The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland

Bibliographic Details
Main Author:	Cawley, Kaelin Marie
Language:	English
Published:	The Ohio State University / OhioLINK 2005
Subjects:	Environmental Science
Online Access:	http://rave.ohiolink.edu/etdc/view?acc_num=osu1406647483

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spelling	ndltd-OhioLink-oai-etd.ohiolink.edu-osu14066474832021-08-03T06:26:15Z The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland Cawley, Kaelin Marie Environmental Science Non-point source pollution including herbicides, nutrients, pharmaceuticals, and personal care products contributes to the degradation of surface waters around the world. Indirect photolysis of these contaminants in wetland environments rich in dissolved organic matter (DOM) and nitrate has been shown to be an important degradation pathway. One major goal of this research is to determine whether wetlands are a good setting for the photochemistry of two commonly used agrochemicals: atrazine and metolachlor. In particular, I would like to determine the relative importance of DOM and nitrate to the photolysis of these chemicals. The other goal is to determine if the isolation method and water source have an effect on the photochemical reactivity of DOM when probed with 2,4,6-trimethylphenol (TMP), a substituted phenol.In order to determine the pathway for the degradation of both TMP and the herbicides, scavenging experiments were used. MeOH was used to remove OH• from the reaction. The TMP reaction rate was not changed by the addition of MeOH, while both herbicide reactions were essentially shut down completely by the addition of MeOH. Therefore, it seems that the relative rate of OH• production by natural water is important to the degradation of herbicides and not involved in the photolysis of TMP. The herbicides did not have a significantly different reaction rate when argon sparged to remove the majority of O2 from the system. This indicates that pathways involving O2 are not important for the degradation of either TMP or the herbicides. Two major sources of OH• that are produced anoxically involve DOM and nitrate. A ROS pathway involving O2 is not important to the degradation of the herbicides. TMP reacted more quickly when sparged with argon indicating that O2 was probably scavenging the reactive moiety. Singlet oxygen is known to be produced by the reaction of O2 with triplet state DOM. Using NaN3 as a scavenger for singlet oxygen, the TMP reaction rate did not change. This indicates that triplet DOM is most likely responsible for the photolysis of TMP.TMP reactions were also performed using isolates from two water sources. Old Woman Creek (OWC) is a eutrophic wetland in northwestern Ohio on the coast of Lake Erie. Water from a seep located along Oksirukuyurik (Oks) Creek in the Alaskan Artic was also used. The DOM from OWC is a mixture of microbial and terrestrial DOM, while Oks DOM is almost entirely terrestrially derived from higher tundra plants. TMP degradation was on average faster in OWC DOM solutions than Oks DOM solutions. The DOM from the two different water sources was isolated by two chromatography methods: XAD and C-18 and a physical method tangential flow ultrafiltration (TFUF). The OWC isolates all had statistically different reaction rates. The TFUF and XAD Oks isolates had statistically different reaction rates, but C-18 was not statistically different.The herbicides degraded more quickly than would be expected if nitrate was the only OH• producing moiety. So, DOM is hypothesized to be important. However, Fe might be involved as well.So, the wetland system looks like it is very good for photochemistry of the herbicides since there are both DOM and high nitrate concentrations that coincides with high herbicide concentrations to produce the hydroxyl radical. The isolation method used to concentrate the DOM and water source also affect the reactivity of TMP which means that it probably has an effect on the reactivity of other chemicals. 2005 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1406647483 http://rave.ohiolink.edu/etdc/view?acc_num=osu1406647483 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection	NDLTD
language	English
sources	NDLTD
topic	Environmental Science
spellingShingle	Environmental Science Cawley, Kaelin Marie The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland
author	Cawley, Kaelin Marie
author_facet	Cawley, Kaelin Marie
author_sort	Cawley, Kaelin Marie
title	The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland
title_short	The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland
title_full	The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland
title_fullStr	The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland
title_full_unstemmed	The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland
title_sort	sensitized photolysis of 2,4,6-trimethylphenol, atrazine and metolachlor in a temperate eutrophic wetland
publisher	The Ohio State University / OhioLINK
publishDate	2005
url	http://rave.ohiolink.edu/etdc/view?acc_num=osu1406647483
work_keys_str_mv	AT cawleykaelinmarie thesensitizedphotolysisof246trimethylphenolatrazineandmetolachlorinatemperateeutrophicwetland AT cawleykaelinmarie sensitizedphotolysisof246trimethylphenolatrazineandmetolachlorinatemperateeutrophicwetland
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The sensitized photolysis of 2,4,6-Trimethylphenol, Atrazine and Metolachlor in a temperate Eutrophic wetland

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