Soil Restoration Research Articles

Strategies for Soil Rehabilitation and Yield Improvement under Saline Irrigation Water Conditions: The Role of Combining Soil amendments and Compost Tea

Strategies for Soil Rehabilitation and Yield Improvement under Saline Irrigation Water Conditions: The Role of Combining Soil amendments and Compost Tea

Management of the soil environment using biochar and zeolite in various combinations: impact on soil condition and economical aspects

Abstract Purpose Both biochars (BCs) and zeolites (Zs) are defined as soil conditioners affecting various parameters of soil environment. In most cases, BCs and Zs are characterized by well-developed specific surface area, high porosity, and excellent sorption properties, which is highly helpful in soil reclamation or conditioning. This literature review compares impact of BCs and Zs on the physicochemical properties of various soils as well as economic aspects of their synthesis. Materials and methods The review was prepared based on the articles published in the last 5 years (2018–2023). The articles were selected from the ScienceDirect® database using the keywords: ‘biochar/zeolite impact on soil physicochemical properties’, ‘biochar/zeolite impact on water retention of soil’ and ‘biochar/zeolite economic aspects’. Results and discussion Based on the available data, it can be stated that both BCs and Zs have good sorptive properties, which usually contributes to better growth of crops. Comparing them and choosing which one is more promising depends on the specific purpose and type of soil to which they are to be applied. BCs usage contributes mainly to providing organic matter and improving soil structure, while Zs enhance soil water retention. The profitability of BCs/Zs production depends largely on the precursor as well as the synthesis method. Conclusions Due to the fact that impact of synthetic Zs on the soil environment is much less frequently investigated than that of BCs, the research using Zs and various soil types is especially needed. In some cases, it is advisable to apply biochar (BC) and zeolite (Z) simultaneously. Combinations of these materials may provide benefits in soil structure, water retention, and fertility. Such mixed techniques should be investigated in the near future.

Optimized Irrigation Strategies for Saline Soil Remediation in Agricultural Lands Under Water-Limited Conditions

Soil salinization is a prevalent global issue, significantly impacting crop cultivation and food production. This study investigates the potential of sustainably harnessing rainwater for the remediation of saline soils in water-scarce regions. Soil column leaching experiments were performed to evaluate the effectiveness of different methods for salt removal from the tillage layer. The findings demonstrated that intermittent leaching was more effective than continuous leaching in remediating NaCl-type saline soils. When continuous leaching with 27 cm of rainwater was applied, the salt removal in soil layers below 5 cm ranged from 12.28% to 26.86%. Intermittent leaching increased the salt removal rate to between 44.49% and 54.18%. This higher desalination efficiency of intermittent leaching is attributable to the extended soil–water contact time. When the leaching time in continuous leaching was increased from 1.5 h to over 4.5 h, comparable desalination effects were produced. The rainwater leaching demonstrated similar salt removal patterns in Na2SO4-type saline soils. However, due to the stronger affinity of SO42− for clay particles, their effluent concentration and removal were lower than Cl− under the same conditions. To optimize desalination efficiency, operational parameters can be adjusted to reduce the leaching depth of rainwater from 27 cm to 15 cm, and the interval between leaching events from 24 h to 4.5 h. The findings of this study may serve as a valuable reference for saline soil restoration and improvement efforts in water-scarce regions.

Переваги використання органічних добрив для відновлення родючості порушених війною ґрунтів

