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Fuel, a petroleum derivative, contributes to soil pollution because of its hydrocarbons, which are difficult to decompose. Bioremediation can assist by introducing microbes that are capable of degrading hydrocarbons and enhancing this process by adding nutrients. This study validated previous research by adding the most optimum nutrients, bacteria with the right ratio, and pre-treatment of soil washing on the degradation value of hydrocarbons in crude oil-contaminated soil. Pre-treatment involved washing the soil with surfactant tween-80, determining the type of mixed bacterial culture variables, adding varying concentrations of inoculum and inorganic nutrients, and determining the optimal total petroleum hydrocarbon (TPH) reduction. The study found that the provision of nutrients, bacteria, and pre-treatment in soil washing had no significant effect on the original soil TPH. [ABSTRACT FROM AUTHOR]

This work presents the development and system integration of a ground agricultural mobile manipulator robot that is capable of traversing a field in order to monitor the health of the field and crops. The robotic platform consists of a 4-wheeled drive base rover that has a 6 degrees of freedom (DOF) robotic manipulator attached to it, which is equipped with a multitude of sensors that are used for navigation, crop inspection, and soil monitoring. To accurately measure the moisture of the soil using the moisture probe, the insertion process is very important, as the probe has to be inserted to the correct depth and be flush with the soil. It is for this reason, that the insertion process is difficult, as the field can be rough and uneven terrain. Utilizing a camera attached to the wrist of the robotic manipulator, the soil insertion process can be adjusted to more accurately insert the soil probe into the terrain with a varying degree of slopes. Along with detecting the slope of the soil to perform an accurate soil insertion, the robotic system is capable of detecting plants in various stages of development, and capture images to visually determine the crops health. The successful operation of the robot for in-situ soil measurements, crops image capturing, plant's physical characteristics detection, and an autonomous soil slope alignment for sensor insertion have been demonstrated. [ABSTRACT FROM AUTHOR]

Contamination of heavy metal(loid) in soils is a global problem. Various remediation technologies have thus been applied to mitigate the ecological and health risk of heavy metal(loid)s in contaminated soils. Majority of review studies mainly focus on the mobility or accumulation of heavy metal(loid)s, but little attention has been paid to the alteration of soil fertility (e.g. soil nutrient, structure and enzyme activities) which are most closely related to plant growth during the remediation process. Here, we summarized influence of physical, chemical and biological remediation technologies of contaminated soils on soil fertility, and they indicated that: (1) thermal treatment and soil washing usually decreased soil nutrients and enzyme activities, as well as deteriorated soil structure; (2) biological technologies usually improved soil structure or microorganism activities, but the decrease of soil fertility through nutrient uptake by plants cannot be ignored; (3) the soil amendments displayed various influence on soil fertility, which depended on their properties; (4) combination of multiple technologies could neutralize the negative influence of single technology on soil fertility. In the future, technologies which could both decrease heavy metal(loid) toxicity and improve soil fertility are more recommended. [ABSTRACT FROM AUTHOR]

Copper compounds in the form of fungicides are most commonly used as a measure of protection against vine diseases. Typically, around a dozen treatments are done throughout a year with a dispersion of approximately 5–10 kg of Cu per hectare. For many years, the remediation of heavy metals has often involved the use of ex-situ soil washing with chelating reagents. Amino acids have a lower metal chelation capability compared to EDTA and its derivatives, but they have numerous other advantages in comparison. The main goal of this research was to investigate the ability of 9 amino acids and one dipeptide to extract Cu from various vineyard soil samples and compare their chelating ability with other 'green' chelating agents. The average content of Cu extracted with amino acids is 34.7 ± 16.7 mg/kg or 30.3 ± 5.43 wt% relative to the pseudo-total content. This is more than what was extracted with carboxylic acid salts (9.91 ± 7.49 mg/kg or 8.45 ± 5.56 wt%) but less than with EDTA (98.5 ± 42.7 mg/kg or 79.9 ± 7.12 wt%). The descending order of tested amino acids relative to the removed Cu (mg/kg) is: His > Ser > Thr > Leu > Gly > Val > Phe > Gly-Gly ~ Ala > Arg. The results of this paper show that the amino acid structure is the most important factor for efficient Cu extraction, while the physicochemical properties of the vineyard soil have less impact. [ABSTRACT FROM AUTHOR]

Exposures to pollutants and contaminants can occur through water or soil, which can be contaminated naturally or through human activities. The toxicity and adverse health effects of these substances depend on exposure route, quantity, and duration. Mechanisms of water contamination include runoff, flooding, infrastructure failures, and contamination from air and surface water pollution. Pesticides and organophosphates commonly are used in agricultural and residential applications, frequently cause water contamination, and commonly cause poisoning in agricultural workers and gardeners. Soil contamination disproportionately affects minority and low-income populations because they are more likely to live in proximity to a pollution source. Fetuses, children, and individuals with preexisting medical conditions are more vulnerable to adverse health effects of soil contamination compared with healthy adults. Some of the most common soil pollutants are heavy metals, pesticides, and polychlorinated biphenyls. Preventing exposure to contaminated soil involves avoidance of historically contaminated sites and ingestion of soil. Approaches to cleanup depend on the extent of contamination, location, and planned future use of the land. Remediation strategies include containment, bioremediation, chemical oxidation, soil washing, and thermal treatment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using natural deep eutectic solvents (NADESs) as a green reagent is a step toward producing environmentally friendly and sustainable technology. This study screened three natural DESs developed using quaternary ammonium salt and organic acid to analyse their capability to extract nickel ions from contaminated mangrove soil, which are ChCl: Acetic Acid (ChCl-AceA), ChCl: Levulinic Acid (ChCl-LevA), and ChCl: Ethylene Glycol(ChCl-Eg) at molar ratio 1:2. The impact of various operating parameters such as washing agent concentration, pH solution, and contact time on the NADES performance in the dissolution of Ni ions batch experiments were performed. The optimal soil washing conditions for metal removal were 30% and 15% concentration, a 1:5 soil-liquid ratio, and pH 2 of ChCl-LevA and ChCl-AceA, respectively. A single removal washing may remove 70.8% and 70.0% Ni ions from the contaminated soil. The dissolution kinetic of Ni ions extraction onto NADES was explained using the linear kinetic pseudo and intraparticle mass transfer diffusion models. The kinetic validation demonstrates a good fit between the experimental and pseudo-second-order Lagergren data. The model's maximum Ni dissolution capacity, Qe are 51.56 mg g−1 and 52.00 mg g−1 of ChCl-LevA and ChCl-AceA, respectively. The synthesised natural-based DES has the potential to be a cost-effective, efficient, green alternative extractant to conventional solvent extraction of heavy metals. [ABSTRACT FROM AUTHOR]

