Influence of biochars on plant uptake and dissipation of two pesticides in an agricultural soil

The roles of organic amendments and plant treatments in soil polychlorinated biphenyl dissipation under oxic and sequential anoxic-oxic conditions

Understanding polychlorinated biphenyl (PCB) degradation in sequential anaerobic-aerobic remediation is crucial for effective remediation strategies. In this study, microcosm and greenhouse experiments were conducted to dissect the effects of organic amendments (carbon-based) and plant treatments (ryegrass) on soil PCB dissipation under oxic and sequential anoxic-oxic conditions. We analyzed the soil bacterial community in greenhouse experiments using high-throughput sequencing to explore plant-pollutant-microbe interactions. Microcosm results showed that organic amendments alone did not facilitate aerobic PCB removal, but significantly accelerated PCB dechlorination under anoxic conditions altering the profiles of PCB congeners. In standard greenhouses, plant treatments substantially increased PCB dissipation to 50.8 ± 3.9%, while organic amendments aided phytoremediation by promoting plant growth, increasing PCB removal to 65.9 ± 3.2%. In sequential anaerobic-aerobic greenhouses, plant growth was inhibited by flooding treatment while flooding stress was markedly alleviated by organic amendments. Plant treatments alone during sequential treatments did not lead to PCB dissipation; however, dissipation was significantly promoted following organic amendments, achieving a removal of 41.2 ± 5.7%. This PCB removal was primarily due to anaerobic dechlorination during flooding (27.8 ± 0.5% removal), rather than from plant growth stimulation in subsequent planting phase. Co-occurrence network and functional prediction analyses revealed that organic amendments recruited specific bacterial clusters with distinct functions under different conditions, especially stimulating plant-microbe interactions and xenobiotics biodegradation pathways in planted systems. The findings provide valuable guidance for the design of practical remediation strategies under various remedy scenarios, such as in arable or paddy fields.

Humic substances sorption from wastewater on the biochar produced from the waste materials

In recent years, increasing attention has been paid to the possibility of converting waste materials, e.g. manure, bio-waste, green waste, waste from the water and sewage industries (e.g. post-fermentation sludge), and agri-food waste into biochars (BCs) by pyrolysis. The ability of biochar to improve soil health and fertility is driving growing interest in its use as a soil amendment. A high soil stability of BCs and their excellent nutrient sorption properties are the main reasons for the superiority of such materials over other organic soil amendments. In addition, BCs can retain soil-relevant compounds, including humic substances (HSs). Since most of the resources used to produce humic fertilisers are non-renewable, the effluent from anaerobic digestion of sewage sludge (reject water, RW), which contains high levels of HSs, is considered a promising target for their recovery. In this study, the potential of ten BCs derived from pine, oak, straw, sunflower, and digestate at different pyrolysis temperatures for the recovery of HSs from RW was evaluated. The sorption of HSs on the applied BCs was conducted using contact method for 24 h and then determined spectrophotometrically. The most effective sorbents for HSs from RW were BCs obtained from straw in the low and high temperatures with the sorption capacity of 3.10 mg g-1 and 5.31 mg g-1, respectively. It was observed that the BCs produced from the same biomass at different pyrolysis temperatures had different sorption capacities for FA, HA, and a mixture of these compounds. The results indicated that BCs obtained from sunflower at different temperatures and oak at high temperature were the most promising sorbents for the recovery of HSs from RW. Such materials have the potential to be applied to soil and were selected for further evaluation due to their ability to enhance soil quality and immobilize pollutants. Further studies will assess their effectiveness in different soil conditions, their stability and persistence, and their impact on plant health and growth.

Response of chemical and biochemical soil properties to the spreading of biochar-based treated olive mill wastewater

Despite the polluting potential olive mill wastewater (OMW) can be a useful source of nutrients and organic compounds to improve soil properties. The aim of this paper was to verify if biochar-based treatment of OMW could be an efficient method to contrast the richness in phenolic compounds and phytotoxicity of OMW making it more suitable. for soil amendment. In this study poplar biochar (BP) was more effective than conifer biochar (BC) in terms of adsorbing phenols and reducing phytotoxicity at different biochar rates (5 and 10 %). In soil amendment BP-treated OMW induced an increase of organic carbon by approximately 15 % and notably BP10 treated OMW enhanced available phosphorous by 25 % after 30 days of incubation. In soil amended with 10 % BP-treated OMW microbial biomass and enzymatic activities were significantly enhanced after 30 and 90 days, with no effect on cress seed germination. Therefore, biochar based-treatment could be cost-effective and able to facilitate the long-term management of OMW in terms of storage and disposal.

Exceptional anti-toxic growth of water spinach in arsenic and cadmium co-contaminated soil remediated using biochar loaded with Bacillus aryabhattai

Functionalized biochars are crucial for simultaneous soil remediation and safe agricultural production. However, a comprehensive understanding of the remediation mechanism and crop safety is imperative. In this work, the all-in-one biochars loaded with a Bacillus aryabhattai (B10) were developed via physisorption (BBC) and sodium alginate embedding (EBC) for simultaneous toxic As and Cd stabilization in soil. The bacteria-loaded biochar composites significantly decreased exchangeable As and Cd fractions in co-contaminated soil, with enhanced residual fractions. Heavy metal bioavailability analysis showed a maximum CaCl2-As concentration decline of 63.51% and a CaCl2-Cd decline of 50.96%. At a 3% dosage of composite, rhizosphere soil showed improved organic matter, cation exchange capacity, and enzyme activity. The aboveground portion of water spinach grown in pots was edible, with final As and Cd contents (0.347 and 0.075 mg·kg⁻¹, respectively) meeting food safety standards. Microbial analysis revealed the composite's influence on the rhizosphere microbial community, favoring beneficial bacteria and reducing plant pathogenic fungi. Additionally, it increased functional microorganisms with heavy metal-resistant genes, limiting metal migration in plants and favoring its growth. Our research highlights an effective strategy for simultaneous As and Cd immobilization in soil and inhibition of heavy metal accumulation in vegetables.

