Sorption Capacity Of Soils Research Articles

Sorption modelling of crude oil-contaminated soils using a derived spectral index

Theoretical models to describe and evaluate sorption of hydrocarbons on soil particles are well documented but experimental results in the literature are scarce. This study describes the use of a spectral index to evaluate sorption phenomena in oil-contaminated soils at micro and macro levels. Experiments involved oil-dosing from 0.25 mL to 4 mL and the application of a spectral index to estimate the sorption capacity of different soils based on change in statistically derived Critical Point (CP). Results show that sorption of oil varies with soil type, specifically the proportion of clay in a soil/sediment and the clay species, in the order smectite > illite > kaolinite. In support of theoretical models, this work proposes a model from experimental data that explains observed phenomena of soil-oil interaction with changing soil composition. The location and prominence of the CP is also strongly affected by soil moisture, particularly in coarse-grained soils, potentially providing insight to soil-oil–water interaction. The methods developed using a simple synthetic crude provide potential to explore other contamination scenarios including different soil compositions, types of petroleum products and different environmental controls.

Factors influencing the increased 90Sr radioisotope migration in highly alkaline groundwater at Chornobyl NPP site

This paper analyses the formation of high Sr2+ concentration in strong alkaline (pH = 9.5–12.5) groundwater using data of the 27 years of observations around the destroyed Chernobyl NPP Unit 4. It appears that the formation of strong alkaline groundwater in different monitoring wells is consistent with the distribution of 90Sr, pH and main ions.The reason for the increase in 90Sr concentrations is the process of its migration from the sources of contamination - leaks of highly active water localized in certain premises inside the «Shelter » object.These computational experiments showed that for the groundwater in pH range 9.5–12.4, the concentration of strontium in the form of SrOH + increases and in the form of Sr2+ - decreases. In addition, the fraction of 90Sr in the form of a soluble neutral complex compound SrCO30, which is not sorbed, reaches 14–35%. Increased fractions of 90Sr in forms of SrOH+ and SrCO3 are factors which reduce the isotope ability to be sorbed by soils and therefore increase its migration ability. In strongly alkaline groundwater a sharp increase in 90Sr volumetric activity may also be caused by ionic strength (IS) increase above 5 mmol/L. Thus, the factors that influence the increase in 90Sr volumetric activity in strongly alkaline groundwater are the formation of its complex compounds and an increase in ionic strength (IS), which reduces the thickness of the double electric layer and, as a result, reduces the sorption capacity of soils.

A machine learning and experimental-based model for prediction of soil sorption capacity toward phenanthrene

Sorption by soil is the fundamental basis for environment fate of hydrophobic organic contaminants (HOCs), which varies significantly depending on diverse properties of soils. Therefore, a generalized approach to predict HOC sorption by soils is required. In this study, 488 data points were extracted from references and adopted to develop models for estimating the sorption capacities of phenanthrene in soils using six different machine learning (ML) approaches. The extreme gradient boosting (XGBT) model demonstrated the most favorable performance, achieving a coefficient of determination of 0.91 and root-mean-square errors of 0.24 for the testing dataset. The XGBT model's performance was further demonstrated by comparing with experimental data from batch sorption tests conducted on 20 soil samples collected from 17 provinces of China. The differences between the predicted values and the experimental values were statistically equal to zero (p = 0.14). Leveraging the XBGT model together with soil properties from the Harmonized World Soil Database, the distribution of sorption capacities in Chinese soils was successfully depicted on a national scale. This research is expected to contribute to a deeper understanding of the migration of persistent organic pollutants in terrestrial system. Furthermore, the established model holds implications for more precise and scientific soil environmental management.

Alginate-encapsulated biochar as an effective soil ameliorant for reducing Pb phytoavailability to lettuce (Lactuca sativa L.).

