Potential Groundwater Contamination Research Articles

Evaluation of the Effectiveness of Existing Preventive Fire-Fighting Measures in the City of Douala, Cameroon, to Improve Decision-Making and Public Safety

The storage of hydrocarbons in urban areas poses significant risks to local populations, including the potential for fire, explosion, groundwater contamination, and air pollution. The objective of this study is to evaluate the efficacy of current fire prevention and suppression strategies in the city of Douala. The study will be approached by first identifying, geolocating, and characterizing urban firefighting equipment. Subsequently, a proposal will be put forth for a response system to safeguard the city in the event of a catastrophic fire at a service station. In order to achieve this objective, the current regulatory framework governing the location of FH facilities was subjected to a thorough examination. Subsequently, pivotal compliance factors were identified, operationalized, and an audit checklist was formulated. A safety questionnaire was utilized to assess the equipment within service stations. GPS technology was employed to record the GPS coordinates of the FHs. GIS10.3.1 software was utilized to evaluate the BI distribution model. The data obtained from the questionnaires were analyzed using SPSS20.0 software, which revealed that the 142 BIs studied were essentially randomly distributed across the following neighborhoods. The results of the election yielded the following results: Bonamoussadi 27 (19%), Bonandjo 19 (13%), Bali 02 (1%), Deido 09 (6%), Akwa Nord 03 (2%), Bonamoussadi 18 (12%), Makepe 18 (12%), and B. The remaining 5% is distributed among the following: Assa, Bepanda, Cité-Sic, Ndogbong, Cité des Palmiers, Bonaberi, and New-Bell. Of the 142 FH identified, 30 (21.12%) lack water, and 4 (2.81%) have a flow rate of less than 30 m³/h with a dynamic pressure of less than 1 bar. Seventeen (11.97%) are inaccessible; 79 (55.63%) are operational; five (3.52%) are challenging to operate; and seven (4.92%) are situated within a private enclosure. The response time of the fire department is inadequate for all stations situated more than 3 km from their base in Ngondi-Douala. Only 17 (11.52%) of the stations are situated at distances of less than 5.83 km, which is conducive to efficient intervention. In contrast, 134 (88.74%) of the stations are located at distances of 5.83 km or more from the fire department base, which is not conducive to efficient intervention. The results indicate that the BIs are situated at considerable distances from the stations. Notably, the Total Laquitinie station is the sole city station with a FH located at its entrance. The database developed in this study could serve as a valuable resource for policymakers to inform appropriate action.

Water quality and dissolved load in the Chirchik and Akhangaran river basins (Uzbekistan, Central Asia)

Uzbekistan (Central Asia) is experiencing serious water stress as a consequence of altered climate regime, past over-exploitation, and dependence from neighboring countries for water supply. The Chirchik–Akhangaran drainage basin, in the Tashkent province of Uzbekistan, includes watersheds from the Middle Tien Shan Mountains escarpments and the downstream floodplain of the Chirchik and Akhangaran rivers, major tributaries of the Syrdarya river. Water in the Chirchik–Akhangaran basin is facing potential anthropogenic pressure from different sources at the scale of river reaches, from both industrial and agricultural activities. In this study, the major and trace element chemistry of surface water and groundwater from the Chirchik–Akhangaran basin were investigated, with the aim of addressing the geogenic and anthropogenic contributions to the dissolved load. The results indicate that the geochemistry of water from the upstream catchments reflects the weathering of exposed lithologies. A significant increase in Na+, K+, SO42−, Cl−, and NO3− was observed downstream, indicating loadings from fertilizers used in croplands. However, quality parameters suggest that waters are generally suitable for irrigation purposes, even if the total dissolved solid indicates a possible salinity hazard. The concentration of trace elements (including potentially toxic elements) was lower than the thresholds set for water quality by different regulations. However, an exceedingly high concentration of Zn, Mo, Sb, Pb, Ni, U, As, and B compared with the average river water worldwide was observed. Water in a coal fly-ash large pond related to the Angren coal-fired power plants stands out for the high As, Al, B, Mo, and Sb concentration, having a groundwater contamination potential during infiltration. Spring waters used for drinking purposes meet the World Health Organization and the Republic of Uzbekistan quality standards. However, a surveillance of such drinking-water supplies is suggested. The obtained results are indicators for an improved water resource management.

