Contaminated Sandy Soil Research Articles

Evaluation of heating and liming treatments in sand samples artificially contaminated with Ancylostoma spp. eggs.

Ancylostoma spp. are found worldwide. Infected dog and cat feces can contaminate soil in public places. Despite prophylactic measures being available, studies on direct remediation of Ancylostoma-contaminated soils are scarce. This study aimed to determine the impact of heat treatment and liming on the viability of Ancylostoma spp. eggs in artificially contaminated sandy soil. Sterilized sand samples were contaminated with Ancylostoma spp. eggs extracted from infected dogs' feces. Samples were heated (trial I) to 70 °C or 80 °C, then sieved after 24 hours (212, 90, 38, and 25 µm). Larval cultures were assessed for larval development following heat treatment. Five quicklime concentrations (trial II; 50, 30, 20, 10 and 5%) were used to treat sand. The effect of liming on larval cultures was assessed by measuring embryonic development. Filariform larvae were exposed to 20% quicklime (25 °C and 37 °C, 20 min). Heat treatment destroys Ancylostoma spp. eggs and prevents in vitro larval development. Liming at 50, 30, and 20% concentrations made embryonic development impossible. However, filariform larvae treated with 20% lime solution retained their motility. Heating at 70 °C and liming at 20% were sufficient to make Ancylostoma spp. egg embryogenesis impossible in experimentally contaminated sand samples.

Enhanced flushing mechanism of petroleum hydrocarbon contaminated sandy soil by air nano bubbles

The NBs have the best removal rate of petroleum hydrocarbon pollutants in porous media under weakly alkaline condition (pH = 7–8). Both strong acidity and strong alkalinity are not conducive to the flushing removal of pollutants.

Effect of willow biochar and fly ash-derived zeolite in immobilizing heavy metals and promoting enzymatic activity in a contaminated sandy soil

Great difficulties associated with the reclamation of contaminated soils make it necessary to improve its methods and search for new, innovative technological solutions. Both biochars and synthetic zeolites have properties to control the mobility, and bioavailability of heavy metals in the soil through surface adsorption, ion exchange, or complexation. The aim of this study was to determine the effectiveness of soil supplementation with biochar and zeolite in immobilizing heavy metals (Cd, Pb, Zn) and promoting enzymatic activity in contaminated loamy sandy soil. The study was conducted on biochar produced from plant (willow) biomass at 350 °C and 550 °C, zeolite hydrothermally synthesized from fly ash and obtained from conventional coal combustion, as well as mixtures of these materials. Experimental pots were filled with loamy-sandy soil. The soil was contaminated with the following toxic metals: Cd, Pb, and Zn. Two factors were used in the experiment: (i) grass species (Dactylis glomerata L., Festuca arundinacea Schreb.) and (ii) soil treatment. Soil supplementation with functionalized materials reduced the share of mobile and carbonate-bound forms of cadmium, lead, and zinc. The study indicated that functionalized materials, such as biochar and zeolite, are moderately effective when used separately, but better results can be obtained by applying these materials together as mixtures. The results of the two-year study carried out on soil freshly contaminated (spiked) with heavy metals proved that the time after which significant changes in the bioavailable metal contents are observed is an important element in the assessment of soil supplementation with functionalized materials. The beneficial effect of the applied functionalized materials and their mixtures in promoting soil enzymatic activity is closely related to the effect of these materials on the chemical properties, such as pH or EC. Therefore, in addition to the chemical properties of contaminated soils, the design of heavy metal immobilization processes should also consider the microbial response as a key element in restoring soil health.

Sensitive fluorometric determination of picric acid and antioxidant stabilizers in propellant compositions using amine-rich nitrogen-doped carbon quantum dots

