Infiltration Of Contaminants Research Articles

MODELING OF GROUND WATER DYNAMICS AND ITS POLLUTION

Problem statement. Large accumulators of liquid waste (e.g., mine water ponds, tailing ponds, etc.) are long-term sources that change the hydrological regime. A negative consequence of this process is flooding of the territory. In addition, the infiltration of contaminated water from such hazardous sources changes the quality of groundwater. Therefore, it is important to analyze the impact of such anthropogenic sources on the process of flooding and deterioration of groundwater quality. To solve this problem, it is very important to use the method of mathematical modeling as an effective mean of researching problems of this class, since the use of physical modeling is practically impossible within the scope of problems of this class. The purpose of the article. Development of numerical models for predicting changes in the hydrological regime (flooding of the territory) and groundwater quality under the influence of anthropogenic pollution sources. Methodology. To assess the dynamics of changes in the hydrological regime, a two-dimensional equation of filtration of a non-pressure groundwater flow is used. A two-dimensional geomigration equation (planned model) is used to analyze changes in groundwater quality during infiltration of contaminated water from the settling pond. This equation takes into account the convective transfer of contaminants in the filtration flow, dispersion, and the intensity of contaminant infiltration into the groundwater flow. The method of total approximation is used for numerical integration of the filtration equation. For the numerical integration of the geomigration equation, an implicit splitting scheme is used. Scientific novelty. Effective numerical models for rapid assessment of changes in groundwater dynamics and quality under the influence of anthropogenic sources that change the hydrological regime are proposed. The constructed numerical models take into account a set of important physical factors that affect the process of geomigration and flooding of the territory, namely: filtration coefficient, variable depth of free-flowing groundwater, dispersion, intensity of the source of impurity emission into the groundwater flow. This makes it possible to obtain a comprehensive assessment of the process of flooding and groundwater pollution.. Practical significance. A computer code has been created that allows practical usage of the developed numerical models. This code is an effective tool for theoretical study of non-stationary processes of territory flooding and anthropogenic groundwater pollution. Conclusions. A numerical model for calculating groundwater dynamics has been developed. The model allows to predict the level of groundwater rise under the influence of a man-made source of wastewater infiltration from a settling pond. A numerical model for calculating the process of geomigration from an anthropogenic source of emissions has been developed. The model makes it possible to predict the dynamics of contamination zone formation in a non-pressure groundwater flow. The developed numerical models take into account the most important parameters that affect the formation of flooding zones and groundwater contamination.

Laboratory and numerical simulations of infiltration process and solute transport in karst vadose zone

Groundwater in karst systems is a vital resource, which is often highly vulnerable to contaminants that infiltrate through the vadose zone. Understanding the processes of water and contaminant infiltration in the vadose zone is extremely important for protecting and managing karst water resources. A laboratory-scale physical model based on a typical conceptual model of the karst vadose zone was constructed to characterize the influence of the rainfall intensity and internal structure on the infiltration process and solute transport in the karst vadose zone under controlled conditions. Five factors, including the rainfall intensity, the surface slope, the degree of karstification, the thickness of the transfer zone, and the existence of epikarst, were considered in laboratory experiments. A corresponding lumped-parameter model was subsequently developed to further analyze and investigate the water and solute infiltration processes in the laboratory scale physical model. Recession- and breakthrough curves generated from the lab experiments and the water and solute loss from each reservoir generated from the simulation results were analyzed. The downward trend of breakthrough curves' peak value and the variation of solute loss's proportion in three rainfall events demonstrate that both the increase in thickness and karstification degree will intensify the buffer effect of the karst vadose zone, and this buffer effect is mainly affected by the slow flow system which can be inferred from the increasing percentage of cumulative discharge of slow reservoir (qS). With increasing karstification degree, the recession coefficient (α) exhibits opposite trends depending on the existence of epikarst or not, indicating the karstification degree has a more significant effect on hydraulic conductivity (K) when an epikarst is present while affecting effective porosity (φ) more noticeably in the absence of epikarst. The rainfall intensity affects the results of both experimental and numerical simulation most significantly. The percentage of discharge and solutes flowing from the slow reservoir (qS and msoil_S) have negative correlations with rainfall intensity, suggesting a greater influence on fast flow with increasing rainfall intensity.