A data-driven approach to identifying PFAS water sampling priorities in Colorado, United States.

Per and polyfluoroalkyl substances (PFAS), a class of environmentally and biologically persistent chemicals, have been used across many industries since the middle of the 20th century. Some PFAS have been linked to adverse health effects. Our objective was to incorporate known and potential PFAS sources, physical characteristics of the environment, and existing PFAS water sampling results into a PFAS risk prediction map that may be used to develop a PFAS water sampling prioritization plan for the Colorado Department of Public Health and Environment (CDPHE). We used random forest classification to develop a predictive surface of potential groundwater contamination from two PFAS, perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). The model predicted PFAS risk at locations without sampling data into one of three risk categories after being "trained" with existing PFAS water sampling data. We used prediction results, variable importance ranking, and population characteristics to develop recommendations for sampling prioritization. Sensitivity and precision ranged from 58% to 90% in the final models, depending on the risk category. The model and prioritization approach identified private wells in specific census blocks, as well as schools, mobile home parks, and public water systems that rely on groundwater as priority sampling locations. We also identified data gaps including areas of the state with limited sampling and potential source types that need further investigation. This work uses random forest classification to predict the risk of groundwater contamination from two per- and polyfluoroalkyl substances (PFAS) across the state of Colorado, United States. We developed the prediction model using data on known and potential PFAS sources and physical characteristics of the environment, and "trained" the model using existing PFAS water sampling results. This data-driven approach identifies opportunities for PFAS water sampling prioritization as well as information gaps that, if filled, could improve model predictions. This work provides decision-makers information to effectively use limited resources towards protection of populations most susceptible to the impacts of PFAS exposure.

Integration of Geophysical and Hydrochemical Methods to Determine the Groundwater Contamination in Al-Hosayniat Landfill South East Mafraq City, Jordan

An integration of Geophysical – Electromagnetic and hydro-chemical methods was used to investigate the potential of groundwater contamination due to Al-Hosayniat Municipal Landfill (HL) southeast of Mafraq city. Twenty-five Time Domain Electromagnetic (TDEM) soundings were carried out inside and outside the HL in addition to one WNW-ESE Very Low Frequency (VLF) profile. The TDEM's results help to define the subsurface geology and structures down to 240m depth. The results also depict the presence of a major fault striking NW-SE that crosses the whole landfill, this fault is documented in the surface geological map, and it was delineated and imaged by TDEM measurements and detected at larger depths. VLF results also detected the presence of a major fault beneath the landfill. The presence of the fault just beneath the HL may enhance the leachate movement which can imply groundwater contamination hazards for a longer period as it is a preferential pathway for contaminants. The results of water quality analyses of adjacent wells show higher concentrations of Na+, SO-24, TDS in some wells and this can be ascribed to agricultural activities and over-pumping in the area rather than landfill leachate. The heavy metal concentrations were found to be within the permissible limits and did't indicate direct contamination due to the HL. However, Fluorite (F-) shows a high concentration of (1.3mg/l) in WS4 and WS5 wells and approaches the permissible limit (1.5mg/l) according to the Jordan Water Standards (JWS). Bromide (Br) shows high concentration of (0.6mg/l) in well Al-2462.

Long-Term Polyethylene (Bio)Degradation in Landfill: Environmental and Human Health Implications from Comprehensive Analysis.

This study investigates the process of long-term (bio)degradation of polyethylene (PE) in an old municipal waste landfill (MWL) and its implications for environmental and human health. Advanced techniques, such as ICP-ES/MS and IC-LC, were used to analyze heavy metals and anions/cations, demonstrating significant concentration deviations from control samples. The soil's chemical composition revealed numerous hazardous organic compounds, further indicating the migration of additives from PE to the soil. Toxicological assessments, including Phytotoxkit FTM, Microtox® bioassay, and Ostracodtoxkit®, demonstrated phytotoxicity, acute toxicity, and high mortality in living organisms (over 85% for Heterocypris Incongruens). An unusual concentration of contaminants in the MWL's middle layers, linked to Poland's economic changes during the 1980s and 1990s, suggests increased risks of pollutant migration, posing additional environmental and health threats. Moreover, the infiltration capability of microorganisms, including pathogens, into PE structures raises concerns about potential groundwater contamination through the landfill bottom. This research underscores the need for vigilant management and updated strategies to protect the environment and public health, particularly in older landfill sites.