Determination of both trace explosives in soil samples and antioxidant stabilizers in propellant compositions using the same quantum dots is an important challenge in analytical chemistry. For this purpose, unmodified carbon quantum dots (CQDs) were prepared with surface heteroatom (nitrogen and oxygen) doped, water-soluble and highly fluorescent properties. The CQDs were synthesized by reflux method using citric acid (CA) and N-(4-methylpyridin-2-yl)ethane-1,2-diamine (NMPE) as carbon- and nitrogen-sources, respectively, and displayed a quantum yield as high as 48.30%. Surface morphology of CQDs was determined by STEM, IR, Raman and XPS techniques, and optical properties were determined by fluorescence spectroscopy, fluorescence lifetime measurement, and UV–vis spectroscopy. CQDs, excited at 310 nm, have a spherical structure with an average diameter of 2.0 nm, and emit strong blue fluorescence at a wavelength of 380 nm. With the static fluorescence quenching phenomenon based on the internal filter effect (IFE) mechanism, CQDs can precisely detect picric acid (PA), curcumin, and amine-type antioxidants used as stabilizers (i.e. N-phenyl-p-phenylenediamine, N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, and diphenylamine). With detection limits of 0.5 nmol L−1 for picric acid, 70 nmol L−1 for curcumin, and 600 nmol L−1 for N-phenyl-p-phenylenediamine, CQDs can detect analytes with good recovery in the range of 95% to 105% in the presence of different explosives (i.e., tetryl, TNT, PETN, HMX, and RDX for picric acid), metal ions (Cd2+, Fe2+, Mg2+, Cu2+, Zn2+, Mn2+, and Ca2+ for picric acid and curcumin), anions (Cl−, NO3−, NO2−, SO42−, and CO32− for picric acid and curcumin), biomolecules (glucose, trypsin, lysine, l-phenylalanine, and DL-alanine for curcumin), and camouflage materials (i.e. paracetamol, glucose, detergent, aspartame, and acetyl salicylic acid for picric acid). The developed method was validated against LC-MS/MS (for picric acid) and spectrophotometric CUPRAC (for curcumin) by comparatively analyzing picric acid in contaminated sandy soil and curcumin in synthetically prepared propellant composition.

Zero valent iron or Fe3O4-loaded biochar for remediation of Pb contaminated sandy soil: Sequential extraction, magnetic separation, XAFS and ryegrass growth

In this study, the feasibility of using zero-valent iron (ZVI) and Fe3O4-loaded biochar for Pb immobilization in contaminated sandy soil was investigated. A 180-day incubation study, combined with dry magnetic separation, chemical extraction, mineralogical characterization, and model plant (ryegrass, namely the Lilium perenne L.) growth experiment was conducted to verify the performance of these two materials. The results showed that both amendments significantly transferred the available Pb (the exchangeable and carbonates fraction) into more stable fractions (mainly Fe/Mn oxides-bound Pb), and ZVI alone showed a better performance than the magnetic biochar alone. The magnetic separation and extended X-ray absorption fine structure (EXAFS) analysis proved that Fe (oxyhydr)oxides on aged ZVI particles were the major scavengers of Pb in ZVI-amended soils. In comparison, the reduced Pb availability in magnetic biochar-amended soil could be explained by the association of Pb with Fe/Mn (oxyhydr)oxides in aged magnetic biochar, also the possible precipitation of soil Pb with soluble anions (e.g. OH−, PO43−, and SO42−) released from magnetic biochar. ZVI increased ryegrass production while Fe3O4-loaded biochar had a negative effect on the ryegrass growth. Moreover, both markedly decreased the Pb accumulation in aboveground and root tissues. The simple dry magnetic separation presents opportunities for the removal of Pb from soils, even though the efficiencies were not high (17.5% and 12.9% of total Pb from ZVI and biochar-treated soils, respectively). However, it should be noted that the ageing process easily result in the loss of magnetism of ZVI while the magnetic biochar tends to be more stable and has high retrievability during the dry magnetic separation application.

Effects of Pb-, Cd-resistant bacterium Pantoea sp. on growth, heavy metal uptake and bacterial communities in oligotrophic growth substrates of Lolium multiflorum Lam.

Phosphate-solubilizing bacteria (PSB) can accelerate phytoremediation, especially in those fertilized soils. However, PSB function in oligotrophic growth substrates remains poorly studied. In this study, we isolated lead (Pb)- and cadmium (Cd)-resistant PSB from contaminated sandy soil at an abandoned lubricant plant. The isolated Pantoea sp. PP4 (PP4 hereafter) can produce organic acid and IAA (Indole-3-acetic acid) and dissolve up to 238mg/L of inorganic phosphate Ca2(PO4)3, exhibiting biosorption capability for Pb and bioprecipitation for Pb and Cd. In the sand pot experiment, inoculation of PP4 increased the accumulation of Pb and Cd in Lolium multiflorum Lam. by 28.9% and 95.5%, respectively, and increased the available phosphorous in oligotrophic river sand by 30.8% (P < 0.05). Meanwhile, the growth of Lolium multiflorum Lam. was also stimulated, resulting in 89.2%, 57.1%, 184.6%, and 28.5% increase in fresh weight, dry weight, root length, and shoot length, respectively. NMDS analysis showed that the bacterial communities in river sand were more clustered after inoculation with PP4. These results indicated that the application of Pantoea sp. PP4 can facilitate the phytoremediation of Pb and Cd in oligotrophic growth substrates, forming a convergent bacterial community. Our findings highlighted the importance of identifying ideal PSB to improve phytoremediation efficiency in oligotrophic environments.

