Influence of biochar amendments on the sorption-desorption of aminocyclopyrachlor, bentazone and pyraclostrobin pesticides to an agricultural soil

Effect of liming using Lithothamnium calcareum on atrazine and S-metolachlor leaching and persistence in soil

The objective of this study was to evaluate the effect of soil liming using Lithothamnium calcareum in comparison to dolomitic limestone and unlimed soil on leaching and persistence of atrazine and S-metolachlor herbicides in soil. The highest atrazine concentration was obtained between 0 and 20 cm in the unlimed soil, between 30 and 40 cm in the dolomitic limestone-treated soil, and between 10 and 20 cm in soil treated with L. calcareum. The highest S-metolachlor concentration was obtained between 20 and 30 cm in the unlimed soil, between 10 and 20 cm in the soil treated with dolomitic limestone, and between 0 and 10 cm in the soil treated with L. calcareum. The half-life of atrazine was 8.3 days in unlimed soil and 7.9 days in limed soil. The half-life of S-metolachlor was 12.1 days in unlimed soil, 13.5 days in soil using dolomitic limestone, and 11.6 days in soil using L. calcareum. Cucumber plants were controlled up to 90 days after application (DAA) of atrazine for all soil treatments. Sorghum plants were controlled up to 15 DAA of S-metolachlor for the unlimed soil and up to 30 DAA for the limed soil. Soil liming and type of soil improver influence atrazine e S-metolachlor leaching and persistence in soil, which may affect crops and adjacent areas and surface and groundwater.

Enhanced remediation of acetochlor-contaminated soils using phosphate-modified biochar: Impacts on environmental fate, microbial communities, and plant health

Given that acetochlor (ACT) persists in soil for extended periods, disrupting microbial community structure and causing phytotoxicity to sensitive crops, this study investigated the potential of phosphate-modified biochar (PBC-800) to remediate ACT-contaminated soil. Incorporating 0.5 % PBC-800 into fluvo-aquic, red, and black soils increased their adsorption capacities by 80.4 mg g-1, 76.6 mg g-1, and 76.0 mg g-1, respectively. Even after six months of aging, the Kf values remained 1.6 to 5.1 times higher than in untreated soils. PBC-800 also accelerated ACT degradation across all three soil types, reducing residual ACT levels by 34.3 % to 76.4 % after 60 days, and shortening the degradation half-life by 5 to 7 days. High-throughput sequencing revealed that ACT reduced soil microbial diversity and disrupted community structure, while 0.5 % PBC-800 amendments promoted the growth of degradation-capable genera such as Rhodococcus, Lysobacter, and Gemmatimonas, enhancing microbial ecosystem stability. Furthermore, the amendment of soil with 0.5 % PBC-800 reduced ACT residue concentrations in maize and soybeans by 76.5 % to 82.9 %, and restored plant biomass, leaf chlorophyll content, and mesophyll cell ultrastructure to levels comparable to the control. Therefore, amending ACT-contaminated soil with PBC-800 mitigates ecological and environmental risks, boosts microbial activity, and safeguards plant health.

Biochar combined with humic acid improves the soil environment and regulate microbial communities in apple replant soil

Apple replant disease (ARD) negatively affects plant growth and reduces yields in replanted orchards. In this study, biochar and humic acid were applied to apple replant soil. We aimed to investigate whether biochar and humic acid could promote plant growth and alleviate apple replant disease by reducing the growth of harmful soil microorganisms, changing soil microbial community structure, and improving the soil environment. This experiment included five treatments: apple replant soil (CK), apple replant soil with methyl bromide fumigation (FM), replant soil with biochar addition (2 %), replant soil with humic acid addition (1.5 ‰), and replant soil with biochar combined with humic acid. Seedling biomass, the activity of antioxidant enzymes in the leaves and roots, and soil environmental variables were measured. Microbial community composition and structure were analyzed using ITS gene sequencing. Biochar and humic acid significantly reduced the abundance of Fusarium and promoted the recovery of replant soil microbial communities. Biochar and humic acid also increased the soil enzymes activity (urease, invertase, neutral phosphatase, and catalase), the plant height, fresh weight, dry weight, the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), and root indexes of apple seedlings increased in replant soil. In sum, We can use biochar combined with humic acid to alleviate apple replant disease.

Toxicological analysis of Eisenia fetida in soil under the coexistence of rockwool substrate andtricyclazole

This study investigated the combined effects of rockwool, a novel seedling substrate, and tricyclazole (TCA) on the bioavailability of TCA to Eisenia fetida. The single addition of rockwool and TCA alone to the soil inhibited the growth of E. fetida. A high concentration (300 mg·L-1) of TCA significantly decreased the biomass of E. fetida. The addition of 20-mesh rockwool reduced this effect on earthworm biomass by decreasing the soil TCA through adsorption, effectively mitigating TCA bioaccumulation in earthworms. A mechanistic analysis showed that the Mg-O functional group on the rockwool surface combined with the CC functional group in TCA to generate Mg-O-C, and the adsorption process was dominated by chemisorption. Toxicology experiments demonstrated that malondialdehyde and cellulase could be used as biomarkers of inhibitory effects of combined rockwool and TCA in soil on E. fetida. Macrogenomic analyses revealed that small particle sizes and high concentrations of rockwool caused co-stress effects on earthworms when TCA was present. When the particle size of rockwool increased, the toxic effect of TCA on earthworms instead decreased at higher rockwool concentrations. Therefore, in practical agricultural production, the particle size of rockwool can be controlled to realize the adsorption of TCA and reduce the toxic effects of TCA and rockwool on earthworms.

The boom era of emerging contaminants: A review of remediating agricultural soils by biochar

Emerging contaminants (ECs) are widely sourced persistent pollutants that pose a significant threat to the environment and human health. Their footprint spans global ecosystems, making their remediation highly challenging. In recent years, a significant amount of literature has focused on the use of biochar for remediation of heavy metals and organic pollutants in soil and water environments. However, the use of biochar for the remediation of ECs in agricultural soils has not received as much attention, and as a result, there are limited reviews available on this topic. Thus, this review aims to provide an overview of the primary types, sources, and hazards of ECs in farmland, as well as the structure, functions, and preparation types of biochar. Furthermore, this paper emphasizes the importance and prospects of three remediation strategies for ECs in cropland: (i) employing activated, modified, and composite biochar for remediation, which exhibit superior pollutant removal compared to pure biochar; (ii) exploring the potential synergistic efficiency between biochar and compost, enhancing their effectiveness in soil improvement and pollution remediation; (iii) utilizing biochar as a shelter and nutrient source for microorganisms in biochar-mediated microbial remediation, positively impacting soil properties and microbial community structure. Given the increasing global prevalence of ECs, the remediation strategies provided in this paper aim to serve as a valuable reference for future remediation of ECs-contaminated agricultural lands.

Biochar obtained from eucalyptus, rice hull, and native bamboo as an alternative to decrease mobility of hexazinone, metribuzin, and quinclorac in a tropical soil

Mobile herbicides have a high potential for groundwater contamination. An alternative to decrease the mobility of herbicides is to apply materials with high sorbent capacity to the soil, such as biochars. The objective of this research was to evaluate the effect of eucalyptus, rice hull, and native bamboo biochar amendments on sorption and desorption of hexazinone, metribuzin, and quinclorac in a tropical soil. The sorption-desorption was evaluated using the batch equilibrium method at five concentrations of hexazinone, metribuzin, and quinclorac. Soil was amended with eucalyptus, rice hull, and native bamboo biochar at a rate of 0 (control-unamended) and 1% (w w-1), corresponding to 0 and 12 t ha-1, respectively. The amount of sorbed herbicides in the unamended soil followed the decreasing order: quinclorac (65.9%) > metribuzin (21.4%) > hexazinone (16.0%). Native bamboo biochar provided the highest sorption compared to rice hull and eucalyptus biochar-amended soils for the three herbicides. The amount of desorbed herbicides in the unamended soil followed the decreasing order: metribuzin (18.35%) > hexazinone (15.9%) > quinclorac (15.1%). Addition of native bamboo biochar provided the lowest desorption among the biochar amendments for the three herbicides. In conclusion, the biochars differently affect the sorption and desorption of hexazinone, metribuzin, and quinclorac mobile herbicides in a tropical soil. The addition of eucalyptus, rice hull, and native bamboo biochars is a good alternative to increase the sorption of hexazinone, metribuzin, and quinclorac, thus, reducing mobility and availability of these herbicides to nontarget organisms in soil.