The alginate-biochar formulation for metal removal from aquatic environments has been widely tried but its use for lowering phytoavailability of metals in the soil-crop continuum is limited. Biochar has been increasingly used as a soil amendment due to its potential for soil carbon sequestration and sorption capacity. Handling of powdery biochar as a soil top-dressing material is, however, cumbersome and vulnerable to loss by water and wind. In this experiment, biochar powder, which was pyrolyzed from oak trees, was encapsulated into beads with alginate, which is a naturally occurring polysaccharide found in brown algae. Both batch and pot experiments were conducted to examine the effects of the alginate-encapsulated biochar beads (BB), as compared to its original biochar powdery form (BP), on the Pb adsorption capacity and phytoavailability of soil Pb to lettuce (Lactuca sativa L.). The BB treatment improved reactivity about six times due to a higher surface area (287 m2g-1) and five times due to a higher cation exchange capacity (50 cmolc kg-1) as compared to the BP treatment. The maximum sorption capacity of Pb was increased to 152 from 81mgg-1 because of surface chemosorption. Adsorption of Pb onto BB followed multiple first-order kinetics and comprised fast and slow steps. More than 60% of the Pb was adsorbed in the fast step, i.e., within 3h. Also, the BB treatment, up to the 5% level (w/w), increased soil pH from 5.4 to 6.5 and lowered the phytoavailable fraction of Pb in soil from 5.7 to 0.3mgkg-1. The Pb concentrations in lettuce cultivated at 5% for the BP and BB treatments were similar but 63 and 66% lower, respectively, than those of the control soil. The results showed that the encapsulation of biochar with alginate enhanced adsorption by the biochar.

Prediction of antibiotic sorption in soil with machine learning and analysis of global antibiotic resistance risk

Although the sorption of antibiotics in soil has been extensively studied, their spatial distribution patterns and sorption mechanisms still need to be clarified, which hinders the assessment of antibiotic resistance risk. In this study, machine learning was employed to develop the models for predicting the soil sorption behavior of three classes of antibiotics (sulfonamides, tetracyclines, and fluoroquinolones) in 255 soils with 2203 data points. The optimal independent models obtained an accurate predictive performance with R2 of 0.942 to 0.977 and RMSE of 0.051 to 0.210 on test sets compared to combined models. Besides, a global map of the antibiotic sorption capacity of soil predicted with the optimal models revealed that the sorption potential of fluoroquinolones was the highest, followed by tetracyclines and sulfonamides. Additionally, 14.3% of regions had higher antibiotic sorption potential, mainly in East and South Asia, Central Siberia, Western Europe, South America, and Central North America. Moreover, a risk index calculated with the antibiotic sorption capacity of soil and population density indicated that about 3.6% of soils worldwide have a high risk of resistance, especially in South and East Asia with high population densities. This work has significant implications for assessing the antibiotic contamination potential and resistance risk.

Efeito da aplicação do biochar na mobilidade do corante têxtil vermelho drimaren em uma camada de solo aluvionar

ABSTRACT The region of Alto Capibaribe, in the Brazilian semiarid, faces an environmental issue due to contamination from textile activities. Inadequate release of dyes and other toxic substances threatens human health and water resources, such as alluvial reserves. Thus, biochar, a low-cost adsorbent produced by biomass pyrolysis, helps mitigate these problems by increasing soil retention capacity. This study analyzed the effect of applying biochar, produced from coffee husks, a biomass already established in biochar production, at temperature of 530 °C with a pyrolysis time of 10 to 12 hours, in a homemade metallic furnace, resulting in a product with 67.11% carbon. This biochar was applied to evaluate the mobility of the textile dye Red Drimaren, at a concentration of 25 mg.L-1, used for garment dyeing in local industries, in a subsurface layer of an alluvial deposit located in the dry bed of the Capibaribe River. Fourier Transform Infrared Spectroscopy (FTIR) showed that the highest spectral vibrations are in the range of 1400-1800 cm-1, indicating the presence of amine and amide functional groups, favoring the biosorption process. The pH in water is higher than in KCl for all situations, with biochar being basic and the alluvial soil being acidic. The zero charge point values are equal to 6.96 and 7.96 for the proportions Soil+0.25%BC and Soil+1.00%BC, respectively. Layers with 0.25%BC and 1.00%BC added had an increase in adsorptive capacity of 31.68% and 8.62%, respectively, compared to the natural soil sorption capacity. Kinetic data best fit the pseudo-second-order model, and intra-particle diffusion was not the determining mass transfer process nor the occurrence of the adsorption process. Linear and Freundlich isotherm models consistently described the process under varying concentrations, and the Langmuir model did not show a valid physical significance.