Potential ability of tobacco (Nicotiana tabacum L.) to phytomanage an urban brownfield soil.

The ability of tobacco (Nicotiana tabacum L. cv. Badischer Geudertheimer) for phytomanaging and remediating soil ecological functions at a contaminated site was assessed with a potted soil series made by fading an uncontaminated sandy soil with a contaminated sandy soil from the Borifer brownfield site, Bordeaux, SW France, at the 0%, 25%, 50%, 75%, and 100% addition rates. Activities of sandblasting and painting with metal-based paints occurred for decades at this urban brownfield, polluting the soil with metal(loid)s and organic contaminants, e.g., polycyclic aromatic hydrocarbons, in addition to past backfilling. Total topsoil metal(loid)s (e.g., 54,700 mg Zn and 5060 mg Cu kg−1) exceeded by seven- to tenfold the background values for French sandy soils, but the soil pH was 7.9, and overall, the 1M NH4NO3 extractable soil fractions of metals were relatively low. Leaf area, water content of shoots, and total chlorophyll (Chl) progressively decreased with the soil contamination, but the Chl fluorescence remained constant near its optimum value. Foliar Cu and Zn concentrations varied from 17.8 ± 4.2 (0%) to 27 ± 5 mg Cu kg−1 (100%) and from 60 ± 15 (0%) to 454 ± 53 mg Zn kg−1 (100%), respectively. Foliar Cd concentration peaked up to 1.74 ± 0.09 mg Cd kg−1, and its bioconcentration factor had the highest value (0.2) among those of the metal(loid)s. Few nutrient concentrations in the aboveground plant parts decreased with the soil contamination, e.g., foliar P concentration from 5972 ± 1026 (0%) to 2861 ± 334 mg kg−1 (100%). Vulnerability to drought-induced embolism (P50) did not differ for the tobacco stems across the soil series, whereas their hydraulic efficiency (Ks) declined significantly with increasing soil contamination. Overall, this tobacco cultivar grew relatively well even in the Borifer soil (100%), keeping its photosynthetic system healthy under stress, and contaminant exposure did not increase the vulnerability of the vascular system to drought. This tobacco had a relevant potential to annually phytoextract a part of the bioavailable soil Zn and Cd, i.e., shoot removals representing here 8.8% for Zn and 43.3% for Cd of their 1M NH4NO3 extractable amount in the potted Borifer soil.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-16411-y.

Application of Green Surfactants in the Remediation of Soils Contaminated by Hydrocarbons

Among the innovative technologies utilized for the treatment of contaminated soils, the use of green surfactants appears to be a biocompatible, efficient, and attractive alternative, since the cleaning processes that normally use synthetic surfactants as additives cause other problems due to toxicity and the accumulation of by-products. Three green surfactants, i.e., two biobased (biobased 1 and biobased 2) surfactants produced by chemical synthesis and a microbial surfactant produced from the yeast Starmerella bombicola ATCC 22214, were used as soil remediation agents and compared to a synthetic surfactant (Tween 80). The three surfactants were tested for their ability to emulsify, disperse, and remove different hydrophobic contaminants. The biosurfactant, which was able to reduce the water surface tension to 32.30 mN/m at a critical micelle concentration of 0.65 g/L, was then used to prepare a commercial formulation that showed lower toxicity to the tested environmental bioindicators and lower dispersion capacity than the biobased surfactants. All the green surfactants showed great emulsification capacity, especially against motor oil and petroleum. Therefore, their potential to remove motor oil adsorbed on different types of soils (sandy, silty, and clay soil and beach sand) was investigated either in kinetic (flasks) or static (packed columns) experiments. The commercial biosurfactant formulation showed excellent effectiveness in removing motor oil, especially from contaminated sandy soil (80.0 ± 0.46%) and beach sand (65.0 ± 0.14%) under static conditions, while, in the kinetic experiments, the commercial biosurfactant and the biobased 2 surfactant were able to remove motor oil from all the contaminated soils tested more effectively than the biobased 1 surfactant. Finally, the S. bombicola commercial biosurfactant was evaluated as a soil bioremediation agent. In degradation experiments carried out on motor oil-contaminated soils enriched with sugarcane molasses, oil degradation yield in the sandy soil reached almost 90% after 60 days in the presence of the commercial biosurfactant, while it did not exceed 20% in the presence of only S. bombicola cells. These results promise to contribute to the development of green technologies for the treatment of hydrophobic pollutants with economic gains for the oil industries.