The results of a field study of the erosion–accumulative patterns of the soil cover of a key area in the zone of dark chestnut soils (Kastanozems) are presented, and the information content of multitemporal remote sensing data on the bare soil surface for its identification and mapping is analyzed. The site is located on the Millerovo–Morozovskaya inclined plain within the Don–Donetsk hilly-ridge plain, in Oblivsky district of the Rostov region. The soil cover of the key area is represented by a combination of low-contrasting soils on convex and concave surfaces within an elongated ridge and its slopes, including agro-dark chestnut solonetzic and nonsolonetzic soils, agrozems (washed away soils that have lost the middle-profile xerometamorphic horizon), and stratozems (aggraded soils). The development of this soil cover pattern is determined by a combination of mesorelief landforms and two types of soil-forming rocks. The map of the C coefficient of the multitemporal soil line reveals the heterogeneity of the soil cover related to the activity of erosion/deposition processes. In the key area, three groups of contrasting soil combinations differ significantly in the form of different variations and combinations-variations forming a kind of framework of the soil cover. Combinations of eroded and aggraded soils located between the above three groups of soil combinations significantly differ from their neighbors, but their interpretation has an increased uncertainty. [ABSTRACT FROM AUTHOR]

As the energy demand increases, there is a significant expansion and utilization of oil resources, resulting in the inevitable occurrence of environmental pollution. Oil has been identified as a prevalent soil contaminant, posing substantial risks to the soil ecosystems. The remediation of soil contaminated with oil is a formidable undertaking. Increasing evidence shows that chemical washing, a remediation technique employing chemical reagents like surfactants to augment the solubilization, desorption, and separation of petroleum hydrocarbons in soil, proves to be an efficacious approach, but the latest advances on this topic have not been systematically reviewed. Here, we present the state of knowledge about the surfactant-based chemical washing to remediate oil-contaminated soil. Using the latest data, the present article systematically summarizes the advancements on ex situ chemical washing of oil pollution and provides a concise summary of the underlying principles. The use of various surfactants in chemical washing and the factors influencing remediation efficiency are highlighted. Based on the current research status and knowledge gaps, future perspectives are proposed to facilitate chemical washing of oil-polluted soil. This review can help recognize the application of chemical washing in the remediation of oil-polluted soil. [ABSTRACT FROM AUTHOR]

The processes of surfactant-enhanced soil washing have been widely applied to the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil, accompanied by the production of soil washing eluent. In this study, novel composite materials of beads containing alginate, carboxymethyl cellulose and diatomite (SCD) were used to encapsulate Bacillus subtilis to remove phenanthrene (PHE) from simulated soil washing eluent with rhamnolipid. The effects of dosage, pH and temperature on the PHE removal performance were explored, and the optimal PHE removal conditions [SCD bead dose 16.2% (w:v), pH 7.1 and 30.6°C] were determined using response surface methodology. After incubation in simulated soil washing eluent for 7 d, SCD beads removed 84.92% of PHE, which was 49.18% higher than by free bacteria. In addition, SCD beads mainly removed PHE through biodegradation processes, and the degradation rate (1.38 mg L−1 d−1) was higher than that of free bacteria (0.64 mg L−1 d−1). Characterization results revealed that the immobilized substrate provided the micro-environment for bacteria and reduced the intense effect of high rhamnolipid concentration. Reusability results showed that SCD beads could be recycled four times to remove 80.05% of PHE. Collectively, SCD beads have great prospects for the decontamination of soil-washing eluent containing complex components. [ABSTRACT FROM AUTHOR]

In mountainous watersheds, floodplain sediments are typically characterized by gravel bed layers capped by an overlying soil unit that serves as a hotspot for biogeochemical reactivity. However, the influence of soil biogeochemistry on gravel bed underflow composition remains unclear, especially during hydrological transitions that alter the vertical connectivity between overlaying soils and the underlying gravel bed. This study investigates these dynamics by measuring hydraulic gradients and water compositions over three hydrological years in a typical mountainous, low‐order stream floodplain in the Upper Colorado River Basin. Results indicate that the timing of hydrological conditions strongly influences the vertical exchanges that control water quality. Specifically, during flooding events such as beaver ponding, that induce downward flushing of the soil, anoxic conditions prevalent in the biogeochemically active soil are transferred downstream via gravel bed underflow. Conversely, snowmelt and drought conditions increase oxic conditions in the gravel bed due to diminished hydrological connectivity with the overlying soil. To compare water quality response to hydrological transitions across similar floodplain environments, we propose a conceptual model that quantifies the inundation‐induced flushing of soil porewater to measure solute exchange efficiency with the gravel bed solute convergence efficiency (SCE). This model provides a framework for quantifying biogeochemical processes in hydrological underflow systems, which is critical for water and elemental budgets in these globally important mountainous ecosystems. Plain Language Summary: Mountains are important sources of freshwater for humans and ecosystems. They are however increasingly impacted by climate change. In this paper, we investigate how changes in water availability (droughts, snowmelt, inundations) can cascade into changes in water quality (concentrations of dissolved chemical elements). We show that in mountain valleys, the zone of contact between the soil and the underlying gravel bed aquifer is important for water quality. Chemical elements from the soil can be flushed down into the gravel bed aquifer, then transported by groundwater to the stream. Chemical elements from the soil can also react with chemical elements present in the aquifer. Our research can be used to better predict the water and elemental budgets in these important mountainous systems. Key Points: Soil / gravel bed connectivity in floodplains is important for water qualitySnowmelt and drought both reduce soil / gravel bed connectivityBeaver ponding increases downward flushing to gravel bed unit [ABSTRACT FROM AUTHOR]

Soil fulfils vital functions for life on Earth and so, just like water and air, its protection from all sources of contamination is a major concern. However, the extensive use of petroleum derived products, either as energy sources or as commodities, leads to important environmental liabilities. Ex situ soil washing is a technology to concentrate contaminants, allowing soil cleaning and the reuse of extracted petroleum derived products. This work focuses on the optimization of ex situ soil washing process using surfactants, introducing an evaluation of the washing solution recycling and its after use safe disposal, promoting the reduction of raw materials, energy and water resources costs. Two surfactants, sodium dodecyl sulphate (SDS) and polyoxyethylene sorbitan monooleate (Tween 80), were tested in the decontamination of an artificially contaminated soil with engine lubricant oil waste. The optimization of the washing conditions, such as stirring speed, liquid–solid ratio, number of washing stages, and surfactant concentration, was carried out using a design of experiments (DOE) software, so that the maximum extraction efficiency of total petroleum hydrocarbons (TPHs) was achieved. A TPH removal efficiency of (80.7 ± 3.2)% was obtained with Tween 80 after 5 h of washing and (90.7 ± 2.8)% with SDS after 2 h at 200 rpm on an orbital shaker with a liquid to solid ratio (L/S) of 15. The potential for reuse of the washing solutions was evaluated. Finally, the discharge of the washing solution was considered using activated carbon to remove the surfactants and ensure its safe disposal. [ABSTRACT FROM AUTHOR]