Long-term impact of wastewater effluent discharge on groundwater: Identification of contaminant plume by geochemical, isotopic, and organic tracers' approach

Infiltration of effluents from wastewater treatment plants (WWTP) into groundwater can be a source of Contaminants of Emerging Concern (CECs), such as pharmaceutical compounds, that are not fully removed during the treatment processes. A multi-tracer approach, based on hydrogeochemical, isotopic, and organic tracers, is applied in the Vistrenque Aquifer (Gard, France) to assess the dispersion of such unintentional plumes and its potential implication on groundwater quality for CECs in a small catchment area. In this area, a point source of WWTP effluent causes contaminant infiltration and unintentional transfer to the aquifer. This strong impact of an urban effluent was revealed from the Br/Cl ratio, boron concentrations and δ11B isotopic signature of the groundwater in the direct vicinity of the infiltration point. With increasing distance from that point, dilution with groundwater rapidly attenuates the urban signal from these hydrogeochemical and isotopic tracers. Nevertheless, a gadolinium anomaly, resulting from discharges of urban wastewater containing the contrast agents used for magnetic resonance imaging (MRI), highlights the presence of a wastewater plume further along the flow line, that comes with a series of organic molecules, including pharmaceutical residues. Monitoring persistent or reactive molecules along the plume provides a more detailed understanding of the transfer of CECs into groundwater bodies. This highlights the relevance of pharmaceutical compounds as co-tracers for WWTP plume delineation. The present multi-tracer approach for groundwater resource vulnerability towards CECs allows a more in-depth understanding of contaminant transfer and their fate in groundwater.

Reactive contaminant infiltration under dynamic preferential flow

Biodegradation is an important mechanism of contaminant removal from soils. We use numerical simulations to study the contaminant transport in heterogeneous soils subject to transient flow conditions and anaerobic multicomponent biodegradation. These processes and their interactions affect contaminant travel times, the extent of reactant mixing, solute and microbial biomass distributions in the soil, and biodegradation outcomes. Especially when flux variations are large, the combination of soil heterogeneity and transient flow gives rise to dynamic preferential flow zones, which affects reactant mixing and biodegradation outcomes. Results show that soil heterogeneity may reduce contaminant leaching due to enhanced reactant mixing, especially when biodegradation is more limited by reactant mixing. Furthermore, unlike under steady-state flow, under transient flow soil heterogeneity does not substantially reduce contaminant residence times. As preferential flow zones change dynamically, the spatio-temporally averaged transport, mixing, and biodegradation experienced by various parts of contaminant plumes become homogenized. Therefore, knowing the initial biodegradation rate of a contaminant upon infiltration, and its mean residence time in the soil, enables a relative sensitivity analysis. This allows biodegradation outcomes of various scenarios to be approximately ranked, even under soil heterogeneity and transient flow, using information that is straightforward to measure or estimate in the field.

Intrinsic Vulnerability Assessment of the Qingduo Karst System, Henan Province

Groundwater vulnerability assessments are vital for protecting valuable resources by revealing susceptibility to contamination. This study developed an enhanced index model to assess the intrinsic vulnerability of a supplied karst aquifer in Qingduo, Henan Province. The model considered the 3-D geological structure and modified indices to account for Northern China’s mild karstification. Emphasizing the absolute infiltration capacity of surface contaminants, the model also integrated the groundwater sources and sinks (SS) index. The vulnerability map revealed that over 60% of the aquifers, including the Qingduo wellfield, exhibited very low to low vulnerability. Conversely, only small areas (<5%) along the Kejing (KJ) fault’s southern wall were classified as highly vulnerable. These findings highlighted the significant role of groundwater flow alongside aquifer conditions. The upward groundwater flow through the Fengmenkou (FMK) faults slowed the downward infiltration of surface contaminants into the lower karst aquifer, effectively reducing vulnerabilities. Lower levels of dissolved lead (Pb) and nitrate (NO3−) in Qingduo groundwater aligned with PISSR vulnerability mapping. Sensitivity analysis assessed the results’ sensitivity to index weight assignment. The inclusion of the sources and sinks (SS) index holds implications for semi-quantitatively assessing dynamic groundwater vulnerability by delineating flow patterns.