Engineered biochars from catalytic microwave pyrolysis for reducing heavy metals phytotoxicity and increasing plant growth

Pb, Ni, and Co are among the most toxic heavy metals that pose direct risks to humans and biota. There are no published studies on biochars produced at low temperatures (i.e., 300 °C), which possess high sorption capacity for heavy metal remediation and reclamation of contaminated sandy soils. This research studied the effect of catalytic microwave pyrolysis of switchgrass (SG) using bentonite and K3PO4 to produce biochar at low temperature (300 °C) with high sorption capacity for reducing the phytotoxicity of heavy metals, and investigated the synergistic effects of catalyst mixture on biochar sorption capacity. The quality of the biochars was examined in terms of their impacts on plant growth, reducing phytotoxicity and uptake of heavy metals in sandy soil spiked with Pb, Ni, and Co. All catalysts increased the micropore surface area and cation-exchange capacity of biochars, and resulted in biochars rich in plant nutrients, which not only decreased heavy metal phytotoxicity, but also boosted plant growth in the spiked soil by up to 140% compared to the sample without biochar. By mixing bentonite and K3PO4 with SG during microwave pyrolysis, the efficacy of biochar in reducing phytotoxicity and heavy metals uptake was further enhanced because of the highest micropore surface area (402 m2/g), moderate contents of Ca, Mg, K, and Fe for ion-exchange and moderate concentration of phosphorus for the formation of insoluble heavy metal compounds. Generally, the biochar created at 300 °C (300-30KP) showed similar performance to the biochar created at 400 °C (400-30KP) in terms of reducing heavy metal bioavailability.

The effect of earthworms on plant response in metal contaminated soil focusing on belowground-aboveground relationships.

Contaminated soils are lands in Europe deemed less favourable for conventional agriculture. To overcome the problem of their poor fertility, bio-fertilization could be a promising approach. Soil inoculation with a choice of biological species (e.g. earthworm, mycorrhizal fungi, diazotroph bacteria) can be performed in order to improve soil properties and promote nutrients recycling. However, questions arise concerning the dynamics of the contaminants in an inoculated soil. The aim of this study was to highlight the soil-plant-earthworm interactions in the case of a slightly contaminated soil. For this purpose, a pot experiment in controlled conditions was carried out during 2 months with a Cd, Zn, and Cu contaminated sandy soil, including conditions with or without earthworms (Aporrectodea caliginosa) and with or without plants (Lolium perenne). The three components of the trace element bioavailability were studied to understand the belowground-aboveground relationships and were quantified as followed: i) environmental availability in soils by measuring trace element concentrations in soil solution, ii) environmental bioavailability for organisms by measuring trace element concentrations in depurated whole earthworms bodies and in the plant aerial biomass, and iii) toxicological bioavailability, by measuring survival rate and body weight changes for earthworms and biomass for plants. The results showed that earthworm inoculation increased the content of all studied TE in soil solution. Moreover, lower concentrations of Cd and Zn were found in plants in the presence of earthworms while the bioavailability decreased when compared to the condition without plants. The trace element bioaccumulation in earthworms did not produce a direct toxicity, according to the earthworm survival rate and body weight results. Finally, our pot experiment confirmed that even in contaminated soils, the presence of A.caliginosa promotes plant adaptation and improves biomass production, reducing trace element uptake.