Suffusion is arguably the most complicated type of internal erosion. Although there are several popular assessment methods, the most realiable assessment is possibly still laboratory testing. However, there is not a standardised test for suffusion yet as different laboratories use different equipment and test configurations. Hence, a reliable comparison of outcomes across laboratories may not be able to achieve yet. This paper presents a new and simple, but very effective, way to test the susceptibility of soil to internal erosion using a novel segregation test. The test employs standard equipment which can be easily found in any geotechnical laboratory. There are some common characteristics of internal erosion and transport segregation, where fine particles are transported through the pore constrictions formed by the soil's primary fabric. In segregation, particles are transported by gravitational/mechanical force to the bottom of the soil mass. Meanwhile, they are washed out of the soil mass by hydraulic force in internal erosion. Laboratory testing for internal erosion often requires specific equipment and a long duration. Meanwhile, segregation test could be undertaken with standardised sieving tower, which is available in any geotechnical laboratory. The approach was verified with an acrylic setup and some 3D-printed details. Later, the tests of 25 mixtures were undertaken with standard sieving sets. The correlation of laboratory results shows good agreement and prompts the common application of the new approach. The new test may not be able to completely replace the conventional suffusion test yet as it overlooks the critical hydraulic gradients at this stage, but it can be very useful if the research focuses on only the erodible mass and susceptibility to suffusion. In addition, it is a standardisable test with no specific requirements on equipment. The new approach may also be a starting point to study other types of internal erosion. [ABSTRACT FROM AUTHOR]

Matured sewage sludge compost is a rich source of humic substances (HS) with reduction capacity. To improve the reduction performance of sludge compost and to obtain a mature compost, the effects of moisture content, aeration rate and biochar addition on sludge compost were analyzed. HS with optimal reduction performance was selected for the removal of arsenic (As) in soil to investigate the removal efficiency and environmental risk. The result showed that the aeration rate and the addition of biochar had a significant effect on the total reduction capacity (TRC) of the compost. The compost with a moisture content of 65%, an aeration rate of 0.2 L·min-1·kg-1 and biochar addition possessed the highest TRC (2062 μmol/g). A removal efficiency of 25% was obtained by washing As-contaminated soil with extracted HS. There was no effect on the concentration of metals, physicochemical properties and phase composition of the soil after washing with HS. Further EEM studies revealed that quinoid functional groups of HS were involved in the washing process and converted between hydroquinone, benzoquinone and quinone oxide after the reaction. Reducing functional groups separated and released arsenic and iron minerals by reductive dissolution. Recycle experiments showed that HS could be used three times. HS from sewage sludge compost is a green and economical washing agent. [ABSTRACT FROM AUTHOR]

• High specific surface area reusable UiO66 composites were synthesized. • UiO66 composites maintains high adsorption capacity for Metal-EDTA complexes in soil. • UiO66 composites application improved the efficiency of EDTA-assisted washing. • Magnetic fields achieved harmful heavy metal recovery from the soil. • UiO66 composites reduced residual heavy metals mobility of soil. The coupling of washing with adsorption process can be adopted for the treatment of soils contaminated with heavy metals pollution. However, the complex environment of soil and the competitive behavior of leaching chemicals considerably restrain adsorption capacity of adsorbent material during washing process, which demands a higher resistance of the adsorbents to interference. In this study, we synthesized strongly magnetic, high specific surface area (573.49 m2/g) UiO66 composites (i.e., UiO66-Fe 3 O 4) using hydrothermal process. The UiO66-Fe 3 O 4 was applied as an adsorbent during the ethylene diamine tetraacetic acid (EDTA)-assisted washing process of contaminated soil. The incorporation of UiO66-Fe 3 O 4 results in rapid heavy metal removal and recovery from the soil under low concentrations of washing agent (0.001 mol/L) with reduced residual heavy metal mobility of soil after remediation. Furthermore, UiO66-Fe 3 O 4 can quickly recollect by an external magnet, which offers a simple and inexpensive recovery method for heavy metals from contaminated soil. Overall, UiO66-Fe 3 O 4 configuration with EDTA-assisted washing process showed opportunities for heavy metals contaminated sites. [Display omitted] [ABSTRACT FROM AUTHOR]

Soil washing has been widely applied and studied in the remediation of heavy metal contamination soil. However, it proves easily limited by soil texture. To this end, the method of freeze-thaw and washing is used to enhance washing efficiency of clayey soils. An array of experiments of laboratory indirectness washing and freeze-thaw and washing were carried out to investigate the removal effect of single and compound washing on heavy metals. The results showed that the stability of soil aggregates would be destabilized by repeated freezing and thawing, contributing to a sufficient contact reaction between eluents and contaminations. The process can also remove heavy metals under a lower liquid-solid ratio, thus reducing the risk of secondary contamination of the soil environment. The eluent has a certain viscosity, which increases the viscosity of the pore water. Accordingly, the water migration resistance increases and inhibits the soil frost heaving-water intake, resulting in the reduction of removal efficiency. The removal effect of compound washing is preferable to the single washing, proving effectively removing the weak acid extractable fractions, reducible fractions, as well as residue fractions of Cd and the weak acid extractable fractions and reducible fractions of Pb in the soil. The research results provide a novel method of reusing natural cold energy to remedy clayey soil contamination with heavy metals. [ABSTRACT FROM AUTHOR]

PAHs are harmful pollutants, and their remediation from contaminated aquifers is crucial for sustainable development. Soil washing is a common method used for this purpose, where the solubility of PAHs in solution plays a significant role in the efficiency of the process. Ethanol, as an environmentally friendly co-solvent, can enhance the solution's ability to extract PAHs from contaminated aquifers. In this study, a physical model was used to analyze the effect of variables such as flow rate, ethanol fraction, phenanthrene initial concentration, times of soil washing, and pH on PAHs removal efficiency. Response surface methodology was employed to optimize the physical model. The results showed that increasing the flow rate improved the PAHs removal efficiency and reduced ethanol consumption. The maximum PAHs removal efficiency was achieved at a flow rate of 0.538 L/min, ethanol fraction of 74.74%, phenanthrene initial concentration of 351.007 mg/kg, and 9 times soil washing, with a removal efficiency of 84%. The study has implications for sustainable remediation of PAH-contaminated aquifers using a cost-effective and environmentally friendly approach. [ABSTRACT FROM AUTHOR]

Kudzu (Pueraria lobata (Willd.) Ohwi) is a fast growing leguminous vine plant that has strong reproductive ability and low requirements on its growing conditions. It has been considered an invasive plant in some places because of its aggressive growth, which can destroy the habitat for native plants and animals. However, its strong environmental adaptability makes it easily cultivated as a sustainable resource. Kudzu can also keep soil from washing away and play an important role in ecological protection. Kudzu has had numerous practical uses in our daily lives since ancient times. For example, its root, stem, flower and pod are used in traditional Chinese medicine. Its root is a healthy food. And its leaf is used as fodder and forage for livestock. Moreover, some recent studies on kudzu have found that it is in rich of bioactive ingredients, especially isoflavones, which further broadens its uses in medicine, healthy food, and cosmetics industries. Its high starch and cellulose content makes it a promising feedstock for biofuel production and paper preparation. This editorial will give a brief discussion on kudzu and its comprehensive utilization. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aqueous solutions of humic acid (HA) derivatized by a catalyzed O-alkylation reaction with methyl, pentyl, and benzyl groups at 40, 60, and 80% of total HA acidity were used to wash off polycyclic aromatic hydrocarbons (PAHs) from two contaminated soils. The enhanced surfactant properties enabled the alkylated HA to remove phenanthrene, anthracene, fluoranthene, and pyrene from both soils more extensively than the original unmodified HA, the 60% benzylation generally showing the greatest soil washing efficiency. For both soils, all alkylated HA revealed greater PAH removals than Triton X-100 nonionic surfactant, while the benzylated and methylated HA nearly and fully matched pollutants release by the anionic SDS in the coarse- and fine-textured soils, respectively. A consecutive second washing with 60% benzylated HA removed additional PAHs, in respect to the first washing, from the coarser-textured soil, except for fluoranthene, while removal from the finer-textured soil incremented even more for all PAHs. These findings indicate that the enhanced hydrophobicity obtained by a simple and unexpensive chemical derivatization of a natural humic surfactant can be usefully exploited in the washing of polluted soils, without being toxic to the soil biota and by potentially promoting the subsequent bio-attenuation of organic pollutants. [ABSTRACT FROM AUTHOR]

