Arthur E L, Anhalt J C, Anderson T A, Coats J R
Department of Entomology, Iowa State University, Ames, USA.
J Environ Sci Health B. 1997 Sep;32(5):599-620. doi: 10.1080/03601239709373105.
The degradation of deethylatrazine (DEA), a major metabolite of atrazine, was studied by using radiotracers in soils with two different atrazine histories. DEA degradation was enhanced in soils which had received long-term exposure to atrazine (atrazine-history soil) compared with soils that had not received long-term atrazine exposure (no-history soil). After 60 days of incubation, mineralization of DEA to 14CO2 in the atrazine-history surface soil was twice that in the no-history surface soils, with 34% and 17% of the applied 14C-DEA as CO2, respectively. In surface soils, 25% of the applied 14C remained as DEA in the atrazine-history soil, compared with 35% in the no-history soil. Microbial plate counts indicated an increase in numbers of bacteria and fungi in soils incubated with DEA compared to control soils. No significant difference in total microbial respiration was seen among atrazine-history and no-history soils incubated with DEA, but DEA-treated soils had greater microbial respiration than untreated control soils after 6 days. A 14C-most-probable-number procedure was used to enumerate specific DEA degraders. A greater number of DEA degraders were indicated in atrazine-history subsurface soil compared with all other soils in this study (p < 0.05). From this study, it appears that an increase in microbial activity contributes to decreased persistence and increased degradation of DEA in soils that have had long-term exposure to atrazine at field application rates, compared to soils with no long-term exposure. Decreased persistence of this major metabolite of atrazine in atrazine-history soils is important in that there will be less available for movement in surface runoffs.
使用放射性示踪剂，在两种具有不同阿特拉津历史的土壤中研究了阿特拉津的主要代谢产物去乙基阿特拉津（DEA）的降解情况。与未长期接触阿特拉津的土壤（无历史土壤）相比，长期接触阿特拉津的土壤（阿特拉津历史土壤）中DEA的降解有所增强。培养60天后，阿特拉津历史表层土壤中DEA矿化生成(^{14}CO_2)的量是无历史表层土壤的两倍，分别有34%和17%施加的(^{14}C - DEA)以(CO_2)形式存在。在表层土壤中，施加的(^{14}C)有25%在阿特拉津历史土壤中以DEA形式残留，而在无历史土壤中这一比例为35%。微生物平板计数表明，与对照土壤相比，用DEA培养的土壤中细菌和真菌数量增加。用DEA培养的阿特拉津历史土壤和无历史土壤之间，总微生物呼吸未见显著差异，但6天后，经DEA处理的土壤比未处理的对照土壤有更强的微生物呼吸。采用(^{14}C)最可能数法对特定的DEA降解菌进行计数。与本研究中的所有其他土壤相比，阿特拉津历史亚表层土壤中显示出更多的DEA降解菌（p < 0.05）。从这项研究来看，与未长期接触的土壤相比，长期以田间施用量接触阿特拉津的土壤中，微生物活性的增加有助于降低DEA的持久性并增加其降解。阿特拉津的这种主要代谢产物在阿特拉津历史土壤中持久性降低很重要，因为其在地表径流中迁移的可能性会降低