Urbanization increases the risk of phosphorus loss in sandy soils of tropical ecosystems

Phosphorus (P) is naturally present in soils. However, urbanization can promote additional inputs of P into the soil that lead to saturation of the binding sites exceeding the maximum sorption capacity. Soils saturated with P act as important diffuse sources of pollution of water resources. The flow of P from the soil to aquatic ecosystems is an aggravating factor for water scarcity, especially in the semiarid region. Knowing phosphorus dynamics in the soil is essential to protect water quality and ensure its multiple uses. In this paper, a total of fifty soil samples, twenty-five from natural soils and twenty-five from urban soils, were evaluated for the effect of urbanization on P sorption characteristics and their relationship with the physical and chemical attributes of the soil. The soil samples were characterized physically and chemically, and the P sorption characteristics were obtained from the adjustment of Langmuir and Freundlich equations by nonlinear regression. Urbanization results in increased soil P saturation and reduced P sorption capacity. Our results show that the sandy texture of the soils studied had a standardizing effect on the soil's physical properties, maintaining, even after urbanization, the physical quality similar to natural soil. In contrast, pH (in water and KCl), base saturation, sodium saturation, potential acidity, exchangeable Al3+, exchangeable Mg2+, available P, and P-rem are valuable indicators in the segregation between natural and urban soils. The reduction of P sorption capacity in urban soils increases the risks related to P loads in aquatic ecosystems that experience urban expansion worldwide. These data serve as a basis for decision-making regarding the appropriate soil monitoring and management of urban expansion areas in watersheds to control P flow to aquatic systems.

Effect of Ash from Salix viminalis on the Biomass and Heating Value of Zea mays and on the Biochemical and Physicochemical Properties of Soils

Wood ash is sometimes used as an alternative to mineral fertilizers; however, there is still a paucity of reliable data concerning its effect on plants—and on biological properties of soil. The present study aimed to determine the possible extent of soil pollution with ash from Salix viminalis that does not disturb the growth of Zea mays L., intended for energetic purposes, in order to identify how the increasing ash doses affect biochemical and physicochemical properties of soil and to finally to establish the neutralizing effects of soil additives, i.e., compost and HumiAgra preparation, on this soil pollutant. The study demonstrated that the heating value of Zea mays L. was stable and not modified by the excess content of ash from Salix viminalis in the soil. This finding points to the feasibility of Zea mays L. cultivation on soils contaminated with ash from Salix viminalis and its use in bio-power engineering. The biomass of the aboveground parts of Zea mays L. was significantly reduced after soil contamination with Salix viminalis ash dose of 20 g kg−1 d.m. soil, whereas the smaller ash doses tested (5–10 g kg−1 d.m. soil) did not impair either the growth or the development of Zea mays L. The ash inhibited activities of all analyzed soil enzymes but increased soil pH and sorption capacity. Fertilization with compost proved more effective in neutralizing the adverse effect of ash on enzymatic activity of the soil.

Optimizing Soil Management for Sustainable Viticulture: Insights from a Rendzic Leptosol Vineyard in the Nitra Wine Region, Slovakia

Properly chosen soil management practices can stabilize the nutrient regime in the soil, including the mobility and bioavailability of hazardous elements. This study aimed to identify the optimal soil management practices in a productive vineyard on Rendzic Leptosol in the Nitra wine region (Slovakia). Soil samples were collected each spring from two depths, 0–30 cm, and 30–60 cm, with the following treatments: T—soil tillage, P + FYM—plowed farmyard manure, G—grass strips, G + NPK1—first-level fertilization, and G + NPK2—second-level fertilization, from 2019 to 2023. The results indicated that more pronounced changes in soil properties occurred in the 0–30 cm layer. Higher NPK rates significantly affected soil sorption capacity and decreased soil pH when compared to other treatments. While G + NPK2 showed the highest storage of total N, S, P, K, and available P and K, it exhibited the lowest levels of total and available Ca. The T treatment displayed the lowest storage of C, N, S, P, and available K. In terms of hazardous metals (Cr, Ni, Pb, and Zn) none exceeded the limiting values in any of the soil management practices. However, in the 0–30 cm layer, Cu concentrations exceeded the limits set by Slovak Republic regulations in the T, P + FYM, G, G + NPK1, and G + NPK2 treatments by 62.6, 73.7, 70.2, 82.1, and 102.9 mg kg−1, respectively. Additionally, as total C increased, Cr concentration was observed to decrease with correlation (r = −0.46). Positive correlations were found between total C and Zn, as well as CaCO3 and Zn in the 0–30 layer.

