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Environmental transformations of chl...

Carlson, Daniel Lawrence.

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Environmental transformations of chloroacetamide herbicides: Hydrolysis and reactions with iron pyrite.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Environmental transformations of chloroacetamide herbicides: Hydrolysis and reactions with iron pyrite./
Author:	Carlson, Daniel Lawrence.
Description:	255 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 5145.
Contained By:	Dissertation Abstracts International64-10B.
Subject:	Engineering, Environmental. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3107488
ISBN:	0496550379

Environmental transformations of chloroacetamide herbicides: Hydrolysis and reactions with iron pyrite.
Carlson, Daniel Lawrence.

Environmental transformations of chloroacetamide herbicides: Hydrolysis and reactions with iron pyrite. - 255 p.

Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 5145.

Thesis (Ph.D.)--The Johns Hopkins University, 2004.

Chloroacetamides, as a class, are the most widely used herbicides in the U.S., with annual application of approximately 47 million kg. They are also heavily applied in Europe, South America, and Asia (where use is increasing exponentially). This has resulted in widespread contamination of the environment, especially of aquifers. Unlike in surface waters, where transformation can occur relatively rapidly, chloroacetamide fate in groundwater is likely controlled by slower abiotic reactions with water or minerals. This dissertation work investigated the effect of chloroacetamide structure and the surface speciation of iron pyrite on the kinetics and mechanisms of hydrolysis and reactions with pyrite.

ISBN: 0496550379Subjects--Topical Terms:

783782
Engineering, Environmental.

Environmental transformations of chloroacetamide herbicides: Hydrolysis and reactions with iron pyrite.
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100 1 $a Carlson, Daniel Lawrence. $3 1926622
245 1 0 $a Environmental transformations of chloroacetamide herbicides: Hydrolysis and reactions with iron pyrite.
300 $a 255 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 5145.
500 $a Adviser: A. Lynn Roberts.
502 $a Thesis (Ph.D.)--The Johns Hopkins University, 2004.
520 $a Chloroacetamides, as a class, are the most widely used herbicides in the U.S., with annual application of approximately 47 million kg. They are also heavily applied in Europe, South America, and Asia (where use is increasing exponentially). This has resulted in widespread contamination of the environment, especially of aquifers. Unlike in surface waters, where transformation can occur relatively rapidly, chloroacetamide fate in groundwater is likely controlled by slower abiotic reactions with water or minerals. This dissertation work investigated the effect of chloroacetamide structure and the surface speciation of iron pyrite on the kinetics and mechanisms of hydrolysis and reactions with pyrite.
520 $a Under strongly basic and acidic conditions, hydrolysis products and rates of reaction for nine chloroacetamides were found to be affected by the type and size of substituent present. The base-catalyzed reactions typically proceed via intermolecular SN2 mechanisms to produce the hydroxy-substituted derivatives. The products of acid-catalyzed reactions are dependent on the presence and type of N-(alkoxy)alkyl substituent, with three general pathways observed; chloroacetamide reactivity varies over four orders of magnitude. With one notable exception, amide hydrolysis is slow under both acidic and basic conditions, most likely due to steric hindrance. Many of the hydrolysis products were also observed to form in small amounts at neutral pH over a period of 1--3 years.
520 $a Reactions of chloroacetamide herbicides with pyrite (FeS2), a common constituent of aquifers and sediment, revealed that the primary reaction in all cases but one was reductive dechlorination. The reactions occurred on an environmentally relevant time scale, on the order of days. Similar reactivity was observed with pyrrhotite (FeS). Modeling exercises illustrated that both sorption and reaction rate at the pyrite surface influence the overall rate of reaction. Surface spectroscopy revealed an iron oxide layer on reactive pyrite surfaces, which likely facilitates reductive dechlorination. Reactions with chloroacetamide analogs demonstrated that the presence of an alpha-anilide or thioanilide substituent greatly enhances the rate of reductive dechlorination. Sulfur-substituted products and enhanced hydrolysis rates relative to homogeneous aqueous solution were also observed in the pyrite system, likely the result of reaction with pyrite oxidation products.
590 $a School code: 0098.
650 4 $a Engineering, Environmental. $3 783782
650 4 $a Environmental Sciences. $3 676987
650 4 $a Chemistry, Agricultural. $3 1021829
690 $a 0775
690 $a 0768
690 $a 0749
710 2 0 $a The Johns Hopkins University. $3 1017431
773 0 $t Dissertation Abstracts International $g 64-10B.
790 1 0 $a Roberts, A. Lynn, $e advisor
790 $a 0098
791 $a Ph.D.
792 $a 2004
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3107488