Saline and hydrocarbon-bearing fluids detected in shallow aquifers of southern New Brunswick, Canada: Natural occurrence, or deep migration along faults and industrial wellbores?

Unconventional hydrocarbon production has sparked public concerns for several years, especially regarding potential potable groundwater contamination by hydrocarbons, brines, and various chemicals related to hydraulic fracturing operations. One possible contamination mechanism is upward migration of deep-seated contaminants over large vertical distances, through preferential pathways such as leaky well casings or permeable geological faults. In New Brunswick (Canada), thermogenic hydrocarbons and brackish water were previously reported in shallow water wells, some of them located close to unconventional gas wells or to major faults, but the exact origin of these fluids remained uncertain. The objective of this paper is to determine whether the presence of these fluids is the result of migration from the deep (>1 km) hydrocarbon bearing units (via natural or anthropogenic migration pathways), or whether they rather originate within the shallow aquifer (<100 m) or from intermediate zone. Tracking fluid origin was achieved by fingerprinting compositional and isotopic values of three indicators: 1) water isotopic signature (including tritium (3H), radiocarbon (14CDIC), δ18OH2O, δ2HH2O), 2) salinity (including Na, Ca, K, SO4, Cl, Br, 87Sr/86Sr), and 3) hydrocarbons (compositional data and δ13CCH4). These various analyses were conducted, when relevant, on samples of different matrices composing the hydrogeological system, namely shallow groundwater (12–90 m depth), shallow bedrock gas (8–131 m), and intermediate zone evaporitic rocks (173–332 m); they were compared with previously published values for deep basin brines and gases (1940–3168 m) from the hydrocarbon bearing Carboniferous Albert Formation. This unique suite of indicators, analytes and matrices allowed drawing the conclusion that thermogenic gas and high salinities present in the sampled wells were naturally occurring and originating from shallow and intermediate-zone bedrock units. Results obtained through this approach did not provide any evidence that hydrocarbon wells in this area have acted as preferential migration pathways for deep-seated fluids towards shallow aquifers.

Biochar obtained from eucalyptus, rice hull, and native bamboo as an alternative to decrease mobility of hexazinone, metribuzin, and quinclorac in a tropical soil.

Mobile herbicides have a high potential for groundwater contamination. An alternative to decrease the mobility of herbicides is to apply materials with high sorbent capacity to the soil, such as biochars. The objective of this research was to evaluate the effect of eucalyptus, rice hull, and native bamboo biochar amendments on sorption and desorption of hexazinone, metribuzin, and quinclorac in a tropical soil. The sorption-desorption was evaluated using the batch equilibrium method at five concentrations of hexazinone, metribuzin, and quinclorac. Soil was amended with eucalyptus, rice hull, and native bamboo biochar at a rate of 0 (control-unamended) and 1% (w w-1), corresponding to 0 and 12 t ha-1, respectively. The amount of sorbed herbicides in the unamended soil followed the decreasing order: quinclorac (65.9%) > metribuzin (21.4%) > hexazinone (16.0%). Native bamboo biochar provided the highest sorption compared to rice hull and eucalyptus biochar-amended soils for the three herbicides. The amount of desorbed herbicides in the unamended soil followed the decreasing order: metribuzin (18.35%) > hexazinone (15.9%) > quinclorac (15.1%). Addition of native bamboo biochar provided the lowest desorption among the biochar amendments for the three herbicides. In conclusion, the biochars differently affect the sorption and desorption of hexazinone, metribuzin, and quinclorac mobile herbicides in a tropical soil. The addition of eucalyptus, rice hull, and native bamboo biochars is a good alternative to increase the sorption of hexazinone, metribuzin, and quinclorac, thus, reducing mobility and availability of these herbicides to nontarget organisms in soil.

