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在巴西伯南布哥州锡林哈埃姆的热带土壤实验室条件下氟虫腈的降解情况。

Degradation of fipronil under laboratory conditions in a tropical soil from sirinhaém pernambuco, Brazil.

作者信息

Masutti Carmem S M, Mermut Ahmet R

机构信息

Colegiado de Engenharia Agrícola e Ambiental, Fundação Universidade Federal do Vale do São Francisco, Petrolina, Brazil.

出版信息

J Environ Sci Health B. 2007 Jan;42(1):33-43. doi: 10.1080/03601230601017981.

Abstract

The objective of this research was to assess the degradation of fipronil [5-amino-1-(2,6-dichloro-alpha,alpha,alpha -trifluoro-p-tolyl)-4-trifluoromethylsulfinylpyrazole-3-carbonitrile] in soils from sugar cane fields in Northeastern Brazil. Degradation experiments were carried out under laboratory conditions (controlled temperature and in the dark), where sterile and non-sterile soils (Ustoxs) were incubated [under moisture content of 55% of the water holding capacity (WHC)] and analyzed for fipronil disappearance and metabolite formation. Microbial communities present in the soil degrade fipronil. However, biodegradation seems to be dependent on the bioavailability of the fipronil and the half-life according to the zero-order model. Fipronil degradation rate appeared to be biphasic. Degradation fipronil ranged from 83 days (initial concentration = 978 ng g(-1); short-term experiment) to 200 days (initial concentration = 689 ng g(-1); long-term experiment). This an initial slower rate followed by a faster rate after 90 days of incubation may lead to shorter half-life than that calculated with the zero-order model. The sulfone derivative (an oxidation product) was the predominant metabolite, but the sulfide (a reduction product) and amide (a hydrolysis product) derivatives were also formed under non-sterile conditions after 120 days of incubation. The metabolites underwent further biodegradation, particularly the sulfone derivative. Bioavailability appears to affect fipronil degradation in soils with an effective capacity to adsorb fipronil (such as Ustoxs), while redox potential was important for the formation of metabolites. Despite the fine texture, more aerobic sites were present, thus favoring the formation of the sulfone metabolite over that of the sulfide metabolite. Therefore, microaggregation of Ustoxs, with high clay content, played a very important role in determining the types of metabolites formed.

摘要

本研究的目的是评估氟虫腈[5-氨基-1-(2,6-二氯-α,α,α-三氟对甲苯基)-4-三氟甲基亚砜基吡唑-3-腈]在巴西东北部甘蔗田土壤中的降解情况。降解实验在实验室条件下(控制温度且避光)进行,将无菌和非无菌土壤(氧化土)在持水量(WHC)的55%湿度下进行培养,并分析氟虫腈的消失情况和代谢产物的形成。土壤中存在的微生物群落会降解氟虫腈。然而,根据零级模型,生物降解似乎取决于氟虫腈的生物有效性和半衰期。氟虫腈的降解速率似乎呈双相。氟虫腈的降解时间从83天(初始浓度=978 ng g⁻¹;短期实验)到200天(初始浓度=689 ng g⁻¹;长期实验)不等。这种初始较慢的速率随后在培养90天后加快的速率可能导致半衰期比用零级模型计算的更短。砜衍生物(一种氧化产物)是主要的代谢产物,但在非无菌条件下培养120天后,也会形成硫化物(一种还原产物)和酰胺(一种水解产物)衍生物。这些代谢产物会进一步发生生物降解,尤其是砜衍生物。生物有效性似乎会影响氟虫腈在具有有效吸附氟虫腈能力的土壤(如氧化土)中的降解,而氧化还原电位对代谢产物的形成很重要。尽管质地细腻,但存在更多的好氧位点,因此有利于砜代谢产物的形成而非硫化物代谢产物。因此,高粘土含量的氧化土的微团聚作用在决定形成的代谢产物类型方面起到了非常重要的作用。

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