Theoretical explanation of direct photolysis and indirect photolysis of bendazone with •OH, •SO4-, and •CO3- in water: mechanism insights and ecotoxicity evaluation

Bendazone (BNTE) is an herbicide and a highly concerned pollutant in aquatic environments. Understanding the photochemical behavior of BNTE in water is crucial for evaluating its photochemical conversion process in aquatic environments. This study analyzed the direct photolysis and indirect photolysis pathways of two dissociated forms of BNTE in water through density functional theory and time-dependent density functional theory method. The results show that the reaction types of indirect photolysis of BNTE with free radicals (•OH, •SO4-, and •CO3-) are OH- addition, SO4- addition, and CO3- addition. In the process of indirect photolysis of BNTE and free radicals, the photolysis of •OH and BNTE was the easiest, followed by •SO4-. In addition, the active site of BNTE reacting with •OH is C8, and the active site of BNTE reacting with •SO4- is C10. However, the photolysis effect of •CO3- on BNTE is very small, indicating that •CO3- in water plays a secondary role in the indirect photolysis of BNTE. In the direct photolysis of BNTE, N1-C6 bond breaking is difficult to occur spontaneously in the environment due to its high endothermic property and energy barrier. The direct photolysis pathway of BNTE involves the break of the N1-S2/S2-N3/N3-C12 bond. In addition, the ecological toxicity evaluation showed that toxicity of most of the degradation products were reduced, but the toxicity level was still maintained at a harmful level. Our findings provide the photochemical fate of BNTE in aquatic environments and will help to more accurately understand their photochemical conversion mechanisms in the environment.

Biochar modulating soil biological health: A review

Biochar can be used for multifunctional applications including the improvement of soil health and carbon storage, remediation of contaminated soil and water resources, mitigation of greenhouse gas emissions and odorous compounds, and feed supplementation to improve animal health. A healthy soil preserves microbial biodiversity that is effective in supressing plant pathogens and pests, recycling nutrients for plant growth, promoting positive symbiotic associations with plant roots, improving soil structure to supply water and nutrients, and ultimately enhancing soil productivity and plant growth. As a soil amendment, biochar assures soil biological health through different processes. First, biochar supports habitats for microorganisms due to its porous nature and by promoting the formation of stable soil micro-aggregates. Biochar also serves as a carbon and nutrient source. Biochar alters soil physical and chemical properties, creating optimum soil conditions for microbial diversity. Biochar can also immobilize soil pollutants and reduce their bioavailability that would otherwise inhibit microbial growth. However, depending on the pyrolysis settings and feedstock resources, biochar can be comprised of contaminants including polycyclic aromatic hydrocarbons and potentially toxic elements that can inhibit microbial activity, thereby impacting soil health.

A critical review of sustainable application of biochar for green remediation: Research uncertainty and future directions

Biochar, a carbon-rich material produced from the pyrolysis of organic biomass, has gained significant attention as a potential solution for sustainable green remediation practices. Several studies analyze biomass-derived biochar techniques and environmental applications, but comprehensive assessments of biochar limitations, uncertainty, and future research directions still need to be improved. This critical review aims to present a comprehensive analysis of biochar's efficacy in environmental applications, including soil, water, and air, by sequentially addressing its preparation, application, and associated challenges. The review begins by delving into the diverse methods of biochar production, highlighting their influence on physical and chemical properties. This review explores the diverse applications of biochar in remediating contaminated soil, water, and air while emphasizing its sustainability and eco-friendly characteristics. The focus is on incorporating biochar as a remediation technique for pollutant removal, sequestration, and soil improvement. The review highlights the promising results obtained from laboratory-scale experiments, field trials, and case studies, showcasing the effectiveness of biochar in mitigating contaminants and restoring ecosystems. The environmental benefits and challenges of biochar production, characterization, and application techniques are critically discussed. The potential synergistic effects of combining biochar with other remediation methods are also explored to enhance its efficacy. A rigorous analysis of the benefits and drawbacks of biochar for diverse environmental applications in terms of technical, environmental, economic, and social issues is required to support the commercialization of biochar for large-scale uses. Finally, future research directions and recommendations are presented to facilitate the development and implementation of biochar-based, sustainable green remediation strategies.

Fermented biochar has a markedly different effect on fate of pesticides in soil than compost, straw, and a mixed biochar-product

Current knowledge about how biochars affect the fate of pesticides in soil is based on studies that used pure biochars. After finding that an additional biological post-pyrolysis treatment, such as co-composting or lactic fermentation, is required for biochars for superior performance in temperate arable soils, a knowledge gap formed of how such further processed biochar products would affect the fate of pesticides in soil. This study compared the effects of a novel fermented biochar alone or mixed with biogas residues on the fate of two pesticides, 4-chloro-2-methylphenoxyacetic acid (MCPA) and metalaxyl-M, in a temperate arable soil to the traditional organic amendments wheat straw and compost. The fate of 14C-labeled MCPA was markedly affected in different ways. Fermented biochar effectively reduced the water-extractability and mineralization due to adsorption that was comparable to adsorption strengths reported for pure biochars. However, this effect was weak for the biochar mixed with biogas residues. Straw reduced water-extractable amounts due to increased biodegradation and formation of likely biogenic non-extractable residues of MCPA. In contrast, compost decelerated mineralization and increased the water solubility of the MCPA residues due to released dissolved organic matter. The amendments' effects were minor regarding 14C-metalaxyl-M, except for the fermented biochar which again reduced water-extractability and delayed degradation due to adsorption. Thus, the effects of the organic amendments differed for the two pesticide compounds with only the fermented biochar's effect being similar for both. However, this effect was no longer present in the mixed product containing 20% biochar. Our findings clearly show that biologically treated biochar-containing products can affect the fate of pesticides in soil very differently, also when compared to traditional organic amendments. Such impacts and their desirable and undesirable ecotoxicological implications need to be considered before the large-scale application of biochars to temperate arable soils.

Influence by varying organic matter content and forms in suspended particulate matter: impacts on the adsorption of tetracycline and norfloxacin

Antibiotics are commonly detected in natural waters. The organic matter (OM) in suspended particulate matter (SPM) has a critical impact on the adsorption of antibiotics in water. We investigated the contribution of OM content and form to the adsorption of tetracycline (TC) and norfloxacin (NOR) in the SPM of Taihu Lake. To change the content and form of OM in SPM, the samples were subjected to pyrolysis at 505 ˚C and oxidization with H2O2, respectively. Combustion almost completely removed OM, while oxidation removed most of the OM and transformed the remaining OM. Regardless of whether the OM changed or not, the adsorption of NOR and TC by SPM was more in line with the pseudo-second-order kinetic model instead of pseudo-first-order. The fitting of the intraparticle diffusion model showed that the removal of OM had a certain degree of change in the adsorption process. The isothermal adsorption of TC in all samples was more in line with the Temkin model. The isothermal adsorption of NOR in the oxidized sample conformed to the Temkin model, while it conformed to the Langmuir model in the original sample and the sample removed OM via combustion. The adsorption capacity of SPM with almost complete removal of OM significantly decreased, while conversely, the adsorption capacity of SPM after oxidation increased. This indicates that both the content and form of OM affect the adsorption of antibiotics by SPM, and the form of OM has a greater impact. The contribution of OM to NOR adsorption was greater than that of TC. In conclusion, the results verify the importance of OM in adsorbing antibiotics onto SPM, which may provide basic data for antibiotic migration in surface water.

