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Harvesting of timber using ground based machinery is still a common practice around the world. Track and road building, and movement of machinery during harvesting operations cause soil disturbance. Therefore the aim of this study was to investigate the change in soil properties after logging operation on skid trails (2 years and 7 years after logging) and compare disturbed soil properties with control sampling (undisturbed soil). For this purpose, soil samples were collected from the skid trail and undisturbed area. Electrical conductivity, pH, organic carbon, moisture equivalent, moisture, total porosity and bulk density were determined on the skid trail and undisturbed area. Soil characteristics were examined in two ages (2 years and 7 years skid trail). There were crucial differences in the values of electrical conductivity, organic carbon, moisture, total porosity and bulk density from skid trail and undisturbed area in 2 years skid trail (p<0.05). But on 7 years skid trail, there were no significant differences in values of mentioned factors from skid trail and undisturbed area (p>0.05) except bulk density (p=0). It has been concluded that 7 years after logging, all soil properties except bulk density were completely recovered on skid trail. These findings have important implications for assessing the impact of skidders traffic and recovery time in skid trails.

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Soil contamination by heavy metals is a worldwide environmental challenging issue. Due to the industrial activities, a site located in North West of Shiraz (Fars Province, Iran) has the potential to be contaminated by different heavy metals. The objective of this study was to assess the effectiveness of dicalcium phosphate (DCP) and sodium tripoly phosphate (STPP) for immobilizing lead, copper and cadmium in contaminated soils. Leaching column tests performed on the soil without any stabilizing agent demonstrated a uniform leachate of metals in the effluent during the experimental period. After mixing DCP or STTP with the contaminated soils, the release of all three heavy metals through the effluent was ceased. The results further indicated that 0.1 to 0.2 percent by weight of these stabilizers is effective for immobilizing of applied metals through the experimental soil. Penetration of acid sulfuric solution with pH of 5 had no influence on stabilizing efficiency and almost whole the applied heavy metals seem to be immobilized through the soil media.

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This paper presents a numerical model based on  the explicit finite difference method for contaminant transport under electrokinetic remediation process. The effect of adsorption, precipitation and water auto-ionization reactions were considered  to  set of algebraic equations. Also the effect of electrolysis reaction in anode and cathode cells was considered with appropriate boundary conditions. The model predictions are compared with experimental results of electrokinetic lead removal from kaolinite in the literature. The coefficient of determination and index of agreement between the lead concentration of experimental result and model prediction was 0.974 and 0.884, respectively. The coefficient of determination and index of agreement between the pH value of  the experiment and the pH prediction was 0.975 and 0.976, respectively

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In this study, the relative performance of two soils as a sustainable natural material in retaining the selected heavy metal ions, cadmium (Cd²⁺) and nickel (Ni²⁺), from aqueous solutions has been evaluated. Red earth soil (RS) and black cotton soil (BCS) originating from India, were selected and batch equilibrium tests including sorption kinetics and leaching studies were conducted. The experimental data was used to plot sorption isotherms, Langmuir isotherm was found to be more suitable than Freundlich isotherm for both the soils. Monolayer sorption capacity was calculated from Langmuir isotherm. Kinetic data was fitted on four models namely pseudo first order, second order, Elovich and intraparticle diffusion. Correlation coefficients obtained by all models fitted well in the following ranking: Elovich>Intraparticle diffusion > Pseudo second order> Pseudo first order. Based on extensive experimental data, it is concluded that the ranking on sorption was of the order Cd > Ni for both the soils and BCS exhibited relatively higher retention levels compared to RS.  It is further concluded that, BCS can be used as a substitute to filter material, RS a substitute to main liner material in attenuating Cd²⁺ and Ni²⁺ from an industrial landfill leachate.

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The present study focuses on measuring the effects of industrial wastewater disposed from thermal electricity power plant as by-product on the geotechnical properties of sandy soil and applying washing process to remediate the contaminated soil samples and measure the efficiency of washing technique. The disturbed sandy soil samples were obtained from Al-Kufa City located to the southwest of Iraq and the industrial wastewater obtained from Al-Musayib thermal electricity power plant. The intact sandy soil was contaminated in the laboratory with four percentages of industrial wastewater (10, 20, 40 and 100%) calculated according to the weight of dry soil. The industrial wastewater is mixed with distilled water to constitute the solution used in the contamination process of soil through soaking the soil by this solution for 30 days. The study results showed that with increasing the percentages of the contaminant, there was a slight increase in both the liquid limit and particle size, while there was a significant increase in the optimum water content. Nevertheless, a slight decrease was observed in the specific gravity, maximum dry unit weight, and void ratio, while, a considerable decrease was noticed in the angle of the internal friction and coefficient of permeability of soil. The proposed remediation technique “soil washing” is efficient, economical, and time saving when used to remediate sandy soils. After remediation, the results showed an increase in the cohesion, angle of internal friction and maximum dry unit weight. Also, a slight increase was observed in the specific gravity, void ratio and permeability coefficient of remediated soil samples when compared with that of contaminated samples. The removal efficiencies of contaminant from soil were (97.63, 96.79, 96.58, and 93.87%) for the soil samples contaminated with industrial wastewater by (10, 20, 40 and 100%), respectively.