The goal of the study is the scientific substantiation of the criteria for the use of fertilizers safe for the health of the population in soil restoration with the implementation of European requirements for the quality of organic materials in order to implement the decision of the National Security and Defense Council of Ukraine “On measures to increase the level of chemical safety in the territory of Ukraine” (clause 2.3), put into effect the Decree of the President of Ukraine dated March 19, 2021 No. 104/202/ Objects and methods of research. The objects of the research are the physical, chemical and sanitary-toxicological indicators of fertilizers (reports of own research of past years), the conditions of their use according to the nature of the action according to the regulatory and technical documentation agreed in previous years. The work was carried out by the method of hygienic analysis of available data and comparative sanitary-hygienic assessment of the features of the impact on the soil using the analysis of literary data. The research used data from its own laboratory instrumental studies, performed according to approved methods on certified equipment. Research results and discussion. Currently, reclamation measures to restore the state and fertility of the soil are extremely important, they are a guarantee and one of the most important components of the country's food security. The amount of nutrients available to plants in the soil is constantly decreasing, and therefore the main measure to increase productivity in agriculture is the application of various types of fertilizers: mineral, organo-mineral, organic and complex. Fertilizers have the main function of creating optimal harmonic ratios between nutrients in the soil. Based on the analysis of indicators of the main mineral (synthetic) and organic groups of fertilizers, signs of their influence on the condition (structure, physical and chemical properties, fertility) of the soil were established. When using fertilizers (nitrogen, phosphorus, potassium), the yield of cultivated agricultural plants increases significantly, but the mobility of nutrients and exchangeable forms of calcium and magnesium in the soil increases dramatically, which disrupts soil processes, in particular, increases acidity, deteriorates physical, physical, chemical and microbiological properties. Long-term application of fertilizers as nutrients leads to deterioration of soil fertility and changes in their structure. Unlike synthetic fertilizers, organic fertilizers work to improve and restore depleted lands, which leads to improved conditions for plant growth. The greatest advantage of organic fertilizers is a positive natural effect on soil quality indicators, since the introduction of organic substances increases the soil's ability to retain moisture, promotes the restoration of colonies of agronomically useful microorganisms and adds the main nutrients (N, P2O5 and K2O) in a plant-friendly form. For soils affected by military actions, the most effective fertilizers are organic fertilizers, which are able to bind heavy metals with the formation of immobile complexes, contribute to the restoration of microbiota and the humus layer after fire damage. In turn, soil microorganisms participate in the transformation and retention of carbon dioxide and nitrogen oxide, which not only prevents the emission of greenhouse gases, but also ensures the absorption of carbon from the atmosphere and the accumulation and retention of it and nitrogen in the soil, contributing to the mitigation of the effects of climate change. In addition, the use of organic fertilizers from natural renewable sources (plants, animal by-products, minerals) creates conditions for the development of organic agriculture with the production of products that are more beneficial for health. Conclusions. It has been established that, by all indications, organic fertilizers are more suitable for the tasks of restoration of disturbed soils and in the future should replace traditional mineral (synthetic) fertilizers and protect the environment. The use of organic and organo-mineral fertilizers and soil improvement mixtures will benefit both the environment and agriculture, as improving the quality of the soil will contribute to the improvement of conditions for plant growth and the nutritional value of agricultural crops, increase yields on a long-term permanent basis and reduce costs for producers. Keywords. Soil, fertility, recovery, organic and mineral fertilizers, nutrients, effect on quality, beneficial effect.

Impact of Large-Scale Sodic Soils Reclamation Projects in Uttar Pradesh: Key Insights for Policy Implications

Impact of Large-Scale Sodic Soils Reclamation Projects in Uttar Pradesh: Key Insights for Policy Implications

Impact of stockpiling on soil fungal communities and their functions

Fungal communities are important components of soil biology and play crucial roles in multiple ecosystem functions and services; therefore, they can be used as effective indicators of soil function in stockpiled reclamation soils. We profiled the fungal communities of seven stockpiles of different ages (0.5, 1.5, 2, 5, 7, 11, and 28 years old) at various soil depths (0–300 cm) in two oil sand extraction locations in northern Alberta. Fungal communities of the stockpiles differed from the communities in the nearby undisturbed reference soils. The differences with the reference soils were more pronounced for the oldest and some of the younger stockpiled soils. Similar to previous studies, there was a decrease in fungal richness and overall diversity with increasing stockpile depth. Furthermore, soil stockpiling generated a shift in the functional composition based on inferred fungal guilds and trophic modes. Ectomycorrhizal fungi decreased and saprotrophic fungi increased in the stockpiles relative to the reference soils. Such a shift may have important implications for ecosystem functions and services associated with fungal communities, such as litter decomposition and plant growth promotion, when these stockpiles are used to reclaim ecosystems. Our results align with previous research identifying the negative effects of stockpiling on soil microbial communities, shed light on the soil functions that may be affected by this disturbance and their consequences for ecosystem functioning, and reflect the high sensitivity of fungal communities to soil disturbances like stockpiling.

