2026-09-21T23:51:01Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/49688 2023-07-11 col_2142_5131 col_2142_14737 com_2142_5130 com_2142_690 com_2142_397

Sims, Gerald K. Kent, Angela D. Sims, Gerald K. Metcalf, William W. Yannarell, Anthony C. Kanissery, Ramdas 2014-05-30T17:04:55Z 2014-05-30T17:04:55Z 2016-09-22T20:59:28Z 2014-05 2014-05-30T17:04:55Z 2014-05 Metolachlor and glyphosate are two extensively used herbicides in the USA and throughout the globe. Despite the prevalence of anaerobic wet situations in the soil, the predictive capability for the environmental fate and bioavailability of these herbicides is based primarily on well-drained soil conditions. Anoxic events and flooding ubiquitous to agroecosystems may pose a threat for persistence and transport or conversely may facilitate herbicide degradation. This study was undertaken to explore the knowledge gap in the microbial bioavailability and degradation of metolachlor and glyphosate in aerobic and anaerobic soil conditions. Metolachlor retention pattern in the soils were significantly influenced by anaerobic conditions. Anaerobic soil incubations induced better degradation and mineralization of metolachlor in the range of soils evaluated, despite the differences in soil properties. The findings also confirmed the activity of microorganisms in the degradation and mineralization of metolachlor in the soils in spite differences in their soil properties and redox conditions. The anaerobic degradation and mineralization of metolachlor coincided with the iron (Fe) reducing conditions in soil namely Fe2+ formation and suggested a probable role of Fe in the microbial fate of metolachlor under such soil environmental conditions. Stable isotope probing (SIP) facilitated the identification of microorganisms responsible for the mineralization of metolachlor in aerobic and anaerobic soils. The 16S rRNA gene sequences of clones implied the role of organisms closely related to Bacillus spp. in aerobic and Acidobacteria in anaerobic mineralization of metolachlor in soils. Glyphosate also was influenced by soil redox conditions for bioavailability and mobility in soils. Contrary to metolachlor, the degradation and mineralization of glyphosate exhibited a slower kinetics in anaerobic soils compared to corresponding aerobic soils in all the soil types investigated. Glyphosate degradation was also deduced as a purely microbiological process as almost no degradation or mineralization occurred in sterile control soils. The addition of phosphate suppressed the adsorption of glyphosate in both aerobic and anaerobic soils and confirmed the widespread competition between glyphosate and phosphate for adsorption sites in soils. In summary, the results from this dissertation research clearly highlight the significance of aerobic versus anaerobic soil conditions as an important factor affecting the bioavailability of metolachlor and glyphosate in soils. The information generated from the current study could be applied towards efficacious use of metolachlor and glyphosate in soils and also for framing a viable strategy for the efficient clean-up of soils contaminated by these herbicides. Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2014-04-21T20:18:23Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Kanissery_Ramdas.docx: 3310258 bytes, checksum: d754c29d8f582b8bdd07deb6b7f6a984 (MD5) Kanissery_Ramdas.pdf: 2442920 bytes, checksum: 289e7b146e56d8f3a3d81cfa2de57f62 (MD5) Made available in DSpace on 2014-05-30T17:04:55Z (GMT). No. of bitstreams: 3 Ramdas_Kanissery.pdf: 2440889 bytes, checksum: 6d57b66d59efbeebafca7771ccb61667 (MD5) Kanissery_Ramdas.docx: 3310258 bytes, checksum: d754c29d8f582b8bdd07deb6b7f6a984 (MD5) license.txt: 4066 bytes, checksum: 239c0e326f6f57313c55a342f4709e69 (MD5) Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Seth Robbins (robbins.sd@gmail.com) on 2014-05-30T17:09:35Z Item is restricted until 2016-05-30T17:09:03Z Restriction data tranferred 2014-07-01T11:38:37-05:00 Original Data Group with Access UIUC Users [automated] Release Date: 2016-05-30 12:09:03 UTC Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system U of I Only Restriction Lifted for Item 49739 on 2016-09-22T20:59:28Z. http://hdl.handle.net/2142/49688 en Copyright 2014 Ramdas Kanissery Metolachlor Glyphosate Herbicide Bioavailability Aerobic Soil Anaerobic Soil Adsorption Degradation Mineralization Stable Isotope Probing Bioavailability of metolachlor and glyphosate in aerobic and anaerobic soils text Dissertation Ph.D. Natural Res & Env Sci 1875 Natural Res & Env Sciences 0190 University of Illinois at Urbana-Champaign PHD:Nat Res & Envrn Sci -UIUC 10KS0190PHD