Resveratrol alleviates pyraclostrobin-induced lipid peroxidation, oxidative stress, and DNA damage in rats

Pyraclostrobin (Pyra) is a fungicide in the strobilurin class and has proven to be very toxic to organisms primarily aquatic species. Resveratrol (Res) is a phytoalexin that exhibits multiple bioactivities as anti-oxidative, anti-inflammatory, cardiovascular protective, and anti-aging and is found in plant species such as mulberry, peanut, and grape. This study aimed to determine the protective effect of Res against Pyra-induced lipid peroxidation, oxidative stress, and DNA damage in rats. For this purpose, a total of 48 male rats divided into 6 groups - 8 in each group - were exposed to 30 mg/kg Pyra by oral gavage once a day for 30 days and to three different concentrations of Res (5, 10, and 20 mg/kg) together with Pyra. Pyra administration increased liver enzyme parameters and malondialdehyde (MDA) levels whereas decreased glutathione (GSH) levels and activities of superoxide dismutase (SOD) and catalase (CAT). Also, Pyra treatment increased pro-apoptotic (Bax), apoptotic (Caspase-3, Caspase-8, and Caspase-9), pro-inflammatory (NFκB), cancer (CYP2E1), and cell regulatory (p53) gene expressions and decreased anti-apoptotic (Bcl-2) gene expression in the liver. Furthermore, DNA damage in blood and histopathological changes in the liver and kidney were observed with Pyra administration. In contrast, Res administrations in a dose-dependent manner improved Pyra-induced lipid peroxidation, oxidative and DNA damages, expression levels of these genes in the liver, and histopathological changes in the liver and kidney. Consequently, the treatment of Res, known for its anti-oxidant and protective properties, exhibited a protective effect on Pyra-induced lipid peroxidation, oxidant/anti-oxidant status, gene expressions, and DNA damage in rats.

Cellulose Acetate Film Containing Bonechar for Removal of Metribuzin from Contaminated Drinking Water

Bonechar presents high sorption capacity for mobile herbicides retained in soil and water. However, its use in a granulated and/or powder form makes it difficult to remove water. The objective of this study was to produce a cellulose acetate film with bonechar as a viable alternative to remove metribuzin from water. The treatments were composed of 2 and 3 g of bonechar fixed on a cellulose acetate film, pure bonechar, and a control (no bonechar). The sorption and desorption study was carried out in the equilibrium batch mode with five concentrations of metribuzin (0.25, 0.33, 0.5, 1, and 2 mg L−1). The water used in the experiment was potable water. Herbicide analysis was performed by High-Performance Liquid Chromatography (HPLC). The addition of 2 and 3 g of the bonechar fixed on the acetate film sorbed 40% and 60%, respectively, of the metribuzin at the lowest concentrations (0.25, 0.33, and 0.5 mg L−1). For both additions, desorption was low, being 7% and 2.5% at 24 and 120 h, respectively. There are still no reports of the production of cellulose acetate film with bonechar for herbicide removal in water, considered an alternative of easy handling and indicated for water treatment plants.

Biochar application for remediation of organic toxic pollutants in contaminated soils; An update

Bioremediation of organic contaminants has become a major environmental concern in the last few years, due to its bio-resistance and potential to accumulate in the environment. The use of diverse technologies, involving chemical and physical principles, and passive uptake utilizing sorption using ecofriendly substrates have drawn a lot of interest. Biochar has got attention mainly due to its simplicity of manufacturing, treatment, and disposal, as it is a less expensive and more efficient material, and has a lot of potential for the remediation of organic contaminants. This review highlighted the adverse impact of persistent organic pollutants on the environment and soil biota. The utilization of biochar to remediate soil and contaminated compounds i.e., pesticides, polycyclic aromatic hydrocarbons, antibiotics, and organic dyes has also been discussed. The soil application of biochar has a significant impact on the biodegradation, leaching, and sorption/desorption of organic contaminants. The sorption/desorption of organic contaminants is influenced by chemical composition and structure, porosity, surface area, pH, and elemental ratios, and surface functional groups of biochar. All the above biochar characteristics depend on the type of feedstock and pyrolysis conditions. However, the concentration and nature of organic pollutants significantly alters the sorption capability of biochar. Therefore, the physicochemical properties of biochar and soils/wastewater, and the nature of organic contaminants, should be evaluated before biochar application to soil and wastewater. Future initiatives, however, are needed to develop biochars with better adsorption capacity, and long-term sustainability for use in the xenobiotic/organic contaminant remediation strategy.

Environmental fate and efficiency of bispyribac‑sodium in rice soils under conventional and alternative production systems affected by fresh and aged biochar amendment

Irrigation and tillage practice alternatives to conventional flooding production, with or without organic amendments, are attracting great interest to adapt rice cultivation to climate change. However, they can alter the behaviour of pesticides and their efficiency against weeds. A two-year field experiment was conducted to investigate how the environmental fate and the weed control efficiency (WCE) of bispyribac‑sodium (BS) were influenced by biochar produced from holm oak prunings (BHO) testing both the fresh and the aged effects. The treatments were: flooding irrigation and tillage (FT), sprinkler irrigation and tillage (ST), sprinkler irrigation and no-tillage (SNT), and the corresponding homologues with BHO addition (FT-BHO, ST-BHO, and SNT-BHO, respectively). Fresh BHO amendment decreased the sorption of BS onto the soil in all treatments, while, after aging, it also decreased sorption in FT-BHO (1.3-fold) but increased it in SNT-BHO and ST-BHO (1.1-fold). BHO addition reduced BS persistence under non-flooding and flooding incubation conditions, except for FT under the former condition for which t_1/2 increased ≈1.5-fold in both years. The addition of BHO led to a decrease in BS leaching from 58.3 % and 44.6 % and from 70.4 % and 58.1 % in ST and FT to 50.1 % and 38.3 % and 63.6 % and 50.3 % in the homologue amended soils for the fresh and aged years, respectively. While fresh BHO addition decreased the WCE of BS in SNT-BHO, ST-BHO, and FT-BHO on average by a factor of 1.5, with aged BHO there was only such a decrease (by a factor of 1.4) in FT-BHO. The use of BHO could be effective for reducing water contamination by BS in flooding or sprinkler irrigation rice farming as long as conventional tillage is used. But it may also contribute to greatly reducing the herbicide's efficiency, although with time to allow aging, this reduction would only persist under conventional flooding production.

Biochar changed the distribution of imidacloprid in a plant-soil-groundwater system

The use of biochar has increased, as its physicochemical properties reduce the adverse effects of pesticides. However, few studies have comprehensively investigated the effects of biochar on the distribution of pesticides in a plant-soil-groundwater system. In this study, a biochar produced from rice straw at 550 °C was chosen, and column experiments with five rated of biochar application (application rates = 0.0, 1.0, 2.0, 3.0, and 4.0% w/w for B0-B4, respectively) were conducted to investigate the capacity of biochar to immobilize imidacloprid (IMI) in soil, thereby decreasing its uptake by plants and leaching from soil into groundwater. Our results showed that IMI in plants, leached from soil, and detected in soil accounted for 3.78, 1.76, and 36.4% of the total IMI input, respectively, and the biochar treatments dramatically decreased the IMI distribution to 0.57, 0.11, and 13.4%, respectively. By contrast, the percentage of undetected IMI increased from 58.1% in the B0 treatment to an average of 86.0% in the biochar treatments. Biochar treatments increased IMI immobilization in soil, which could be related to the increased soil carbon content, surface area, cation exchange capacity. This study indicates that biochar with characters of high surface area and porosity can stabilize IMI and reduce its potential to harm plants and groundwater.

Pyrolysis Temperature and Application Rate of Sugarcane Straw Biochar Influence Sorption and Desorption of Metribuzin and Soil Chemical Properties

Pyrolysis temperature and application rate of biochar to soil can influence herbicide behavior and soil fertility. The objective was to investigate the effect of soil amendments with application rates of sugarcane straw biochar, produced at different pyrolysis temperatures, on the sorption–desorption of metribuzin in soil. The analysis was performed using high-performance liquid chromatography (HPLC). The treatments were three pyrolysis temperatures (BC350, BC550 and BC750 °C) and seven application rates (0, 0.1, 0.5, 1, 1.5, 5 and 10% w w−1). Amended soil with different application rates decreased H + Al and increased pH, OC, P, K, Ca, Mg, Fe, Mn, CEC and BS contents. Kf values of sorption and desorption of metribuzin were 1.42 and 0.78 mg(1−1/n) L1/n Kg−1, respectively, in the unamended soil. Application rates < 1% of biochar sorbed ~23% and desorbed ~15% of metribuzin, similar to unamended soil, for all pyrolysis temperatures. Amended soil with 10% of BC350, BC550 and BC750 sorbed 63.8, 75.5 and 89.4% and desorbed 8.3, 5.8 and 3.7% of metribuzin, respectively. High pyrolysis temperature and application rates of sugarcane straw biochar show an ability to immobilize metribuzin and improve soil fertility, which may influence the effectiveness in weed control.