Microbial biopolymers have emerged as promising solutions for environmental pollution-related human health issues. Poly-γ-glutamic acid (γ-PGA), a natural anionic polymeric compound, is composed of highly viscous homo-polyamide of D and L-glutamic acid units. The extracellular water solubility of PGA biopolymer facilitates its complete biodegradation and makes it safe for humans. The unique properties have enabled its applications in healthcare, pharmaceuticals, water treatment, foods, and other domains. It is applied as a thickener, taste-masking agent, stabilizer, texture modifier, moisturizer, bitterness-reducing agent, probiotics cryoprotectant, and protein crystallization agent in food industries. γ-PGA is employed as a biological adhesive, drug carrier, and non-viral vector for safe gene delivery in tissue engineering, pharmaceuticals, and medicine. It is also used as a moisturizer to improve the quality of hair care and skincare cosmetic products. In agriculture, it serves as an ideal stabilizer, environment-friendly fertilizer synergist, plant-growth promoter, metal biosorbent in soil washing, and animal feed additive to reduce body fat and enhance egg-shell strength. [ABSTRACT FROM AUTHOR]

Soil erosion is caused by increased agricultural activities and a lack of necessary measures to prevent erosion. This leads to the destruction of soil, which takes thousands of years to regenerate. The study area in the Mediterranean Basin is one of the subbasins most affected by global climate change. Erosion in burned areas, especially after large forest fires, occurs as water can wash away the soil and increase the risk of erosion. Burned vegetation also reduces the soil's erosion resistance. The increase in erosion in burned areas can lead to a series of problems, such as water source pollution, damage to agricultural areas, and environmental pollution. The study aims to determine that the Google Earth Engine (GEE) platform is an effective tool for combating erosion after fire lands. Erosion is predicted using the RUSLE model on GEE in pre-fire (2020) and post-fire (2022). This study determined areas at risk of erosion, and preventative measures were taken to prevent environmental problems like soil loss, water pollution, habitat loss, and biodiversity loss. In the results of the study, it was determined that the average soil loss after forest fires in the Manavgat River Basin was 9.47 ton−1 ha−1 year−1. According to the study, changes in soil loss were found depending on land use during the pre-fire and post-fire periods, and there was a general increase in soil loss of 0.10 ton−1 ha−1 year−1 after the fire. It was found that soil loss was lower before the fires. The study area experienced soil loss higher than the Türkiye average. The RUSLE-GEE method used in the study and other methods for estimating soil loss emphasizes the need to use strategies such as changing agricultural methods, using sediment trapping systems, protecting soil cover, and implementing policies and laws together to reduce soil erosion. [ABSTRACT FROM AUTHOR]

In this study, the extent of Pb contamination around an active military shooting range is re-assessed to ascertain current contamination status comparatively to data's reported 20 years ago. This is because lead bullet disintegration and mobility takes several years and extensively affects levels of soil-Pb contamination. A total of 120 topsoil samples were collected within the impact area (front) and non-impact area (back) for Pb determination. High concentrations of Pb were found at impact berm both front (28940±2996 μg/g) and back (775±128 μg/g). Spatial distribution of contamination reflects the distances from berm. Soil-Pb contamination around non-impact area was notable at back berm through to 100 m distance with significant difference in Pb, Cr, Ni and Zn levels. Concentration of Pb at berm was observed to have increase five-fold over a period of about twenty years from previous study with accumulation factor of about 1000. Principal component analysis PCA indicated 67 % of total metal load of range soil was majorly from impact areas of the berm. The correspondence analysis relay plot shows pollution order of Pb > Ni > Cd > Cr > Zn > Cu. This confirms soil contamination especially around the impact area, i.e. impact berm and firing lines and non-impact area at 0 m, 10 m, 50 m and 100 m. Environmental consequence of high soil-Pb levels within the range especially non-impact areas utilized for farming activities will leave much to desire. Hence, extensive and continuous monitoring is needed. However, remediation through appropriate soil washing technique could reduce Pb levels and improve soil condition regardless of age. [ABSTRACT FROM AUTHOR]

The continuous release of toxic heavy metals (HMs) in the soil has made the soil vulnerable to the environment. Metals come into the soil through natural processes (geogenic and air-borne) and human-induced actions like agricultural, industrial and mining. Heavy metals are not suitable for the soil quality and agriculture-friendly microbes found in the soil. The quality of crop products will also be affected by these metals as metals adversely affect plant physiology. Furthermore, HMs enter the human body through the food web and build up in human tissues. Severe diseases have been reported due to metal toxicities, including carcinogenicity, neural disorders, brain damage, etc. Physicochemical methods, microbes and plants are commonly applied for HMs remediation from the soil. Immobilization, stabilization, verification and soil washing are popular techniques for soil remediation. The application of different types of nanomaterials for soil remediation is an advance and effective method. However, nowadays, phytoremediation has attracted increasing interest in the elimination of HMs present in the soil because of its on-site application benefits and eco-friendly nature. Phytoremediation includes plant extraction, plant stabilization, plant filtration, plant volatilization, photodegradation and plant degradation. In the current review, sources of HMs, their ecological impacts and recent advances in phytoremediation approaches for soil treatment have been critically described. Further, different types of hyperaccumulator plants are also compiled in this paper. Mechanisms and factors affecting phytoremediation are the new dimensions of the present study. Limitations, challenges and future prospective of phytoremediation are also part of this study. [ABSTRACT FROM AUTHOR]

In this study, an evaluation of washing-based treatment for diesel-contaminated soil using non-ionic surfactants such as Tween-20, NP-9.5, and Triton X-100 at 5% (v/v) dosage for three days of washing in removing diesel as well as improvement of geotechnical properties was performed. The initial diesel content of 0.8 mg/g was identified using the gravimetric method in the soil. The geotechnical test results of the surfactant-washed diesel-contaminated soil show an increase in shear strength, a decrease in compression, and swelling. The contaminated and treated soil samples are also subjected to instrumental techniques like X-ray diffraction (XRD) and Fourier transform infrared radiation (FTIR). On analyzing the results from FTIR spectra, NP-9.5 is found to be the most efficient surfactant in removing the diesel. This study establishes that surfactant-aided soil washing is a prospective method for enhanced removal of diesel and leads to significant improvement in geotechnical properties of the treated soil. [ABSTRACT FROM AUTHOR]