Effects of sublethal fipronil exposure on cross-generational functional responses and gene expression in Binodoxys communis

The effective systemic insecticide fipronil is widely used on a variety of crops and in public spaces to control insect pests. Binodoxys communis (Gahan) (Hymenoptera: Braconidae) is the dominant natural enemy of Aphis gossypii Glover (Homoptera: Aphididae), an important cotton pest, and has good efficiency in inhibiting aphid populations. The direct effects of environmental residues of sublethal fipronil doses on adult B. communis have not previously been reported. This study therefore aimed to evaluate the side effects and transcriptomic impacts of sublethal fipronil doses on B. communis. The results showed that exposure to the LC10 dose of fipronil significantly reduced the survival rate and parasitism rate of the F0 generation, but did not affect these indicators in the F1 generation. The LC25 dose did not affect the survival or parasitic rates of the F0 generation, but did significantly reduce the survival rate of F1 generation parasitoids. These results indicated that sublethal doses of fipronil affected B. communis population growth. Transcriptome analysis showed that differentially expressed genes (DEGs) in B. communis at 1 h after treatment were primarily enriched in pathways associated with fatty acid elongation, biosynthesis of fatty acids, and fatty acid metabolism. DEGs at 3 days after treatment were mainly enriched in ribosomal functions, glycolysis/gluconeogenesis, and tyrosine metabolism. Six DEGs (PY, ELOVL, VLCOAR, MRJP1, ELOVL AAEL008004-like, and RPL13) were selected for validation with real-time fluorescent quantitative PCR. This is the first report of sublethal, trans-generational, and transcriptomic side effects of fipronil on the dominant parasitoid of A. gossypii. The results of this study show that adaptation of parasitoids to high concentrations of pesticides may be at the expense of their offspring. These findings broaden our overall understanding of the intergenerational adjustments used by insects to respond to pesticide stress and call for risk assessments of the long-term impacts and intergenerational effects of other pesticides.

Response of chemical and biochemical soil properties to the spreading of biochar-based treated olive mill wastewater

Olive mill wastewater (OMW) is the effluent derived from the oil extraction processes from olives. Despite the polluting potential OMW can be a useful source of nutrients and organic compounds to improve soil properties. OMW could negatively affect soil and water quality as this waste is rich in phenolic compounds and has high COD and BOD5. Biochar-based treatment could be an efficient method to remediate OMW. In this study poplar biochar (BP) was more effective than conifer biochar (BC) in terms of adsorbing phenols and reducing phytotoxicity at different biochar rates (5 and 10 %). BP-treated OMW was used in soil amendment and induced an increase in chemical properties, especially in organic carbon after 30 days of incubation. In soil amended with 10 % BP-treated OMW microbial biomass, enzymatic activities, and cress seed germination were significantly enhanced after 30 and 90 days.

When biochar is involved in rhizosphere dissipation and plant absorption of pesticides: A meta-analysis

Clarifying the influences of biochar input on the rhizosphere dissipation and plant absorption of pesticides is a crucial prerequisite for utilizing biochar in the restoration of pesticide-contaminated soils. Nevertheless, the application of biochar to pesticide-contaminated soils does not always achieve consistent results on the rhizosphere dissipation and plant absorption of pesticides. Under the new situation of vigorously promoting the application of biochar in soil management and carbon sequestration, a timely review is needed to further understand the key factors affecting biochar remediation of pesticide-contaminated soil. In this study, a meta-analysis was conducted utilizing variables from three dimensions of biochar, remediation treatment, and pesticide/plant type. The pesticide residues in soil and the pesticide uptake by plant were used as response variables. Biochar with high adsorption capacity can impede the dissipation of pesticides in soil and mitigate their absorption by plants. The specific surface area of biochar and the type of pesticide are critical factors that affect pesticide residues in soil and plant uptake, respectively. Applying biochar with high adsorption capacity, based on specific dosages and soil characteristics, is recommended for the remediation of continuously cultivated soil contaminated with pesticides. This article aims to provide a valuable reference and understanding for the application of biochar-based soil remediation technology and the treatment of pesticide pollution in soil.

Succession of biochar addition for soil amendment and contaminants remediation during co-composting: A state of art review

This paper aimed to highlight the succession of biochar addition for soil amendment and contaminants remediation during composting process. Biochar incorporated into the compost mixture promotes composting performance and enhances contaminants reduction. Co-composting with biochar for soil biota has been demonstrated via modified soil biological community abundance and diversity. On the other hand, adverse alterations to soil properties were noted, which had a negative impact on the communication of microbe-to-plant interactions within the rhizosphere. As a result, these changes influenced the competition between soilborne pathogens and beneficial soil microorganisms. Co-composting with biochar promoted the heavy metals (HMs) remediation efficiency in contaminated soils by around 66-95%. Notably, applying biochar during composting could improve nutrient retention and mitigate leaching. The adsorption of nutrients such as nitrogen and phosphorus compounds by biochar can be applied to manage environmental contamination and presents an excellent opportunity to enhance soil quality. Additionally, the various specific functional groups and large specific surface areas of biochar allow for excellent adsorption of persistent pollutants (e.g., pesticides, polychlorinated biphenyls (PCBs)) and emerging organic pollutants, such as microplastic, phthalate acid esters (PAEs) during co-composting. Finally, future perspectives, research gaps, and recommendations for further studies are highlighted, and potential opportunities are discussed.

Environmental emissions and pollution characteristics of mosquitocides for the control of dengue fever in a typical urban area

Mosquitocides are frequently used to control the spread of dengue fever in tropical and sub-tropic urban regions worldwide, resulting in their discharge into the environment via rainfall runoff, causing adverse effects on ecological health. This study quantitatively evaluated mosquitocide emissions and environmental pollution in a typical urban district in China affected by the dengue fever epidemic, using a method combining market surveys, monitoring campaigns and SWMM (storm water management model) modelling tools. During the assessment period, the total mosquitocide usage in the urban district reached 6334 kg, with an estimated load of 56.55 g entering the receiving environment via rainfall runoff, 91.04 % of which occurred in the rainy season. Monitoring results indicated that the initial 0.5-1 h was the main period of mosquitocide wash off into the receiving water. Environmental mosquitocide pollution levels were found to be affected by the mosquitocide type and the time interval between mosquitocide application and precipitation events. The measured environmental concentrations of mosquitocides in this study were generally higher than those areas unaffected by the dengue fever epidemic. The modelled mosquitocide concentrations were in accordance with monitoring results. The finding of this study are important for assessing the environmental impact of dengue fever control activities, while also providing valuable baseline data for the effective environmental management of mosquitocides.

Effects of microplastics and chlorpyrifos on earthworms (Lumbricus terrestris) and their biogenic transport in sandy soil

Although microplastics (MPs) are ubiquitous in agricultural soil, little is known about the effects of MPs combined with pesticides on soil organisms and their biogenic transport through the soil profile. In this study, we conducted mesocosm experiments to observe the effects of microplastics (polyethylene (LDPE-MPs) and biodegradable microplastics (Bio-MPs)) and chlorpyrifos (CPF) on earthworm (Lumbricus terrestris) mortality, growth and reproduction, as well as the biogenic transport of these contaminants through earthworm burrows. The results showed that earthworm reproduction was not affected by any treatment, but earthworm weight was reduced by 17.6% and the mortality increased by 62.5% in treatments with 28% Bio-MPs. Treatments with 28% LDPE-MPs and 7% Bio-MPs combined with CPF showed greater toxicity while the treatment with 28% Bio-MPs combined with CPF showed less toxicity on earthworm growth as compared to treatments with only MPs. The treatments with 1250 g ha^-1 CPF and 28% Bio-MPs significantly decreased the bioaccumulation of CPF in earthworm bodies (1.1 ± 0.2%, w w^-1), compared to the treatment with CPF alone (1.7 ± 0.4%). With CPF addition, more LDPE-MPs (8%) were transported into earthworm burrows and the distribution rate of LDPE-MPs in deeper soil was increased. No effect was observed on the transport of Bio-MPs. More CPF was transported into soil in the treatments with LDPE-MPs and Bio-MPs, 5% and 10% of added CPF, respectively. In addition, a lower level of the CPF metabolite 3,5,6-trichloropyridinol was detected in soil samples from the treatments with MPs additions than without MP additions, indicating that the presence of MPs inhibited CPF degradation. In conclusion, Bio-MPs caused significant toxicity effects on earthworms and the different types of MPs combined with CPF affected earthworms differently, and their transport along the soil profile. Thus, further research is urgently needed to understand the environmental risks of MPs and MP-associated compounds in the soil ecosystem.

