the dominant source of trace metals (are they mainly coming from aquifer sediments, or leaking brine), and whether the trace metals released during the leakage phase recover to background levels if the leakage were to be detected and stopped. In this paper, reactive transport simulations that model the behavior of trace metals and organic compounds in response to the leakage of CO2 and brine into a shallow aquifer are presented to address these questions. Model results show that the metals and organic compounds brought by the leaking brine form a plume at the bottom of the aquifer because the density of the brine is higher than that of groundwater. In contrast, metals are mobilized by CO2 over a larger vertical extent because of the spreading of gaseous CO2 by buoyancy. The concentration of organic contaminants is strongly attenuated by adsorption and degradation, with degradation playing the major role in the modeled scenarios. Although the leaking brine is assumed to contain elevated concentrations of As, Pb, Cd, and Ba, it does not contribute significantly to the contamination of the modeled shallow aquifer by these elements. Once the leakage stops, mobilized organic compounds that undergo degradation vanish, while less degradable compounds linger for a longer time; the dissolved concentrations of trace metals decrease significantly, as a result of re‐sorption and reversal of processes leading to Ca‐driven cation exchange. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Technology Focus: Health, Safety, Security, Environment, and Social Responsibility

Technology Focus According to Investopedia, in 2015, the oil and gas industry accounted for between 4.6 and 6.5% of the global economy. In a recent discussion I had with a friend, we spoke about the effect this industry has on the lives of so many people. Many of the effects are positive, and, as we see in the current discussions of climate change, some are potentially negative. As Janeen Judah, 2017 SPE president, stated in her April 2017 JPT column, we have the power to build sustainable communities and improve the lives of people where we operate. Our innovation across all aspects of health, safety, security, environment, and social responsibility not only helps our industry reduce the chances, or consequences, of unplanned events but also may help develop the capacity of a country or village to take care of its own citizens. Some of these recent improvements can be seen in the papers that follow, from understanding well control and human factors better to using robotics to remove people from hazardous environments. We also see increasing interest in effects on the environment from our activities in the form of publicly funded studies on the potential for groundwater contamination. At the 2017 SPE Health, Safety, Security, Environment, and Social Responsibility Conference—North America, held in April in New Orleans, we held a series of plenary discussions on the science of the human brain, on social interactions, and on how to apply this knowledge to improve our performance. Our industry is conducting some amazing research and development, and the tools and processes we develop will help us, and the world, to better develop and use the natural resources we need now and in the future. Recommended additional reading at OnePetro: www.onepetro.org. SPE 181109 Monitoring of Nontechnical Barriers by S. Næss, Statoil, et al. SPE 183117 iRisk: A New Practical Guide to Cross-Functional Risk Leadership in Oil and Gas Megaprojects by Zarina Kenzhetayeva, Maersk Oil Kazakhstan, et al. SPE 183595 Whole Systems Analysis of a High-Reliability Organization by C.O. Chukwunta, Imperial College London SPE 185188 Developing Regulations Concerning Dispersant Use—A Recommended Good-Practice Approach by T.S. Coolbaugh, ExxonMobil, et al. IPTC 18827 The Survey for Prevention of Work-Related Musculoskeletal Disorders Among Workers Performing Manual Material-Handling Work by A. Thongpradit, PTT Exploration and Production, et al. SPE 180365 Dynamic Considerations for Induced Seismicity by Robert L. Walker, University of Southern California, et al. OTC 27750 Use of a Cybersecurity Laboratory in Support of the Virtual-Vessel Concept To Increase Safety Onboard Marine and Offshore Assets by Naveen Selvam, ABS, et al.

THE USE OF THE DRASTIC METHOD AND GIS IN ASSEESSING THE VULNERABILITY OF THE GROUNDWATER, IN THE VELIPOJA -ZADRIMA AQUIFER, ALBANIA