Microbial, chemical, and isotopic monitoring integrated approach to assess potential leachate contamination of groundwater in a karstic aquifer (Apulia, Italy)

Landfill sites are subjected to long-term risks of accidental spill of leachate through the soil and consequential contamination of the groundwater. Wide areas surrounding the landfill can seriously be threatened with possible consequences to human health and the environment. Given the potential impact of different coexisting anthropic pollution sources (i.e., agriculture and cattle farming) on the same site, the perturbation of the groundwater quality may be due to multiple factors. Therefore, it is a challenging issue to correctly establish the pollution source of an aquifer where the landfill is not isolated from other anthropic land uses, especially in the case of a karstic coastal aquifer. The present study is aimed at setting in place an integrated environmental monitoring system that included microbiological, chemical, and isotope methods to evaluate potential groundwater pollution in a landfill district in the south of Italy located in Murgia karstic aquifer. Conventional (microbial plate count and physical–chemical analyses) and advanced methods (PCR-ARISA, isotope analysis of δ18O, δ2H, 3H, δ 13C, δ 15N-NO3−, and δ 18O-NO3−) were included in the study. Through data integration, it was possible to reconstruct a scenario in which agriculture and other human activities along with seawater intrusion in the karst aquifer were the main drivers of groundwater pollution at the monitored site. The microbiological, chemical, and isotope results confirmed the absence of leachate effects on groundwater quality, showing the decisive role of fertilizers as potential nitrate sources. The next goal will be to extend long-term integrated monitoring to other landfill districts, with different geological and hydrogeological characteristics and including different sources of pollution, to support the ecological restoration of landfills.

Durability, Capillary Rise and Water Absorption Properties of a Fiber-Reinforced Cement-Stabilized Fly Ash–Stone Dust Mixture

The management of unutilized fly ash poses challenges due to concerns about storage and its potential groundwater contamination. Within the road industry, where the bulk utilization of fly ash is feasible, its unsuitability for use in the base and sub-base layers of pavements due to its low strength and a high proportion of fine particles has been a limitation. The incorporation of stone dust alongside fly ash, treated with lime or cement, yields superior strength and stiffness. Apart from strength, the stabilized mix’s durability, capillary rise, and water absorption properties are crucial for determining its suitability for pavement applications. Observations from this study reveal that fiber-reinforced cement-stabilized fly ash–stone aggregate specimens treated with 4% and 6% cement, with and without fibers, met the limiting mass loss of 20%, as specified in IRC SP: 89. The mass loss decreases with an increase in cement and fiber content. However, the capillary rise in the mixes increases with a higher percentage of fly ash and fiber content but decreases with increased cement content. Cement addition results in a reduction in water absorption; however, the addition of fibers results in an increase in water absorption. A linear correlation has been established between mass loss and UCS and IDT, which can be used to evaluate the suitability of materials for the structural layer without conducting a wet–dry durability test, which typically takes one month. This study proposes that cement-stabilized fly ash and stone aggregate mixtures with 4% and 6% cement can be used as the subbase and base of pavement based on wet–dry mass loss criteria and water absorption criteria. Observations from this study reveal that fiber-reinforced cement-stabilized fly ash–stone aggregate specimens treated with 4% and 6% cement, with and without fibers, met the limiting mass loss of 20%, as specified in IRC SP: 89. The mass loss decreases with an increase in cement and fiber content. However, the capillary rise in the mixes increases with a higher percentage of fly ash and fiber content but decreases with increased cement content. Cement addition results in reduction in water absorption. However, the addition of fibers results in increase in water absorption. A linear correlation is established between mass loss and UCS and IDT, which can be used to evaluate the suitability of materials for the structural layer without conducting wet–dry durability tests, which take one month. This study proposes that cement-stabilized fly ash and stone aggregate mixtures with 4% and 6% cement can be used as the subbase and base of pavement based on wet–dry mass loss criteria and water absorption criteria.