Application of Poultry Manure Improves the Soil Sorption Capacity and Nutrient Regime of Vineyard Soils

ABSTRACT The sorption capacity and nutrient regime under different soil management practices (C – control, T – tillage and PM – tillage + poultry manure) in productive vineyard soil (Rendzic Leptosol) in the Nitra vineyard region (Nitra-Dražovce, Slovakia, Central Europe) were studied for the years 2013–2022. With T and PM, the soil pH was significantly lower than with C. The soil sorption capacity for both studied depths (0–30 and 30–60 cm) increased in the following order: T < PM < C. For all the soil management practices and soil depths, the soil sorption complex was fully saturated with basic cations. With T, in the 0–30 cm layer, the total nitrogen (Nt) content was lower by 218 and 292 mg kg−1, respectively, than with C and PM. However, in the period 2013–2022, the Nt increased statistically significantly, by 50.9, 87.6 and 97.8 mg kg−1 year−1 with T, C and PM, respectively. The application of PM had a positive effect on the increase in available phosphorus (P) – there was an increase with C and T of 96 and 112%, respectively. The content of available P increased linearly with all soil management practices. However, in the case of T, it was statistically significant (increase of 23.2 mg kg−1 year−1) over the period of 10 years. With PM, at 0–30 cm, the content of available potassium was significantly higher, by 29 and 91%, than with treatments C and T.

Assessment of the barrier function of Chernozem and Luvisol under their experimental contamination by copper ions

The aim of the work was to assess the ecological resistance of topsoils of Chernozem and Luvisol to modeled copper contamination. To determine the sorption capacity of soils and to obtain the required levels of contamination the experiment was carried out. Soils were contaminated by the Cu acetate solutions with concentrations from 20 to 200 mg/L, which corresponds to the input of 20–2 000 mg/kg of Cu. Approximation of Cu adsorption isotherms by the Langmuir equation was statistically significant. The obtained values of maximum adsorption (Cmax) and Langmuir constant (KL) for Chernozem were higher than for Luvisol. This indicates a higher adsorption capacity and stronger retention of adsorbed Cu in Chernozem compared with Luvisol. This fact can be explained by the higher content and composition of organic matter, the heavier texture and the neutral pH value of Chernozem. By the method of sequential selective extractions, it was found that in uncontaminated soils, more than 50% of Cu is strongly bounded to silicate fraction (&gt;50%). Assessment of Cu fractionation at different levels of contamination reveals a slight increase in the percentage of Cu bioavailable forms (exchangeable and acid-soluble) in Chernozem at 200 mg/kg and its significant increase in Luvisol at 200 mg/kg. At contamination of about 2 000 mg/kg Cu, both soils are characterised by a predominance of pools of bioavailable and bound to (hydr)oxide of Fe and Mn forms. The mobility factor does not exceed 10% for Chernozem and 25% for Luvisol in the native and contaminated by 200 mg/kg soils, which indicates low and medium bioavailability of Cu in them, respectively. Contamination by 2 000 mg/kg of Cu increased the mobility factor up to 25% in Chernozem and up to 40% in Luvisol, which means the medium and high risk of Cu migration into the adjacent environments.

Biotransformation of cyproterone acetate, drospirenone, and megestrol acetate in agricultural soils: Kinetics, microbial community dynamics, transformation products, and mechanisms

The occurrence of biologically active synthetic progestins in agricultural soils is of growing concern due to their potential to disrupt the endocrine function of aquatic fish in nearby surface waters. This study investigated the biotransformation outcomes of cyproterone acetate (CPA), drospirenone (DRO), and megestrol acetate (MGA) in four agricultural soils. The biotransformation data were fitted to a first-order decay model (R2 = 0.93–0.99), with half-lives and first-order decay coefficients ranging from 76.2–217 h and 9.10 × 10−3–3.20 × 10−3 (h−1), respectively. Abundant biotransformation products (TPs) were generated during incubation, with the number and yields varying across the four soils. 1,2-Dehydrogenation was the main transformation pathway of DRO in the four soils (yields of 32.3–214 %). Similarly, 1,2-dehydrogenation was the most relevant transformation pathway of MGA in the four soils (yields of 21.8–417 %). C3 reduction was the major transformation pathway of CPA in soils B, C, and D (yields of 114–245 %). Hydrogenation (yield of 133 %) and hydroxylation (yield of 21.0 %) were the second major transformation pathway of CPA in soil B and C, respectively. In particular, several TPs exhibited progestogenic and antimineralocorticoid activity, as well as genotoxicity. The high-throughput sequencing indicated that interactions between microorganisms and soil properties may affect biotransformation. Spearman correlation and bidirectional network correlation analysis further revealed that soil properties can directly interfere with the soil sorption capacity for the progestins, thus affecting biotransformation. In particular, soil properties can also limit or promote biotransformation and the formation of TPs (i.e., biotransformation pathways) by affecting the relative abundances of relevant microorganisms. The results of this study indicate that the ecotoxicity of synthetic progestins and related TPs can vary across soils and that the assessment of environmental risks associated with these compounds requires special consideration of both soil properties and microbial communities.