Mapping Polylepis Forest Using Sentinel, PlanetScope Images, and Topographical Features with Machine Learning

Globally, there is a significant trend in the loss of native forests, including those of the Polylepis genus, which are essential for soil conservation across the Andes Mountain range. These forests play a critical role in regulating water flow, promoting soil regeneration, and retaining essential nutrients and sediments, thereby contributing to the soil conservation of the region. In Ecuador, these forests are often fragmented and isolated in areas of high cloud cover, making it difficult to use remote sensing and spectral vegetation indices to detect this forest species. This study developed twelve scenarios using medium- and high-resolution satellite data, integrating datasets such as Sentinel-2 and PlanetScope (optical), Sentinel-1 (radar), and the Sigtierras project topographic data. The scenarios were categorized into two groups: SC1–SC6, combining 5 m resolution data, and SC7–SC12, combining 10 m resolution data. Additionally, each scenario was tested with two target types: multiclass (distinguishing Polylepis stands, native forest, Pine, Shrub vegetation, and other classes) and binary (distinguishing Polylepis from non-Polylepis). The Recursive Feature Elimination technique was employed to identify the most effective variables for each scenario. This process reduced the number of variables by selecting those with high importance according to a Random Forest model, using accuracy and Kappa values as criteria. Finally, the scenario that presented the highest reliability was SC10 (Sentinel-2 and Topography) with a pixel size of 10 m in a multiclass target, achieving an accuracy of 0.91 and a Kappa coefficient of 0.80. For the Polylepis class, the User Accuracy and Producer Accuracy were 0.90 and 0.89, respectively. The findings confirm that, despite the limited area of the Polylepis stands, integrating topographic and spectral variables at a 10 m pixel resolution improves detection accuracy.

Effects of Fresh and Composted Azolla on Soil Chemical Properties

The rise in chemical fertilizer use in Malaysia raises concerns about soil degradation and potential long-term yield reductions, highlighting the importance of using organic matter for soil restoration. Azolla has been extensively studied as an alternative soil amendment due to its high nitrogen and nutrient content, as well as its rapid growth. However, the effects of fresh and composted Azolla amendments on soil chemical properties are not yet fully understood. A soil incubation study was thus conducted to determine the effects of fresh and composted Azolla on soil chemical properties over a 3-month incubation period. The soil treatments consisted of non-amended soil (control); fresh Azolla at 3, 6, and 9% w/w; and composted Azolla at 1, 2, and 3% w/w, with soil water holding capacity maintained at 55% throughout the incubation period. The collected soil samples were analyzed for soil pH and electrical conductivity (EC), total carbon (C) and nitrogen (N), available phosphorus, exchangeable bases—potassium (K), calcium, and magnesium, using inductively coupled plasma optical emission spectrometry, and cation exchange capacity (CEC). All data were subjected to variance analysis for statistical analysis. The study revealed significant effects of interaction between soil treatments and incubation periods for all soil parameters. At the end of the incubation period, the soil treated with 3% composted Azolla exhibited higher soil EC, total C and N, exchangeable K, and CEC compared to other soil treatments. The 3% fresh Azolla treatments were also observed to improve the soil’s exchangeable calcium by the end of the incubation period. In conclusion, 3% composted Azolla is best to help restore soil nutrient levels for crop uptake.

Rare and Abundant phoD‐Harboring Bacteria Mediate the Mineralization of Organic Phosphorus Fractions in Soil Aggregates During Cut Slope Restoration