Use of activated peat for remediation of soils contaminated with petroleum products

One of the most serious environmental problem in the Far North of the Russian Federation is the pollution of the territory by oil and oil products. Ecosystems of this region are extremely vulnerable, their remediation after anthropogenic impact, such as spill of fuels, can last for decades. This is the reason for necessity of the development of effective methods for cleaning and restoring oil-contaminated lands. As a result of undertaken laboratory study, the possibility of bioremediation of soils contaminated with oil products using activated peat as a sorbent and organic fertilizer was shown. Two weeks after the addition of activated peat, the content of petroleum hydrocarbons in the soil decreased by 22-47% due to dilution of pollution and improvement of air and nutrient regime. After reclamation, the germination rate of the seeds of a test culture increased by 1,6-3,7 times. The optimum amount of peat required for adding into contaminated sandy soil, depending on the degree of contamination, has also been established. Based on the studies, recommendations for the remediation of the contaminated area of 0.07 ha located in the north-west of the Murmansk region using peat and mineral fertilizers were developed.

Multimarker approach to assess the exposure of the wild rodent Calomys laucha to a simulated crude oil spill.

A mysterious oil spill occurred in the ocean near Brazil in 2019, which affected coastal areas in northeastern Brazil. When oil pollution occurs in coastal zones, organisms such as small mammals can suffer deleterious effects to their health. This study aimed to evaluate the effects of exposure to contaminated sandy soil with different crude oil concentrations in males of the species Calomys laucha. The exposure to crude oil resulted in multiple health issues for the subjects in the very first days of exposure. Furthermore, the exposure resulted in mutagenic damage to bone marrow blood cells and behavioral and morphological alterations, which were almost always in a dose-dependent form. The present study demonstrates the sensibility of the biomarkers used and highlights that small wild mammals such as C. laucha are useful for predicting environmental damage caused by the exposure to crude oil.

Application of biochars and solid fraction of digestate to decrease soil solution Cd, Pb and Zn concentrations in contaminated sandy soils.

Biochar prepared from waste biomass was evaluated as a soil amendment to immobilize metals in two contaminated soils. A 60-day incubation experiment was set up on a French technosol which was heavily contaminated with Pb due to former mining activities. Grass biochar, cow manure biochar (CMB) and two lightwood biochars differing in particle size distribution (LWB1 and LWB2) were amended to the soil at a rate of 2% (by mass). Rhizon soil moisture samplers were employed to assess the Pb concentrations in the soil solution at regular times. After 30days of incubation, soil solution concentrations in the CMB-amended soil decreased by more than 99% compared to the control. CMB was also applied to a moderately contaminated Flemish soil and resulted in lowered soil solution Cd and Zn concentrations. While the application of 4% CMB resulted in 90% and 80% reductions in soil solution concentrations of Cd and Zn, respectively, the solid fraction of digestate (as a reference) reduced the soil pore water concentrations by only 63% for Cd and 73% for Zn, compared to the concentrations in the control. These results emphasize the potential of biochar to immobilize metals in soil and water systems, thus reducing their phytotoxicity.

Efficient Removal of the Toxic Lead Ions from ContaminatedSandy Soils using Newly Engineered Carbon Black Nanoadsorbent

Soils contaminated with heavy metals can embarrass a fatal risk to the environment and human life via the direct uptake of the heavy metal-contaminated agricultural crops. Hence, the treatment of metal-contaminated soils is attracting a lot of research activities to reduce the negative impact on the environment. In the current study, I have activated the surface of the carbon black (CB) adsorbent by introducing functional groups capable to efficiently capture the lead (Pb) metal ions from a Pb-contaminated sandy soil. The soil properties (e.g. electrical conductivity, acidity, carbon and nitrogen content, and organic matter) were studied before and after the treatment with the CB adsorbent. I also showed a comprehensive adsorption study in soil-batch extraction experiments, evaluating a series of factors such as the effects of soil pH (pH 3.0 to pH 7.0), Pb concentration into the soil (5-100 mg/L), and the soil temperature (15-50 °C).Furthermore, the recyclability of the adsorbent was highlighted to evaluate adsorption efficiency upon use. The results of the study were remarkable where a 100 % removal efficiency of Pb ions was obtained using only a 40 ppm of the oxidized CB compared to a 60% removal efficiency when using a pristine CB at the same concentration. The adsorption capacity of Pb ions was as high as 100 mg/g at 30 mg/L of oxidized CB adsorbent. The life cycle of oxidized CB adsorbent was also remarkable compared to that of pristine adsorbent. The recyclability data of the functionalized CB has showed an easy regeneration process with an efficient reusefor 5 cycles with 30 %a performance decline of 30 % only from the initial adsorption efficiency

