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Mineralization of Soil‐Aged Isoproturon and Isoproturon Metabolites by Sphingomonas sp. Strain SRS2
Author(s) -
Johannesen Helle,
S⊘rensen Sebastian R.,
Aamand Jens
Publication year - 2003
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2003.1250
Subject(s) - mineralization (soil science) , aniline , chemistry , environmental chemistry , isopropyl , sorption , cometabolism , organic chemistry , bioremediation , nitrogen , contamination , biology , ecology , adsorption
The aim of the study was to determine the effect of aging of the herbicide isoproturon and its metabolites monodesmethyl‐isoproturon and 4‐isopropyl‐aniline in agricultural soil on their availability to the degrading bacterium Sphingomonas sp. strain SRS2. The 14 C‐ring‐labeled isoproturon, monodesmethyl‐isoproturon, and 4‐isopropyl‐aniline were added to sterilized soil and stored for 1, 49, 71, or 131 d before inoculation with strain SRS2. The availability of the compounds was estimated from the initial mineralization and the amount of 14 CO 2 recovered after 120 d of incubation. Aging in soil for 131 d reduced the initial mineralization of isoproturon and monodesmethyl‐isoproturon and, in the case of isoproturon, also reduced the recovery of 14 CO 2 Initial mineralization and recovery of 14 CO 2 from aged 4‐isopropyl‐aniline were slightly reduced, but less 14 CO 2 was generally produced than with isoproturon or monodesmethyl‐isoproturon. Thus, recovery of 14 CO 2 from 14 C‐isoproturon and 14 C‐monodesmethyl‐isoproturon was 50.7 to 64.4% of the initially added 14 C, while recovery from 14 C‐4‐isopropyl‐aniline was only 11.7 to 17.0%. Sorption measurements revealed similar Freundlich constants ( K f ) for isoproturon and monodesmethyl‐isoproturon, whereas K f for 4‐isopropyl‐aniline was more than fivefold greater. The findings imply that in soil, partial degradation of isoproturon to 4‐isopropyl‐aniline may lead to reduced mineralization of the herbicide due to sorption of the aniline moiety.