Subsurface Soil Contamination Research Articles

Applying Some Indices For Soil Pollution Assessment In Northern Industrial Area From Erbil Governorate

Soil pollution by some heavy metals including: Cr, Mn, Fe, Ni, Cu, Zn, As, Mo, Cd and Pb from northern industrial area of Erbil City was assessed. The contamination indices including: geoaccumulation (Igeo), contamination factor (CF), enrichment factor (EF), degree of contamination (Cdeg), pollution load index (PLI) and element contamination index (ECI) were applied to assess soil pollution in Erbil North Industrial area at three sites (for both surface and sub-surface soils). Maximum Fe value 34243.6 ppm was recorded in sub-surface soil (site 2). Maximum values 265.4, 248.8, 98.23 and 397.45 ppm were recorded for Cr, Ni, Cu and Zn at sub-surface soil (site 3). Whereas, maximum values of 22.52, 5.36, 23.9, 6.12 and 65.67 ppm were recorded for As, Mo, Ag, Cd and Pb at surface soil (site 3). Results of analysed heavy metals for soil Cr, Mn, Fe, Ni, Cu, Zn, As, Mo, Ag, Cd and Pb have shown that the studied sites were severely contaminated with Cd, so the maximum detected Cd concentration was 6.12 ppm in surface soil (300 meters away from the industrial area). The soil pollution in the studied area was classified as moderate to strong surface and sub-surface soil contamination. Behavioral toxicity experiment showed slight growth effect on Lepidium sativum L.

Study on the soil evaluation methodology of on and offsite Kori Unit 1

To optimize site remediation and reuse, we evaluated contamination of the soil surface and sub-surface in situ, inside and outside of Kori Unit 1. Realistic dose modeling was performed using RESRAD-OFFSITE code, accounting for air dispersion, groundwater transport, and the positional movement of secondary contamination. The Derived Concentration Guideline Level (DCGL) was derived; this is a useful guideline value and exposure factor for estimating maximum groundwater concentration. Site-specific parameters were used to analyze the maximum contributed exposure pathways in and out of the site, and preliminary dose assessment was performed for offsite ‘Area 1’. This study provides a general guideline for soil evaluation of nuclear power plants decommissioning site, from surface and subsurface soil contamination to the establishment of a basement fill model. It may be used as basic site evaluation methodology and guideline values based on this characterization of Kori Unit 1.

Molecular-level simulations of oil-contaminated clays

Petroleum products, besides being the core of the energy source, frequently result in the contamination of subsurface soils. Clay minerals, being electrochemically active components of soils, are the most affected and hence lead to substantial change in behaviour and properties of the soils. This paper provides a multilevel study consisting of macro and micro testings coupled with molecular-level simulations of the behaviour of active clay mineral in the soil structure, pore fluids and dissolved salts when contaminated with crude oil. There was a significant change in the engineering behaviour of the contaminated clay. The coarse-grained soil-like behaviour was observed in the strength of the oil-contaminated clay. The contamination has affected the plasticity and the cation-exchange capacity of the investigated clay. The swelling pressure of the contaminated clay is reduced to about one third of that of the uncontaminated clay, while there was no change observed in the swelling percentage. The formation of oil-coated agglomerates due to the addition of the crude oil has been found to be responsible for most of the physical and mechanical processes in the contaminated clays. The study’s molecular-level simulation modelling concepts can be used to describe the behaviour of clay minerals and other interacting compounds.

Mapping of subsurface contamination zone using 3D electrical resistivity imaging in Hilla city, Iraq

Electrical resistivity imaging (ERI) method is very useful in mapping subsurface contamination zones. In this study, 3D ERI is used to identify the distribution and depth of subsurface soil contamination zone near Al_Furat state company for chemical and pesticides industries in Hilla city, Iraq. A 3D pure image of electrical resistivity distribution is obtained from a perpendicular square grid (80 × 80 m) which consists of three parallel and three perpendicular lines. The electrical resistivity values range from < 1 to 21 O.m, and the total root mean square (RMS) after four iterations is about 7%. The image gives eight different depth slices for the estimated model with a depth interval of about 1 m. The maximum depth of investigation is 13.7 m. The results mapped the contamination zone, where high electrical resistivity values (about 21 O.m) are observed possibly due to accumulation of alkaline waste disposed from the company. The ERI results show that the subsurface layers up to a depth of 4.99 m are of moderate-to-high electrical resistivity values. The study reveals that 3D ERI is an effective tool for subsurface contamination zone mapping in various depths, which extends in this study from the near-surface to a depth of about 5 m below the ground level.