ABSTRACTPhosphorus (P) is the key nutritional element in the soil of cut road slopes undergoing ecological restoration, and the transformation of organic P (Po) is a crucial part of the P cycle. However, the role of phoD‐harboring bacteria in driving the mineralization of Po fractions in road slope soil aggregates is unclear. This study analyzed road slope soils that had undergone 7, 11, and 14 years of restoration in the western Sichuan Plateau of China. We examined the differences and associations between the Po fraction content, alkaline phosphatase (ALP) activity, and community composition of rare and abundant phoD‐harboring bacteria in soil aggregates of four particle sizes (0.053–0.25, 0.25–2, 0.053–0.25, and, > 2 mm). The results showed that NaHCO3‐extracted Po (NaHCO3‐Po) content in soil aggregates increased with restoration years, while NaOH‐extracted Po (NaOH‐Po) content decreased. ALP activity in soil aggregates increased with restoration years, but there was no significant relationship between ALP activity with the phoD‐harboring bacterial community. There were significant differences in the composition of rare and abundant phoD‐harboring bacterial communities during slope restoration. Soil moisture, pH, organic carbon, and the C:P ratio in soil aggregates were the primary factors affecting the distribution of the Po fractions and the phoD‐harboring bacterial community. NaHCO3‐Po and NaOH‐Po in soil aggregates were likely the main substrates for ALP‐mediated Po mineralization. More genera were involved in Po mineralization in slope soils restored for 14 years than in soils restored for 7 and 11 years, and rare phoD‐harboring genera were more actively involved in Po mineralization than abundant phoD‐harboring genera. This study provides some theoretical basis for P effectiveness enhancement and P management during slope soil restoration.

Effects of Inoculating Symbiotic Microorganisms on Acacia mangium Grown on Coconut Fiber

The ability of Acacia mangium to grow on degraded soils, thanks to its ability to fix atmospheric nitrogen, makes it a very important species in agroforestry and in the restoration of impoverished soils. However, all the experiments on Acacia mangium, whether inoculated or not, have only been carried out on a single type of substrate, i.e. soil. The aim was to determine whether inoculation significantly increased the biomass and height growth of Acacia mangium grown on coconut fiber. The experimental design comprised 5 treatments (Ta, T, M, R, and MR) with 5 replicates. Characterizing the coconut fiber and the dry biomass of Acacia mangium above ground and roots consisted of determining the content of elements such as P, K, Ca, Mg, and N. The number of nodules was also counted The results showed that inoculation (M, R and, MR) had no significant effect on the height growth and biomass of Acacia mangium. Non-inoculated (Ta and T) plants showed greater growth, probably due to the richness of nutrients (N, P) in the coconut fiber. The presence of nodules in the non-inoculated plants indicates the presence of indigenous strains in the coconut fiber. Double inoculation (mycorrhizae/rhizobia) significantly stimulated the growth and nodulation of Acacia mangium. Double inoculation also increased substrate fertility, which had a positive effect on plant growth. The Glomus-Bradyrhizobium combination appeared to be the most effective in improving the growth and nodulation of Acacia mangium.

Reclamation and Improvement of Saline Soils Using Organo–Mineral–Natural Resources, Treated Saline Water, and Drip Irrigation Technology

Reclamation and management of saline soil in arid regions fundamentally require more consideration to attain sustainable agriculture. Experiments were conducted at Abo-Kalam Farm, South Sinai, Egypt. Split-split-plot design experiments were carried out to study the effect of treatments on saline soil hydrophysical properties, sorghum, and cv. ‘Dorado’ plants during the summer season. Pea cv. ‘Entsar 3’ plants were cultivated during the winter season for the residual effect of treatments. Organo–mineral amendment (rice straw compost + mineral sulfur at different rates) was assigned as the main factor, natural rock or artificial fertilizers were assigned as subfactors, and humic acid at different rates was the sub-subfactor. Results showed that organo–mineral amendments improved the hydrophysical properties of the soil, plant nutrient uptake, crop yield, and crop water productivity; however, it diminished by 10 tons/fed (4200 m2) of compost plus 700 kg/fed of mineral sulfur. Therefore, it is recommended that economically using the combination of applying organic–mineral amendments of 4 tons/fed of compost plus 400 kg/fed of mineral sulfur and 5 kg/fed of humic acid plus natural rock fertilizer is the best safe management for reclamation and improvement of saline soils using partially treated saline irrigation water and natural resources.

