A critical review of the interactions between rhizosphere and biochar during the remediation of metal(loid)contaminated soils

Biochar has a large specific surface area,well-developed pore structure,abundant surface functional groups,and superior nutrient supply capacity,which is widely available and environmentally friendly with its advantages in waste resource utilization,heavy metal(loid)remediation,and carbon storage.This review focuses on the interactions between biochar(including raw biochar,functional biochar(modified/engineered/designer biochar),and composite biochar)and rhizosphere during the remediation of soil contaminated with heavy metal(loid)s(Pb,As,Cd,Hg,Co,Cu,Ni,Zn,Cr,etc.)and the effects of these interactions on the microbial communities and root exudates(enzymes and low-molecular-weight organic acids(LMWOAs)).In terms of microorganisms,biochar affects the composition,diversity,and structure of microbial communities through the supply of nutrients,provision of microbial colonization sites,immobilization of heavy metal(loid)s,and introduction of exogenous microorganisms.With regard to root exudates,biochar provides electron transfer support between the microorganisms and exudates,regulates the secretion of enzymes to resist the oxidative stress stimulated by heavy metal(loid)s,ameliorates rhizosphere acidification caused by LMWOAs,and promotes the activity of soil enzymes.The roles and mechanisms of biochar on rhizosphere soils are discussed,as well as the challenges of biochar in the remediation of heavy metal(loid)-contaminated soils,and the issues that need to be addressed in future research are foreseen.

Paving the way toward soil safety and health:current status,challenges,and potential solutions

Soil is a non-renewable resource,providing a majority of the world’s food and fiber while serving as a vital carbon reservoir.However,the health of soil faces global threats from human activities,particularly widespread contamination by industrial chemicals.Existing physical,chemical,and biological remediation approaches encounter challenges in preserving soil structure and function throughout the remediation process,as well as addressing the complexities of soil contamination on a regional scale.Viable solutions encompass monitoring and simulating soil processes,with a focus on utilizing big data to bridge micro-scale and macro-scale processes.Additionally,reducing pollutant emissions to soil is paramount due to the significant challenges associated with removing contaminants once they have entered the soil,coupled with the high economic costs of remediation.Further,it is imperative to implement advanced remediation technologies,such as monitored natural attenuation,and embrace holistic soil management approaches that involve regulatory frameworks,soil health indicators,and soil safety monitoring platforms.Safeguarding the enduring health and resilience of soils necessitates a blend of interdisciplinary research,technological innovation,and collaborative initiatives.

Low-carbon stabilization/solidification of municipal solid waste incineration fly ash

Municipal solid waste incineration(MSWI)fly ash(FA)is classified as hazardous waste,which requires additional treatment before disposal or further utilization.Stabilization/solidification(S/S)is regarded as a low-cost and high-efficient method for MSWI FA treatment.“Low-carbon S/S”has captured extensive interest in recent years,which could treat hazardous wastes and enable resource recycling in a sustainable way.This article introduced the state-of-art low-carbon S/S strategies for MSWI FA treatment.The immobilization mechanisms of pollutants in various matrices were also discussed.Prospects were raised to foster the actualization of sustainable management of MSWI FA.