Impact of Forest Combustion on Soil Contamination by PAHs Using QuEChERS and GC-MS/MSTQD

The present study was conducted in one of the most dense forest area of Asir region located in the southwest of Saudi Arabia to study the Impact of Forest Combustion on surface and subsurface soil contamination by Poly Aromatic Hydrocarbons (PAHs). The major toxic effects of PAHs including cancers, immunity suppression, loss of fertility, mutagenic and cardiovascular diseases. The extraction and analytical methods, have been developed and validated for quantification of trace levels of 17 PAHs namely, Naphthalene, Acenaphthylene, Acenaphthene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, Retene, Benzo [b+j] fluoranthene, Benzo (a)pyrene, Benzo [k] fluoranthene, 3-methylchol-anthrene, Dibenz [a,h] acridine, Indeno [1,2,3-cd]pyrene, Dibenz [a,h] anthracene and Benzo [ghi] perylene. Surface and subsurface soil samples were collected from Alsaqa and Murir post-fire forests in Asir Province, Saudi Arabia, and extracted by Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) and analyzed by Gas Chromatography-Mass Spectrometry Triple Quadrupole (GC-MS/MSTQD). The experimental results of 17 compounds of PAHs were highly satisfactory linearity, recovery and precision, especially with the tested soil samples. Recovery % ranged from 96.48±2.19 to 105.61±3.21%., the limit of detection (LOD) ranged from 3.71 to 6.77 µg kg-1. Meanwhile the limit of quantification (LOQ) for the analyzed PAHs were in the range of 10.47 to 16.42 µgkg-1. This method featured good sensitivity, lower quantification limits and the precision of the analyzed 17 PAHs. The calibration curves were linear over wide concentration ranges with correlation coefficients (r2) 0.7478 to 0.9822 for 17 PAHs analyzed by GC-MS/MSTQD. The concentrations of the investigated PAHs in Alsaqa forest surface (S) and subsurface (SS) soils ranged from F24.81±4.29 to 57.28±3.56 and 24.10±2.31to 55.47±4.15 mg kg-1dry weight respectively. Meanwhile, the PAHs concertation in Murir surface and subsurface soils ranged from 12.48±2.37 to 28.83±3.35 and 12.83±1.37 to 25.59±4.31 mg kg-1 dry weight respectively. Retene compound was detected in Alsaqa, and Murir forest investigated surface, and subsurface soil sample ranged from 57.28, 55.47, and 28.83, 25.59 mg/kg-1(ppm) respectively. Meanwhile, Retene was not detected (ND) in the control surface and subsurface soil sample. The detected PAHs by applying the modified QuEChERS and GC-MS/MSTQD method were applied successfully for the extraction and determination of the 17 PAHs in burned forest soil samples.

Geophysical and geochemical site investigation of eastern part of Lagos metropolis, southwestern Nigeria

Geophysical and geochemical studies were carried out in the eastern part of Lagos metropolis to determine the possible contamination of subsurface soils and groundwater as a result of dumping of waste into the canal. The geophysical method involved the use of 2D electrical resistivity imaging which was acquired along five (5) traverses, while the geochemical method involved the physicochemical analysis of water samples from nine (9) wells within the study area. The geochemical study includes the analysis of physical parameters like total dissolved solids (TDS), electrical conductivity (EC), pH and temperature. Seventy elements which include trace elements (such as As, B, Ba, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, U and Zn), major cations (such as Ca, K, Mg and Na) and anions (Cl and Br) were analysed, and the concentrations of the elements were compared with the World Health Organization (WHO) and Nigerian Standard for Drinking Water Quality (NSDWQ) permissible level for drinking water. Geophysical results show that the lithology is composed of topsoil, clayey sand, peat and sand. 2D electrical resistivity tomography revealed that the leachate and polluted water from the canal have percolated to the subsurface soil down to a depth of about 37 m with low resistivity values of 1–13 Ω m. In addition to this, result of physicochemical analysis of water samples shows that Mn, Br, TDS, and EC were high in some wells, above the WHO and NSDWQ standard. It was deduced that the subsurface has been invaded by the polluted water from the canal consequently, making the groundwater unsuitable for human consumption.