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.

Effect of biochar amendment on metal mobility, phytotoxicity, soil enzymes, and metal-uptakes by wheat (Triticum aestivum) in contaminated soils

The use of low-cost substances such as biochar could be a sustainable approach to reduce the mobility, accumulation, and toxic impact of heavy metals in crop systems. This study investigates the effect of biochar amendment on heavy metal (Cr, Cd, Cu, Pb, Ni, Zn, Mg and Fe) mobility, bioaccumulation factor (BAF), plant (wheat) metal-uptake, plant oxidative stress, and soil enzymatic profile in contaminated industrial soil. Biochar was obtained from slow pyrolysis of Lantana (LBC), and Parthenium (PBC) biomass, and applied at 3% rates in contaminated soils for wheat crop study under a greenhouse experimental setup. Results show in comparison with control setups, low mobility of Cr (14.15-16.35%), Cd (7.17-15.24%), Cu (9.81-12.97%), Pb (7.99-15.23%), Ni (1.52-2.38%), Zn (10.47-14.42%), Mg (48.85-52.89%), and Fe (19.13-19.90%) contents in soils. The heavy metal uptake rates were 63.08% (Cr), 78.07% (Cd), 74.61% (Cu), 78.11% (Pb), 75.73% (Ni), 69.71% (Zn), 28.78% (Mg), and 49.26% (Fe) lower in biochar amendments, compared with the control treatments. Similarly, the biochar amended treatments exhibited low oxidative stress in wheat plants than control setups. In addition, soil enzymes (dehydrogenase, β-glucosidase, alkaline phosphatase, and urease) alleviated in biochar amended soils indicating reduced toxicity of metals in experimental soils. In summary, this study indicates that biochar amendment in contaminated soils not only improves plant growth but also lowers the rates of soil and plant toxicity and metal bioavailability as well.

Plant resistance to disease: Using biochar to inhibit harmful microbes and absorb nutrients

Phytosanitary concerns are part of today's agricultural environment. The use of chemicals to treat plant diseases is both a source of pollution and allows pathogens to become resistant. Additionally, it can improve the chemical, physical, and biological properties of soil. Therefore, the soil environment is more conducive to healthy plant growth. By improving the chemical, physical, and biological attributes of soil, biochar can enhance plant resistance. Agricultural success has been attributed to biochar's acidic pH, which promotes beneficial soil microorganisms and increases soil nutrients; it is also porous, which provides a home and protects soil microorganisms. By improving soil properties, biochar becomes even more effective at controlling pathogens. The article also discusses the benefits of biochar for managing pathogens in agricultural soils. In addition, we examine several research papers that discuss the use of biochar as a method of combating soil-related pathogens and plant diseases. Biochar can be used to combat soil-borne diseases and other conditions.

Biochar application strategies for polycyclic aromatic hydrocarbons removal from soils

Polycyclic aromatic hydrocarbons (PAHs) are known as a hazardous group of pollutants in the soil which causes many challenges to the environment. In this study, the potential of biochar (BC), as a carbonaceous material, is evaluated for the immobilization of PAHs in soils. For this purpose, various bonding mechanisms of BC and PAHs, and the strength of bonds are firstly described. Also, the effect of impressive criteria including BC physicochemical properties (such as surface area, porosity, particle size, polarity, aromaticity, functional group, etc., which are mostly the function of pyrolysis temperature), number of rings in PAHs, incubation time, and soil properties, on the extent and rate of PAHs immobilization by BC are explained. Then, the utilization of BC in collaboration with biological tools which simplifies further dissipation of PAHs in the soil is described considering detailed interactions among BC, microbes, and plants in the soil matrix. The co-effect of BC and biological remediation has been authenticated by previous studies. Moreover, recent technologies and challenges related to the application of BC in soil remediation are explained. The implementation of a combined BC-biological remediation method would provide excellent prospects for PAHs-contaminated soils.

Biochar alleviated the toxicity of atrazine to soybeans, as revealed by soil microbial community and the assembly process

Atrazine has a detrimental effect on soybean growth in corn-soybean rotation systems. A knowledge gap exists regarding how rhizosphere microbial interactions respond to atrazine stress, and specifically, whether they may alleviate the detriment of atrazine on soybeans, this serving as a target to alleviate the adverse impact. Biochar are widely used for remediation in herbicide contamination soil, however, little is known about how biochar fuels the microbiomes in rhizosphere to improve soybean performance. We investigated the response of the microbial community to atrazine stress with and without biochar application to soybean cultivation in a greenhouse experiment. Atrazine had detrimental effects on soybeans and nodules, reshaping the microbial community in both the bulk and rhizosphere soil. Biochar application was able to ameliorate atrazine effects on soybean and nodule activity, with an increase in competition among microbes in the soybean rhizosphere soils. Biochar favored the probiotics such as the bacteria Lysobacter, Paenarthrobacter, and Sediminibacterium in the rhizosphere soils. The relative abundance of Lysobacter exhibited strong-negative correlations with potential pathogens. Elastic net regression with bioindicators and environmental factors accurately predicted the residual content of atrazine in soil. Collectively, our results provide a practical strategy of using biochar to improve soil quality for corn-soybean rotation that is contaminated with residual atrazine. Overall, beneficial plant microbes and changes in microbial interactions and assembly processes in the soybean rhizosphere are capable of alleviating atrazine stress on soybean growth.

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.

Carbon-based catalyst for environmental bioremediation and sustainability: Updates and perspectives on techno-economics and life cycle assessment

Global rise in the generation of waste has caused an enormous environmental concern and waste management problem. The untreated carbon rich waste serves as a breeding ground for pathogens and thus strategies for production of carbon rich biochar from waste by employing different thermochemical routes namely hydrothermal carbonization, hydrothermal liquefaction and pyrolysis has been of interest by researchers globally. Biochar has been globally produced due to its diverse applications from environmental bioremediation to energy storage. Also, several factors affect the production of biochar including feedstock/biomass type, moisture content, heating rate, and temperature. Recently the application of biochar has increased tremendously owing to the cost effectiveness and eco-friendly nature. Thus this communication summarized and highlights the preferred feedstock for optimized biochar yield along with the factor influencing the production. This review provides a close view on biochar activation approaches and synthesis techniques. The application of biochar in environmental remediation, composting, as a catalyst, and in energy storage has been reviewed. These informative findings were supported with an overview of lifecycle and techno-economical assessments in the production of these carbon based catalysts. Integrated closed loop approaches towards biochar generation with lesser/zero landfill waste for safeguarding the environment has also been discussed. Lastly the research gaps were identified and the future perspectives have been elucidated.