Exploratory study of groundwater infiltration in lough arrow using thermal imagery and geochemical tracers

abstract: Groundwater dynamics were investigated in Lough Arrow in the north-west of Ireland. The lake is designated under the EU Habitats Directive (92/43/EEC) for its representative Annex I habitat from which charophytes are the main feature of interest. Groundwater interactions are considered a significant component of the lough's hydrology with its Annex I archetype deemed vulnerable to the pressures of nutrient pollution. This study utilised thermal imagery and geochemical tracers to detect and quantify groundwater inputs. Landsat 7 Thermal Infrared Imagery from two dates in both summer and winter was processed to investigate the potential occurrence of localised seepage points of groundwater captured as anomalous spatial plumes. In situ surveys of radon were undertaken in summer to confirm the presence of groundwater in the lake. Results were subsequently modelled to estimate the total groundwater discharge into the lake during the survey period. Additionally, a conceptual site model was created to characterise potential pressures to the lake from groundwater interactions within the catchment. Thermal imaging failed to conclusively identify thermal plumes consistent with localised groundwater inputs in Lough Arrow. However, the radon inventory applied to the mass balance estimated the lake was subject to 6,722m3 of groundwater influx per day at the time of the survey. The conceptual site model determined the lake was subject to potential pollution pressures from groundwater due to the catchment's physical attributes and land use activities. This is primarily due to the presence of a karst aquifer in the majority of the catchment coupled with significant agricultural and forestry practices. The vulnerability of the aquifer and the influx of groundwater to the lake highlights the potential threat groundwater contamination may pose to the favourable conservation condition of Lough Arrow's Annex I habitat.

Termite IPM in historic sites

Abstract Given the traditional use of wood, historical structures are susceptible to termite damage which can irreversibly affect their historical significance. Methods like drilling into the foundation for termiticide injection are impractical and potentially harmful to the structural integrity of these structures. Moreover, the location of these structures in ecologically sensitive areas prohibits the use of soil termiticides due to potential contamination of groundwater, rivers, or oceans. Termite Integrated Pest Management (IPM) strategies include baiting programs that use minimal quantities of benign insecticides to reduce environmental impact. This approach is consistent with the risk management component of termite IPM. Bait systems are proven to be effective in eliminating termite colonies, contributing to the benefit component of IPM by preserving the value of historical sites. This article discusses successful baiting interventions at notable locations such as the Statue of Liberty National Monument, New York, USA, the Christiansted National Historic Site in St. Croix, US Virgin Islands, and the Historic Tzu-Su Temple in Taiwan.

Seawater softening by nanofiltration enables ecofriendly Dead Sea level stabilisation while creating the basis for cost-effective inland desalination

Increased water extraction led to accelerated shrinkage of the Dead Sea, seriously damaging the environment and posing an economic risk for industry and tourism. The surrounding countries are willing to avert this looming crisis; however, previous approaches became infeasible due to economic, political and ecological hurdles. Motivated by this issue, we propose an alternative sustainable concept based on nanofiltration. We carried out basic design and cost estimations, showing that nanofiltration permeate produced from seawater allows environmentally friendly Dead Sea recharge, minimising gypsum precipitation, algae blooms and groundwater contamination potential on the conveyance routes. Dead Sea level stabilisation with nanofiltration permeate from Med Sea water costs between 0.54 and 0.7 $/m3 at 7 % weighted average cost of capital, significantly lower than treating Red Sea water (0.76 to 0.86 $/m3). Furthermore, providing NF permeate at the Dead Sea in transboundary exchange with Israel allows Jordanian and Palestinian inland desalination for regional potable water production. In the Jordan case, potable water costs at the major demand center, Amman, range between 1.56 and 1.76 $/m3, significantly lower than the national supply from the Red Sea. This study promises a new, feasible solution for trilateral research and implementation cooperation on the Dead Sea issue.

Microplastics attenuation from surface water to drinking water: Impact of treatment and managed aquifer recharge – and identification uncertainties