Regional characterization of the vulnerability of the unconfined groundwaters in Bulgaria

Groundwater vulnerability to contaminant infiltration from the surface, and to state deterioration, is related to the spatial distribution of rocks with diverse porosities, flow characteristics and unsaturated zone thickness. For the present regional assessment of groundwater vulnerability, it is considered most appropriate to adopt a method based on spatial differences in the geological and tectonic, and related hydrogeological, conditions in Bulgaria. The objective of the present study is to compile a vulnerability map of the unconfined groundwater in the country. This groundwater type is very important for drinking water supply, and it is at the highest risk of contamination. The groundwater on the territory of the Republic of Bulgaria has been divided into seven vulnerability classes, based on the corresponding hydrogeological units. The map is based on the geological map of Bulgaria in scale 1:100 000. It shows that groundwater is of low vulnerability over a large part of the country’s area (57%). Medium to medium-high groundwater vulnerability is defined for approximately 31% of the total area, while high and very high vulnerability are defined for 7% and 5%, correspondingly.

Formation mechanism of Fe-based amorphous powders produced by spark erosion

Spark erosion is a convenient, flexible, and low-cost method to quickly produce fine powders of metals, alloys, and semiconductors in size ranging from nearly a hundred micrometers to submicrometer by repetitive spark discharges. Due to the complexity of the powder-forming journey, normally accompanied by high temperature, high pressure, decomposition, diffusion and rapid quenching caused by discharge plasma, the mechanisms of powder formation and possible contaminant infiltration are still controversial, posing a significant challenge to control particle size and chemical composition of the powder produced by this method. In this study, Fe-based amorphous powders in different particle-size distributions with high sphericity were fabricated by spark erosion under different discharge-energy conditions. The maximum particle size of the resultant powders can be correlated with discharge parameters, crater depth, and crater radius, respectively. A multi-ring-breakup model is proposed to reveal the particle-size distribution of the powder formed from the electrode melt under a single-pulse discharge. Furthermore, a dielectric-element infiltration model is provided to quantitatively evaluate the infiltration mass ratio of the contaminant elements, stemming from the decomposed products of dielectric liquid, in the resultant powder with different particle sizes. The models verified through the experimental data are significant for the development of high-performance fine Fe-based amorphous powder with controlled particle size and chemical composition.

Assessment of the activity of the mbalmayo thermal power plant on groundwater quality

Groundwater is essential for daily life in Cameroon, but pollution sources can harm its quality through infiltration and dispersal of contaminants in the ground. This study focuses on estimating groundwater quality near the Mbalmayo Thermal Power Plant using a predictive model combining genetic algorithms and neural networks. The genetic algorithms were used to optimize the objective function, while neural networks learned the data to predict concentration values. From January 2017 to December 2021, several moisture content values were experimentally determined using collected dried and weighed soil samples. The results showed that moisture content varied from 1 to 82%. During this study period, the model takes into account the water content of the soil, porosity and permeability which have the same effect on the concentration level of the fuel oil in the groundwater. The average concentration of fuel oil was below 50 mg/l, which is the World Health Organisation standard However, there is a risk of groundwater pollution by fuel oil in the event of heavy activity at the Mbalmayo thermal power plant in the 0-445 m range. For protection during this period, the results show that the installation of populations on a perimeter located beyond 445 m and the construction of a water purification station are recommended. The results are decision support tools for the authorities.

지하철 객실 내 에어커튼의 미세먼지 차단 효용성의 수치해석 연구

This study evaluates the effectiveness of air curtains in alleviating contaminant infiltration to subway cabins when doors are opened. We perform numerical simulations of contaminant transports in the subway station under various conditions(passenger ingress, air curtain operation, seasonal effect, and pressurized cabin). The performance of the air curtain is assessed based on mass transfer rate and separation efficiency. Air curtain-induced air flows promote particle infiltrations into the cabin by lowering the cabin pressure. However, the temperature and pressure differences between in and out of the cabin do not significantly affect the separation efficiency, except for no air curtain operation.