Bearing capacity of isolated square footing resting on contaminated sandy soil with crude oil

The main objective of this paper is the evaluation of bearing capacity of isolated square footing resting on clean and oil-contaminated sand. The study is aimed at determining the effect of percentage of oil content in sand and the depth of the contaminated sand layer under the footing on the bearing capacity of footing. A series of routine laboratory tests were carried out on sand to obtain the physical, mechanical, and chemical properties. Crude oil is used as a contamination material. The research-included the completion of experimental work that consists of a series of loading tests carried on model of isolated square footing resting on clean and oil-contaminated sand. The contaminated sand layers were prepared by mixing the sand with crude oil at percent (10 and 20) % by weight of dry sand to simulate the field conditions. The depth of contaminated sand layer (d) under the footing was chosen depending on the footing width (B) as expressed by (d/B) ratio and varied as (0.5, 1, 1.5 and 2) to simulate the field conditions. The results showed that the contamination influences the load-settlement curves and leads to a reduction in its bearing capacity. The bearing capacity of the footing decreases significantly with increasing both the percentage of oil content and the depth of the contaminated sand layer. The results also showed that the presence of oil in sand changes the mode of shear failure in sand under the footing from local shear failure to the punching shear failure.

Removal of phenanthrene and pyrene from contaminated sandy soil using hydrogen peroxide oxidation catalyzed by basic oxygen furnace slag.

Soil contamination with polycyclic aromatic hydrocarbons (PAHs) is a serious problem in Northeast China, especially in the steel industrial area. The objective of this study was to evaluate the feasibility of using basic oxygen furnace (BOF) slag to activate the Fenton-like remediation of PAH-contaminated soil to achieve the objectives of "waste control by waste" and "resource recycling" in Chinese steel industry. The effects of BOF slag dosages, H2O2 concentrations, and exothermicity-driven evaporation were evaluated with respect to the removal efficiencies of phenanthrene (Phe) and pyrene (Pyr). Results indicated that PAH oxidation was proportional to the BOF slag dosages and was increased exponentially with H2O2 concentrations. Evaporation due to increasing temperature caused by exothermic reaction played an important role in total soil PAH losses. The sequential Fenton-like oxidation with a 3-times application of 15% H2O2 and the same BOF slag repeatedly used were able to remove 65.87% of Phe and 58.33% of Pyr, respectively. Soluble iron oxides containing in BOF slag were reduced, while amorphous iron oxide concentration remained stable during the repeated Fenton-like process. Column study mimics real field applications showing high removal efficiencies of Phe (36.05-83.20%) and Pyr (21.79-68.06%) in 30-cm depth of soil profile. The tests on soluble heavy metal concentrations after the reactions with high slag dosage or high H2O2 concentration confirmed that BOF slag would not cause heavy metal contamination. Consequently, BOF slag may provide an efficient way for enhancing the Fenton-like based remediation of heavily PAH-polluted soil with little risk on collateral heavy metal contamination. However, an external gas collection and purification equipment would be essential to eliminate the evaporated PAHs.

Long Term Ageing Effect on Physical and Shear Strength Characteristics of Oil Contaminated Sandy Soils of Al-Ahmadi Field in Kuwait

Serious environmental damage was caused to Kuwait when more than 600 oil wells were set alight following the 1991 Gulf War, leading to hydrocarbon contamination and a series of ‘oil lakes’ being created in the desert. The effects of these highly damaging actions are still detectable today, 27 years later. The main contribution of this paper is that the effects on the behavior of physical and shear strength properties of the Al-Ahmadi field sand brought about via the long-term ageing influence of hydrocarbon contamination will be explored, using the methodology of comparing contaminated and non-contaminated soil samples. For the purpose of this paper, nine samples, from more than 28 years’ oil contaminated site, were subject to both physical and shear strength tests alongside hydrocarbon analysis using Gas Chromatograph Mass Spectrometer (GC-MS) testing. The results of these tests showed a notable increase in both the mean values of fines particles (from 7.8% to 11.8%) and of gravel particles (from 5.8% to 27.8%). These results clearly illustrate that the overall effect of the change in soil gradation was a poorer one. A reduction in strength was also observed in these tests, which possibly related to accumulation of particles within the soil layer leading to poorer grain size and to ageing effect that increase asphalting lead to weak bonding between particles.

