The Chemical Speciation And Phase Distribution Of Atmospheric Oxidized Mercury
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The Chemical Speciation And Phase Distribution Of Atmospheric Oxidized Mercury
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Author : Avik Ghoshdastidar
language : en
Publisher:
Release Date : 2019
The Chemical Speciation And Phase Distribution Of Atmospheric Oxidized Mercury written by Avik Ghoshdastidar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
"Mercury is a potent global neurotoxin that causes cognitive and neuromuscular damage. it is released through natural and anthropogenic processes, such as fossil fuel combustion, and travels far from its source of origin. A global concern, 130 countries have signed the 2013 UN Convention on Mercury, committing to reducing emissions. Atmospheric mercury primarily exists as three bulk species of which gaseous elemental mercury (GEM) predominates. GEM travels far from its source of origin due to its long atmospheric residence time and deposits in marine and terrestrial environments following chemical transformation to the more water-soluble, bioavailable gaseous oxidized mercury (GOM) and after binding to particulates. In marine environments, oxidized forms of mercury may convert to the highly neurotoxic methylmercury organic species. Conventional mercury analysis techniques cannot determine the chemical forms of mercury present in the atmosphere only whether mercury is present as GEM, GOM or particulate forms. It is also not clear that what is measured as gaseous mercury is entirely gaseous but may be comprised of nano-particulate mercury. Nano-particulate mercury would have significantly different chemical, biologic and human health implications, and would fundamentally change how we model the fate of mercury in the atmosphere, its transformations and risks to ecosystems.In this work, we develop a technique to determine and measure the chemical speciation of atmospheric oxidized mercury using soft-ionization mass spectrometry, generate and characterize reproducible sources of oxidized mercury nanoparticles and assess the determine the gaseous and particulate contributions of mercury(II) bromide and mercury(II) chloride at pg/m3 concentrations in Montreal urban air. " --
Atmospheric Mercury
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Author : Robert W. Talbot
language : en
Publisher: MDPI
Release Date : 2018-09-27
Atmospheric Mercury written by Robert W. Talbot and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-09-27 with Electronic book categories.
This book is a printed edition of the Special Issue "Atmospheric Mercury" that was published in Atmosphere
Examining The Chemistry Of Atmospheric Mercury Using Aircraft Based Measurements And A Global Chemical Transport Model
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Author : Viral Pinakin Shah
language : en
Publisher:
Release Date : 2015
Examining The Chemistry Of Atmospheric Mercury Using Aircraft Based Measurements And A Global Chemical Transport Model written by Viral Pinakin Shah and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Mercury is a potent neurotoxin that accumulates in fish and enters the human food chain. The largest source of mercury to the oceans is from the deposition of atmospheric mercury. Oxidized mercury species (Hg(II)) in the atmosphere are highly soluble and deposit efficiently; thus strongly influence the amount and the spatial distribution of mercury deposition. Currently, the distribution of oxidized mercury species in the atmosphere, and their source from in situ oxidation of elemental mercury (Hg(0)) by reaction with bromine atoms remain poorly understood. The Nitrogen, Oxidants, Mercury, and Aerosol Distribution, Sources, and Sinks (NOMADSS) aircraft experiment was designed with the aim of addressing these limitations. Speciated mercury concentrations were measured over the Southeastern US between June 1 and July 15, 2013 using a novel instrument developed at the University of Washington-Bothell. In this thesis, I use the GEOS-Chem chemical transport model to interpret the NOMADSS mercury measurements, and place new constraints on mercury chemistry in the free troposphere. The mean (and standard deviation) of the observed concentration of total atmospheric mercury (THg) was 1.49 +̲ 0.16 ng/m3, while that of Hg(II) was 111 +̲ 106 pg/m3. 60% of the Hg(II) observations were below the instrument's limit of detection. High concentrations of Hg(II) (300-680 pg/m3) were observed in clean, dry air masses originating in the upper troposphere of the subtropical anticyclones, where fast production and lack of deposition lead to accumulation of Hg(II). The mean THg concentrations modeled by GEOS-Chem are found to be in close agreement with the observations. In contrast, the modeled Hg(II) concentrations are found to be low by a factor of three relative to the observations, indicating a faster than expected oxidation rate.I perform two sensitivity simulations with GEOS-Chem: (i) by increasing bromine radical concentrations by a factor of three, and (ii) by using a faster oxidation rate constant. The model underestimate of observed Hg(II) concentrations in the clean, dry air masses is reduced from a factor of 3 to factors of 2 and 1.6 in the two sensitivity simulations. The modeled lifetime of Hg(0) against oxidation to Hg(II) decreases from 4.8 months in the base simulation to 2.8 months and 1 month, respectively, in the sensitivity simulations. The model predicts that the 500 hPa summertime Hg(II) concentrations are three to five times higher in the subtropical anticyclones than elsewhere, highlighting the role of these regions as significant reservoirs for the global long-range transport of Hg(II). The model results imply that the faster oxidation of Hg(0) leads to a significant increase in the importance of reduction of Hg(II) in the cycling of mercury in the atmosphere.