Geohydraulic characteristics and groundwater vulnerability assessment of tropically weathered and fractured gneissic aquifers using combined georesistivity and geostatistical methods

Sustainable groundwater yield in aquifers depends on the protective capacity of the subsurface lithologies and conduit systems. Electrical resistivity tomography (ERT) and its Schlumberger vertical electrical sounding (VES) technique were employed to assess the groundwater yield of aquifer units and their vulnerability to contaminants in Araromi (Akungba-Akoko), southwestern Nigeria. Geohydraulic parameters: aquifer resistivity (\rho0), hydraulic conductivity (K), transmissivity (T), permeability (\Psi), hydraulic resistance (KR), and longitudinal conductance (S) were also evaluated. In addition, regression analysis was utilized to establish the empirical relationships between the K and other geohydraulic parameters, with their percentage contributions to posing vulnerability risk. The georesistivity results revealed four distinct layers: topsoil, weathered layer, partially weathered/fractured bedrock unit, and fresh bedrock. The K model regression-assisted analysis showed that the \rho, T, \Psi, and S contributed about 97.8%, 14%, 99.9%, and 11.5%, respectively, to the estimated aquifers’ K values for the study area. Except for T and S, the regression results had moderate to strong positive correlations with K; hence, this illuminates the essentiality of K in assessing groundwater potential and vulnerability. The aquifer units have low to moderate groundwater yield based on T values (1.67-17.57 m/day) caused by the generally thin overburden (<4 m). However, the deep-weathered and fractured aquifer units with depths ranging from 39-55 m could supply high groundwater yield for sustainable abstraction. The estimated S values (0.0226-0.1926 mhos) for aquifer protective capacity ratings rated the aquifer units in the area as poor to weak. Based on the estimated low logarithm of KR (log KR) values of 0.79-2.25 years, these aquifers have extremely high to moderate aquifer vulnerability index. As a result, prospective wells/boreholes in the study area and settings with similar geohydraulic and vulnerability characteristics should be developed adequately to prevent the infiltration of surface contaminants for potable groundwater abstraction.

Influence of on-site sanitation on groundwater quality from large diameter wells

Field work was conducted to understand the possible influence of on-site sanitation on groundwater quality, estimate minimum bore well volumes of water to be purged from large wells to obtain representative aquifer samples, and unravel possible trends in variability in physico-chemical water quality of water samples from wells lying between the hills and discharge areas. We applied a chemical pollution risk assessment of wells modified from microbial risk assessment to enable the quantification of risk to chemical pollution of wells from on-site sanitation. For two wells, 3.2 well volumes were purged with progressive sampling and physico-chemical quality of purged and recovered water. Physico-chemical quality of samples was analyzed for wells lying between hills and discharge areas. Commonly identified contamination sources are sullage drains, pit latrines, waste dumps and septic tanks, and 14 out of the 15 wells (93%) studied at risk to pollution. Anion concentrations and EC values increased during purging and were stable and high during recovery indicating inflow of water with high ion content possibly from identified risks to chemical anion pollution. Stabilised physical water quality (EC and pH) during recovery indicate representative aquifer samples from large diameter wells in the shallow aquifer of the area may be possible after removing at least three well volumes of water. Apart from Nitrate, average concentrations of anions and EC were high in water samples from wells in the low-lying area. Results of pump test and sampling between the hills and discharge areas, we, respectively, conclude that: the wells are hydraulically connected to contamination sources and the observed groundwater quality may due to effluents from identified contamination sources, and dissolution of minerals and increased infiltration of contaminants may be responsible for high electrical conductivity and anion concentration in the low-lying discharge areas of the study area.

Contaminant transport model in transient and unsaturated conditions applied to laboratory column test with tailings

Mining is an important economic activity in the modern world. However, despite the generated benefits, mining produces tremendous volumes of tailings, an environmental liability with numerous adverse effects. Researches about contaminant transport in tailings dam are important to assess the degree of contamination and to propose preventive or remedial measures. In geotechnical practice, the flow of solutes is generally characterized by numerical solution of the Richards equation to describe water movement followed by advection-dispersion equation to describe contaminant movement. This study aimed to model and simulate contaminant transport in a laboratory column test, using a new analytical formulation and mathematical codes, through tailings in transient unsaturated conditions. The analytical solution for the Richards equation was used to simulate the variation in the volumetric water content and to determine the transient contaminant plume using the advection-dispersion equation subsequently. The models were used to calibrate experimental data from hydraulic characterization and contamination tests. Finally, the normalized contaminant plume (cw/c0) was simulated as a function of time and space. Comparisons with experimental data showed that the analytical formulations adequately expressed the process of contaminant infiltration through the unsaturated porous medium. The formulations offered effectively and are configured as a new approach to solve various contamination problems in transient unsaturated conditions, providing insights into many complex processes that occur in the lab tests and requires far less computational effort compared with current programs to modeling the solute transport using numerical solutions, as the versatile commercial Software HYDRUS.