Diversity of microbial community structure and their association with phthalic acid esters and physicochemical parameters in informal landfills

Informal landfill is a common waste treatment method employed in rural areas of China, and phthalic acid esters (PAEs) are one of the typical pollutants in landfill leachate. However, there is no corresponding theoretical basis for whether microbial treatment technology can be used to reduce environmental risk of PAEs in informal landfills. Thus, a typical informal landfill site in northern China was selected and approximately 1,133,023 effective sequences were obtained from 21 samples collected from three layers (different deposit depths) of the landfill. This research explored the correlation between PAEs and the composition and distribution of microbial community in specific environments of informal landfill sites. Here we found that dis(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DOP), and diethyl phthalate (DEP) were positively and significantly correlated with Bhargavaea, Planococcus, Virgibacillus, and Oceanobacillus, respectively. The redundancy analysis demonstrated that moisture content, pH, NO2--N, and SUVA254 among the seven physicochemical factors (pH, TN, NO3--N,NO2--N,NH4+-N, SUVA254, and moisture content) significantly affected bacterial communities. The research conclusion can provide theoretical basis for the degradation technology of PAEs by microorganism and research basis for the treatment of informal landfill sites.

Preparation and Characterization of Apricot Kernel Shell Biochar and Its Adsorption Mechanism for Atrazine

In this study, the preparation of apricot kernel shell biochar by a hydrothermal method and its adsorption mechanism for atrazine was studied by scanning electron microscopy (SEM) and infrared spectrum (FTIR) analytical techniques. The results show that the biochar prepared from the apricot kernel shell has an evenly distributed, nonaggregated carbon microsphere structure and contains a large number of oxygen-containing groups. The higher the preparation temperature is, the more functional groups exist and the better the potential adsorption performance is. The adsorption kinetics of atrazine on apricot kernel shell biochar were fitted with a quasi-second-order kinetic equation (R2 ≥ 0.995, p < 0.05). The isothermal adsorption data were in accordance with the Freundlich model (R2 ≥ 0.911, p < 0.05). The adsorption of atrazine on apricot kernel shell biochar includes two processes: surface adsorption and diffusion. The adsorption capacity of apricot kernel shell biochar for atrazine increases with increasing preparation temperature and decreases with increasing pH and Ca2+ concentration. The adsorption mechanism includes hydrogen bonding and hydrophobic interactions. Therefore, biochar prepared from apricot shells, an agricultural waste, exhibits good adsorption performance for atrazine and has a good application prospect in addressing agricultural non-point source pollution, especially in pesticide residue pollution control.

Biochar as environmental armour and its diverse role towards protecting soil, water and air

Biochar has been of considerable importance for various environmental applications in recent years. It has exhibited substantial advantages like favourable structural and surface properties, easy process of preparation and widely available feedstocks. These set of exceptional properties make it an efficient, cost-effective and environment friendly source for diversified elimination of pollutants. The heterogeneity of physico-chemical properties offers a possibility for biochar to optimize its efficacy for targeted applications. This review aims to highlight the critical role that biochar plays in various environmental applications, be it in soil, water or air. In particular the article offers a comprehensive review of the recent research findings and updates related to the diversified role of biochar. Also, the interaction of pollutants with biochar functional groups and the impact of variation of parameters on biochar attribute relevant to specific pollutant removal, modifications, mechanisms involved and competence for such removal has been discussed. Different technologies for production of biochar have also been summarized with an emphasis on post treatment of biochar, such as modification and doping. In addition to this, the underlying gaps in the studies carried out so far and recommendations for future research areas in biochar have also been deliberated.

Reducing environmental risks of chlorpyrifos application in typical soils by adding appropriate exogenous organic matter: Evidence from a simulated paddy field experiment

Chlorpyrifos (CPF), as an organophosphate insecticide extensively used in the modern agricultural system, has been gradually banned in many countries due to its reported health risks to organisms, including humans. This study used simulated paddy field experiments and carbon-14 tracing to explore the possibility of reducing environmental risks of chlorpyrifos application through appropriate agronomic practice. Results showed ¹⁴C-CPF concentration in rice plants planted in the red soil (RS) was significantly higher than that in black soil (BS) and fluvo-aquic soil (FS). The application of biochar and chicken manure in RS reduced ¹⁴C-CPF accumulation in rice plants, and the content of ¹⁴C-CPF in rice grains decreased by 25% and 50%, respectively. Adding biochar to all three soils reduced the migration of ¹⁴C-CPF, especially in FS with the highest risk of ¹⁴C-CPF migration. The addition of chicken manure in FS reduced the migration of ¹⁴C-CPF and the total residual amount of ¹⁴C-CPF in the soil. In addition, chicken manure treatment increased the formation of ¹⁴C-bound residues (BRs) in soils and changed the distribution ¹⁴C-BRs in humus. The results indicated that the degree of environmental risks associated with the CPF application varies with soil types and could be reduced by introducing suitable exogenous organic matter into different soils, which is of great significance for guiding the scientific application of chlorpyrifos in agronomic practices.

Applications of Biochar and Modified Biochar in Heavy Metal Contaminated Soil: A Descriptive Review

Given that the problem of contaminated soil continues to grow, the development of effective control and remediation measures has become imperative, especially for heavy-metal-contaminated soil. Biochar and modified biochar are eco-friendly and cost-effective remediation materials that are widely used in the remediation of contaminated soil. This review provides an overview of the different raw materials used in the preparation of biochar as well as the modification of biochar using various synthesis methods, highlighting their differences and providing recommendations for biochar and modified biochar as applied toward ameliorating pollution in soil contaminated by heavy metals. We also explore the effects of the physicochemical properties of raw materials, pyrolysis temperature, additives, and modification methods on the properties of the resulting biochar and modified biochar, and systematically present the types of soil and operating factors for repair. Moreover, the mechanisms involved in remediation of heavy-metal-contaminated soil by biochar and modified biochar are outlined in detail, and include adsorption, complexation, precipitation, ion exchange, and electrostatic attractions. Finally, the corresponding monitoring technologies after remediation are illustrated. Future directions for studies on biochar and modified biochar in the remediation of contaminated soil are also proposed to support the development of green environmental protection materials, simple preparation methods, and effective follow-up monitoring techniques.