Exploring the growth and phytoremediation efficacy of Suaeda fruticosa in agricultural soil contaminated by shrimp aquaculture

Plants face numerous environmental challenges from biotic and abiotic stressors, with soil salinization emerging as a significant global concern. The coastal regions of Tamil Nadu, face severe environmental challenges due to discharge of saline water from shrimp farms exacerbates this issue, compromising the viability of paddy and other crops in the vicinity. This study explores the phytoremediation potential of Suaeda fruticosa in addressing soil salinity resulting from shrimp farming activities under field conditions over a 120-day period to restore soil health in salt affected soil. This research demonstrates Suaeda fruticosa’s exceptional salt tolerance and bioaccumulation potential in facilitating soil restoration. Significant enhancements were observed in various growth parameters, including 466% increase in plant height, 338% in fresh weight and 387% in dry weight. Biochemical parameters also showed substantial enhancements with total chlorophyll, protein, proline, phenol, and glycinebetaine levels increasing by 655%, 588%, 690%, 153%, and 531%, respectively. Enzymatic activities exhibited notable elevations as well, with catalase, peroxidase, and polyphenol oxidase activities escalating by 258%, 587%, and 121% respectively, indicating robust adaptation to saline environments. Moreover, Suaeda fruticosa exhibited remarkable bioaccumulation capabilities, accumulating 461 kg NaCl ha−1. This led to substantial improvements in soil characteristics, including a reduction in pH from 8.8 to 6.49, electrical conductivity from 5.7 to 1.53 dSm−1, and sodium adsorption ratio from 16.1 to 4.4 mmol L−1. The successive cultivation of Suaeda fruticosa in this study, has proven to be a viable strategy for reclaiming salt-affected lands, thereby alleviating a significant constraint on crop productivity.

COMPARATIVE EVALUATION OF SORBENTS BASED ON NATURAL MATERIALS FOR CLEANING OIL-POLLUTED SOILS IN THE KOLA NORTH

The article presents the results of using sorbents based on natural materials as soil reclamation agents in the Arctic zone of the Russian Federation to reduce the negative impact of oil and oil product spills. It has been established that the most effective are composite sorbents based on sphagnum moss and peat in various combinations with excess activated sludge. The effectiveness of sorbents based on natural materials is compared with the commercial sorbent OilSorb. High dynamics of reducing the content of oil products in the first days in soil samples with the addition of composite sorbents, including natural sorption material and activated sludge, is noted.

Methodological insights into soil elemental nickel in typical Karst areas: comprehensive analysis of geochemical characteristics, source determination, and influencing factors.

Excessive levels of Nickel in the soil can compromise the security of agricultural products, posing a threat to health of human beings; therefore, the repair and treatment of Nickel exceeding the standard levels in soil are particularly critical. Although it is crucial that the potential restoration of Nickel in ensuring the security of both soil and farm produce within karst regions., few studies have been conducted on the potential restoration of large-scale Nickel-contaminated soils. In this study, the soil in Wuming, Guangxi, a typical karst area, was comprehensively studied. 12,547 surface soil samples, 134 deep soil samples and 60 soil profiles were collected systematically. The results showed that the Nickel background value of the surface soil was 34.9mg/kg, indicating strong background characteristics and high variability. Principal component analysis showed that soil Nickel was primarily derived from natural sources in the geological background and partly derived from agricultural sources. Analysis of variance showed that the Nickel content of the soil was affected by the parent rock, soil type, soil use type, and topography. In addition, the distribution of Nickel in the soil profile increased exponentially with depth. Therefore, the exponential model and multiple integrals were used to derive the formula for the Nickel potential restoration amount at different depth ranges, and the potential restoration amount of soil Nickel was calculated based on different parent material, soil, and land use types. The formula is reasonable and representative and can provide a theoretical basis for the remediation and treatment of Nickel-polluted soil in karst areas.