Transport and deposition of Suwannee River Humic Acid/Natural Organic Matter formed silver nanoparticles on silica matrices: The influence of solution pH and ionic strength

The transport and deposition of silver nanoparticles (AgNPs) formed from Ag+ reduction by Suwannee River Humic Acid (SRHA) and Suwannee River Natural Organic Matter (SRNOM) utilizing a silica matrix is reported. The morphology and stability of the AgNPs was analyzed by transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential measurements. The percentage conversion of the initial [Ag+] to [AgNPs] was determined from a combination of atomic absorption (AAS) and UV–Vis spectroscopy, and centrifugation techniques. The results indicate higher AgNP transport and consequently low deposition in the porous media at basic pH conditions and low ionic strength. However, at low acidic pH and high ionic strength, especially with the divalent metallic cations, the mobility of the AgNPs in the porous media was very low, most likely due to NP aggregation. Overall, the results suggest the potential for AgNP contamination of subsurface soils and groundwater aquifers is mostly dependent on their aggregation state, controlled by the soil water and sediment ionic strength and pH.

Pilot-scale vadose zone biobarriers removed nitrate leaching from a cattle corral

Agricultural activities that involve animal wastes can result in the contamination of subsurface soils by nitrates (NO₃). In saturated or nearly saturated soils, microbial biobarriers are a common method used to remove contaminants from water. This study evaluated the presence of NO₃ in the soil profile beneath a cattle corral and the use of biobarriers to prevent the movement of NO₃ through these semiarid vadose zone soils. Soils from beneath the pen contained as much as 330 mg kg⁻¹ (330 ppm) nitrate-nitrogen (NO₃-N), and a well located ~50 m (~55 yd) from the pens contained 18 mg L⁻¹ (18 ppm) NO₃-N, indicating that denitrification activity in the surface soils of the corral had not prevented NO₃ from migrating into deeper soils where denitrification activity was limited by electron donor (i.e., carbon [C] substrate) availability. Biobarriers used to intercept the percolating soil water contaminated with NO₃ included a control that contained only sand and treatment biobarriers that contained sand blended with sawdust, soybean (<i>Glycine max</i> L.) oil, or sawdust and soybean oil. A distinctive attribute of the study was that the biobarriers were installed near the surface of a semiarid soil well above the water table. Results show that all of the treatment biobarriers removed NO₃ from percolating soil water. Water collected from beneath the control barriers contained 99 mg L⁻¹ (99 ppm) NO₃-N while NO₃-N levels in water that moved through the sawdust, soybean oil, and sawdust plus soybean oil barriers averaged 4, 17, and 28 mg L⁻¹ (4, 17, and 28 ppm) NO₃-N for removal efficiencies of 96%, 83%, and 72%, respectively. In waters from the sawdust plus soybean oil barriers, 6.8 mg L⁻¹ (6.8 ppm) nitrite-N was detected. With all three substrate combinations, biobarrier life was such that barriers of this type should last for many years before substrates need to be replaced.

Contamination of soils with heavy metals in the industrialized region of western Ukraine - western Podole Upland.

Contamination of surface soil horizons with heavy metals is usually related to long-lasting air pollution and might poten- tially affect soil fauna, as well as plant growth, harvesting and health of plant consumer. In order to estimate potential health risk, we investigated surface and subsurface soil contamination with heavy metals in arabie area in one of the most industrial­ized region of western Ukraine, western Podole Upland. In total 80 samples from the area of about 35 km 2 were sampled and ana­lyzed for content of zinc, nickel, copper, cobalt, lead, arsenie and quicksilver. The research revealed several anomalies, where the content of these elements exceed 3-5 Ukrainian quality guidance for arabie soils. Soils are the most contaminated with arsenie and quicksilver, with maximum concentrations exceeding local geo- ehemieal baekground about 20 times. Maximum niekel and zine concentrations are about 10 times higher than the baekground while the content of copper and cobalt is elevated up to several times

