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Chemical transformations of mercury ...

Lin, Che-Jen.

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Chemical transformations of mercury in the multiphase atmosphere.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Chemical transformations of mercury in the multiphase atmosphere./
Author:	Lin, Che-Jen.
Description:	257 p.
Notes:	Chair: Simo Pehkonen.
Contained By:	Dissertation Abstracts International60-04B.
Subject:	Chemistry, Inorganic. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9928147
ISBN:	0599278994

Chemical transformations of mercury in the multiphase atmosphere.
Lin, Che-Jen.

Chemical transformations of mercury in the multiphase atmosphere. - 257 p.

Chair: Simo Pehkonen.

Thesis (Ph.D.)--University of Cincinnati, 1998.

Understanding the chemical reactions responsible for interchanging atmospheric mercury between different oxidation states is critical to evaluate the global cycling of mercury in the environment.

ISBN: 0599278994Subjects--Topical Terms:

517253
Chemistry, Inorganic.

Chemical transformations of mercury in the multiphase atmosphere.
LDR:04516nam 2200349 a 45 001 933175
005 20110505
008 110505s1998 eng d
020 $a 0599278994
035 $a (UnM)AAI9928147
035 $a AAI9928147
040 $a UnM $c UnM
100 1 $a Lin, Che-Jen. $3 1256914
245 1 0 $a Chemical transformations of mercury in the multiphase atmosphere.
300 $a 257 p.
500 $a Chair: Simo Pehkonen.
500 $a Source: Dissertation Abstracts International, Volume: 60-04, Section: B, page: 1505.
502 $a Thesis (Ph.D.)--University of Cincinnati, 1998.
520 $a Understanding the chemical reactions responsible for interchanging atmospheric mercury between different oxidation states is critical to evaluate the global cycling of mercury in the environment.
520 $a The first phase of the study is to investigate the aqueous-phase photoreduction of dissolved divalent mercury [Hg(II)] in the presence of formate, acetate and oxalate under the irradiation of simulated sunlight. It is found that Hg(II) can be readily reduced in the presence of oxalate under the irradiation. The responsible reductant is hydroperoxyl radical (HO2<super>· </super>), which is formed by the photolysis of oxalate. The second-order rate constant for the Hg(II)-HO2<super>·</super> reaction is determined to be 1.7 × 10<super>4</super> M<super>−1</super>s<super> −1</super>.
520 $a The second phase of the study is to investigate the photocatalytic effect of various iron oxides and ambient aerosols in the Hg(II)-organic acid system. It is found that the presence of the iron oxides can enhance the photoreduction of Hg(II) in the aqueous phase. In the presence of both hematite and oxalate, Hg(II) is reduced at the beginning of the photochemical experiment, followed by a re-oxidation of the reduced mercury species back to Hg(II). The enhancement of Hg(II) reduction is due to the facilitation of HO2<super>·</super> production in the presence of iron oxides, while the re-oxidation is caused by the formation of hydroxyl radical (<super>·</super>OH) in the oxalate-hematite system. The second-order rate constant for Hg<super>0</super>-<super>·</super>OH reaction is measured to be 2.0 × 109 M<super>−1</super>s<super>−1</super>.
520 $a The third phase of the study is to develop a chemical kinetic model for evaluating mercury chemistry in a multiphase atmospheric environment (e.g., cloud, fog or haze aerosol). The model components include the chemical reactions and equilibria important for mercury transformations and mass transfer of the reacting species between the two phases. Mass transfer of the reactants does not limit the rate of the transformations of mercury, and the gaseous-phase oxidation of elemental mercury (Hg0) can contribute a significant fraction of Hg(II) in the aqueous phase.
520 $a The fourth phase of the study is to investigate the stoichiometry and kinetics of Hg<super>0</super> oxidation by aqueous chlorine (HOCl/OCl<super> −</super>). The stoichiometry is found to be 1:1, the same as the electron transfer ratio between Hg<super>0</super> and aqueous chlorine. The second-order rate constants of the Hg<super>0</super>-HOCl and Hg<super>0</super>-OCl<super> −</super> reactions are measured to be 2.09 × 10<super>6</super> and 1.99 × 10<super>6</super> M<super>−1</super>s<super>−1 </super>, respectively. Simulations using the chemical kinetic model with the obtained kinetic parameters show that ozone (O3) and <super> ·</super>OH are the dominant oxidants for Hg<super>0</super> in the daytime atmosphere, while chlorine is the dominant oxidant in the nighttime atmosphere.
520 $a The fifth phase of the study is to critically review all the transformation pathways of atmospheric mercury identified to date. Thermodynamic data of mercury of atmospheric interest are presented. The instability of Hg(I) and methylated mercury species, aqueous speciation of Hg(II), and the role of sunlight radiation and atmospheric particles are addressed. (Abstract shortened by UMI.)
590 $a School code: 0045.
650 4 $a Chemistry, Inorganic. $3 517253
650 4 $a Environmental Sciences. $3 676987
650 4 $a Physics, Atmospheric Science. $3 1019431
690 $a 0488
690 $a 0608
690 $a 0768
710 2 0 $a University of Cincinnati. $3 960309
773 0 $t Dissertation Abstracts International $g 60-04B.
790 $a 0045
790 1 0 $a Pehkonen, Simo, $e advisor
791 $a Ph.D.
792 $a 1998
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9928147