Assessment of Aquifer Protective Capacity, Against the Surface Contamination. A Case Study of Kaduna Industrial Village, Nigeria

Geo-electric soundings was carried out in 22 different locations at Kaduna Refinery Petrochemical Corporation (KRPC) and White Oil and Gas Layout, Mahuta, Kaduna. The aquifer protective capacity and Hydraulic characteristics of the study area was computed from the Geoelectric parameters using Dar-Zarrouk and hydrological parameters. The interpreted data were presented in tabular form, Geoelectric/geology soil profiles and contoured maps. The results show that the study area aquifer is relatively protected with an average value of 0.5 mhos with an indication of infiltration of contaminant in some location. The hydraulic parameter values also show that the study area aquifer has the capacity to produce water non-stopping if the wells are sited based the geophysical investigation. The computed hydraulic characteristics and transmissivity of the area has an average value of 5.5 m/day and 6.1 /hour, which implies that, the study area has the capacity to transmit groundwater through a distance of 5.5 m in 24-hour and can covers 6.1 in one hour.

Development and Description of a Composite Hydrogeologic Framework for Inclusion in a Geoenvironmental Assessment of Undiscovered Uranium Resources in Pliocene- to Pleistocene-Age Geologic Units of the Texas Coastal Plain

A previously completed mineral resources assessment of the Texas Coastal Plain indicated the potential for the future discovery of uranium resources. Geoenvironmental assessments that include the hydrogeologic framework can be used as a tool to understand the potential effects of mining operations. The hydrogeologic framework for this study focused on the composite hydrogeologic unit of the tract permissive for the occurrence of uranium consisting of the upper part of the Miocene-age Fleming Formation/Lagarto Clay, Pliocene-age Goliad and Pleistocene-age Willis Sands, Pleistocene-age Lissie and Beaumont Formations, and Holocene-age alluvial sediments (fluvial alluvium and eolian sand deposits). This composite hydrogeologic unit, which contains the Chicot and Evangeline aquifers of the Gulf Coast aquifer system, is intended for inclusion in a regional-scale geoenvironmental assessment of as yet undiscovered uranium resources. This article provides (1) a brief literature review describing the geologic and hydrogeologic settings, (2) the methodology used to develop a composite hydrogeologic framework, and (3) descriptions and maps of the land-surface altitude, composite hydrogeologic unit base and midpoint depth, water-level altitude, depth of water, unsaturated and saturated zone thickness, and transmissivity and hydraulic conductivity. A composite hydrogeologic unit, created by combining geologic and hydrogeologic data and maps for individual geologic and hydrogeologic units, is intended for use as a tool in a geoenvironmental assessment to evaluate potential contaminant migration through various avenues. Potential applications include using the hydrogeologic framework as an input into a geoenvironmental assessment to help estimate the potential for (1) runoff of contaminants into surface water, (2) infiltration of contaminants into the groundwater (aquifers), or (3) movement of contaminants from the mining area through wind, groundwater-flow, or streamflow in a given permissive tract. The procedures outlined in this paper also provide a method for developing hydrogeologic frameworks that can be applied in other areas where mining may occur.