Experiment and Model Study on the Destination of 3,5,6-Trichloro-2-pyridinol in the Purple Soil of Southwestern China with a High Ratio of Biochar Applied

3,5,6-Trichloro-2-pyridinol (TCP), the main degradation production of the pesticide chlorpyrifos and the herbicide triclopyr, features anti-degradation and high water solubility that challenge the in situ prevention of the migration of TCP from soils to water bodies. Biochar is a widely used amendment, but previous studies focused on the low content of biochar application that restricted the off-site prevention. In this study, therefore, both experiments and models were employed to explore the destination of TCP in purple soil, an Entisol with low organic matter content, large pores, and high water conductivity in southwestern China with a high ratio of biochar applied. Soil columns were homogeneously packed by mixing biochar at 0, 1%, 2%, 3%, 4%, 5%, 7.5%, 10%, 15%, and 20%, then the impulsive input of the breakthrough curves was used to explore the adsorption and desorption process of TCP, and the release of adsorbed TCP was traced by Br−. Following the dynamic outflow during the adsorption processes was simulated using the cumulative distribution function of gamma distribution, and the release of TCP was simulated by coupling the mass balance equation and first-order decay kinetics equation. The results revealed that the adsorption ability of the soil increased exponentially with the content of mixed biochar, implying a much larger increment at high content. For the removal rate of 90%, e.g., the increment was about 20 mg/kg when the content of biochar was raised from 15% to 20%, while it was about 7 mg/kg when the content was raised from 0 to 5%. The dynamic release and the unreleasable TCP could be well simulated by the first-order decay kinetics equation and the logarithmic model, respectively. The releasable TCP showed an increase–decrease pattern, and the maximum was observed at a 5% biochar content. These results above will provide a systematic experimental scheme, model support, and data reference to control organic pollutants with high solubility, stability, and strong migration using biochar in an off-site pattern such as an ecological ditch system.

The effect of reactor scale on biochars and pyrolysis liquids from slow pyrolysis of coffee silverskin, grape pomace and olive mill waste, in auger reactors

Several studies have addressed the potential biorefinery, through small-scale pyrolysis, of coffee silverskin (CSS), grape pomace (GP) and olive mill waste (OMW), which are respectively the main solid residues from coffee roasting, wine making and olive oil production processes. However, increasing the scale of reactor to bring these studies to an industrial level may affect the properties, and hence applications, of the resulting products. The aim of this study is therefore to perform pilot scale experiments to compare and verify the results of analytical study (TGA) and bench scale reactor runs, in order to understand the fundamental differences and create correlations between pyrolysis runs at different scales. To this end, pyrolysis liquids and biochars from the slow pyrolysis of CSS, GP and OMW, performed using different scale auger reactors (15 kg/h and 0.3 kg/h), have been analysed (TGA, pH, density, proximate and ultimate analyses, HHV, FTIR, GCMS) and compared. The results showed no major differences in biochars when the temperature and the solid residence time were fixed. However, regarding pyrolysis liquids, compounds from the lab reactor were more degraded than pilot plant ones, due to, in this case, the vapour residence time was longer. Regarding the properties of the pyrolysis products, GP 400 °C biochars showed the best properties for combustion; CSS biochars were especially rich in nitrogen, and 400 °C GP and OMW pyrolysis liquids showed the highest number of phenolics. Hence, this study is considered a first step towards industrial scale CSS, GP and OMW pyrolysis-based biorefinery.

Iron-Modified Biochar Strengthens Simazine Adsorption and Decreases Simazine Decomposition in the Soil

Currently, modified biochar has been successfully used in the remediation of soil polluted with heavy metals. However, the effects of the modified biochar on pesticides (such as simazine) are still unclear. Herein, the environmental fate of simazine, such as decomposition, leaching, and adsorption in unamended soil, in the soil amended with unmodified and modified biochar (biochar + FeCl₃, biochar + FeOS, biochar + Fe) were evaluated. In addition, an incubation experiment was also performed to observe the influence of modified biochar on the microbial community and diversity in the soil. The results showed that modified biochar significantly decreased the decomposition of simazine in the soil compared to its counterpart. Modified biochar also reduced the concentration of simazine in the leachate. Compared with the control, soil microbial biomass in the soil amended with unmodified biochar, biochar + FeCl₃, biochar + Fe, and biochar + FeOS was decreased by 5.3%, 18.8%, 8.7%, and 18.1%, respectively. Furthermore, modified biochar changed the structure of the microbial community. This shows that modified biochar could increase the soil adsorption capacity for simazine and change the amount and microbial community that regulates the fate of simazine in the soil. This study concludes that iron-modified biochar has positive and negative effects on the soil. Therefore, its advantages and side effects should be considered before applying it to the soil.

Rice straw biochar in combination with farmyard manure mitigates bromoxynil toxicity in wheat (Triticum aestivum L.)

Herbicide residues in agriculture commodities are a serious threat for human health and crop production. We investigated the efficient utilization of rice straw biochar and farmyard manure as organic amendments in mitigating the bromoxynil residues in leaves, grain, husk and root tissues of wheat plants. Growth and yield of wheat plants were also examined under field conditions through a 02-year field experiment. The experiment was set up using two wheat cultivars (Faisalabad-08 and Galaxy-2013) as main plot factors and different formulations of biochar and farmyard manure as sub-plot factors in a randomized complete Block design (split plot arrangement) with 03 replications. Different formulations of biochar (BC) and farmyard manure (FYM) i.e., 100 BC: 00 FYM, 75 BC: 25 FYM, 50 BC: 50 FYM, 25 BC: 75 FYM, 00 BC: 100 FYM and 00 BC: 00 FYM as control were prepared and mixed with soil (2% m/m) at the time of sowing. The wheat crop was sprayed with recommended dose (Buctril Super 60 EC, 825 mL ha^-1) of bromoxynil 40 days after sowing of the crop. Grain, husk, and root samples were collected at maturity while leave samples were taken 10 days after the herbicide application. Results revealed that the organic amendments significantly reduced the bromoxynil concentration in different tissues of wheat plant besides increasing the growth and yield of plants. The highest concentration of bromoxynil residues was found in control treatment whereas; sole biochar (100 BC:00 FYM) reduced the herbicide residues up to 78% in grain and husk of wheat, 40% in leaves and 64% in root tissues along with 41-44% increase in the grain yield. So, rice straw biochar along with farmyard manure could be considered as a promising option for mitigating the residual herbicide issues in the crop plants along with increase in the yield of wheat crop.

Sorption/Desorption and Kinetics of Atrazine, Chlorfenvinphos, Endosulfan Sulfate and Trifluralin on Agro-Industrial and Composted Organic Wastes

The use of pesticides presents a risk to terrestrial and aquatic ecosystems. For this reason, the development of strategies to prevent and restore pollution is of the greatest interest, including the adsorption to organic matter. The aim of the present study was to investigate the sorption/desorption and kinetics of atrazine, chlorfenvinphos, endosulfan sulfate, and trifluralin onto several raw organic wastes by batch experiments. Three kinetic models were used to fit the obtained sorption kinetics data and two to fit the obtained adsorption isotherm data; both the Freundlich and pseudo-second-order kinetic models described the sorption isotherms well. The desorption study revealed hysteresis in all cases, showing strong, and not completely reversible, adsorption in most cases, with the exception of atrazine-sawdust and chlorfenvinphos-sawdust and chicken manure combinations, for which responses were weak and irreversible. The best kinetic, adsorption and desorption constants were achieved for the hydrophobic pesticides. With respect to sorption-desorption rates, orujillo was found to be the best adsorbent for atrazine, while composted urban solid waste was more suitable for trifluralin and endosulfan sulfate. Sorption constants and simple correlations indicated that, not only the organic matter content, but also the nature of the organic matter itself, and the pesticide and adsorbent properties, determine pesticide sorption-desorption. The use of wastes as efficient and cheap adsorbents for reducing the risk of pesticide pollution is proposed.

Accessing biochar's porosity using a new low field NMR approach and its impacts on the retention of highly mobile herbicides

Agrowaste biochars [sugarcane straw (SS), rice husk (RH), poultry manure (PM), and sawdust (SW)] were synthesized at different pyrolysis temperatures (350, 450, 550, and 650 °C) to evaluate their potential to retain highly mobile herbicides, such as hexazinone and tebuthiuron that often contaminate water resources around sugarcane plantations. A new low field nuclear magnetic resonance approach based on decay due to diffusion in internal magnetic field (NMR-DDIF) was successfully used to determine biochar's porosity and specific surface area (SSA) to clear the findings of this work. SSA of pores with diameters >5.0 μm increased with pyrolysis temperatures and seemed to dictate biochar's retention, which was >70% of the applied amounts at 650 °C. These macropores appear to act as main arteries for herbicide intra-particle diffusion into smaller pores, thus enhancing herbicides retention. Biochar granulometry had little, but herbicide aging had a significant effect on sorption, mainly of tebuthiuron. However, soils amended with 10,000 kg ha^-1 of the biochars showed low sorption potential. Therefore, higher than usual biochar rates or proper incorporation strategies, i.e., surface incorporation, will be needed to remediate areas contaminated with these highly mobile herbicides, thus precluding their leaching to groundwaters.