Chelating-Agent-Enhanced Copper, Lead and Zinc Extraction From Iraqi Contaminated Sandy Soil.

This research aims to investigate extraction of copper, lead, and zinc from Iraqi sandy contaminated soil. Two systems were tested single and ternary component systems. Chelating agent ethylenediaminetetraacetic acid disodium salt (Na2EDTA) was utilized as extractant. Amount of 500 mg of metal per kg soil was prepared to form artificially contaminated soil. Extraction of metals was achieved using column extraction mode. Experimental tests were conducted at different conditions of Na2EDTA concentration,flow rate, and contact time. The results illustrated that the maximum removal percentages for single component system were 92% ,76% and 68% at equilibrium time 6, 8, and 8 hours for Pb , Cu and Zn, respectively. While for ternary system were 82%, 72% and 65%, respectively, at equilibrium time 6 hours for Cu and 8 hours for Pb and Zn. In addition to the best equilibrium time, the other optimum conditions for both systems were 0.1 mol/L extractant concentration, pH 4 and flow rate 20 ml/hr. The sequence of heavy metals removal was Pb &gt; Cu &gt;Zn. The experimental data were tested by applying it in four kinetic models; first order, two constant, parabolic diffusion, and Elovich model. Elovich and parabolic diffusion were the most fitted models to the experimental data.

Grain Size Distribution Characteristics Variationin Oily Contaminated Sandy Soils Dueto Long Term Aging Effectin Al-Ahmadi Field at Kuwait

Almost three decades on, the negative environmental impacts arising from the burning of over 600 oil wells in Kuwait following the 1991 Gulf War are still evident. At the time of the incident, the Kuwaiti desert region became polluted with hydrocarbon, with a number of ‘oil lakes’ forming, causing critical harm to local land. This paper discusses the shifts in particle size distribution (PSD) found in soil taken from Kuwait’s Al-Ahmadi oil field, caused by aging sandy soil polluted with hydrocarbon. The analysis of changes in PSD was achieved using 16 contaminated and uncontaminated soil samples, with the samples undergoing PSD analysis along with Unified Classification Soil System (UCSS), Scanning Electronic Microscopy (SEM) and Gas Chromatograph Mass Spectrometer (GC-MS) analyses.The analyses revealed a significant reduction in the mean values of both sand and silty/clay particles, which fell from 44.6% to 9.0% and 7.8% to 3.4%, respectively. The analyses also showed a significant increase in the mean values of gravel particles, rising to 44.6% from 6.1%. These results obviously clarify that the overall outcome of the alteration in soil gradation was a poorer one, which may be due to bigger particles forming out of fine particles as a result of oil contamination. The results presented in this paper are intended to support the treatment (soil washing and cement stabilisation) of contaminated sandy soil based on the insights gained into how soil grain size distribution is impacted by oil contamination.

Vermicompost dose and mycorrhization determine the efficiency of copper phytoremediation by Canavalia ensiformis.

The phytoremediation of copper (Cu)-contaminated sandy soils can be influenced by the addition of vermicompost to the soil and the mycorrhization of plants. The objective of this study was to evaluate the effects of inoculation with the mycorrhizal fungus Rhizophagus clarus and the addition of different doses of bovine manure vermicompost on the phytoremediation of a sandy soil with a high Cu content using Canavalia ensiformis. Soil contaminated with 100mgkg-1 Cu received five doses of vermicompost and was cultivated with C. ensiformis, with and without inoculation with mycorrhizal fungus, and the Cu and nutrients in the soil and soil solution were evaluated. The concentrations of Cu and other nutrients and the biomass and Cu phytotoxicity in the plants were quantified by gauging the photochemical efficiency, concentration of photosynthetic pigments and activity of oxidative stress enzymes. The vermicompost increased the soil pH and nutrient concentrations and reduced the Cu content of the solution. When the vermicompost was applied at a dose equivalent to 80mg phosphorus (P) kg-1, the phytoextraction efficiency was higher, but the phytostabilization efficiency was higher for vermicompost doses of 10 and 20mg P kg-1. The presence of mycorrhizal fungi increased Cu phytostabilization, especially at vermicompost doses of 10 and 20mg P kg-1. The use of vermicompost at low doses and inoculation with mycorrhizal fungi increase the phytostabilization potential of C. ensiformis in sandy soil contaminated by Cu.