Impact of weather conditions and building design on contaminant infiltration from crawl spaces in Swedish schools\u2014Numerical modeling using Monte Carlo method

Some Swedish school buildings built in the 1960s and 1970s experience indoor air quality problems, where the contaminants are suspected to come from the crawl space underneath the building. The poor indoor air quality causes discomfort among pupils and teachers. Installing an exhaust fan to maintain a negative pressure difference in the crawl space relative to indoors or increasing the ventilation in the classroom are two examples of common measures taken to improve the indoor air quality. However, these measures are not always effective, and sometimes the school building has to be demolished. The relation between pressure distribution, contaminant concentration in the classroom, outdoor temperature, wind, mechanical ventilation, and air leakage distribution is complex. A better understanding of these relations is crucial for making decisions on the most efficient measure to improve the indoor air quality. In this paper, a model for contaminant infiltration from the crawl space is used together with the Monte Carlo method to study these relations. Simulations are performed for several cases where different building shapes, building orientations, shielding conditions, and geographical locations are simulated. Results show, for example, that for a building with an imbalanced ventilation system, air is leaking from the crawl space to the classroom for the majority of cases and that concentration levels in the classroom are usually the highest during mild and calm days.

Organochlorine pesticides in the drinking water of Merida and its Metropolitan Zone, a Karst Region

ABSTRACT This study was conducted to evaluate the quality of drinking water in 28 homes of Merida and 7 municipalities of its Metropolitan Zone, in Yucatan, Mexico. The organochlorine pesticides (OCP) were investigated since it represents important health risks. The karst groundwater in Yucatan is vulnerable due to the easy infiltration of contaminants. The use of prohibited OCP in agriculture and livestock production as well as the minimal infrastructure for drinking water sanitation also pose important public health risks. Samples were analyzed by GC-ECD. The concentrations of lindane (0.01896 ppm), heptachlor (0.09741 ppm), endosulfan (0.05796 ppm), DDT (0.00519 ppm), and endrin (0.00125 ppm) were above the international standards. Samples were analyzed for physicochemical parameters such as pH, electrical conductivity, CaCO3, MgCO3, hardness, Na+, K+, SO4˭, and Cl−. Total hardness (405–646 mg/L) were above of international criterion. Adequate infrastructure to obtain safe drinking water for human consumption is strongly recommended.

Cultivation and Molecular Studies to Reveal the Microbial Communities of Groundwaters Discharge Located in Hungary

In the present study 12 water samples of five sampling sites (Tatabánya, Dandár, Szentendre, Szent Flórián and Ciprián groundwaters) known as nutrient-depleted aquatic environments were studied using amplicon sequencing (NGS) and cultivation techniques. Diversity indices and cell counts were determined to assess the species richness in relation to the cell counts within the samples, and the oligocarbophile growth capability of the isolated bacteria was tested in microtiter plates. Altogether, 55 bacterial phyla were identified from the samples by amplicon sequencing. The microbial communities of the different sampling times of the same sites did not differ significantly. Patescibacteria and Proteobacteria were present in all samples. Ciprián sample was dominated by Bacteroidetes, while in Dandár sample a high ratio of Chloroflexi was detected. Rokubacteria and WOR-1 dominated Szent Flórián sample and Tatabánya had a high number of Epsilonbacteraeota. Nine archaeal phyla were also detected; the samples were characterized by the presence of unclassified archaea and Nanoarchaeota, among them Woesearchaeia, as the most dominant. Crenarchaeota and Altiarchaeota were detected in high ratios in Dandár water samples. Among Thaumarchaeota the family Nitrosopumilaceae, and orders of Nitrosotaleales and Nitrososphaerales appeared in Szent Flórián and Tatabánya samples. Key organisms of the different biogeochemical cycles were discovered in these nutrient-depleted environments: methanogenic archaea, methanotrophic bacteria, ammonia oxidizer, nitrate reducers, diazotrophs, sulfate reducers, and sulfur oxidizer. Diversity indices and cell counts of the samples show negative correlation in case of bacteria and positive in case of archaea in Ciprián sample. The high diversity indices in Szentendre samples are connected to low cell counts, most probably due to the vulnerability of the groundwaters to the external environment factors which lead to the infiltration of soil microbes and contaminants to the water. The isolated bacteria were affiliated into four phyla, most of them belonging to Proteobacteria (59%) followed by Actinobacteria (21%), Firmicutes (17%) and Verrucomicrobia (1%). The members of the facultative chemolithotrophic genera of Sphingobium, Sphingomonas, Sphingopyxis were characterizing only Szentendre, Szent Flórián and Tatabánya samples. Only 10% of the isolated species showed an obligate oligocarbophile character. From the samples, a high number of novel bacterial taxa were cultivated. As a conclusion, our results confirmed the predominance of unclassified and unknown taxa in subsurface water, pointing to the importance and necessity of further studies to characterize these microbial populations.