Indaziflam sorption-desorption and its three metabolites from biochars- and their raw feedstock-amended agricultural soils using radiometric technique

This study aimed to characterize the effect of amending soils with biochars derived from soybean residues, sugarcane bagasse, and wood chips on the sorption-desorption of indaziflam and indaziflam-triazinediamine (FDAT), indaziflam-triazine-indanone (ITI), and indaziflam-carboxylic acid (ICA) metabolites applied to soils from three Midwestern U.S. states, a silt loam and a silty clay loam. Biochars produced from different feedstock were used as soil amendments and compared with raw feedstock. Sorption-desorption experiments of indaziflam and its three metabolites were performed using the batch equilibration method and analyzed for ¹⁴C activity by liquid scintillation counting (radiometric technique). In all soils, the use of organic amendments promoted greater sorption and less desorption of indaziflam and ITI. The addition of biochar to soils promoted greater sorption of the four tested chemical products compared with the corresponding raw materials. Among the biochars, grape wood chips showed greater potential in sorb indaziflam and ITI. In general, none of the biochars affected the sorption and desorption of FDAT and ICA. Characterization of biochar to be used as a soil amendment (immobilizer) is highly recommended prior to field addition to optimize the sorption process and to prevent increased soil and water contamination of indaziflam and its metabolites following biochar addition.

Enhanced mineralization of chlorpyrifos bound residues in soil through inoculation of two synergistic degrading strains

Bioaugmentation methods are frequently employed for pesticide pollution remediation; however, it is not clear whether the introduced bacteria affect the pesticide bound residue (BRs) composition and whether the BRs can be catabolized by the introduced strains. This study aimed at answering these questions by using ¹⁴C-chlorpyrifos (¹⁴C-CPF) and two CPF-degrading strains (Pseudomonas sp. DSP-1 and Cupriavidus sp. P2). The results showed that the BRs can be up to 83.0%, and that the CPF-BRs formed can be further transformed into ¹⁴CO₂ by the strains. Indeed, the microbial inoculation can increase the CPF mineralization by 1.0-22.1 times and can decrease the BRs by up to ~50% of the control (on day 20). Compared with the control without bioaugmentation, microbial inoculation enhanced the release of BRs by 2.2-18.0 times. Adding biochar to the soil can greatly inhibit CPF mineralization and maintain the BR content at a relatively stable level. The CPF residue can affect the composition of the indigenous soil microbial community, but the introduction of bacteria for remediation did not have a significant effect. The results indicate that Pseudomonas sp. DSP-1 and Cupriavidus sp. P2 are useful for remediating both CPF extractable and bound residues.

Impact of rice straw biochar addition on the sorption and leaching of phenylurea herbicides in saturated sand column

The application of phenylurea herbicides (PUHs) may lead to the extensive distribution in soils, while the role of straw biochar as a soil amendment on the transport and sorption of PUHs are still unclear. Thus, the transport and sorption behavior of three typical PUHs with rice straw biochar (RSB) was studied in both adsorption simulation experiments of aqueous solution and packed column experiments. The sorption mechanism of RSB to herbicides was investigated through batch sorption studies with three influencing factors including dosage of RSB, pH, and ionic strength (IS) with orthogonal test. The sorption coefficients were improved significantly by increasing the dosage of RSB, while there was no obvious influence by enhancing the pH and IS value. The optimal sorption conditions (pH value at 3, IS at 0.1 M, and RSB dosage at 60 mg) of three herbicides were set and the maximum removal rates of Monuron, Diuron, and Linuron were 41.9%, 25%, and 56.8%, respectively. The co-transport process of RSB and PUHs were investigated under different RSB dosage, pH value, and IS value. The retention effect increased greatly with enhancing the RSB dosage and pH value. However, IS did not have a significant influence on the retention of RSB, and therefore it had little effect on the adsorption capacity, which was consistent with the results of sorption experiments. The breakthrough curves (BTCs) for co-transport were well simulated by the two-site non-equilibrium convection-dispersion equation (CDE). Most of the regression coefficients (R²) were above 0.99, which uncovered the co-transport in packed column were affected by physical absorption and chemical forces. According to the fitting parameters analysis, the RSB particles and PUHs were subjected to a greater resistance and a stronger stability by reducing pH value in porous media. The presence of RSB increased the amount of dynamic sorption sites in the entire co-transport system, which led to a significant promotion of the PUHs' sorption and interception.

Fabrication a controlled-release pesticide for improving UV-shielding properties and reducing toxicity via coating polydopamine

Controlled-release formulations (CRFs) have potential applications in modern agriculture, for it can not only prolong the duration of agrochemicals but also alleviate the adverse effect on non-target organism. In this study, we constructed pyraclostrobin@SiO₂@polydopamine microcapsule (Pyr@SiO₂@PDA MC). The resulting microcapsule is a near-rod shape (about 1.15 μm), which has a drug-loading efficiency of 55%. Fourier transform infrared (FTIR) and thermogravimetric analysis (TG) revealed the successful entrapment of the pesticide. The coating of polydopamine (PDA) endowing the microcapsule with superior UV-shielding properties than pyraclostrobin@SiO₂ microcapsule (Pyr@SiO₂ MC). Compared with pyraclostrobin emulsifiable concentrate (EC), the Pyr@SiO₂@PDA MC exhibited 9.07-, 5.50-, 4.93- and 4.16-fold higher fungicidal activity against Rice blast fungus (Pyricularia oryzae) at concentrations of 0.5, 1, 2 and 4 mg/L. Moreover, acute toxicity tests demonstrated that the sample on zebrafish with lower toxicity on the first day. These results showed that the obtained microcapsule may process broader application potential in agriculture.

Co-transport of biochar colloids with organic contaminants in soil column

Co-transport of biochar (BC) colloids with coexisting organic contaminants (OCs) in soil involves complex interactions among BC colloids, OCs, and soil particles, which is significant for the environmental application and risk assessment of BC and yet has not been well addressed. This study explored co-transports of three typical OCs (i.e., phenanthrene (PHN), atrazine (ATZ), and oxytetracycline (OTC)) and BC colloids obtained from bulk BCs with different charring temperatures (200-700 °C) and particle sizes (250 nm, 500 nm, and 1 μm) in a soil column of 9 cm in height. Considerable transport of BC colloids alone was observed and the maximum breakthrough concentration (C/C_o) increased from 0.08 to 0.77 as the charring temperature decreased from 700 to 200 °C. The mobilities of PHN, OTC, and ATZ alone were very low but were greatly increased by co-transports with BC colloids, and their maximum C/C_o values were within 0.05-0.33, 0.03-0.44, and 0.05-0.62, respectively, in the absence and presence of various BC colloids. The enhancement effect of BC colloids on the OC transport decreased with increasing charring temperature or particle size of BC colloids. BC colloids mainly acted as a vehicle to facilitate the transport of OCs, and dissolved organic carbon from BC colloids also contributed to the increased mobility of OCs in dissolved form. These findings provide new insights into co-transport of BC colloids and contaminants in soil.