Antimony (Sb) and arsenic (As) contamination in agricultural soil poses human health risks through agricultural products. Soil washing with degradable low molecular weight organic acids (LMWOAs) is an eco-friendly strategy to remediate agricultural soils. In this study, three eco-friendly LMWOAs, oxalic acid (OA), tartaric acid (TA), and citric acid (CA), were used to treat Sb and As co-contaminated agricultural soil from Xikuangshan mine area. The OA, TA, and CA washed out 18.4, 16.8, and 26.6% of Sb and 15.3, 19.9, and 23.8% of As from the agricultural soil, with CA being the most efficient reagent for the soil washing. These organic acids also led to pH decline and macronutrients losses. Fraction analysis using a sequential extraction procedure showed that the three organic acids targeted and decreased the specifically sorbed (F2) (by 19.3–37.6% and 2.41–23.5%), amorphous iron oxide associated (F3) (by 49.1–61.2% and 51.2–70.2%), and crystallized iron oxide associated (F4) (by 12.3–26.0% and 26.1–29.1%) Sb and As. The leachability of Sb and As, as well as their concentrations and bioconcentration factor (BCF) in vegetables reduced due to the soil washing. It demonstrated that the bioavailability of both the elements was decreased by the organic acids washing. The concentrations of Sb and As in typical vegetable species cultivated in CA washed soil were less than the threshold value for consumption safety, while those in OA and TA washed soils were still higher than the value, suggesting that only CA is a potential washing reagent in soil washing for Sb- and As-contaminated agricultural soil. [ABSTRACT FROM AUTHOR]

The paper aims to present the influence of erosion processes on the Chernozem subtype argic in the Station for the Study of Soil Erosion perimeter, located on the Valea cu Drum hydrographic basin, located of the left slope Slănic from Buzau County, in the area of Aldeni, Romania. The main objectives of this study were to present and interpret the data regarding the annual rainfall regime and the vegetation period, the study of the rains that produced runoff and erosion, respectively the surface runoff determined by these rains and the annual amount of soil washed from the plots control, differentially cultivated. The analysis of the experimental results shows that the year 2023 was dry, the recorded temperatures exceeded 190C in the June-August period, out of 17 rains recorded at the station during the summer period, 47% were less than 10 mm. Quantitative and qualitative study of the erosion process allowed the assessment of the amount of material washed from the soil surface (this being 41.9 t ha-1 on a 15%) by the runoff produced by the rains that fell during the summer. [ABSTRACT FROM AUTHOR]

As the energy demand increases, there is a significant expansion and utilization of oil resources, resulting in the inevitable occurrence of environmental pollution. Oil has been identified as a prevalent soil contaminant, posing substantial risks to the soil ecosystems. The remediation of soil contaminated with oil is a formidable undertaking. Increasing evidence shows that chemical washing, a remediation technique employing chemical reagents like surfactants to augment the solubilization, desorption, and separation of petroleum hydrocarbons in soil, proves to be an efficacious approach, but the latest advances on this topic have not been systematically reviewed. Here, we present the state of knowledge about the surfactant-based chemical washing to remediate oil-contaminated soil. Using the latest data, the present article systematically summarizes the advancements on ex situ chemical washing of oil pollution and provides a concise summary of the underlying principles. The use of various surfactants in chemical washing and the factors influencing remediation efficiency are highlighted. Based on the current research status and knowledge gaps, future perspectives are proposed to facilitate chemical washing of oil-polluted soil. This review can help recognize the application of chemical washing in the remediation of oil-polluted soil.

In the present work, the application of a combined process including soil washing by using the non-ionic surfactant Tween 80 and EDTA and electrocoagulation in remediation of phenanthrene (PHE) and cadmium (Cd) contaminated soils was investigated. In order to examine the effect of operational parameters on the efficacy of the process, Response Surface Methodology under Box–Behnken design was applied in both stages. Tween 80 solution and EDTA with concentrations of 1000–3000 and 1000–2000 mg L−1 respectively, at liquid/soil (L/S) ratio of 10, 20, and 30 v/w in a time interval of 2–24 h, were applied to remove PHE and Cd simultaneously from the co-contaminated soil. PHE and Cd extraction efficiency were mostly influenced by Tween 80 and EDTA concentration, respectively (Pvalue< 0.0001). L/S ratio also improved the removal efficiency of the contaminants significantly (Pvalue< 0.0001). Soil washing process under the optimal operational conditions of the surfactant concentration ≅ 3000 mg L-1, EDTA concentration ≅ 2000 mg L-1, L/S ratio ≅ 30 v/w and washing time = 2 h resulted in the removal efficiency of 59.284 ± 4.347% and 74.35 ± 3.632% for PHE and Cd, respectively. Electrocoagulation of the adjusted synthetic effluent based on the optimal operational conditions of soil washing phase was carried out at pH values of 3–11, with a voltage of 10–30 v, and in reaction time of 45–90 min. The results demonstrated that the removal efficiency of both contaminants was mostly enhanced by increasing pH (Pvalue< 0.0001). The factor of voltage had also a positive significant effect on the responses (Pvalue< 0.0001). The presented optimum conditions for electrocoagulation including pH of 11, a voltage of 30 v, and reaction time of 45 min provided a removal efficiency of 94.85 ± 1.715 and 100% for PHE and Cd respectively. [ABSTRACT FROM AUTHOR]

Background: Agrobacterium mediated genetic transformation experiments were carried out in Dolichos bean Cv. (Konkan Bhushan) showing better regenerability. Methods: Three cry genes viz. cry1Aabc, cry1Fa1 and cry2Aa were used for the transformation each of which were linked to CaMV35S promoter and nptII gene under control of nos promoter and terminator. A vector system consisting of the disarmed hyper virulent Agrobacterium tumefaciens strain EHA-105 harboring pBinAR or BinBt3 was used. Mature embryo axis with single cotyledon was used as explant. Kanamycin as well as PCR screening was carried out to assess the transformation frequency. Progeny analysis using PCR was also carried out to assess the transgene segregation and stable transformation. Result: Kanamycin concentration of 500 mg/l was found as optimum for selection of a transgenic turning leaf blades albino. Among five methods of colonization used, the method employing mild injury to explant with dipping in Agrobacterium culture for 20 minutes followed by co-cultivation for 48 hours, cefotaxime washing and sowing in soil resulted in maximum survival (74.80%) associated with maximum transformation frequency through PCR analysis (2.13%). Among three cry genes, the gene cry2Aa was found the most effective in transforming Dolichos bean. The progeny analysis of transformants has shown the 3:1 mendelian segregation ratio confirming stable transformation of transgene. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the effectiveness of two surfactants (Polysorbate 80 – Tween 80 and Sodium Dodecyl Benzensulphonate – SDBS) for the remediation of hydrocarbon-contaminated soil. To study the effectiveness of these surfactants, an experimental laboratory-scale apparatus was set up for the simulation of a soil flushing intervention. Different surfactant concentrations and flushing flow rates were investigated. At the end of the experiments, the removal efficiency was evaluated and phytotoxicity tests were performed by means of germination index (GI). Results showed that the use of both surfactants allows to reach high removal efficiency (∼50% for Tween 80 and ∼70% for SDBS) of hydrocarbons from soil and that either the surfactant concentration and the contact time between surfactant and contaminant affected the extraction performance. GI results showed different effects of the two surfactants on the phytotoxic features of the soil after treatment. Indeed, while the soil treated with SDBS was found to be more phytotoxic, leading to a lowering of the GI (10.88 %), the soil samples flushed with Tween 80 were characterized by higher values (146.61%). These results might be of interest in the case of surfactant application in remediation interventions in soils intended for future agricultural activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Azo-dyes such as crystal violet are commonly used ingredient in all types of dying industries which more often eventually reach water and soil due to washing and disposal practices. They are non-biodegradable inside higher organisms and are less biodegradable due to their xenobiotic character. However, some of the microbes exhibit their extensive potential to degrade such recalcitrants. This study reports the isolation and characterization of a newly isolated Klebsiella sp. strain RGUDBI01 from petroleum-contaminated soil samples. The species-level identification was done by 16S rDNA gene sequencing (ON945611.1). The isolate exhibited 88% azo-dye degradation just after 3 days of incubation under optimized conditions. The treated samples exhibited a significant increase in the growth of Cicer arietinum seeds compared to the control group. This result suggests that the dye-contaminated samples, after treatment, displayed non-cytotoxic behavior. The strain also showed its potential to tolerate and withstand a wide range of pH, salinity, and substrate concentration which supports its futuristic environmental application. In addition to the above, the strain could also produce biosurfactants with ʋC=C, ʋC=C-H, and ʋC-C functional groups which were evaluated based on FTIR spectral analysis. [ABSTRACT FROM AUTHOR]