Sustainable remediation of hazardous environmental pollutants using biochar-based nanohybrid materials

Biochar is a well-known carbon material with diversified functionalities and excellent physicochemical characteristics with high wastewater treatment potential. This review aims to summarize recent advancements in the development of biochar and biochar-based nanohybrid materials as a potential tool for the removal of harmful organic compounds such as synthetic dyes/effluents. The formation of biochar using pyrolysis of renewable feedstocks and their applications in various industries are explained hereafter. The characteristics and construction of biochar-based hybrid materials are explained in detail. Diversity of feedstocks, including municipal wastes, industrial byproducts, agricultural, and forestry residues, endows different biochar types with a wide structural variety. The production of cost-effective biochar drives the interest in manipulating biochars and induces desire functionality using nanoscale reinforcements. Various types of biochars, such as magnetic biochar, layered nanomaterial coated biochar, nanometallic oxide composites, chemically and physically functionalized biochar, have been produced. With the aid of nanomaterial, hybrid biochar exhibits a high potential to remove toxic contaminants. Depending upon biochar type, dyes/effluents can be removed via different mechanisms, including the Fenton process, photocatalytic degradation, π-π interaction, electrostatic interaction, and physical adsorption. In conclusion, desired physicochemical features, and tunable surface properties of biochar present high potential material in removing organic dyes and other effluents. The blended biochar with different materials/nanomaterials endows broader development and multi-functional opportunities for treating dyes/effluents.

Alleviation of Chlorpyrifos Toxicity in Maize (Zea mays L.) by Reducing Its Uptake and Oxidative Stress in Response to Soil-Applied Compost and Biochar Amendments

Chlorpyrifos (CP) is a pesticide used extensively in agricultural crops. Residual CP has been found in a variety of soils, vegetables and fruits indicating a serious danger to humans. Therefore, it is necessary to restrict its entry into agricultural products for food safety. A wire-house pot experiment was conducted with maize plants in biochar- and compost-amended soil (at 0.25% and 0.50%, respectively, in weight-by-weight composition) contaminated with 100 and 200 mg kg⁻¹ of CP, respectively. Results indicated toxicity at both CP levels (with 84% growth reduction) at CP 200 mg kg⁻¹. However, application of compost and biochar at the 0.50% level improved the fresh weight (2.8- and 4-fold, respectively). Stimulated superoxide dismutase (SOD) and peroxidase (POX) activities and depressed catalase (CAT) activity were recorded in response to CP contamination and were significantly recovered by the amendments. Both amendments significantly decreased the CP phytoavailability. With biochar, 91% and 76% reduction in the CP concentration in maize shoots and with compost 72% and 68% reduction was recorded, at a 0.50% level in 100 and 200 mg kg⁻¹ contaminated treatments respectively. Compost accelerated the CP degradation in postharvest soil. Therefore, biochar and compost amendments can effectively be used to decrease CP entry in agricultural produce by reducing its phytoavailability.

Biochars and Engineered Biochars for Water and Soil Remediation: A Review

Biochars (BCs) are considered as ecofriendly and multifunctional materials with significant potential for remediation of contaminated water and soils, while engineered biochars (E-BCs) with enlarged surface areas and abundant surface functional groups can perform even better in environmental remediation. This review systematically summarizes the key physical and chemical properties of BCs that affect their pollutant sorption capacities, major methods employed for modification of E-BCs, the performance of BCs/E-BCs in removing major types of organic (e.g., antibiotics and pesticides) and inorganic pollutants (e.g., heavy metals), and the corresponding removal mechanisms. The physical and chemical properties of BCs—such as ash or mineral contents, aromaticity, surface structures, pH, and surface functional groups (e.g., C=O, -COOH, -OH, and -NH2)—depend primarily on their feedstock sources (i.e., plant, sludge, or fecal) and the pyrolysis temperature. Ion exchange, precipitation, electrostatic attraction, and complexation are the main mechanisms involved in the adsorption of inorganic pollutants on BCs/E-BCs, whereas hydrogen bonding, pore filling, electrostatic attraction, hydrophobic interaction, and van der Waals forces are the major driving forces for the uptake of organic pollutants. Despite their significant promises, more pilot and field scale investigations are necessary to demonstrate the practical applicability and viability of BCs/E-BCs in water and soil remediation.

Bioremediation strategies with biochar for polychlorinated biphenyls (PCBs)-contaminated soils: A review

Polychlorinated biphenyls (PCBs) are hazardous organic contaminants threatening human health and environmental safety due to their toxicity and carcinogenicity. Biochar (BC) is an eco-friendly carbonaceous material that can extensively be utilized for the remediation of PCBs-contaminated soils. In the last decade, many studies reported that BC is beneficial for soil quality enhancement and agricultural productivity based on its physicochemical characteristics. In this review, the potential of BC application in PCBs-contaminated soils is elaborated as biological strategies (e.g., bioremediation and phytoremediation) and specific mechanisms are also comprehensively demonstrated. Further, the synergy effects of BC application on PCBs-contaminated soils are discussed, in view of eco-friendly, beneficial, and productive aspects.

Evaluation of Compost and Biochar to Mitigate Chlorpyrifos Pollution in Soil and Their Effect on Soil Enzyme Dynamics

The widespread environmental contamination of chlorpyrifos (CP) has raised human health concerns and necessitated cost-effective methods for its remediation. The current study evaluated the degradation behavior of CP in compost and biochar amended and unamended (original and sterilized) soils in an incubation trial. Two levels of CP (100 and 200 mg kg−1), compost and biochar (0.50%) were applied, and soil was collected at different time intervals. At the higher CP level (200 mg kg−1), CP a showed lower degradation rate (ƙ = 0.0102 mg kg−1 d−1) compared with a low CP level (ƙ = 0.0173 mg kg−1 d−1). The half-lives of CP were 40 and 68 days for CP at 100 and 200 mg kg−1 in original soil, respectively, and increased to 94 and 141 days in sterilized soils. CP degradation was accelerated in compost amended soils, while suppressed in biochar amended soils. Lower half lives of 20 and 37 days were observed with compost application at CP 100 and 200 mg kg−1 doses, respectively. The activities of soil enzymes were considerably affected by the CP contamination and significantly recovered in compost and biochar amended soils. In conclusion, the application of organic amendments especially compost is an important strategy for the remediation of CP contaminated soil.

The Role of Biochar in Regulating the Carbon, Phosphorus, and Nitrogen Cycles Exemplified by Soil Systems

Biochar is a carbon-rich material prepared from the pyrolysis of biomass under various conditions. Recently, biochar drew great attention due to its promising potential in climate change mitigation, soil amendment, and environmental control. Obviously, biochar can be a beneficial soil amendment in several ways including preventing nutrients loss due to leaching, increasing N and P mineralization, and enabling the microbial mediation of N2O and CO2 emissions. However, there are also conflicting reports on biochar effects, such as water logging and weathering induced change of surface properties that ultimately affects microbial growth and soil fertility. Despite the voluminous reports on soil and biochar properties, few studies have systematically addressed the effects of biochar on the sequestration of carbon, nitrogen, and phosphorus in soils. Information on microbially-mediated transformation of carbon (C), nitrogen (N), and phosphorus (P) species in the soil environment remains relatively uncertain. A systematic documentation of how biochar influences the fate and transport of carbon, phosphorus, and nitrogen in soil is crucial to promoting biochar applications toward environmental sustainability. This report first provides an overview on the adsorption of carbon, phosphorus, and nitrogen species on biochar, particularly in soil systems. Then, the biochar-mediated transformation of organic species, and the transport of carbon, nitrogen, and phosphorus in soil systems are discussed. This review also reports on the weathering process of biochar and implications in the soil environment. Lastly, the current knowledge gaps and priority research directions for the biochar-amended systems in the future are assessed. This review focuses on literatures published in the past decade (2009–2021) on the adsorption, degradation, transport, weathering, and transformation of C, N, and P species in soil systems with respect to biochar applications.

