Sorption and degradation of imidacloprid and clothianidin in Chinese paddy soil and red soil amended with biochars

Abstract

Application of biochar technology in the remediation of organic contaminated soils has drawn growing interest in recent years. In this study, sorption and degradation of two typical neonicotinoid insecticides, imidacloprid (IMI) and clothianidin (CLO) in Chinese typical paddy soil and red soil amended with six kinds of biochars were investigated. The results showed that surface area (SA), pH, total organic carbon and dissolved organic carbon (DOC) of the two soils all increased after biochar amendment, while H/C decreased. With biochar pyrolyzing temperature (PT) increasing from 300 °C to 700 °C, the sorption of the two insecticides on biochar-soil mixtures increased by more than 4.3-fold, due to the increasing SA and decreasing H/C. The acidic pH of the two tested soils also favored the enhanced sorption of the insecticides by removing the ash on biochar. The amendment of low-PT (300 °C) biochar promoted the biodegradation of IMI and CLO by 11.3-41.9% via providing more DOC and available N for microorganisms, while inhibiting the chemical degradation. Oppositely, the high-PT (500-700 °C) biochars inhibited the biodegradation of the insecticides by decreasing their bioavailability and promoted the chemical degradation by providing mineral active groups, and generating •OH and other free radicals. In addition, soil type also affected the effects of biochar remediation. The highest 60-day degradation extent was achieved for CLO (90.5%) and IMI (81.4%) in paddy soil by adding biochar derived from pig manure at 700 °C PT. In summary, the effect of biochar on the fate of organic contaminants in soil is a comprehensive result involving several processes and a systematic study considering the type and property of biochar and soil is needed to optimize biochar technology.

Biochar for the removal of contaminants from soil and water: a review

“…However, the half-life of THI in the soil increased from 89.4 to 120 days, suggesting that BC450 elevated the persistence of soil THI. Zhang et al (2020d) examined the adsorption and degradation of two representative neonicotinoid insecticides in typical Chinese paddy soil and red soil by six types of biochars. The results indicated that the pH value, total organic carbon, dissolved organic carbon, and surface area of each soil type exhibited an increase following biochar amendment, while H/C reduced.…”

Assessing influences of farmyard manure addition, elevated CO2, soil sterilization, soil types, and soil moisture on clothianidin dissipation kinetics

“…Degrading rate of clothianidin in consortia treatment was much higher than that of natural attenuation and biostimulation, which transforms nitroimino moiety of clothianidin to urea compound by cleavage of different bonds (Wang et al, 2019). Recently, Zhang et al (2020) found that degradation of clothianidin in soil may be associated with biotic and abiotic processes. More specifically, the microbial degradation of neonicotinoids could be greatly influenced by the concentration of insecticides, soil temperature, moisture content, and microorganism adaptability (Pietrzak et al, 2020).…”

A Review on Methods for the Elimination of Imidacloprid: 2018–2022

“…The low pyrolysis temperature favours the biodegradation of pesticide due to the availability of N‐atoms to microorganisms while the high pyrolysis temperature favours the chemical degradation of imidacloprid due to the formation of reactive oxygen species. Among the various kinds of biochar utilized, the best degradation results were found for pig manure biochar at a pyrolysis temperature of 700 °C [56] …”

“…Among the various kinds of biochar utilized, the best degradation results were found for pig manure biochar at a pyrolysis temperature of 700 °C. [56] Voorhees et al, investigated a laboratory bench scale experiment for the imidacloprid removal. For the experimental setup activated carbon, Aquacarb® NS, a reactivated coal/ coconut shell charcoal and biochar derived from organic sustainably grown yellow pine wood which was pyrolyzed at 900 °C was utilized.…”