The Albanian plain area is densely populated. The population doubled during the last two decades and most of it uses the groundwaters of these aquifers. Aquifers in lowland areas are vulnerable to pollution. This article assesses the vulnerability of groundwater Velipoj-Zadrimè aquifer. This aquifer has a surface of 237 km2 and an average height of 10m above sea level. Groundwater recourses are connected with alluvial deposits formed by Drini and Buna rivers. The vulnerability Map is an ιmportant tool for the management of the territory. It guides the selection of areas for development projects, in order to avoid negative consequences on the quality of groundwater. Geographic Information Systems are very valuable programme for processing. The DRASTIC method has been used to map the natural aquifer vulnerability of the Velipoja-Zadrima study area. This method, applied to assess the vulnerability of the aquifer, was developed by the "Environmental Protection Agency (US EPA)" and "The National Association of Water Wells (NWWA)". It is a technique to assess the potential contamination of groundwater and is based on seven (7) parameters: Depth (D), Recharge (R), Aquifer media (A), Soil media (S), Topography (T), Impact of vadose zone (I), and Conductivity of the aquifer (C). The DRASTIC index is determined by the sum of the products of the Weight and site ratings of all the parameters. High values of vulnerability cover large areas of the aquifer. The results provide important information for local authorities in the management of resources and territory.

Development of groundwater vulnerability zones in a data-scarce eogenetic karst area using Head-Guided Zonation and particle-tracking simulation methods

Delineation of groundwater vulnerability zones based on a valid groundwater model is crucial towards an accurate design of management strategies. However, limited data often restrain the development of a robust groundwater model. This study presents a methodology to develop groundwater vulnerability zones in a data-scarce area. The Head-Guided Zonation (HGZ) method was applied on the recharge area of Oemau Spring in Rote Island, Indonesia, which is under potential risk of contamination from rapid land use changes. In this method the model domain is divided into zones of piecewise constant into which the values of subsurface properties are assigned in the parameterisation step. Using reverse particle-tracking simulation on the calibrated and validated groundwater model, the simulation results (travel time and pathline trajectory) were combined with the potential groundwater contamination risk from human activities (land use type and current practice) to develop three vulnerability zones. The corresponding preventive management strategies were proposed to protect the spring from contamination and to ensure provision of safe and good quality water from the spring.

Fixed Bed Adsorption of Benzene, Toluene, and Xylene (BTX) Contaminants from Monocomponent and Multicomponent Solutions Using a Commercial Organoclay

Benzene, toluene, and xylene (BTX) are potential contaminants of groundwater, and there is a need to improve current remediation techniques, such as adsorption. Different materials can be applied in this process, like organoclays that have affinity for organic compounds. The aim of this work was to study BTX removal from mono-, bi-, and tricomponent solutions in a dynamic fixed bed system filled with organoclay. For the monocomponent system, using a 1.6 mmol/L adsorbate concentration, the useful removal quantities were 0.012, 0.030, and 0.140 mmol/g for benzene, toluene, and p-xylene, respectively. Based on the results, the affinity order was p-xylene > toluene > benzene. The multicomponent tests presented similar affinity tendency toward the organoclay. The mathematical model of Yan described the majority of the experimental breakthrough curves better than the model of Thomas. Partition was identified as the prevailing mechanism in BTX uptake, and the main adsorption sites were associated with the nanosi...

Column transport studies of 3-nitro-1,2,4-triazol-5-one (NTO) in soils

Development of the new, insensitive, energetic compound, NTO (3-nitro-1,2,4-triazol-5-one), creates need for the data on NTO's fate and transport to predict its behavior in the environment and potential for groundwater contamination. To measure the transport of NTO in soils, we conducted miscible-displacement experiments under steady state and interrupted flow conditions using eight soils having varying physical and geochemical properties. The breakthrough curve (BTC) data were analyzed using temporal moment analysis and simulated using HYDRUS-1D to determine transport parameters and better understand the mechanisms of sorption and transformation. Parameters determined from the miscible-displacement study were compared to results obtained from batch experiments conducted for the same soils, and examined in relation to soil properties. Column NTO linear adsorption coefficients (Kd) were low and correlated well (P = 0.000049) with measurements from the batch studies. NTO transformation rate constants increased and NTO recovery decreased with increase in soil organic carbon (OC) content. Autoclaved soils had slower transformation rates and greater NTO recoveries indicating that microorganisms play a role in NTO transformation. In addition, the transformation rate increased with time in soils with higher OC. Monod-type kinetics was implemented in HYDRUS-1D to simulate the observed increase in transformation rate with time. We think this phenomenon is due to bacterial growth. Results indicate very low adsorption of NTO in a range of soils, but natural attenuation through transformation that, depending on soil OC content and hydraulic residence time, could result in complete removal of NTO.

Development a numerical model of flow and contaminant transport in layered soils

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.