River water can be used to recharge aquifers exploited for drinking water production. Several recent studies reported microplastics (MPs) in river water, and therefore, the potential contamination of groundwater by MPs is a growing concern among stakeholders and citizens. In this research, we investigate the fate of MPs (> 20 μm) along six different stages of a major Managed Aquifer Recharge (MAR)-water supply system in Switzerland. About 20 l of water were filtered using steel meshes at each location in triplicates. In the laboratory, MPs deposited on the anodisc filters were identified using Focal Plane Array (FPA) micro-Fourier-Transform-InfraRed (μFTIR) spectroscopy. The obtained hyperspectral data were processed using the imaging software Microplastics Finder for MPs identification and classification. Our results revealed a 20-fold decrease in MPs concentration from the Rhine River bed water (112 ± 27.4 MPs/l) to after the coagulation, flocculation and sedimentation (5.5 ± 2.2 MPs/l), a further 3-fold decrease to after the sand-filtration system (1.8 ± 0.9 MPs/l), corresponding to an overall removal efficiency of 98.4 %. The MPs concentrations remained low following MAR (2.7 ± 0.7 MPs/l) through a Quaternary gravel aquifer. Activated carbon filters did not substantially further reduce MPs concentrations. The percentage of fragments (≈95 %) prevailed over fibers (≈5 %) at all locations, with fibers being longer and more abundant in the river water. Overall, this study demonstrates the effectiveness of the treatment systems to remove MPs larger than 20 μm. Finally, we calculated an uncertainty in MPs concentrations of one order of magnitude depending on the user-defined parameters inside the MPs identification and classification model. The Quality Assurance/Quality Control approach followed during laboratory analysis highlighted an accumulation of surrogate particles at the edges of the disc, which would have an impact for MPs number upscaling.

Design and evaluation of microencapsulation technology to reduce the environmental impact of copper fungicides in vineyards

Grapevine is a relevant crop in the European area, that has been traditionally linked to the use of copper fungicides for downy mildew control (Plasmopara viticola). The continued use among the years of this type of copper fungicides has caused an environmental impact, mainly accumulating copper ions in the soil and also resulting in surface and groundwater pollution. To reduce the amount of copper used in vineyard crop protection strategies, and for instance, the contamination, a microencapsulated copper product has been developed. Deposition trials in artificial vegetation were assessed in order to define the optimal formulation characteristics linked with leaf deposit. Also, field trials in real conditions were performed to compare the newly developed copper product with a conventional one. These studies were completed with an evaluation of the microencapsulated product behaviour into two different soil types and its leaching that can consequently be potential groundwater contamination. Microencapsulated formulation resulted in higher deposition compared to the reference product. The obtained results are a relevant drawing up on a way to reduce the amount of copper used, due to the microencapsulated product having the potential to reduce the amount of copper used in vineyard crop protection and the environmental impact they cause.

Inventory of pesticides and their potential risk of contamination in the semi-arid region of Ceará (Cariri–CE, Brazil)

The present study deals with pesticides, and their potential risk of contamination in the municipalities of the Cariús River micro-watershed (Cariri – CE). In general terms, it aimed to analyze the environmental fragility to the use of pesticides and to identify the active principles used, their respective environmental risks and their process of accumulation, transport and contamination of soil and water, in the area that covers the municipalities of Santana do Cariri, Nova Olinda, Farias Brito and Cariús, located in the south of the state of Ceará. To carry it out, the GUS Index (Groundwater Ubiquity Score) was applied in the active principles of pesticides sold and applied in the region, as in a model suggested by Neves, Gomes and Spadotto (1998), which takes into account the leaching and resulting surface runoff variables, and the natural characteristics (Pedology, hydraulic conductivity, altitude and slope) in the delimitation of areas with natural susceptibility to environmental impacts resulting from the application of pesticides. The results indicated that the entire region is susceptible to contamination caused by the indiscriminate use of pesticides, with great potential for contamination of groundwater and surface water. Due to their high leaching capacity, the following products should be abolished: Connect, Atrazine Nortox 500 SC, Calaris, Nicosulfuron Nortox 750 WG, DMA® 806 BR, Tucson, Quallis, U46, Artys, Aminol, Tordon and Disparo®. Glyphosate, Karate Zeon 50 CS, Klorpan, Pyrinex 480 EC, and Decis 25EC should be avoided or replaced with alternative techniques. It is recommended to diversify the production and promotion of organic agriculture through sustainable agricultural techniques/practices and with lower environmental impacts.

Potential toxic element contamination and non-carcinogenic risk assessment of groundwater from rapidly growing urban areas in Telangana, India.