Equilibrium adsorption modelling of selected crude oil components following a spill on Niger Delta soil

ABSTRACT When crude oil spills on land, it may leach into the soil and reach the groundwater thus posing a threat to drinking water resources. The Niger Delta region provides such an opportunity to study the migration of environmentally important constituents of crude oil in the soil using adsorption models. Soil properties were determined and data obtained from batch equilibrium experiments were applied to nine adsorption isotherms and the characteristic parameters were obtained from the isotherm models. The results show that the clay and organic matter content controlled the rates of infiltration of contaminants into underground water. The correlation values for the isotherms models studied showed that the data from the selected compounds fitted differently to individual isotherms. Adsorption was not monolayer for all adsorbates and the experimental optimum sorption capacity was phenanthrene (100.01 mg g−1), pyridine (33.23 mg g−1), phenol (13.20 mg g−1) and crude oil (10.20 mg g−1). These results indicate that differences in oil residue components and soil property following spillage will determine the type of sorption processes taking place. The model discussed in the study may contribute to the knowledge of the sorption process for technically informed remediation strategy in the Niger Delta region of Nigeria.

Long-term analysis of the relationships between indoor and outdoor fine particulate pollution: A case study using research grade sensors

The growing concern of air quality and its associated health-related impacts has led to increased awareness of pollutant exposure. Most human populations spend the majority of their time indoors and the COVID-19 pandemic has likely exacerbated this behavior. While significant amounts of research have focused on outdoor air quality, to date there have been no studies that examined simultaneous long-term trends on indoor and outdoor air quality on a site using research-grade sensors. We measured fine particulate matter (PM2.5) for a year using sensors located on the rooftop, air handling room, and indoor office space in a building and captured the impacts of three types of regularly occurring elevated pollution events: wintertime atmospheric inversions, wildfires, and fireworks. The events had different magnitudes and durations, and infiltration rates varied for each event leading to dissimilar indoor air pollution levels. The building's air handling unit and different environmental conditions (lower indoor humidity and temperature during the winter) combined to reduce indoor pollution from inversion events however, particulate matter from wildfires and fireworks infiltrated at higher rates. Together, this suggests possible intervention strategies, such as ventilation rates and filter upgrades, that could be used to mitigate contaminant intrusion during elevated pollution events. This year-long study illustrates an array of ways that elevated pollution events interact with the protective effects that buildings have against air pollution for its occupants. Furthermore, we show that outdoor air pollution is an important variable to consider when studying indoor air quality as contaminant infiltration is strongly dependent on the specific pollution source.

Spatial behavior of the Dar-Zarrouk parameters for exploration and differentiation of water bodies aquifers in parts of Konkan coast of Maharashtra, India

Demarcation of aquifer boundaries and hydro-geologic characterization can help in proper management and conservation of groundwater resources of a coastal region. The objective of the present study is to identify and delineate the groundwater-bearing zones and protection of freshwater aquifers from saltwater ingress in the northern parts of Sindhudurg district, western Maharashtra, India. A total of 86 vertical electrical soundings (VES) were carried out by Schlumberger electrode arrangement to infer the sub-surface lithology around Kankavali, Vijaydurg, and Malvan. The Dar-Zarrouk parameters were computed to generate the spatial variation maps of transverse resistance (T), longitudinal conductance (S), transverse resistivity (ρt), and longitudinal resistivity (ρl), to decipher the resistivity contrast of fresh water and salt water-bearing formations. The results demonstrate that these parameters provide a better resolution in delineating the seawater intrusion in coastal aquifers. The overburden aquifer protective capacity computed from the longitudinal conductance suggests that 59% of the area has poor aquifer protection, while 23% has weak, 11% has moderate and 7% falls in good protective capacity rating. This parameter reveals the infiltration of contaminants and the health of the aquifer. The electrical anisotropy (λ) value ranges from 0.9 to 5.1, suggesting an increase from SW to NE and also from SE to NW. The fracture porosity (φf) ranges from 10−6 to 0.65, which corroborates with the high and low λ values, reflecting that fracturing is due to anisotropy and significant reserves of groundwater could be exploited in this coastal region.