Sorption of ionic liquids in soil enriched with polystyrene microplastic reveals independent behavior of cations and anions

Recently, much attention has been focused on the application of the Ionic Liquids (ILs) with herbicidal activity in agriculture. It has been suggested that through the appropriate selection of cations and anions, one can adjust the properties of ILs, particularly the hydrophobicity, solubility, bioavailability, toxicity. In practical agricultural conditions, it will be beneficial to reduce the mobility of herbicidal anions, such as the commonly applied 2,4-dichlorophenoxyacetic acid [2,4-D] in the soil. Furthermore, microplastics are becoming increasingly prevalent in the soil, potentially stimulating herbicidal sorption. Therefore, we investigated whether cations in ILs influence the mobility of anions in OECD soil supplemented with polystyrene microplastic (PS). For this purpose, we used the 2,4-D based ILs consisting of: a hydrophilic choline cation [Chol][2,4-D] and a hydrophobic choline cation with a C12chain [C12Chol][2,4-D]. Characterization of selected micropolystyrene was carried out using the BET sorption-desorption isotherm, particle size distribution and changes in soil sorption parameters such as soil sorption capacity and cation exchange capacity. Based on the batch sorption experiment, the effect of microplastic on the sorption of individual cations and anions in soil contaminated with micropolystyrene was evaluated. The results obtained indicate that the introduction of a 1–10% (w/w) PS resulted in an 18–23% increase of the soil sorption capacity. However, the sorption of both ILs’ cations increased only by 3–5%. No sorption of the [2,4-D] anion was noted. This suggests that cations and anions forming ILs, behave independently of each other in the environment.The results indicate the fact that ILs upon introduction into the environment are not a new type of emerging contaminant, but rather a typical mixture of ions. It is worth noting that when analyzing the behavior of ILs in the environment, it is necessary to follow the fate of both cations and anions.

An integrated remediation approach using combinations of biochar, Rhizobium leguminosarum, and Vigna radiata for immobilizing and dissipating cadmium contaminants from the soil-mustard plant system.

Cadmium (Cd) contamination of soils is an environmental concern, as cadmium harms food crops and can therefore impact human health. The use of combinations of biochar (seeded with Rhizobium leguminosarum) and Vigna radiata (as an intercrop) has the potential to reduce the mobilization of Cd from soil via mustard plants (Brassica juncea). Mustard plants are grown as a food and oil production crop that is consumed worldwide. However, this plant has the property of hyperaccumulation; thus, it bioaccumulates Cd in its tissues, which in turn, if eaten, can become part of the human food chain. Hence, reducing Cd bioaccumulation in mustard plants is crucial to making these plants a reliable and safe source of food for consumption. To improve soil sorption capacity and immobilization efficiency, biochar (in the form of wheat husk) was mixed with R. leguminosarum and intercropped (using V. radiata) with mustard plants for further investigation. Sampling was performed at an early growth stage (i.e., at 30 days) and at maturity (i.e., at 60 days) to determine the impact of Cd on a plant's morphophysiological attributes. Data were analyzed in two ways: first by analysis of variance (ANOVA) and then by the post hoc Tukey's honestly significant difference (HSD) test. The statistical analysis concluded that combinations effectively improved plant traits by 65%-90% in the early growth stage and by 70%-90% in the maturity stage. The T6 treatment combination [i.e., biochar+R. leguminosarum+V. radiata (BC+RL+VR)] provided the most effective results in terms of growth, biomass, pod yield, and pigmentation content. In addition, this combination reduced the translocation of Cd in mustard plants by 70%-95%. The combination of BC+RL+VR effectively reduced Cd contamination of mustard tissue and provided a suitable growing environment for the plants. A post-harvesting soil analysis using X-ray diffraction (XRD) found that Cd was undetectable in soil. This provides clear confirmation that these approaches can lead to Cd soil remediation. Moreover, this study provided insight into the responses of different morphophysiological attributes of mustard plants to Cd stress and could aid in developing Cd stress tolerance in mustard plants.