Heavy metal(loid)s pose a concern that has drawn significant attention on a worldwide scale due to their persistence, toxicity, and bioaccumulation. For instance, research estimates that globally, the environment has been exposed to around 800,000 t of lead (Pb) and 30,000 t of chromium (Cr) over the course of the last 50 years. In response to this global problem, several techniques such as electrokinetic extraction, surface capping, encapsulation, soil flushing, soil washing, and chemical immobilization have been applied for the remediation of metal-contaminated soils. However, many of these have been classified as expensive, non-ecofriendly and time-consuming. Research has shown that proteobacteria is one of the most abundant phyla in metal-contaminated soils. Proteobacteria are well known for their pathogenic potential, but little is known about their potential for cleaning up contaminated soil. This study assessed the remediation potentials of the proteobacteria consortium on leachate-contaminated soil. About 18 bacterial species that were isolated from the leachate-contaminated soil were reintroduced to the soil. The metals with the highest levels of bioreduction activity in the microcosm modified with proteobacteria isolates were As (61%), Cu (64%), Zn (53%), Mn (47%), and Cr (61%). The shortest bioreduction time detected during remediation by proteobacteria isolates is 69.3 days, which is related to Cu reduction at a rate of 0.01 day−1. It is inferred that the selective blending of proteobacteria isolates promotes the bioreduction of metals in contaminated systems by manipulating microbial diversity. Therefore, it is possible to exploit a potential synergy toward metal reduction through microbial interaction. [ABSTRACT FROM AUTHOR]

Natural based deep eutectic solvent (NADES) is a promising green solvent to replace the conventional soil washing solvent due to the environmental benign properties such as low toxicity, high biodegradability, high polarity or hydrophilicity, and low cost of fabrication process. The application of NADES is intensively studied in the extraction of organic compounds or natural products from vegetations or organic matters. Conversely, the use of the solvent in removing heavy metals from soil is severely lacking. This review focuses on the potential application of NADES as a soil washing agent to remove heavy metal contaminants. Hydrophilicity is an important feature of a NADES to be used as a soil washing solvent. In this context, choline chloride is often used as hydrogen bond acceptor (HBA) whereby choline chloride based NADESs showed excellent performance in the extraction of various solutes in the past studies. The nature of NADES along with its chemistry, preparation and designing methods as well as potential applications were comprehensively reviewed. Subsequently, related studies on choline chloride-based NADES in heavy metal polluted soil remediation were also reviewed. Potential applications in removing other soil contaminants as well as the limitations of NADES were discussed based on the current advancements of soil washing and future research directions were also proposed. [ABSTRACT FROM AUTHOR]

Total petroleum hydrocarbons (TPHs), which are often found in soil, water, sediments, and air. These compounds are a type of pollutant that can have a serious negative impact on living things and human health. Soil washing method is a remediation technique used to remove contaminants from the soil. This process involves the use of water or other solvents to extract contaminants from the soil, followed by separation and disposal of the contaminated solution. This research engineered the effectiveness of soil washing method to remove TPHs from a genuine, sullied soil sample. After analyzing the physical and chemical properties of the soil, the Box-Benken Design (BBD) technique was used to optimize the variables that influence the process's effectiveness. A quadratic model was suggested based on the BBD design, correlation coefficients, and other factors. The minimum, maximum and mean removal of TPHs during the stages of the study were 63.5, 94.5 and 76.7%, respectively. The correlation between the variables was strong, as shown by the analysis of variance (ANOVA), F-value (1064.5) and P-value (0.0001), and the proposed model was highly significant. The most effective soil washing method (SWM) was obtained with pH 7.8, liquid to solid ratio 50:1, reaction time 52 min, surfactant concentration 7.9 mg kg−1, and three washings. A removal rate of 98.8% was accomplished for TPHs from the soil in this context. The kinetic results indicate that the kinetic of TPHs removal follows the first-order kinetics (R2 = 0.96). There was not a major difference in the process's efficiency based on temperature. The removal efficiency heightened from 0 to 150 rpm and then remained steady. Introducing air flow increased the rate of removal, and the combination of ultrasonic waves with the reaction environment increased the process efficiency and decreased the time for the process and the amount of times it needed to be washed. An analysis of the washed soil both physically and chemically revealed a substantial decrease in the concentration of other elements. [ABSTRACT FROM AUTHOR]

Excavated debris (soil and rock) contaminated with geogenic arsenic (As) is an increasing concern for regulatory organizations and construction stakeholders. Chelator-assisted soil flushing is a promising method for practical on-site remediation of As-contaminated soil, offering technical, economic, and environmental benefits. Ethylenediaminetetraacetic acid (EDTA) is the most prevalent chelator used for remediating As-contaminated soil. However, the extensive environmental persistence and potential toxicity of EDTA necessitate the exploration of eco-compliant alternatives. In this study, the feasibility of the conventional flushing method pump-and-treat and two newly designed immersion and sprinkling techniques were evaluated at the laboratory scale (small-scale laboratory experiments) for the on-site treatment of As-contaminated excavated debris. Two biodegradable chelators, L-glutamic acid-N,N′-diacetic acid (GLDA) and 3-hydroxy-2,2′-iminodisuccinic acid (HIDS), were examined as eco-friendly substitutes for EDTA. Additionally, this study highlights a useful post-treatment measure to ensure minimal mobility of residual As in the chelator-treated debris residues. The pump-and-treat method displayed rapid As-remediation (t, 3 h), but it required a substantial volume of washing solution (100 mL g−1). Conversely, the immersion technique demonstrated an excellent As-extraction rate using a relatively smaller washing solution (0.33 mL g−1) and shorter immersion time (t, 3 h). In contrast, the sprinkling technique showed an increased As-extraction rate over an extended period (t, 48 h). Among the chelators employed, the biodegradable chelator HIDS (10 mmol L−1; pH, 3) exhibited the highest As-extraction efficiency. Furthermore, the post-treatment of chelator-treated debris with FeCl3 and CaO successfully reduced the leachable As content below the permissible limit. [ABSTRACT FROM AUTHOR]