Changes in Soil Physicochemical Properties and Fungal Communities Following a Forest Fire in the Pine Forest of Uljin, Republic of Korea

Soil samples from the rhizosphere of pine (Pinus densiflora) stands in the fire-disturbed Uljin forest were collected to analyze their physicochemical properties and fungal communities. In the burned area, soil pH decreased by 0.56, and organic matter content decreased by 0.32%p compared to the undisturbed area. Fungal community analysis revealed that all alpha diversity indices decreased in the burned area, but there were no differences according to fire severity. Soil pH, available phosphorus, and total nitrogen showed a positive correlation with the alpha diversity. Additionally, beta diversity analysis also indicated significant differences in the fungal communities between the burned area and the control sites (p value = 0.031). The changes in fungal communities were considered to be influenced by the decline in the order Atheliales, genus Russula, and genus Trechispora. A prediction analysis of the functional traits of fungi showed that the number of fungi involved in nutrient absorption and decomposition decreased in the burned area. It seems that the soil restoration of pine forests is progressing very slowly, as the soil fungi related to nutrient absorption by pine trees have not recovered even 18 months after the forest fire. Therefore, it is necessary to monitor continuous fungal communities in pine forest restoration after a forest fire to determine forest ecosystem restoration success and stabilization.

The Role of Organic Amendments and Their Impact on Soil Restoration: A Review

Soil organic matter (SOM) plays a pivotal role in maintaining soil health by enhancing its physical, chemical, and biological properties. It improves soil structure, water retention, nutrient availability, and microbial activity, contributing significantly to sustainable agriculture. Organic amendments, including animal manure, compost, biosolids, crop residues, and various organic by-products, are widely used to restore degraded soils by increasing SOM content. These amendments not only supply essential nutrients but also promote biological aggregation, suppress soil-borne pathogens, and improve soil's resistance to environmental stressors such as drought and heavy metal toxicity. The positive impacts of organic amendments on soil properties are well-documented, with key benefits including increased soil organic carbon (SOC), improved nutrient cycling, enhanced microbial diversity, and greater water-holding capacity. Organic materials such as compost and animal manure have been shown to significantly improve soil fertility and restore degraded soils. The application of green manure and crop residues also boosts soil biodiversity, enhances rhizospheric processes, and supports overall ecosystem resilience. This paper emphasizes the importance of adopting holistic soil management practices that include organic amendments, conservation tillage, and sustainable cropping systems to address soil degradation. By focusing on replenishing SOM, improving nutrient availability, and increasing soil biodiversity, these practices can contribute to the long-term sustainability of agricultural systems and environmental health. The restoration of soil organic matter is essential for enhancing soil quality and mitigating degradation, ultimately ensuring food security and ecosystem stability for future generations.

Optimization of Acacia auriculiformis A. Cunn. Ex Benth. Seed Germination Using Pretreatment Analysis

Agroforestry resources play a crucial role in conserving biodiversity, stabilizing soils and improving the livelihoods of rural populations. This study investigates the impact of different treatments on the germination of Acacia auriculiformis, an important tree species for soil restoration in Côte d'Ivoire. The work was carried out at the University Jean Lorougnon GUEDE in Daloa. The seeds used for this work were subjected to four treatments, including a control (T0); those soaked for 3 days in ordinary water (T1); a hot water treatment at 60°C (T3); a boiling water treatment at 100°C and a flame treatment (T4). A randomized block design consisting of four treatments in three blocks. The results showed that seed treatment in hot water at 100°C until cooling gave the best germination percentages and germination speed. The results also showed that soaking the seeds in water for three days produced seedlings with the shortest germination time. The study underlines the importance of pregermination for the selection of better-performing varieties and the implementation of effective reforestation programs. It also highlights the need for further research into the impacts of climate change on tree germination and growth. However, for a better policy of extension, production and improvement of this endangered forest species of socio-economic interest, mastery of the requirements of this species while maintaining optimal conditions for its germination in the nursery is more necessary.