Cow bonechar decreases indaziflam pre-emergence herbicidal activity in tropical soil

The addition of carbonaceous material such as cow bonechar to the soil can affect the availability of applied pre-emergent herbicides such as indaziflam. However, how cow bonechar affects the bioavailability of indaziflam is not yet known. The aim of this study was to evaluate the effect of cow bonechar on herbicidal activity of indaziflam on weeds in a tropical soil. Cow bonechar was added homogeneously to top soil, at 1, 2, 5, 10, and 20 t ha^-1, in addition to treatment with unamended soil. At 21 days after indaziflam (75 g ha^-1) application, injury weed levels, weed species that emerged spontaneously were identified and the weeds present in each sampling unit were collected. Only 1.4 t ha^-1 cow bonechar added to soil was enough to reduce the weed injury level by 50%. From the addition of 2 t ha^-1 cow bonechar the application of indaziflam was not efficient to weed control, being equivalent to treatments without herbicide application. Eight weed species (3 monocots and 5 dicots) were identified in all treatments. Eleusine indica and Digitaria horizontalis accounted for about 99.7% of the entire infestation of the weed community. Cow bonechar decreases indaziflam pre-emergence herbicidal activity in tropical soil for weed control, most likely due to the high sorption and unavailability of the product in the soil solution.

Impact of biochar amendment on the uptake, fate and bioavailability of pharmaceuticals in soil-radish systems

Crops grown in soils receiving wastewaters, biosolids, or manures can accumulate pharmaceuticals in edible parts, raising concerns over potential human exposure to multiple pharmaceuticals. Nonetheless, viable mitigation options for minimizing plant uptake of pharmaceuticals are limited. This study evaluated how biochar amendment could influence the uptake of 15 pharmaceuticals by radish (Raphanus sativus) grown in a sandy loam at two amendment rates (0.1 and 1% w/w). Comparing with that in the unamended soil, the accumulation of acetaminophen, carbamazepine, sulfadiazine, sulfamethoxazole, lamotrigine, carbadox, trimethoprim, oxytetracycline, tylosin, estrone, and triclosan in radish grown in the soil amended with 1.0% of biochar was significantly decreased by 33.3-83.0%. However, the concentration of lincomycin in radish was increased by 36.7-48.2% in the soil amended with 1% biochar. While the soil amended with 1.0% of biochar had increased sorption of all 15 pharmaceuticals, the persistence of 7 pharmaceuticals in the soil were prolonged, including caffeine, sulfadiazine, sulfamethoxazole, lincomycin, estrone, 17 β-estradiol and triclosan. The reduced plant uptake of pharmaceuticals was mainly due to their lowered concentrations in pore water by the presence of biochar. Overall, the estimated daily intake data suggest that biochar amendment could potentially decrease total human exposure to a mixture of pharmaceuticals.

The adsorption and mechanism of the nitrification inhibitor nitrapyrin in different types of soils

The nitrapyrin was easily adsorbed by soil, but most current studies have focused on comparing the effects of nitrapyrin application at different soil organic matter levels and in different soil types. The adsorption kinetics and isotherm adsorption of the nitrification inhibitor nitrapyrin in black soil, chernozem and planosol were studied in this paper. The adsorption kinetics were fitted by quasi-second-order kinetic equation (R2 ≥ 0.8907, p < 0.05) with a lower acting energy of adsorption (Ea < 8.0 kJ mol-1). The isotherm was fitted by the Langmuir equation (R2 ≥ 0.9400*, p < 0.05). The adsorption mechanism was determined to involve a spontaneous endothermic reaction accompanied mainly by physical adsorption to the surface that belonged to the 'L' isotherm curve (n > 1). Temperature promoted the adsorption of nitrapyrin in these three soils, and the maximum adsorption occurring at different temperatures following the order of black soil > planosol > chernozem. The adsorption capacity and rate decreased with decreasing soil organic matter. For the black soil, the nitrapyrin EC adsorption rate was more than seven times higher than that of nitrapyrin CS. The result would determine the dose of nitrapyrin required for availability in different types of soils and to provide a theoretical basis for elucidating the adsorption of nitrapyrin in the soil environment.

Stabilization of heavy metal-contaminated soils by biochar: Challenges and recommendations

Various types of biochar have been widely used to remediate soil contamination from heavy metals (HMs) and to reduce HM mobility and bioavailability in soils in recent years. Most researchers have paid attention to the beneficial effects of biochar during the remediation process, but few have emphasized their negative effects and the challenges for their application. In this review, the negative effects and challenges of applying biochar for the remediation of HM-contaminated soils are thoroughly summarized and discussed, including the changeable characteristics of biochar, biochar over-application, toxic substances in biochar, activation of some HMs in soils by biochar, nonspecific adsorption, and the negative influences of biochar on soil microorganisms and plants. In addition, further research directions and several recommendations (standardization, long-term field experiments, mechanisms research and designer biochars) were also proposed to enable the large-scale application of biochar for the remediation of HM-contaminated soils.

Synergistic use of Plantago major and effective microorganisms, EM1 to clean up the soil polluted with imidacloprid under laboratory and field condition

Imidacloprid is known to induce soil pollution. Herein, we improved phytoremediation of soil contaminated with imidacoprid using Plantago major plus effective microorganisms (EM1) and peat-moss under laboratory conditions for 14-days and using P. major inoculated with EM1 in tomato field for 10-days. Concentration of imidacloprid in soil, roots and leaves was determined. Concentrations of Chlorophyll in leaves were also determined. Our results showed that lower imidacloprid degradation rate was observed in amended soil with peat-moss, while higher imidacloprid degradation rate was observed in soils vegetated with P. major, P. major inoculated by EM1, and P. major amended with peat-moss, respectively. However, degradation rate was high in the case of interaction between soil planted with P. major plus both of EM1 and peat-moss. Concentration of imidacloprid in P. major roots amended with EM1, peat-moss and both was significantly lower than that of P. major roots alone within 1-14 days of treatment. EM1 plus P. major and peat- moss plus P. major had increase of Chlorophyl content in leaves. Cultivation of P. major next to tomatoes crop and inoculated with EM-1 was found to be the most effective process for removing imidacloprid from the soil.