Adopting soil washing to clean up petroleum hydrocarbon contaminated soils with high sand content is considered as a fast and economical method. Cavitation microjet shock wave soil washing system (CMS) enhanced by the use of ozonation was developed for remediation of aged lubricant contaminated soil in this study. Contaminated soil with total petroleum hydrocarbon (TPH) ranging from 1890 mg/kg to 15735 mg/kg were applicable for CMS soil washing system. The impacts of factors including initial TPH concentration hydrocarbon (TPH) concentration, soil particle size, soil washing time, and ozone treatment time onto soil washing were investigated through a 21-month period of field operation. The contaminated soils with particle size between 0.074 mm and 0.25 mm, mainly very fine sand and find sand, demonstrated 31% to 98% of TPH removal by air-injected CMS and 19% to 92% of TPH removal by CMS with ozone addition. The optimal cavitation washing time was 20 minutes. The study indicated that optimal ozone concentration in the slurry was 1.08 mg/L which require air of 27 L/min for ozone produced. However, given the short contact time in the CMS system, ozone addition in the slurry did not improve TPH removal effectively. Considering the compatible TPH removal efficiency and energy cost of ozone addition in the soil washing system, use of air-injected CMS soil washing system may be considered as an alternative way. [ABSTRACT FROM AUTHOR]

The activities of quarrying in Ebonyi State have resulted in the loss of soil nutrients and an increase in soil pollution. This paper examines the environmental impact of quarrying on soil quality in the three zones of Ebonyi State, south-eastern Nigeria. To achieve the main aim of the study, three objectives were set: access the environmental impact of quarrying on the soil quality of the three zones of Ebonyi district; examine the physico-chemical properties of the soil; and evaluate the environmental impact of quarrying on the heavy metal content of the soil. The auger and core samples were collected at a depth of 20 cm to obtain physicochemical soil properties and heavy metal content. The generated data were subjected to factor analysis, which consists of a correlation matrix, KMO and Bartlett's test, communalities, total variance, scree plot, and component matrix. The major results showed that quarrying has significantly negatively impacted the soils of the three zones of Ebonyi State, as it has led to distortions in soil quality. The results also proved that soil quality within 0–50 m of quarry sites was found to be poorer than in the control area. Positive correlation matrix studies between the quarry locations revealed a common origin of pollution and the negative impact of quarry activities on soil. Based on the results, the study strongly recommends that such soils not be used for agricultural production unless remediation methods are in place, such as bioremediation, soil washing, and thermal desorption. [ABSTRACT FROM AUTHOR]

The use of chelators with high biodegradability is a promising strategy to remove potentially toxic elements (PTEs) from soils by washing. The current study investigated the potential of nitrilotriacetic acid (NTA) to remove Cd from Cd-contaminated soil from Iran (calcareous soil, ICd) and Belgium (acidic soil, BCd). Washing tests were carried out with soils artificially contaminated with 2 levels of Cd (20 and 40 mg kg−1), 4 levels of NTA (0, 2, 5, and 15 mmol L−1), different pHs (4, 7, and 10), and different contact times (20, 40, and 60 min). The results showed that the optimal concentrations of NTA were 5 and 2 mmol L−1 for ICd and BCd, respectively. After using NTA5 compared to NTA0, Cd removal at pH 4, 7, and 10 increased by 1, 76, and 80% in ICd20 and 1, 77, and 81% in ICd40, respectively. These values were 46, 53, and 52% in BCd20 and 32, 64, and 62% in BCd40, respectively, after using NTA2. Also, in the first 20 min of the experiment, 95–100% and 75–80% of the maximum extractable Cd were removed from ICd and BCd, respectively. Moreover, NTA extracted a higher percentage of Ca, Fe, Al, Zn, and Cu from BCd compared to ICd (as an exception, the percentage of Ca extracted at pH 4 was higher in ICd compared to BCd). The results showed that the physical/chemical properties of soils affect the washing efficiency and should be taken into account before selecting the type and dose of chelate to remove metals in a given soil. [ABSTRACT FROM AUTHOR]

Heavy metal pollution has increased alarmingly due largely to industrialization, intensive agricultural practices and other anthropogenic activities. Soil heavy metal contamination is the serious threat to the food security worldwide. Due to non-degradative nature, metals persist for a longer period of time in the environment, can be toxic to human health and environments. Acknowledging the toxicity threat, various physical, chemical and biological detoxification strategies such as soil stabilization, soil excavation, soil washing, thermal desorption, chemical extraction and phytoremediation, have been employed in laboratory and under field conditions to treat metal contamination. Such techniques have not completely been successful due to cost, technical complexity, generation of secondary pollutants and conflicting results. Nanotechnology, a rapidly evolving field, has recently been used to remediate hazardous metals. Nanoparticles due to their unique chemical and physical properties are considered important in toxicity alleviation from contaminated environment. The integrated nanoparticles-bioremediation strategies called nano-bioremediation is other promising option that stimulate microbiome functions to remove harmful contaminants from the polluted area. The reported metal removal efficiency of nanobioremediation varies between 12% with biogenic palladium nanoparticle prepared from Spirulina platensis to 100% with iron oxide nanoparticle of Geobacter sulforeducens for palladium and chromium, respectively. This review provides the recent information available in literature about the role of nanotechnology in the metal amelioration from contaminated soils. Understanding the mechanistic interactions between soil microbiome, nanoparticles and contaminants is of paramount importance to explore the microbes-based nanoremediation strategies in the inexpensive abatement of metal enriched environment vis-à-vis crop optimization in contaminated fields. [ABSTRACT FROM AUTHOR]

Composite technique of soil flushing and air sparging was frequently used to remediate the contaminated site. During these processes, the surfactant or chelating agent is bound to affect the efficiency of air sparging. In order to study the effect of the surfactant or chelating agent on the efficiency of air sparging, experiments were performed in a self-made experimental device to test the oxygen diffusion in the surfactant or chelating agent solution. First, the liquid-side mass transfer coefficient (kL) in the surfactant or chelating agent solution was measured at a free gas–liquid interface. Then the value of the diffusion coefficient of oxygen (D) was calculated based on kL, dynamic viscosity, and density of the solution. The results showed that sodium dodecyl benzene sulfonate (SDBS), rhamnolipid (RHA), triton X-100 (TX-100), saponin (SAP), ethylene diamine tetraacetic acid (EDTA), or citric acid (CA) solution presented low kL and D values compared with deionized water. The D in the surfactant solution decreased with an increase in surfactant concentration until its CMC was reached. Among different kinds of surfactant solutions, anionic surfactant and bio-surfactant presented a relatively large impact on D. Based on these results, a correlation between the D in surfactant solution and the concentration of surfactant was adopted to predict the D in surfactant solution. Regarding the influence of the chelating agent on kL and D, it was confirmed that the D decreased with the increase of EDTA or CA concentration. This effect was related to the pH and ionic strength of the chelating agent solution. [ABSTRACT FROM AUTHOR]