Source apportionment and suitability evaluation of seasonal VOCs contaminants in the soil around a typical refining-chemical integration park in China

Accurate source apportionment of volatile organic compounds (VOCs) in soil nearby petrochemical industries prevailing globally, is critical for preventing pollution. However, in the process, seasonal effect on contamination pathways and accumulation of soil VOCs is often neglected. Herein, Yanshan Refining-Chemical Integration Park, including a carpet, refining, synthetic rubber, and two synthetic resin zones, was selected for traceability. Season variations resulted in a gradual decrease of 31 VOCs in soil from winter to summer. A method of dry deposition resistance model coupling partitioning coefficient model was created, revealing that dry deposition by gas phase was the primary pathway for VOCs to enter soil in winter and spring, with 100 times higher flux than by particle phase. Source profiles for five zones were built by gas sampling with distinct substance indicators screened, which were used for positive matrix factorization factors determination. Contributions of the five zones were 14.9%, 20.8%, 13.6%, 22.1%, and 28.6% in winter and 33.4%, 12.5%, 10.7%, 24.9%, and 18.5% in spring, respectively. The variation in the soil sorption capacity of VOCs causes inter-seasonal differences in contribution. The better correlation between dry deposition capacity and soil storage of VOCs made root mean square and mean absolute errors decrease averagely by 8.8% and 5.5% in winter compared to spring. This study provides new perspectives and methods for the source apportionment of soil VOCs contamination in industrial sites.

Characteristics of Phosphorus Sorption Capacity of Hevea Supporting Soils in Southern Region of Nigeria

Characteristics of Phosphorus Sorption Capacity of Hevea Supporting Soils in Southern Region of Nigeria

Mapping the phosphorus sorption capacity of Danish soils in four depths with quantile regression forests and uncertainty propagation

Managing soil phosphorus is essential for agricultural production and environmental protection. This requires information on the phosphorus sorption capacity (PSC) of the soil. In this study, we map the PSC for Danish soils in four depths. Measuring PSC directly is expensive and time-consuming, and we therefore used a pedotransfer function based on oxalate-extractable aluminum (Alo) and iron (Feo). We mapped Alo, Feo, and their uncertainties using Quantile Regression Forests (QRF). We then calculated the uncertainties for PSC with a quasi-Monte Carlo complete combinatorial convolution (CCC) of the prediction quantiles for Alo and Feo. The main factors for predicting Alo were the parent material, topography and precipitation. In many areas, podzolization also affected the vertical distribution of Alo. The main factors for Feo were the soil texture, organic matter and wetland areas. The average predicted PSC was 36 ± 9 mmol kg−1 (±1 SD) in topsoil, but it was generally highest at 25–50 cm depth with a mean value of 37 ± 9 mmol kg−1. The weighted root mean squared error of the mapped properties was 14 mmol kg−1 for Alo, 32 mmol kg−1 for Feo and 19 mmol kg−1 for PSC. The prediction accuracies were moderate at best, but the prediction quantiles were generally reliable. The mapped uncertainties were largest in wetland areas, while they were smallest in young loamy moraine deposits.

Combined remediation effects of biochar and organic fertilizer on immobilization and dissipation of neonicotinoids in soils.

Neonicotinoid (NEO) pesticides have become a potential risk to ecological safety and human health after application. The combined use of biochar and organic fertilizer (OF) is a promising approach to reduce pesticide adverse effects and improve soil fertility in agricultural soils. However, the combined remediation effects of biochar and OF on immobilization and dissipation of NEOs in soils have not previously been systematically investigated. In this study, biochars derived from peanut shell prepared at low/high pyrolysis temperatures (PS400 and PS900) were combined with composted chicken manure (CCM) as an example for OF to remediate contaminated soils toward six typical NEOs, nitenpyram (NIT), thiamethoxam (THIA), clothianidin (CLO), imidacloprid (IMI), acetamiprid (ACE), thiacloprid (THI). Results shown that both biochars and CCM were effective in improving soil sorption capacity and immobilization efficiency. The Freundlich affinity parameters (Kf) of NEOs in soils increased 7.2-12.0 times after the combined remediation of biochar and CCM, and the Kf of six NEOs had negative correlation with their lipophilicity (p<0.05), which followed by THI>ACE ≈ IMI>CLO>THIA>NIT. Meanwhile, NEOs-abiotic degradation was accelerated by biochar, CCM and their combined addition by adjusting soil pH and stimulating hydrolysis action. Biotic degradation was dominant in NEOs dissipation processes in amended soils, and the contribution ratios of biotic degradation (CRbio) were in the range of 25.4-99.0%. The combined use of biochar and CCM selectively stimulated the relative abundance of NEOs-degraders, which simplified abiotic degradation of -NO2-containing NEOs (viz., NIT, THIA, CLO, and IMI), but inhibited -C≡N-containing NEOs (viz., ACE and THI). The combined remediation provided a strategy for immobilizing NEOs and facilitating dissipation of -NO2-containing NEOs in soils. The results in this study provide valuable information for policymakers and decision-makers to choose appropriate soil remediation approaches with respect to the NEO types.