Biochar reduced Chinese chive (Allium tuberosum) uptake and dissipation of thiamethoxam in an agricultural soil

Information about the effect of biochar on the environmental fate of pesticide thiamethoxam (THI) in soil-vegetable ecosystems is limited. Therefore, the influence of a wood-derived biochar produced at 450 °C (BC450) on the uptake of THI by Chinese chive (Allium tuberosum) and its dissipation in soil was investigated using a 42-day pot experiment. BC450 addition decreased THI uptake and its metabolite clothianidin (CLO) by 22.8 % and 37.6 %, respectively. However, the half-life of THI in soil rose from 89.4-120 days, indicating that BC450 increased soil THI's persistence. The decreased bioavailability and increased persistence of THI resulted mainly from the higher sorption capacity of BC450 to THI and CLO, which, in turn, enhanced the soil sorption capacity. Consequently, the application of BC450 increased the soil microbial diversity and altered the structure of the microbial community. Although the abundance of Actinobacteria associated with the biodegradation of THI, increased the persistence of THI in the BC450-amended soil, mainly due to the decrease in bioavailable THI. Our findings provide valuable information about the effect of biochar on the fate of THI and its metabolites in agricultural soil and will help to guide the practical application of biochar to remediate soils contaminated with neonicotinoid pesticides.

Sustainable soil amendments to improve nature-based solutions for wastewater treatment and resource recovery

Vegetation Filters (VFs) can be a sustainable solution to treat wastewater and to recover resources such as nutrients, water and biomass from small municipalities and isolated dwellings. However, under certain conditions, the leakage of nutrients, especially of nitrate, can represent a limitation. The addition of two sustainable soil amendments, woodchips and biochar, has been tested as a strategy to improve nutrient attenuation in VFs increasing sorption sites and microbial activity. To this end, unsaturated infiltration and batch experiments have been carried out at laboratory scale. The systems for infiltration experiments contain natural soil, natural soil amended with woodchips and natural soil amended with biochar. To determine the sorption capacity of NH₄⁺, batch tests were performed using an amendment/SWW ratio of 1:20 and an NH₄⁺ initial concentration ranging from 30 to 600 mg L^-1. Results from the infiltration experiments show a high attenuation (~95%) of total phosphorous (TP) independently of the amendments. Different behaviour is observed for total nitrogen (TN). The removal of this species is obtained only in the soil amended with woodchips (>85%) whereas the natural soil alone and the soil with biochar have no impact on TN attenuation. In these two porous media, all the NH₄⁺ input concentration is transformed to NO₃^- that infiltrates without further reactions. According to batch experiment results, the potential role of biochar in the nutrient attenuation is limited to sorption processes (K_d (NH₄⁺) = 21.37-193.18 L kg^-1). Woodchips act primarily as a labile source of carbon promoting biodegradation, being more effective for nutrient attenuation than the sorption capacity of biochar.

Use of Biochar in agriculture

The objective of this review is to show in a general way how biochar (BC) can be obtained and its effects on the physicochemical properties of soils and physiological behavior of cultivated plants. BC is a product rich in carbon that comes from the pyrolysis of biomass, generally of vegetable origin. BC is obtained by the decomposition of organic matter exposed to temperatures between 200-900 ºC in an atmosphere with low oxygen availability (pyrolysis), which can be slow, intermediate or fast. Depending on the biomass and the temperature used in its production, BC can contain high levels of elements such as carbon, nitrogen, oxygen, hydrogen, sulfur, among others. The main sources to produce biochar are forest, agroindustrial and manure residues. BC quality and physical-chemical characteristics will depend not only on the type of waste or plant material for production, but also on the plant photosynthetic apparatus. The high carbon contents present in organic matter, which are more resistant to biological and chemical decomposition, are stabilized by the pyrolysis process. When incorporated into the soil, BC remains stable for longer periods of time and is not volatilized into the atmosphere; this allows BC to be considered as an important compound for the mitigation of the impacts of polluting substances. Additionally, it has been found that BC application improves the physicochemical characteristics of the soil, including fertility. This improvement generates positive responses in the physiological behavior of cultivated plants such as the increase of germination, accumulation of dry matter, photosynthetic rate, yield and quality of the harvested organ. BC use opens important doors for the sustainable management of agriculture in Colombia. It can be considered in production systems exposed to heavy metals such as vegetables and perennial species, in order to reduce the impact of these substances on human health.

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.

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.

Strong Adsorption of Dieldrin by Parent and Processed Montmorillonite Clays

Widespread use of pesticides has resulted in the accumulation of pesticide residues in the environment due to their persistence and stability. To reduce potential exposures, we have developed broad-acting clay-based sorbents that can be included in the diet as enterosorbents to reduce the bioavailability and toxicity of chemicals. In the present study, parent and acid-processed calcium montmorillonite clays (CM and APM, respectively) were used to determine their potential as sorbents of the organochlorine insecticide dieldrin. We used adsorption isotherms, thermodynamics, and dosimetry studies to determine the capacities and affinities of the clays, the enthalpies of the binding reactions, and potential doses of sorbent that could protect against high exposures. Adsorption isotherms for APM fit a Langmuir model with high enthalpy (suggesting chemisorption) and high capacity (Qmax value = 0.45 mol kg-1 ), indicating tight binding of dieldrin. Cultures of Hydra vulgaris were used to determine the ability of sorbents to protect a living organism from dieldrin toxicity. The inclusion of acid-processed clays resulted in the highest reduction of dieldrin toxicity (70%) in the hydra. Further work indicated that both CM and APM can significantly reduce the bioavailability of dieldrin from soil (p ≤ 0.01). These results suggest that APM (and similar clays) can be effective sorbents of dieldrin and may be included in the diet and/or soil to protect against environmental exposures. Environ Toxicol Chem 2020;39:517-525. © 2019 SETAC.

Dynamic processes in conjunction with microbial response to disclose the biochar effect on pentachlorophenol degradation under both aerobic and anaerobic conditions

Organochlorines are critical soil contaminants and the use of biochar has recently shown potential to improve soil remediation. However, little is known about biochar-microbe interactions nor the impact on environmental processes such as the immobilization and biodegradation of organochlorine compounds. In this study, we performed microcosm experiments to elucidate how biochar affected the biodegradation and sequestration of pentachlorophenol (PCP). Our results showed that the amendment of biochar markedly inhibited PCP biodegradation due to a strong sorption affinity for PCP under both aerobic and anaerobic conditions. Notably, the inhibitory effect was relatively weaker under anaerobic conditions than under aerobic conditions. The addition of biochar can dramatically shift the bacterial community diversity in the PCP-spiked soils. Under aerobic conditions, biochar significantly stimulated the growth of PCP-degrading bacteria Bacillus and Sphingomonas, but reduced the opportunities for microbes to contact with PCP directly. Under anaerobic conditions, the non-strict organohalide-respiring bacteria Desulfovibrio, Anaeromyxobacter, Geobacter and Desulfomonile were the main drivers of PCP transformation. Our results imply that the use of biochar as a soil remediation strategy for organochlorine compounds should be cautious.