Soil contamination is an environmental issue due to increasing anthropogenic activities. Existing processes for soil remediation suffer from long treatment time and lack generality because of different sources, occurrences, and properties of pollutants. Here, we report a high-temperature electrothermal process for rapid, water-free remediation of multiple pollutants in soil. The temperature of contaminated soil with carbon additives ramps up to 1000 to 3000 °C as needed within seconds via pulsed direct current input, enabling the vaporization of heavy metals like Cd, Hg, Pb, Co, Ni, and Cu, and graphitization of persistent organic pollutants like polycyclic aromatic hydrocarbons. The rapid treatment retains soil mineral constituents while increases infiltration rate and exchangeable nutrient supply, leading to soil fertilization and improved germination rates. We propose strategies for upscaling and field applications. Techno-economic analysis indicates the process holds the potential for being more energy-efficient and cost-effective compared to soil washing or thermal desorption. Soil contamination is a pressing environmental concern due to increasing anthropogenic activity. Here, the authors developed a rapid and energy-efficient electrothermal process that simultaneously removes heavy metals and organic pollutants in soil. [ABSTRACT FROM AUTHOR]

The use of remediated soils as end-of-life materials raises some challenges including policy and regulation, permits and specifications, technological limitations, knowledge and information, costs, as well as quality and performance associated with using them. Therefore, a set of procedures must be followed to preserve the quality and fundamental properties of soil during a remediation process. This study presented a comprehensive review regarding the fundamental impacts of thermal desorption (TD) and soil washing (SW) on soil characteristics. The effects of main operating parameters of TD and SW on the physical, chemical, and biological properties of soil were systematically reviewed. In TD, temperature has a more remarkable effect on physic-chemical and biological characteristics of soil than heating time. Therefore, decrease in temperature within a suitable range prevents unreversible changes on soil properties. In SW, more attention should be paid to extraction process of contaminants from soil particles. Using the right dosage and type of chelating agents, surfactants, solvents, and other additives can help to avoid problems with recovery or treatment using conventional methods. In addition, this review introduced a framework for implementing sustainable remediation approaches based on a holistic approach to best management practices (BMPs), which, besides reducing the risks associated with different pollutants, might provide new horizons for decreasing the unfavourable impacts of TD and SW on soil. [ABSTRACT FROM AUTHOR]

Environmental context: Arsenic (As) contamination in agricultural soil threatens safe agricultural production. Therefore, an ex situ magnet-assisted soil washing, using different types of nanoscale zerovalent iron was tested as a remediation option in soil restoration. Uncoated nanoparticles was the best tested option, with As removal at 45.5% and the nanoparticles were reusable up to four times. Rationale: Arsenic (As) contamination in agricultural soil threatens safe food and medicinal herb production for millions of people. Methodology: Therefore, ex situ magnet-assisted soil washing of metal-contaminated soil using bare nanoscale zerovalent iron (NZVI) is proposed as a novel remediation alternative. Conceptually, metal-contaminated soil is mixed with water and bare NZVI, and metals in the soil are transferred to the bare NZVI. The metal-sorbed NZVI is then retrieved from the soil slurry through magnetic separation, leaving behind treated soil. This study evaluated if advanced surface modification can improve ex situ soil restoration efficacy including polymeric coating and sulfidation of NZVI, proven beneficial in situ NZVI application. Sulfur and carboxymethylcellulose (CMC) at various S/Fe and CMC/NZVI ratios were used to modify NZVI via sulfidation and physisorption. Result: Results revealed that sulfidised NZVI (S-NZVI) performed poorer (41.0%) than bare NZVI (45.5%) in As removal, even at the optimised S/Fe ratio of 0.31. This could be due to acid release via oxidative dissolution of FeS[sub 2] on the S-NZVI surface driven by O[sub 2]. The incidental acid-dissolved NZVI sorption sites decreased As removal efficacy. Similarly, CMC-modified NZVI failed to improve As removal efficacy (11.0%) because it reduced NZVI reactivity and blocked As accessibility to NZVI sorptive sites. Discussion: Nevertheless, S-NZVI and CMC-modified NZVI promoted non-phytoavailable As fractions in the treated soil. Overall, bare NZVI performed the best for As removal but moderately transformed As into more non-phytoavailable fractions. Bare NZVI can be reused for four cycles of soil washing. In every case, mobile As in treated soil was lower than the maximum contamination level. [ABSTRACT FROM AUTHOR]

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This study combines a traditional chemical characterization with a simultaneous biological evaluation through histological, immunohistochemical, and enzymatic observations to assess the efficiency and sustainability of soil washing on Hg-contaminated sediment in terms of the bioavailability of the contaminant before and after the treatment, as well as the potential drawbacks of the treatment that are not revealed by a simple chemical characterization of treated sediments on its own. Different extracting agents, that is, ethylenedinitrilotetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), sodium thiosulfate, potassium iodide (KI), and iodine (I2), have been compared in this work to evaluate their efficiency in the removal of Hg from contaminated sediments. Speciation analysis was applied to assess the mobility of Hg from different fractions of aged sediments. Biological evaluation was carried out through the use of large mesocosms and Mytilus galloprovincialis as biological sentinels. Results from bench scale tests have shown Hg removal of up to 93% by means of the multi-step KI/I2 washing process of the sediment. Results from histological, immunohistochemical, and enzymatic analysis have shown significant differences in the degree of alteration of biological tissues and their functional integrity between organisms in contact with contaminated and restored sediments. The reduction in 5-HT3R immunopositivity in the mesocosm with treated sediments suggests a tendency for mussels to recover a healthy condition. This result was also confirmed by the measurement of the enzymatic activity of AChE in mussel gills, which was significantly reduced in organisms from the mesocosm with polluted sediments compared with those from the one with restored sediments. The proposed approach could help stakeholders all over the world select, at an early stage, the most efficient cleaning action from a more holistic perspective, including not only pollutant concentration and economic reduction but also a direct assessment of the ultimate impact of the selected process on the biological system. [ABSTRACT FROM AUTHOR]

The mechanisms underlying the soil CO2 flux (Fs) in dry desert soils are not fully understood. To better understand these processes, we must accurately estimate these small fluxes. The most commonly used method, static chambers, inherently alters the conditions that affect the flux and may introduce errors of the same order of magnitude as the flux itself. Regional and global assessments of annual soil respiration rates are based on extrapolating point measurements conducted with flux chambers. Yet, studies conducted in desert ecosystems rarely discuss potential errors associated with using static chambers in dry and bare soils. We hypothesized that a main source of error is the collar protrusion above the soil surface. During the 2021 dry season, we deployed four automated chambers on collars with different configurations in the Negev, Israel. Fs exhibited a repetitive diel cycle of nocturnal uptake and daytime efflux. CO2 uptake measured over the conventionally protruding collars was significantly lower than over the collars flushed with the soil surface. Using thermal imaging, we proved that the protruding collar walls distorted the ambient heating and cooling regime of the topsoil layer, increasing the mean surface temperatures. Higher soil temperatures during the night suppressed the flux driving forces, i.e., soil–atmosphere CO2 and temperature gradients, ultimately leading to an underestimation of up to 50 % of the actual Fs. Accordingly, the total daily CO2 uptake by the soil in the conventionally deployed collars was underestimated by 35 %. This suggests that desert soils are a larger carbon sink than previously reported and that drylands, which cover approximately 40 % of Earth's terrestrial surface, may play a significant role in the global carbon balance. [ABSTRACT FROM AUTHOR]