An Insight into the Sorption Behavior of 2,3,7,8-Tetrachlorodibenzothiophene on the Sediments and Paddy Soil from Chaohu Lake Basin.

Considering the frequent detection of polychlorinated dibenzothiophenes (PCDTs) in various environmental matrices and the potential ecological health risks, the environmental behavior of such compounds needs to be elucidated further. In this work, the sorption behavior of 2,3,7,8-tetrachlorodibenzothiophene (2,3,7,8-TCDT) onto three sediments and paddy soil from Chaohu Lake were investigated via batch equilibration experiments. From the perspective of sorption kinetics and isotherms, the sorption characteristics and mechanism of 2,3,7,8-TCDT on the above four carriers were compared, and the relationship between their structural characteristics and soil sorption capacity was discussed. Results suggested that rapid sorption played the primary role during the sorption process of 2,3,7,8-TCDT and the corresponding sorption isotherms were well fitted using the Freundlich logarithmic model. Moreover, the effects of pH and dissolved organic matter (DOM) on the sorption of 2,3,7,8-TCDT were investigated. The maximum sorption capacity of 2,3,7,8-TCDT on sediment was under acidic pH condition (pH = 4.0). Meanwhile, DOM at a low level promoted the sorption capacity of sediment toward 2,3,7,8-TCDT, while the high concentration of DOM inhibited this effect. In addition, the values of logKoc were obtained using high-performance liquid chromatography (HPLC) and did not show any significant correlation with organic carbon (OC) contents, thereby indicating that the partition effect was the dominating influencing factor for the sorption of 2,3,7,8-TCDT both on sediments and soil. This work provides useful data to understand the sorption behavior of 2,3,7,8-TCDT on sediments and soil and assess its potential environmental risk.

Phosphorus sorption capacity in soils from freshwater restored coastal wetlands increased with restoration age

• P sorption capacity in soils increased with wetland restoration age. • Elevated P sorption related to the improvement of soil properties in restored wetland. • The P loss potential was less affected by the wetland restoration age. • The restored wetland was identified as the P storage hotspot at the landscape scale. Coastal wetlands, located at the intersection of land and sea, are considered to be a phosphorus (P) sink, source, and reactor in the global P cycle. However, the variation in P sorption capacity with wetland age and the related sorption mechanisms are not well understood. In this study, we collected the surface soil samples (0–20 cm) from 10 coastal freshwater wetlands that had been restored for 0–44 years surrounding China’s Bohai Rim. Through a series of batch experiments, we studied the factors controlling P sorption and release in these soils. The results showed that the maximum P sorption capacity (Q max ) in these wetlands was 294–2447 mg kg −1 , with an average of 1472 mg kg −1 . The Q max generally increased with increasing wetland restoration age. The degree of P saturation (DPS) and the P eutrophication risk index (ERI) for coastal wetlands were 0.5–9.5% and 0.9–21.1%, respectively. The DPS and ERI values did not vary significantly with wetland age. These data suggest that freshwater restoration significantly increases P sorption capacity, while not greatly affecting the P release potential in the coastal wetlands surrounding Bohai Rim. These observations may be related to the soil desalination and organic matter and amorphous Fe and/or Al accumulation that occur during the freshwater restoration of degraded wetlands. Coastal wetlands (especially restored wetlands) were suggested as P storage hotspots among upland, wetland, and offshore along the coastal watersheds of Bohai. These findings indicate that the freshwater restoration significantly improved the soil properties in the degraded coastal wetlands, and therefore increased P sorption capacity in the restored wetlands.