Combined Application of Biochar and Calcium Superphosphate Can Effectively Immobilize Cadmium and Reduce Its Uptake by Cabbage

Biochar and phosphate fertilizer are commonly employed for the mitigation of soil cadmium (Cd) contamination. Nevertheless, there is a dearth of research regarding the mechanism behind their joint implementation. In this study, a combination of corn straw biochar (0 (C0), 5 (C5), and 10 (C10) g kg−1) and calcium superphosphate (0 (P0), 0.1 (P1), 0.2 (P2), 0.5 (P5), and 1.0 (P10) g kg−1) was applied in pot experiments, and the effects of the combined application on Cd bioavailability and its uptake by cabbage were investigated in Cd-contaminated soils. The results demonstrated that the combined treatment of applying biochar and Ca(H2PO2)2 yielded a significant decrease in the uptake of Cd by cabbage in alkaline soil, in contrast to the individual treatments of biochar or Ca(H2PO2)2. Compared to the CK treatment (C0P0), the Cd content in the shoots decreased by 46.26% and in the roots decreased by 24.81%, while the biomass of the cabbage demonstrated a noteworthy increase in C5P10 treatment. Compared to the CK treatment, the content of available phosphate (AP) in the soil increased by 17.57 mg kg−1, residual Cd increased by 22.02%, the exchangeable Cd decreased by 45.86%, and carbonate-bound Cd decreased by 20.55% in the C5P10 treatment. Therefore, it is advisable to use a combination of 5 g kg−1 biochar and 1 g kg−1 Ca(H2PO2)2 for the restoration of soil contaminated with Cd.

Evaluation of the Ability of Ameliorants to Influence the Biological Indicators and Hydrophobicity of Oil-Contaminated Haplic Chernozems

ABSTRACT The aim of the study was to assess the ameliorants effect on the biological parameters and Haplic Chernozems hydrophobicity. In model experiment conditions, Haplic Chernozem was polluted by oil and remediation with application of nitroammophos, Sodium humate, biochar, and Baikal EM-1 was simulated during to 30, 90, and 180 days. Indicators of soils activity – germination and intensity indicators of initial seed growth, the activity of catalase and dehydrogenases, the total number of bacteria, hydrophobicity were studied. On the 30 and 90th days after remediation, the most significant reliable decrease in oil regarding was promoted by 2 D biochar. After 180 days of dose 1 D and dose 2 D nitroammophos, as well as 1 D Baikal EM-1, the total petroleum hydrocarbon content was reduced significantly. Baikal EM-1 and biochar contributes to the greatest decrease in hydrophobicity at all periods of the experiment to a greater extent. On the 30th day, the introduction of nitroammophos, biochar, and 1 D Sodium humate contributed to an increase in the integral indicator of the biological state of oil-contaminated Haplic Chernozem, on the 90th day, the introduction of all doses of biochar led to an increase in the indicator, and on the 180th – all doses of Baikal EM-1, and 0.5 D Sodium humate. The research results may be used when choosing a method of soil restoration after oil pollution.

An enhanced electrokinetic system for remediation of Cu-polluted clay soils by integrating purging solutions and intermittent power

This study investigated the effectiveness and underlying mechanisms of purging solutions enhanced by intermittent power in improving electrokinetic (EK) restoration of clay soils even under high levels of heavy metals (HM). In so doing, the artificially contaminated specimens containing a wide range of copper (Cu) were prepared and then subjected to a series of EK tests with various electrolytes and electric regimes. Macro and micro scale examinations revealed that under the unenhanced EK condition (i.e., continuous current without agents), the formation of non-conducting solid phases and/or the clogged fabric in the samples with the high dosages (> 250 mg/kg) of HM could dramatically impede the metal separation from the soil. Hence, increasing the remediation time would not be very effective in facilitating the decontamination process. It was observed that the EDTA-ameliorated treatment accompanied by pentetic acid and acetic acid can mitigate the metal precipitation/encapsulation effects induced by EK actions, resulting in improved rate of HM removal. In this case; however, a high portion of these enhancers would be required to ensure the stable mobility of ions and to achieve successful recovery. Such a limitation has been shown to be overcome by incorporating pulsed power (PP) at an optimal frequency. In fact, as evidenced by SEM-EDX and XRD analyses, the integration of chemical agents with PP could simultaneously retain the solubilized Cu species in the soil mass and modify the matrix tortuosity (i.e., the establishment of well-linked pores), two features that have been found to play essential roles in providing for favorable activity of HM ions during the EK operation. The corresponding refinements in the binary system would cause an almost 8 folds increase in the removal efficiency and a shorter (up to 30 %) time of treatment compared to conventional EK.