Formation and nature of non-extractable residues of emerging organic contaminants in humic acids catalyzed by laccase

Zhou, Yue; Sun, Feifei; Wu, Xuan; Cao, Siqi; Guo, Xiaoran; Wang, Qilin; Wang, Yongfeng; Ji, Rong

doi:10.1016/j.scitotenv.2022.154300

Cited by 9 publications

(1 citation statement)

References 67 publications

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“…As a result, at the end of incubation, the amount of covalently bound residues in the soil (63 ± 2%) was more than twice that of the entrapped NERs (29 ± 1%); similar distribution was also observed for the sulfadiazine-derived NERs in a silty clay soil . The covalently bound NERs could be formed via ester, ether, and C–C linkages by cross-coupling of free radicals (e.g., phenoxyl radicals) and/or via amide and C–N linkages by nucleophilic addition (e.g., via amino groups) of SMX or TPs to soil organic matter. − Other evidence also suggested that contaminant sequestration in soil could lead to eventual covalent binding of contaminants to the soil matrix during soil aging …”

Section: Resultsmentioning

confidence: 54%

Maize (Zea mays L.) Plants Alter the Fate and Accumulate Nonextractable Residues of Sulfamethoxazole in Farmland Soil

Wu,

Sun,

Cao

et al. 2024

Environ. Sci. Technol.

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The fate of sulfonamide antibiotics in farmlands is crucial for food and ecological safety, yet it remains unclear. We used [phenyl-U-14 C]-labeled sulfamethoxazole ( 14 C-SMX) to quantitatively investigate the fate of SMX in a soil−maize system for 60 days, based on a six-pool fate model. Formation of nonextractable residues (NERs) was the predominant fate for SMX in unplanted soil, accompanied by minor mineralization. Notably, maize plants significantly increased SMX dissipation (kinetic constant k d = 0.30 day −1 vs 0.17 day −1 ), while substantially reducing the NER formation (92% vs 58% of initially applied SMX) and accumulating SMX (40%, mostly bound to roots). Significant NERs (maximal 29−42%) were formed via physicochemical entrapment (determined using silylation), which could partially be released and taken up by maize plants. The NERs consisted of a considerable amount of SMX formed via entrapment (1−8%) and alkali-hydrolyzable covalent bonds (2−12%, possibly amide linkage). Six and 10 transformation products were quantified in soil extracts and NERs, respectively, including products of hydroxyl substitution, deamination, and N-acylation, among which Nlactylated SMX was found for the first time. Our findings reveal the composition and instability of SMX-derived NERs in the soil− plant system and underscore the need to study the long-term impacts of reversible NERs.

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