Sorption-desorption and biodegradation of sulfometuron-methyl and its effects on the bacterial communities in Amazonian soils amended with aged biochar

Sulfometuron-methyl is a broad-spectrum herbicide, used throughout Brazil; however, its environmental impacts in biochar (BC) amended soils is not fully understood. Biochar is known to enhance soil quality but can also have undesired effects such as altering the bioavailability and behavior of herbicides. Microbial communities can degrade herbicides such as sulfometuron-methyl in soils; however, they are known to be affected by BC. Therefore, it is important to understand the tripartite interaction between these factors. This research aimed to evaluate the sorption-desorption and biodegradation of sulfometuron-methyl in Amazonian soils amended with BC, and to assess the effects of the interactions between BC and sulfometuron-methyl on soil bacterial communities. Soil samples were collected from field plots amended with BC at three doses (0, 40 and 80 t ha^-1) applied ten years ago. The herbicide sorption and desorption were evaluated using a batch equilibrium method. Mineralization and biodegradation studies were conducted in microcosms incubated with ¹⁴C-sulfometuron-methyl for 80 days. Systematic soil sampling, followed by DNA extraction, quantification (qPCR) and 16S rRNA amplicon sequencing were performed. The presence of BC increased the sorption of the herbicide to the soil by 11% (BC40) and 16% (BC80) compared to unamended soil. The presence of BC also affected the degradation of ¹⁴C-sulfometuron-methyl, reducing the mineralization rate and increasing the degradation half-life times (DT50) from 36.67 days in unamended soil to 52.11 and 55.45 days in BC40 and BC80 soils, respectively. The herbicide application altered the bacterial communities, affecting abundance and richness, and changing the taxonomic diversity (i.e., some taxa were promoted and other inhibited). A tripartite interaction was found between BC, the herbicide and soil bacterial communities, suggesting that it is important to consider the environmental impact of soil applied herbicides in biochar amended soils.

Soybean seed treatment: how do fungicides translocate in plants?

BACKGROUND

Soybean seed treatment with fungicides is a well-established disease management strategy. However, the movement of these fungicides within seedlings is not always well characterized. Thus, the objectives of this study were to determine the pattern of translocation of three fungicides with different modes of action applied as a seed treatment, and the effect of soil type on translocation.

RESULTS

Most of the absorbed radioactivity was concentrated in the cotyledons and the maximum sum of the rates of absorption by roots, stems, and leaves of the plants was 15%. In most cases, absorption by roots, stems, and leaves were lower than 5% for 14 C-pyraclostrobin and 14 C-metalaxyl, and 1.6% for 14 C-carbendazim. Fungicides absorbed by the roots and the whole seedlings were higher when plants were grown in soil with lower organic matter content. Fungicides in the cotyledons are unlikely to be redistributed and are lost when cotyledons fall off the plants.

CONCLUSION

Cotyledons are the part of the plant where fungicides are most absorbed, regardless of the fungicide. Soil type affects the absorption of fungicides, and in this study it was most likely caused by soil organic matter. These data improve knowledge of the movement of seed treatment fungicides in soybean seedlings and may help the development of seed treatment chemistry to manage seed and soilborne pathogens.

Biochar sorption of PFOS, PFOA, PFHxS and PFHxA in two soils with contrasting texture

The ability to immobilise PFAS in soil may be an essential interim tool while technologies are developed for effective long-term treatment of PFAS contaminated soils. Serial sorption experiments were undertaken using a pine derived biochar produced at 750 °C (P750). All experiments were carried out either in individual mode (solution with one PFAS at 5 μg/L) or mix mode (solution with 5 μg/L of each: PFOS, PFOA, PFHxS and PFHxA), and carried out in 2:1 water to soil solutions. Soils had biochar added in the range 0-5% w/w. Kinetic data were fitted to the pseudo-second order model for both amended soils, with equilibrium times ranging 0.5-96 h for all congeners. PFOS sorption was 11.1 ± 4.5% in the loamy sand compared to 69.8 ± 4.9% in the sandy clay loam. While total sorption was higher in the unamended loamy sand than sandy clay loam for PFHxA, PFOA and PFOS, the effect of biochar amendment for each compound was found to be significantly higher in amended sandy clay loam than in amended loamy sand. Application of biochar reduced the desorbed PFAS fraction of all soils. Soil type and experimental mode played a significant role in influencing desorption. Overall, the relationship between sorbent and congener was demonstrated to be highly impacted by soil type, however the unique physiochemical properties of each PFAS congener greatly influenced its unique equilibrium, sorption and desorption behaviour for each amended soil and mode tested.

The ratio of H/C is a useful parameter to predict adsorption of the herbicide metolachlor to biochars

Biochar adsorbent was produced by pyrolyzing traditional Chinese medicinal herb residue at 300, 500 and 750 °C (referred to as biochar-300, biochar-500 and biochar-750). Basic physical and chemical analyses, Fourier transform infrared spectroscopy (FT-IR), and thermodynamic analyses were performed to elucidate adsorption and properties of biochar. Biochar adsorption capacity of herbicide metolochlor, as measured by batch-type adsorption experiments by Freundlich constant K_f (mg^1-n Lⁿ kg^-1), followed the order: biochar-750 > biochar-300 > biochar-500. Thermodynamic analysis suggested that adsorption of metolachlor on biochar was a spontaneous process. The adsorption isotherm for the biochar produced at the highest pyrolysis temperature was characteristic for adsorption process driven by a high surface area of biochar (85.30 m² g^-1), while the adsorption process for the biochar produced at the lowest temperature was controlled by its higher content of organic matter (39.06%) and abundant functional groups. The FT-IR spectra also showed that the biochar prepared at the lowest temperature had the highest number of surface groups. In general, pore-filling induced by the large surface area of the biochar was the dominant adsorption mechanism. When the H/C value was >0.5, the adsorption mechanism of biochar was dominated by surface chemical bond, while pore-filling played a major role when the H/C value was <0.5.

Effect of ageing process on bisphenol A sorption and retention in agricultural soils amended with biochar

The ageing of biochar and organic pollutant itself in soils can both influence the retention of organic pollutant in field soils. In this study, column experiments were adopted to determine the effect of ageing process on bisphenol A (BPA) sorption and retention in two typical Chinese agricultural soils with lychee branch biochar added. The effect of biochar ageing on soil organic matter (SOM) was specially investigated. Experimental results showed that the addition of biochar significantly increased the condensation and rigid of SOM, which could further increase with biochar ageing in soils. As a result, the addition of biochar significantly increased BPA sorption capacity (5.86 times and 3.30 times) and retention rate (13.60 times and 4.47 times) in fluvo-aquic soil and phaeozem respectively, while BPA sorption capacity and retention rate decreased obviously after biochar ageing in the two soils for 2 months as compared with the freshly incorporated biochar treatments, which may be attributed to the surface coverage and/or pore blockage of some sorption sites owning to DOC. With biochar incorporated, 2 months of BPA ageing increased BPA retention rate by about 4.50 times in both soils as compared with BPA newly spiked treatments. The results of this study could provide important parameters for prediction and control of organic pollutants such as BPA in soils.

A critical review of different factors governing the fate of pesticides in soil under biochar application

Pesticides are extensively used in the modern agricultural system. The inefficient and extensive use of pesticides during the last 5 to 6 decades inadvertently led to serious deterioration of environmental quality with health risk to living organisms, including humans. It is important to use some environmentally-friendly and sustainable approaches to remediate, restore and maintain soil quality. Biochar has gained considerable attention globally as a promising soil amendment because it has the ability to adsorb and as such minimize the bioavailability of pesticides in soils. This review emphasizes the recent trends and implications of biochar in pesticide-contaminated soils, as well as highlights need of the pesticides use and associated environmental issues in context of the biochar application. The overarching aim of this review is to signify the role of biochar on primary processes such as effect of biochar on the persistence, mineralization, leaching and efficacy of pesticides in soil. Notably, the effects of biochar on pesticide adsorption-desorption, degradation and bioavailability under various operating/production conditions are critically discussed. This review delineates the indirect impact of biochar on pesticides persistence in soils and proposes key recommendations for future research which are essential for the remediation and restoration of pesticides-impacted soils.

Effect of Natural Aging of Biochar on Soil Enzymatic Activity and Physicochemical Properties in Long-Term Field Experiment

The effect of different rates of biochar on selected soil properties and enzymatic activity 48, 60, and 72 months after biochar application to soil was investigated. Soil enzymatic activity (dehydrogenase—ADh; phosphatase—Aph; urease—AU), the organic carbon content (TOC), the total nitrogen content (Nt), the mineral nitrogen content (NH4+, NO3−), and soil pH were determined. The study was conducted on Haplic Podzol originating from glaciofluvial fine-grained loamy sand. Biochar was applied to soil under winter rye (Secale cereale L.) at rates of 10 (BC10), 20 (BC20), and 30 t ha−1 (BC30). Plots with biochar-unamended soil were the control treatment (BC0). The pH, TOC, and Nt content in the biochar-amended soil were higher compared to the control soil. A broader C:N ratio was found in the BC0 soil compared to BC10, BC20, and BC30. With increasing biochar rate, the content of the ammonium nitrogen form (NH4+) decreased and was statistically lower than in the control soil (BC0). The soil in the BC20 and BC30 treatments was characterized by the highest content of NO3-, whereas the lowest nitrate nitrogen content was found in the control soil (BC0). Biochar application increased soil enzymatic activity. Dehydrogenase activity increased with increasing biochar rate. As far as phosphatase and urease activity is concerned, a similar relationship was not observed. In this case, the soil amended with biochar at a rate of 20 t ha−1 (BC20) was characterized by the highest phosphatase and urease activity.