Experimental Study on Chromium Containment by Admixed Soil Liner

Chrome tanneries generate large quantities of chromium-laden sludge that require proper disposal in engineered landfills to prevent contamination of subsurface soils and groundwater and reduce the risk to public health and the environment. This study investigates the feasibility of using a fine-grained soil as a suitable landfill liner material for the effective containment of chromium in the sludge leachate. Several series of laboratory permeability, adsorption, and column tests were conducted using soil without and with selected additives (rice husk, bentonite, and fly ash) to determine permeability and adsorption and transport of chromium in the soil. Permeability tests showed that the field soil amended with 17% rice husk and 2% bentonite provides the desired hydraulic conductivity of 10−7 cm/s (or less) to minimize the leachate migration into the surrounding subsurface environment. The rice husk and bentonite admixtures significantly reduced the hydraulic conductivity of the soil from 3×10−7 to 2.8×10−9 cm/s, and this admixture was further tested for its effect on the adsorption and transport of chromium in the soil. The batch kinetics and column tests results showed that the soil possesses relatively high chromium adsorption capacity under natural or slightly alkaline condition. The batch tests showed that the amendment marginally improved the chromium adsorptive capacity of the soil. The column tests showed a slight increase in breakthrough time due to the presence of the amendment. The inclined base column tests showed that a mildly inclined liner configuration has a marginal effect on the chromium attenuation in the soil. Overall, this study showed that soil amended with 17% rice husk and 2% bentonite significantly decreased the hydraulic conductivity of the soil and slightly increased the adsorption of chromium, and therefore, has the potential for usage as a landfill liner in a landfill system to contain chromium contamination.

Treatment of petroleum-hydrocarbon contaminated soils using hydrogen peroxide oxidation catalyzed by waste basic oxygen furnace slag

The contamination of subsurface soils with petroleum hydrocarbons is a widespread environmental problem. The objective of this study was to evaluate the potential of applying waste basic oxygen furnace slag (BOF slag) as the catalyst to enhance the Fenton-like oxidation to remediate fuel oil or diesel contaminated soils. The studied controlling factors that affect the removal efficiency of petroleum hydrocarbons included concentrations of H 2O 2, BOF slag dosages, types of petroleum hydrocarbons (e.g., fuel oil and diesel), and types of iron mineral. Experimental results indicate that oxidation of petroleum hydrocarbon via the Fenton-like process can be enhanced with the addition of BOF slag. Results from the X-ray powder diffraction analysis reveal that the major iron type of BOF slag/sandy loam system was iron mineral (e.g., α-Fe 2O 3 and α-FeOOH). Approximately 76% and 96% of fuel oil and diesel removal were observed (initial total petroleum hydrocarbon (TPH) concentration = 10,000 mg kg −1), respectively, with the addition of 15% of H 2O 2 and 100 g kg −1 of BOF slag after 40 h of reaction. Because BOF slag contains extractable irons such as amorphous iron and soluble iron, it can act as an iron sink to supply iron continuously for Fenton-like oxidation. Results demonstrate that Fenton-like oxidation catalyzed by BOF slag is a potential method to be able to remediate petroleum-hydrocarbon contaminated soils efficiently and effectively.

Subsurface measurement of soil heavy-metal concentrations with the SCAPS X-ray fluorescence (XRF) metals sensor

A heavy-metals sensor for measurement of subsurface soil contamination was constructed and demonstrated in the field. The sensor operates via x-ray fluorescence (XRF) to detect metals heavier than calcium in the periodic table and provide semiquantitative information with little spectral interference and straightforward spectral interpretation. A description of the sensor is followed by details of the calibration methods and some typical field results. © 1998 John Wiley & Sons, Inc. Field Analyt Chem Technol 2: 97–102, 1998

The role of oxygen diffusion in passive bioremediation of petroleum contaminated soils

In passive bioremediation of petroleum hydrocarbon contaminated soils, oxygen diffusion is the primary mechanism for supplying the oxygen which is required for microbial hydrocarbon biodegradation processes. It is the objective of this research to theoretically evaluate whether passive bioremediation can be a feasible treatment alternative for petroleum contaminated soils. In this paper we derive equations for the steady-state oxygen concentration profiles which are expected to develop as a result of simultaneous oxygen diffusion and consumption in hydrocarbon contaminated soils. These equations are used to estimate the maximum oxygen penetration distance and the total cleanup time for several environmental scenarios such as surface and subsurface soil contamination as well as contaminated soil piles. It was found that oxygen is expected to penetrate most contaminated soils for up to several meters if hydrocarbon biodegradation rates are similar to those measured during bioventing respiration tests, i.e. approximately 2.5–10 ppm TPH day −1. Both the depth of oxygen penetration and the total passive bioremediation cleanup time were found to be strongly dependent on the magnitude of the diffusion coefficient for oxygen in soil ( D s). As expected, increased oxygen penetration distances and decreased cleanup times are associated with increased D s values. Since the magnitude of D s is inversely related to the soil moisture content, it is imperative to maintain moderately low soil moisture levels in order to maximize the effectiveness of passive bioremediation treatment. Passive bioremediation is expected to be a feasible and cost-effective treatment alternative for TPH contaminated soils in cases where the minimization of cleanup times is not a major remediation objective.