Groundwater is a critical resource for drinking purposes that is under pressure and polluted with multiple inorganic contaminants. Among various contaminants, potentially toxic element contamination in groundwater has significant public health concerns due to their toxicity at a low level of exposure. This investigation aimed to assess the toxic element contamination and associated non-carcinogenic human health risk at rapidly growing urban centers in Telangana to ensure potable water and to generate baseline data in the study province. Thirteen potential toxic trace elements (Al, As, B, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn) were determined in 35 groundwater samples collected from the Karimnagar and Siddipet smart cities in lower Manair River basin using inductively coupled plasma mass spectrometry (ICP-MS). The trace element concentration is found in the range for Al (1-112µg/L), As (2-8µg/L), B (34-438µg/L), Cd (bdl-2µg/L), Co (bdl-17µg/L), Cr (bdl-4µg/L), Cu (bdl-216µg/L), Fe (4-420µg/L), Mn (bdl-3311µg/L), Ni (5-31µg/L), Pb (bdl-62µg/L), Se (1-18µg/L), and Zn (3-1858µg/L). Analytical data of groundwater revealed the occurrence of toxic elements observed as above the acceptable limits of Bureau of Indian Standards for drinking purposes found in the order of Al > Ni ≥ Mn > Se ≥ Cu ≥ Pb > Fe with 26% > 14% ≥ 14% > 9% ≥ 9% ≥ 9% > 6% of samples, respectively. The non-carcinogenic health risk to humans upon groundwater ingestion has been evaluated and found to be non-hazardous for all the individual elements studied except for aresenic. However, cumulative hazard quotient observed as > 1 in the category of infants and children might be a major potential health concern. This study provided baseline data and suggested implementing preventive measures to protect human health around the urban areas of lower Manair river basin, Telangana, India.

Heavy Metal Transport in Different Drip-Irrigated Soil Types with Potato Crop

Heavy metal (HM)-polluted soil is a serious concern, especially as brackish water is widely used for irrigation purposes in water-scarce countries. In this study, the HYDRUS-2D model was used to simulate HM (copper (Cu), lead (Pb), and zinc (Zn)) transport through agricultural land cultivated with potato crops under surface drip irrigation to explore the potential groundwater contamination risk. Three soil types, namely, silty clay loam, sandy loam, and sandy soil, and two irrigation schemes, irrigation every two days (scheme A) and irrigation every four days (scheme B), were considered during the simulations. Firstly, the ability of HYDRUS-2D to simulate water flow was validated using data obtained from a full growing season of the potato crop in a lysimeter irrigated by surface drip irrigation using El-Salam Canal water, Egypt (i.e., water contaminated by HMs). Secondly, the model was calibrated for solute transport parameters. After that, the investigated simulation scenarios were executed. The results showed that HYDRUS-2D effectively simulated water flow. Moreover, a good agreement between the simulations and experimental results of HM concentrations under the calibrated solute parameters was obtained with R2 values of 0.99, 0.91, and 0.71 for Cu, Pb, and Zn concentrations, respectively. HM distribution is considerably influenced by the HMs’ adsorption isotherm. The results of the investigated scenarios reveal that soil texture has a greater impact on HM concentrations in the simulation domain and on the contamination risk of the groundwater than the irrigation scheme. Under both irrigation schemes, lower HM concentrations were observed in sand, while higher values were observed in silty clay loam. Subsequently, the potential shallow groundwater contamination risk is greater when cultivating potatoes in sand, as higher HM concentrations were found in drainage water compared to the two other investigated soils, regardless of the irrigation scheme. The cumulative Cu, Pb, and Zn concentrations in drainage water corresponding to scheme A for silty clay loam and sandy loam were 1.65, 1.67, and 1.67 and 1.15, 1.14, and 1.15 times higher, respectively, than scheme B. To safeguard the sustainability of groundwater and agricultural lands irrigated with water contaminated by HMs, it is recommended to adopt an irrigation frequency of once every four days in soils with silty clay loam and sandy loam textures.