In-vitro evaluation of rice straw biochars' effect on bispyribac-sodium dissipation and microbial activity in soil

Dissipation of bispyribac-sodium was estimated in an unamended sandy loam soil and soil amended with rice straw and its biochars in pot culture experiment. Effect of herbicide and amendments on abundance and activity of soil microbial parameters was also assessed by determining soil biological parameters. Amendment type, application rate and soil moisture had differential influence on bispyribac-sodium dissipation and soil's microbial parameters. Amendment of soil with rice straw and its biochars enhanced the dissipation of bispyribac-sodium (DT₅₀ = 7.55-18.44 days) as compared to unamended soil (DT₅₀ = 23.13-28.60 days) and dissipation decreased in this order: rice straw >350BC > 550BC > CBC amended soil > unamended soil. Dissipation of bispyribac-sodium decreased with increase in amendment level of rice straw and its biochars in soil. Irrespective of amendment type and application rate, bispyribac sodium was more persistent under submerged conditions than at field capacity and its DT₅₀ was 10.13 to 28.60 and 7.55-27.14 days, respectively. Dehydrogenase, alkaline phosphatase activity and bacterial population indicated that application of the organic amendment decreased negative effects of the herbicide on soil enzymatic activities. These findings prove that biostimulation using rice straw and its biochars has the potential to decrease the persistence of bispyribac-sodium and minimize its environmental hazards.

An examination of the role of biochar and biochar water-extractable substances on the sorption of ionizable herbicides in rice paddy soils

The application of biochar as a soil amendment can increase concentrations of soil organic matter, especially water-extractable organic substances. Due to their mobility and reactivity, more studies are needed to address the potential impact of biochar water-extractable substances (BWES) on the sorption of herbicides in agricultural soils that are periodically flooded. Two paddy soils (100 and 700 years of paddy soil development), unamended or amended with raw (BC) or washed biochar (BCW), were used to test the influence of BWES on the sorption behavior of the herbicides azimsulfuron (AZ) and penoxsulam (PE). The adsorption of AZ to biochar was much stronger than that to the soils, and it was adsorbed to a much larger extent to BC than to BCW. The depletion of polar groups in the BWES from the washed biochar reduced AZ adsorption but had no effect on PE adsorption. The adsorption of AZ increased when the younger soil (P100) was amended with BC and decreased when it was amended with BCW. In P700, which has lower dissolved organic carbon (DOC) content than P100, the adsorption of AZ increased regardless of whether biochar was raw or washed. The adsorption of PE slightly decreased when P100 was amended with BC or BCW and slightly increased when P700 was amended with BC or BCW. In order to evaluate compositional differences in the biochar and BWES before and after the washing treatment, we performed solid-state ¹³C NMR spectroscopy of BC and BCW, and high resolution mass spectrometry of BWES. Our observations stress the importance of proper consideration of soil and biochar properties before their incorporation into paddy soils, since biochar may reduce or increase the mobility of AZ and PE depending on soil properties and time of application.

Biochar for delivery of agri-inputs: Current status and future perspectives

Biochar, a carbonaceous porous material produced from the pyrolysis of agricultural residues and solid wastes has been widely used as a soil amendment. Recent publications on biochar are primarily focussed with its application in climatic aspects, contaminant immobilization, soil amendment strategies, nutrient recovery, engineered material production and waste-water treatment. Numerous studies have reported the positive attribute of biochar's nutrient value that helps in improving plant growth and fertilizer use efficiency. The renewability, low-cost, high porosity, high surface area and customizable surface chemistry of biochar offers ample prospect in several engineering applications, some of which needs significant attention. This review aims at systematically assessing the uses of biochar as a potential carrier material for delivery of agrochemicals and microbes. The key parameters of biochar that are crucial to assess the potential of any material to be used for delivery purposes are discussed. The parameters such as the physicochemical properties of biochar, the mechanistic aspects of adsorption and release of agrochemicals and microbes from biochar, comparative assessment of biochar over other carrier materials, long-term effects of biochar and the economic and environmental benefits of biochar are discussed in detail. At the end, a brief perspective has also been laid out to discuss how nano-interventions could further be helpful to tailor biochar properties useful for delivery applications.

Biochars reduced the bioaccessibility and (bio)uptake of organochlorine pesticides and changed the microbial community dynamics in agricultural soils

Biochar is considered as a universal sorbent used for soil amendment but its impacts on organochlorine pesticides (OCPs) and microbial communities associated with soil and vegetables are unclear. The effects of different biochars (derived from sewage sludge biochar (SSBC), soybean straw biochar (SBBC), rice straw biochar (RSBC) and peanut shells biochar (PNBC)), on bioaccessible fractions of OCPs in a contaminated soil and their subsequent bioaccumulation into vegetables (Chinese cabbage and spring onion) were investigated in this research work. The influence of these amendments on vegetable yields and soil microbial community using Illumina next generation sequencing technology was also assessed. The application of selected biochars significantly (p < 0.01) reduced the bioaccessibility of ∑OCPs in contaminated soil: SSBC (52%), PNBC (51%), RSBC (60%), and SBBC (47%), as compared to the control. The results indicated that following biochar additions, the bio-uptake of ∑OCP bio-uptake was considerably (from 86 to 85%) reduced in grown vegetables. Risk assessment showed that biochar amendments markedly (p < 0.01) decreased the hazard quotient (HQ) indices and incremental lifetime cancer risk (ILTR) values for OCPs associated with the consumption of vegetables. In addition, the results of high-throughput sequencing showed significant differences in microbial community structure between the treatments, which was driven by differences in the relative abundances of soil microbes. The relative abundances of Acidobacteria, Chloroflexi, Nitrospirae and Verrucomicrobia decreased following biochar additions. However, biochar amendments increased the relative abundances of Actinobacteria, Proteobacteria, Planctomycetes, Bacteroidetes, Firmicutes, and Gemmatimonadetes, though the increase in relative abundances of these phyla was strongly dependent on the type of biochar used.

Hydrolysis and photolysis of bentazone in aqueous abiotic solutions and identification of its degradation products using quadrupole time-of-flight mass spectrometry

Hydrolysis and photolysis of bentazone in abiotic aqueous solutions were examined under laboratory conditions. Hydrolysis was studied in different buffer solutions (pH 4.0 ± 0.1, 7.0 ± 0.1, and 9.0 ± 0.1), at different temperatures (15 °C ± 2 °C, 25 °C ± 2 °C, 35 °C ± 2 °C, and 45 °C ± 2 °C), and at different Fe³⁺ concentrations (1, 5, and 10 mg/L). Photolysis was assessed in different buffer solutions and at different solvent (methanol and ethyl acetate) concentrations (10%, 20%, and 30%) or Fe³⁺ (1, 5, and 10 mg/L) concentrations and under mercury or xenon light irradiation. Hydrolysis half-lives ranged 46-99 days at three different conditions. Photolysis half-lives ranged 2.3-7.5 h in three different conditions under mercury and xenon irradiation. Hydrolysis and photolysis of bentazone were accelerated by both alkaline conditions and elevated temperatures, and solvents and Fe³⁺ strongly enhanced bentazone degradation. Photodecomposition was much faster under a mercury lamp than under a xenon lamp. N-methyl bentazone and 6-OH bentazone/8-OH bentazone were identified as degradation products using UPLC-Q-TOF-MS. The data generated from this study could be useful for risk assessment of pesticides in the environment.

