Sørensen Sebastian R, Aamand Jens
Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Oster Voldgade 10, DK-1350 Copenhagen K, Denmark.
Pest Manag Sci. 2003 Oct;59(10):1118-24. doi: 10.1002/ps.739.
Mineralisation of the phenylurea herbicide isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) and two of its known metabolites, 3-(4-isopropylphenyl)-1-methylurea (monodesmethyl-isoproturon) and 4-isopropylaniline, was studied in Danish agricultural soils with or without previous exposure to isoproturon. A potential for rapid mineralisation of isoproturon and the two metabolites was present in soils sampled from three plots within an agricultural field previously treated regularly with the herbicide, with 34-45%, 51-58% and 33-36% of the added [phenyl-U-14C]isoproturon, [phenyl-U-14C]monodesmethyl-isoproturon and [phenyl-U-14C]4-isopropylaniline metabolised to [14C]carbon dioxide within 30 days at 20 degrees C. In contrast, such extensive mineralisation of these three compounds was not observed within this period in soils sampled from two other agricultural fields without previous treatment with isoproturon. The mineralisation patterns indicated growth-linked metabolism of the three compounds in the previously exposed soils, and doubling times for [14C]carbon dioxide production ranged from 1.6 to 3.2, 1.0 to 2.1 and 1.3 to 1.7 days for isoproturon, monodesmethyl-isoproturon and 4-isopropylaniline, respectively. The ability to mineralise [phenyl-U-14C]isoproturon to [14C]carbon dioxide was successfully sub-cultured to a fresh mineral medium which provided isoproturon as sole source of carbon and nitrogen. One of the soils sampled from an agricultural field not previously treated with isoproturon showed accelerated mineralisation of [phenyl-U-14C]4-isopropylaniline toward the end of the experiment, with a doubling time for [14C]carbon dioxide production of 7.4days. This study indicates that the occurrence of rapid mineralisation of the phenyl ring of isoproturon to carbon dioxide is related to previous exposure to the herbicide, which suggests that microbial adaptation upon repeated isoproturon use may occur within agricultural fields.
在丹麦的农业土壤中，研究了苯基脲类除草剂异丙隆（3-(4-异丙基苯基)-1,1-二甲基脲）及其两种已知代谢物3-(4-异丙基苯基)-1-甲基脲（单去甲基异丙隆）和4-异丙基苯胺的矿化作用，这些土壤有的曾接触过异丙隆，有的则没有。在一块曾定期施用该除草剂的农田内，从三个地块采集的土壤中，异丙隆及其两种代谢物具有快速矿化的潜力。在20℃条件下，30天内添加的[苯基-U-¹⁴C]异丙隆、[苯基-U-¹⁴C]单去甲基异丙隆和[苯基-U-¹⁴C]4-异丙基苯胺分别有34 - 45%、51 - 58%和33 - 36%代谢为[¹⁴C]二氧化碳。相比之下，在另外两块未用过异丙隆的农田采集的土壤中，这三种化合物在此期间未观察到如此广泛的矿化作用。矿化模式表明，在先前接触过异丙隆的土壤中，这三种化合物的代谢与生长相关，异丙隆、单去甲基异丙隆和4-异丙基苯胺产生[¹⁴C]二氧化碳的倍增时间分别为1.6至3.2天、1.0至2.1天和1.3至1.7天。将[苯基-U-¹⁴C]异丙隆矿化为[¹⁴C]二氧化碳的能力成功继代培养到一种新鲜的矿物培养基中，该培养基以异丙隆作为唯一的碳源和氮源。在实验快结束时，从一块未用过异丙隆的农田采集的一种土壤中，[苯基-U-¹⁴C]4-异丙基苯胺的矿化加速，产生[¹⁴C]二氧化碳的倍增时间为7.4天。这项研究表明，异丙隆苯环快速矿化为二氧化碳的现象与先前接触该除草剂有关，这表明在农田中，反复使用异丙隆后可能会发生微生物适应现象。