Potential groundwater contamination from oil drilling in the Okavango

Canadian oil and gas company, Reconnaissance Energy Africa (ReconAfrica), plans to exploit potential oil reserves in the Cubango Okavango River Basin (CORB) in Namibia and Botswana, where little is known about the local groundwater systems and how contamination and its effects could impact the region. Using borehole data from target oil and gas areas, we calculated hydraulic gradients, flow direction, and flow velocity to map potential groundwater contamination effects from oil and gas drilling in the region. We also plotted the major geological structures, calculated flowpaths, and estimated travel times for contaminated groundwater that may travel along these preferential flowpaths from the drill sites to the Okavango River and Delta. Results indicate that contaminated groundwater from the oil lease areas could take 3–23.5 years to reach the Okavango River system via the shallow sandy aquifer, but in a worst-case scenario, contamination could reach the Delta within four days via structures associated with dykes and faults that serve as primary flowpaths. Such contamination could adversely affect human health and the region's ecosystems and biodiversity. We recommend prohibiting oil exploration and production activities within the CORB until future studies can determine the impacts of hydrocarbon extraction with greater certainty.

ANALYSIS OF THE PERCOLATION BEHAVIOR OF PETROLEUM DERIVATIVES IN SANDYSOIL OF THE ALAGOAS COAST

Oil and its derivatives are applied in different ways in society and their commercialization, handling, and disposal raise concerns regarding the potential for contamination of soils and groundwater in cases of spillage. The present work aims to evaluate the behavior of the percolation of petroleum derivatives in sandy areas of the Alagoan coast. This analysis used automotive lubricating oil spill tests to evaluate the effect of viscosity (0w20 – 47.6 cSt, 5w30 – 64 cSt and 20w50 – 134.7cSt) and granulometry in sandy media (Praia do Saco – 3.06 μm in diameter, Cruz das Almas – 5.06 μm in diameter, and Barra de Sao Miguel – 5.47 μm in diameter). While verifying the influence of physicochemical characteristics of the soils, values of the average Sauter diameter, distribution of the sizes of the sediments, and the values of the total saturation (100%) of water were determined for all conditions analyzed. Thus, results show that, after determining the physicochemical characteristics of the soils and the oils applied in the bench tests, the viscosity of the oils and the values of the particle diameters of the sandy soils influence the percolation behavior. This influence was determined by the percolation behavior of the oils in sandy media, because for the analysis in a soil with a diameter of 3.06, the radial percolation was more significant for the oil with higher viscosity (20w50 - 134.7cSt) and in the axial percolation the behavior was more present for the lower viscosity oil (0w20 - 47.6 cSt). That is, in a sandy soil of the same diameter, radial flow increases with increasing viscosity and axial flow with the lowest viscosity. In addition, the radial flow is more expressive in smaller granulometries and the axial flow in larger granulometries for the same viscosity condition. However, it is of fundamental importance to evaluate the front of advance of the contaminants and, thus, to know the extent of the damage, so that the measures of environmental remediation are adopted.

Using Water Stable Isotopes and Cross-Correlation Analysis to Characterize Infiltration of Precipitation through Unsaturated Zone at the Velika Gorica Site of Zagreb Aquifer

The unsaturated zone plays a crucial role in the hydrological cycle and is a key factor in modeling and understanding hydrological processes. It regulates water transfer from the land surface to the groundwater while providing protection, transfer, and attenuation of potential groundwater contaminants. This research presents the first results of continuous in situ monitoring of all soil horizons of the Eutric Cambisols and the remaining unsaturated zone of the Zagreb aquifer (Velika Gorica well field). The Zagreb aquifer is the main source of potable water for the inhabitants of the City of Zagreb and Zagreb County, which is protected by the Republic of Croatia. Cross-correlation analysis and water stable isotopes (δ2H and δ18O) were used to investigate whether there is a hydraulic connection between precipitation and groundwater, the approximate duration of percolation, and whether there are indicators that suggest the presence of preferential flow or processes such as water mixing and/or evaporation. The cross-correlation analysis showed and confirmed the assumption of the presence of preferential flow with average lag times ranging from 1.59 up to 3.63 h. The results also indicate that low organic matter content may contribute to higher lag times associated with precipitation infiltration. It was found that only high-intensity precipitation events allow effective infiltration, and that the amount of infiltration depends on the water content of the soil at the beginning of each precipitation event. The isotopic results showed that the isotopic composition of the soil water in the first three soil horizons follows the one of precipitation, while deuterium excess confirmed that the sampled water is mobile water and that an evaporation process is possible in the A horizon. The results also show that suction cups can be used to determine the isotopic signature of both bulk and mobile water, depending mainly on the granulometric composition of the material in which they are installed.