Influence of biochars on the accessibility of organochlorine pesticides and microbial community in contaminated soils

Biochar can be used as a promising potential substance to reduce the availability of toxic elements and compounds in contaminated soils but its effects on the accessibility of pesticides and microbiological interactions still remain unclear. Here, 65 day incubation experiments were conducted to investigate the efficacy of biochars on the accessibility of 21 different organochlorine pesticides (OCPs), and also to evaluate their influence on soil microbial community. The tested soil was collected from an agricultural field, containing loamy sand texture, and historically contaminated with high concentrations of OCPs. The soil was amended with four different kinds of biochars: sewage sludge biochar (SSBC), peanut shells biochar (PNBC), rice straw biochar (RSBC), and soybean straw biochar (SBBC). The results indicated that biochar-amendments had strong effects upon OCP accessibility over time and can act as super sorbent. Despite greater persistence of OCPs in soil, the application of selected biochars significantly (p < 0.01) reduced the accessibility of ∑OCPs in the amended soil in the order of SSBC (8-69%), PNBC (11-75%), RSBC (6-67%), and SBBC (14-86%), as compared to the control soil during 0-65 d incubation period. Moreover, the findings from total phospholipid acid (PLFA) and Illumina next-generation sequencing revealed that the incorporation of biochar have altered the soil microbial community structure over time. Higher abundances of Proteobacteria, firmicutes, Gemmatimonadetes, and Actinobacteria were found in biochar amendments. However, the relative abundances of Acidobacteria and Chloroflexi decreased, following biochar addition. The findings of these experiments suggest that biochar addition to soil at the rate of 3% (w/w) could be advantageous for decreasing accessibility of OCPs, enhancing the soil microbial communities, and their subsequent risk to environment and food chain contamination.

Impact of biochar amendment in agricultural soils on the sorption, desorption, and degradation of pesticides: A review

Extensive and inefficient use of pesticides over the last several decades resulted in serious soil and water contamination by imposing severe toxic effects on living organisms. Soil remediation using environment-friendly amendments to counteract the presence of pesticides in soil seems to be one suitable approach to solve this problem. Biochar has emerged as a promising material for adsorbing and thus decreasing the bioavailability of pesticides in polluted soils, due to its high porosity, surface area, pH, abundant functional groups, and highly aromatic structure, mainly depending on the feedstock and pyrolysis temperature. However, biochar effects and mechanisms on the sorption and desorption of pesticides in the soil are poorly understood. Either high or low pyrolysis temperature has both positive and negative effects on sorption of pesticides in soil, one by larger surface area and the other by a large number of functional groups. Therefore, a clear understanding of these effects and mechanisms are necessary to engineer biochar production with desirable properties. This review critically evaluates the role of biochar in sorption, desorption, and degradation of pesticides in the soil, along with dominant properties of biochar including porosity and surface area, pH, surface functional groups, carbon content and aromatic structure, and mineralogical composition. Moreover, an insight into future research directions has been provided by evaluating the bioavailability of pesticide residues in the soil, effect of other contaminants on pesticide removal by biochar in soils, effect of pesticide properties on its behavior in biochar-amended soils, combined effect of biochar and soil microorganisms on pesticide degradation, and large-scale application of biochar in agricultural soils for multifunction.

Effects of biochar amendment on sorption, dissipation, and uptake of fenamiphos and cadusafos nematicides in sandy soil

BACKGROUND

The application of biochar to soil is supposed to alter its adsorption/desorption potential toward pesticides, thereby affecting their bioavailability and efficacy. This is particularly relevant in the case of nematicides because these pesticides are directly applied to soil.

RESULTS

Biochar was produced from date palm (PB) and eucalyptus (EB) waste at 450 °C and added at a rate of 1% to a sandy soil. The half-life (t_½ ) of fenamiphos was increased from 2.7 to 18.3 and 18.6 days in PB- and EB-amended soils, respectively. By contrast, the half-life of cadusafos was unaffected. Freundlich K_f values increased from 1.22 and 0.39 (μg^1-Nf g^-1 mL^Nf ) to 4.49 and 6.84 in 1% PB-amended soil, and to 3.49 and 4.62 in 1% EB-amended soil for cadusafos and fenamiphos, respectively. Plant uptake of both nematicides in tomato seedlings was reduced by approximately 97% (cadusafos) and 85% (fenamiphos). Although nematicide efficacy against Meloidogyne incognita was not altered at the recommended dosage, it was negatively affected at a half-dose rate. Under these conditions, it decreased from 43.1% in unamended sandy soil to only 18.3% in 1% PB-amended soil.

CONCLUSIONS

Biochar addition increased the sorption capacity of soil. This resulted in a decrease of nematicide bioavailability, together with a reduction of both the dissipation rate and uptake by tomato plants. © 2018 Society of Chemical Industry.

Effect of biochar on fate and transport of manure-borne estrogens in sandy soil

The feasibility of using two types of biochars to reduce steroid hormone pollution from poultry and swine manure application on agricultural land was evaluated. The sorption affinity and desorption resistance of softwood and hardwood biochars were also determined for two estrogen hormones, 17β-estradiol (E2) and its primary metabolite estrone (E1). The softwood and hardwood biochars demonstrated high retention capacity for both estrogens. The effective distribution coefficient (K_d^eff) of soil-softwood-derived biochar (SBS₄₅₀) was significantly higher than soil-hardwood-derived biochar (SBH₇₅₀), indicating the stronger sorption affinity of SBS₄₅₀ for estrogens. To validate the laboratory results, a field lysimeter experiment was conducted to study the fate and transport of E2 and E1 in soil and leachate in the presence of 1% softwood-biochar (BS₄₅₀) in topsoil and to compare it with soil without any amendments. The spatio-temporal distribution of both estrogens was monitored at four depths over a 46-day period. The lysimeters, in which the surface layer of soil was amended with biochar, retained significantly higher concentrations of both estrogen hormones. Although they leached through the soil and were detected in leachates, collected at 1.0m depth, the concentrations were significantly lower in the leachate collected from biochar-amended lysimeters. The result confirmed the efficacy of biochar amendment as a remediation technique to alleviate the manure-borne hormonal pollution of groundwater.

Effects of biochars on the fate of acetochlor in soil and on its uptake in maize seedling

Biochar (BC) can alter the fate and bioavailability of pesticides in soil. In this study, the effects of three types of BCs (made of crofton weed, wood chips and rice hull) on the sorption of acetochlor, a common herbicide, were investigated. The acetochlor sorption constants (K_f value) were 309.96 μg^1-nL^n/kg (biochars made of ricehull, BCR), 3.54 μg^1-nL^n/kg (biochars made of crofton weed, BCH) and 2.27 μg^1-nL^n/kg (biochars made of wood chips, BCW). The persistence of acetochlor was 8 times greater when 1% BCR was added to the soil. Moreover, the half-life of acetochlor increased with increasing amounts of BC in the soil. The soil was amended with BCH (made of crofton weed) for two different aging period (10 d and 20 d) to evaluate the effects of aged BC on acetochlor accumulation in maize seedlings (Zea mays L). Amendment with 10 d-aged BCH in soil decreased the bioaccumulation of acetochlor. However, the concentrations and bioconcentration factors in maize cultivated in 20 d-aged BCH-amended soils were significantly higher than those in soil with no BCH amendments and with 10 d-aged BCH amendments. These results imply that BC aged in soil for a long period can increase the bioaccumulation of acetochlor in plants and the influences of BC on environmental risks of pesticides must be further clarified.

Glyphosate sorption/desorption on biochars - interactions of physical and chemical processes

BACKGROUND

Biochar, a carbon-rich product of biomass pyrolysis, could limit glyphosate transport in soil and remediate contaminated water. The present study investigates the sorption/desorption behavior of glyphosate on biochars prepared from different hardwoods at temperatures ranging from 350 to 900 °C to elucidate fundamental mechanisms.

RESULTS

Glyphosate (1 mg L-1 ) sorption on biochars increased with pyrolysis temperature and was highest on 900 °C biochars; however, total sorption was low on a mass basis (<0.1 mg g-1 ). Sorption varied across feedstock materials, and isotherms indicated concentration dependence. Biochars with a greater fraction of micropores exhibited lower sorption capacities, and specific surface groups were also found to be influential. Prepyrolysis treatments with iron and copper, which complex glyphosate in soils, did not alter biochar sorption capacities. Glyphosate did not desorb from biochar with CaCl2 solution; however, up to 86% of the bound glyphosate was released with a K2 HPO4 solution.

CONCLUSION

Results from this study suggest a combined impact of surface chemistry and physical constraints on glyphosate sorption/desorption on biochar. Based on the observed phosphate-induced desorption of glyphosate, the addition of P-fertilizer to biochar-amended soils can remobilize the herbicide and damage non-target plants; therefore, improved understanding of this risk is necessary. © 2017 Society of Chemical Industry.