An innovative strategy for control of fungus gnats using entomopathogenic nematodes alone or in combination with waterlogging

Chive gnat (Bradysia odoriphaga) is a soil-borne pest of Chinese chives, which causes millions of dollars in yield losses per year. Traditional methods, such as chemical pesticides leave detrimental chemical residues on plants, which potentially threaten human health. To find a sustainable method of reducing the chive gnat, the authors evaluated the effects of waterlogging and the addition of entomopathogenic nematode (EPN) on reducing chive gnat in Chinese chives via three pot experiments and one field demonstration. Results indicated that increasing the duration of waterlogging markedly increases chive gnat mortality. The presence of EPN also caused chive gnat mortality to increase with exposure time. Most importantly, the combination of waterlogging and EPN had synergistic effects on chive gnat mortality; the combination led to higher mortality than using waterlogging and EPN alone. The study demonstrated that a combination of two environmental friendly methods of fungus gnat control could lead to synergistic effects, which may provide novel approaches to economic and environmentally sustainable pest management measures.

Chive gnat (Bradysia odoriphaga) is a soil-borne pest of Chinese chives, which causes millions of dollars in yield losses per year. Traditional methods, such as chemical pesticides leave detrimental chemical residues on plants, which potentially threaten human health. To find a sustainable method of reducing the chive gnat, the authors evaluated the effects of waterlogging and the addition of entomopathogenic nematode (EPN) on reducing chive gnat in Chinese chives via three pot experiments and one field demonstration. Results indicated that increasing the duration of waterlogging markedly increases chive gnat mortality. The presence of EPN also caused chive gnat mortality to increase with exposure time. Most importantly, the combination of waterlogging and EPN had synergistic effects on chive gnat mortality; the combination led to higher mortality than using waterlogging and EPN alone. The study demonstrated that a combination of two environmental friendly methods of fungus gnat control could lead to synergistic effects, which may provide novel approaches to economic and environmentally sustainable pest management measures.

Risk Evaluation of Pyrolyzed Biochar from Multiple Wastes

This paper aims at demonstrating the significance of biochar risk evaluation and reviewing risk evaluation from the aspects of pyrolysis process, feedstock, and sources of hazards in biochar and their potential effects and the methods used in risk evaluation. Feedstock properties and the resultant biochar produced at different pyrolysis process influence their chemical, physical, and structural properties, which are vital in understanding the functionality of biochar. Biochar use has been linked to some risks in soil application such as biochar being toxic, facilitating GHGs emission, suppression of the effectiveness of pesticides, and effects on soil microbes. These potential risks originate from feedstock, contaminated feedstock, and pyrolysis conditions that favor the creation of characteristics and functional groups of this nature. These toxic compounds formed pose a threat to human health through the food chain. Determination of toxicity levels is a first step in the risk management of toxic biochar. Various sorption methods of biochar utilized low-cost adsorbents, engineered surface functional groups, and nZVI modified biochars. The mechanisms of organic compound removal was through sorption, enhanced sorption, modified biochar, postpyrolysis thermal air oxidation and that of PFRs degradation was through activation, photoactive functional groups, magnetization, and hydrothermal synthesis. Emissions of GHGs in soils amended with biochar emanated through physical and biotic mediated mechanisms. BCNs have a significance in reducing the health quotient indices for PTEs risk contamination by suppressing cancer risk arising from consumption of contaminated food. The degree of environmental risk assessment of HM pollution in biomass and biochars has been determined by using potential ecological risk index and RAC while organic contaminant degradation by EPFRs was considered when assessing the environmental roles of biochar in regulating the fate of contaminants removal. The magnitude of technologies’ net benefit must be considered in relation to the associated risks.

Effect of Biochar on the Enantioselective Soil Dissipation and Lettuce Uptake and Translocation of the Chiral Pesticide Metalaxyl in Contaminated Soil

Enantioselectivity is usually ignored when assessing potential biochar-based methods of redressing pesticide contamination of soils. In this study, the effect of woodchip biochar (WBC) on the enantioselective dissipation of metalaxyl in soil and its uptake and translocation by lettuce were investigated. S-metalaxyl (T1/2 = 29.8 days) dissipated more quickly than R-metalaxyl (T1/2 = 36.4 days) in unamended soil. The addition of WBC to the soil decreased the dissipation rate and the enantioselectivity of metalaxyl. Metalaxyl distribution showed opposing enantioselectivity in lettuce, with roots and shoots showing preferences for R-metalaxyl and S-metalaxyl, respectively. Enrichment with WBC decreased the concentrations of metalaxyl and metalaxyl acid enantiomers in lettuce and reduced the ability of the shoots to transport the highly toxic R-metalaxyl from roots. This is the first study to provide evidence that amending soil with biochar affects the enantioselective uptake and translocation of a chiral pesticide.

Remediation of heavy metal contaminated soils by biochar: Mechanisms, potential risks and applications in China

There are global concerns about heavy metal (HM) contamination in soils, which in turn has produced an increased demand for soil remediation. Biochar has been widely documented to effectively immobilize metals in contaminated soils and has received increasing attention for use in soil remediation. Here, we review recent progresses in understanding metal-biochar interactions in soils, potential risks associated with biochar amendment, and application of biochar in soil remediation in China. These recent studies indicate that: (1) the remediation effect depends on the characteristics of both biochar and soil and their interactions; (2) biochar applications could decrease the mobility/bioavailability of HMs in soils and HM accumulation in plants; and (3) despite its advantages, biochar applications could pose ecological and health risks, e.g., by releasing toxic substances into soils or by inhalation of biochar dust. Research gaps still exist in the development of practical methods for preparing and applying different biochars that target specific HMs. In the future, the long term effects and security of biochar applications on soil remediation, soil organisms and plant growth need to be considered.

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.

Soil-applied biochar increases microbial diversity and wheat plant performance under herbicide fomesafen stress

The herbicide "fomesafen" causes phytotoxicity to the rotational wheat crop and may reduce its yield. Considering that biochar may improve remediation and biophysical conditions of the contaminated soil environments to benefit plant growth. Here, we investigated the impacts of three levels of the wheat straw-derived biochar (1%, 2%, and 4% (w/w)) on growth, physiological properties, and rhizosphere microbial communities of the wheat (Triticum aestivum) seedlings under the fomesafen stress using high-throughput sequencing. The results showed that biochar amended into soil significantly reduced the uptake of wheat to fomesafen and thereby eliminate its toxicity to wheat seedlings. Moreover, biochar increased the abundance and diversity of plant beneficial bacterial and fungal taxa in the rhizosphere of wheat seedlings. Compared with the three addition amounts, amendment with 2% of biochar has the best effects to reduce the toxicity of fomesafen on wheat seedlings and maintain the balance of soil microbial community structure in soil contaminated with fomesafen (1.0 mg kg^-1). Overall, our results suggest that the level of biochar application influences the structure and diversity of soil microbiome (and mycobiome) and plant performance under abiotic stress conditions.