Speciation And Distribution Of Atmospheric Mercury
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Author : Guey-Rong Sheu
language : en
Publisher:
Release Date : 2001
Speciation And Distribution Of Atmospheric Mercury written by Guey-Rong Sheu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Atmospheric deposition categories.
Atmospheric Chemistry Of Mercury
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Author :
language : en
Publisher:
Release Date : 1997
Atmospheric Chemistry Of Mercury written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with categories.
Elucidating The Effect Of Photons And Aerosols On The Physical And Chemical Transformations Of Atmospheric Mercury
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Author : Sean Alan Tacey
language : en
Publisher:
Release Date : 2019
Elucidating The Effect Of Photons And Aerosols On The Physical And Chemical Transformations Of Atmospheric Mercury written by Sean Alan Tacey and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
The release of mercury to the atmosphere presents notable concerns due to its toxicity, as it can have significant adverse health effects on humans and wildlife. When it is released to the atmosphere, mercury exists in three primary chemical forms: elemental gaseous (Hg(0)), oxidized gaseous (Hg(II)), and particulate-bound (Hg(p)) mercury. Each chemical form exhibits unique atmospheric transport properties and deposition mechanisms, as Hg(0) remains in the atmosphere for months to years and undergoes global transport, while Hg(II) and Hg(p) deposit relatively quickly and undergo local transport. Therefore, it is critical to develop fundamental insights into the transformations between these three chemical forms, as they will have significant implications for the fate of mercury. Accordingly, this work seeks to address atomic-level mechanistic understandings for the physical and chemical transformations of atmospheric mercury that are lacking in the literature. First, the reduction mechanism for Hg(II) species to Hg(0), shown experimentally to require photons and aerosols, is elucidated on sodium-chloride, iron-oxide, and a range of metal-salt surfaces. Second, we develop a framework for deriving DFT-calculated partitioning coefficients to describe the gas-to-particle phase partitioning of atmospheric mercury. Last, we extend these computational methodologies for studying mercury chemistry to develop descriptors to target novel metal-salt materials for use in mercury-capture technologies. Through this work, we hope to provide information critical to the development of improved atmospheric transport models with increased predictive power, as well as target the implementation of enhanced mercury-capture technologies to mitigate the anthropogenic release of mercury to the atmosphere and prevent its adverse health effects on humanity and wildlife.
Chemical Speciation In The Environment
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Author : A. M. Ure
language : en
Publisher: John Wiley & Sons
Release Date : 2008-04-15
Chemical Speciation In The Environment written by A. M. Ure and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-04-15 with Science categories.
Considerable recent research has focused on the topic of chemical speciation in the environment. It is increasingly realised that the distribution, mobility and biological availability of chemical elements depend not simply on their concentrations but, critically, on the forms in which they occur in natural systems. Continuing developments in analytical chemistry have made speciation practicable even where analytes are present at trace levels (as is often the case in natural samples). In the second edition of this book, the expertise of scientists involved in chemical speciation in various fields have been brought together to provide an overview of the current status of speciation science and indicate how the field may develop in the future.
Atmospheric Mercury
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Author : Robert W. Talbot
language : en
Publisher:
Release Date : 2016
Atmospheric Mercury written by Robert W. Talbot and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Environmental sciences categories.
Mercury is a serious environmental toxin that is distributed globally by large-scale atmospheric circulations. The chapters in this book cover measurements of speciated atmospheric mercury, regional modeling, continental-scale distributions across the U.S. and Canada, large-scale distributions in the free troposphere, and changes in wet deposition across the U.S. The diverse topics give snap-shots of current research areas in atmospheric mercury and some insight into policy issues in Europe. Together, the work demonstrates the complexity of atmospheric mercury and provides aspects on measuring and modeling it. Much work is needed in the future to unravel the chemical forms of oxidized atmospheric mercury and how it is intertwined in global cycling of mercury. The complexities of this work are extremely challenging for emerging atmospheric chemists
Environmental Chemistry And Toxicology Of Mercury
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Author : Guangliang Liu
language : en
Publisher: John Wiley & Sons
Release Date : 2011-11-07
Environmental Chemistry And Toxicology Of Mercury written by Guangliang Liu and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-11-07 with Medical categories.
This book provides the fundamentals, recent developments, and future research needs for critical mercury transformation and transport processes, as well as the experimental methods that have been employed in recent studies. The coverage discusses the environmental behavior and toxicological effects of mercury on organisms, including humans, and provides case studies at the end of each chapter. Bringing together information normally spread across several books, this text is unique in covering the entire mercury cycle and providing a baseline for what is known and what uncertainties remain in respect to mercury cycling.
Dynamics Of Mercury Pollution On Regional And Global Scales
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Author : Nicola Pirrone
language : en
Publisher: Springer Science & Business Media
Release Date : 2005-07-22
Dynamics Of Mercury Pollution On Regional And Global Scales written by Nicola Pirrone and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005-07-22 with Nature categories.
This book provides a comprehensive overview of the different dynamic patterns involved in the redistribution of mercury in the global environment, and its impact on human health and ecosystems. Increasing mercury usage and the lack of emission control policy, especially in fast developing countries, represent a complex environmental and political issue that can only benefit from more accurate measurement.