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Understanding Sources and Cycling of...

Rahman, Nabila,

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Understanding Sources and Cycling of Mercury in Terrestrial and Aquatic Ecosystems Using Mercury Stable Isotopes /

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Understanding Sources and Cycling of Mercury in Terrestrial and Aquatic Ecosystems Using Mercury Stable Isotopes // Nabila Rahman.
作者:	Rahman, Nabila,
面頁冊數:	1 electronic resource (258 pages)
附註:	Source: Dissertations Abstracts International, Volume: 86-05, Section: B.
Contained By:	Dissertations Abstracts International86-05B.
標題:	Geochemistry. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31331336
ISBN:	9798342756815

Understanding Sources and Cycling of Mercury in Terrestrial and Aquatic Ecosystems Using Mercury Stable Isotopes /
Rahman, Nabila,

Understanding Sources and Cycling of Mercury in Terrestrial and Aquatic Ecosystems Using Mercury Stable Isotopes /Nabila Rahman. - 1 electronic resource (258 pages)

Source: Dissertations Abstracts International, Volume: 86-05, Section: B.

Mercury (Hg) is a trace metal pollutant that is a neurotoxin, found in both inorganic (IHg: Hg0 , Hg2+) and the more toxic organo-metallic (e.g., monomethylmercury, MMHg) forms. Both historically and currently, IHg was/is released into aquatic ecosystems through industrial and mining activities, where it can be transformed into MMHg, that bioaccumulates in food webs and poses risks to both humans and wildlife. Legacy Hg pollution can still pose a threat to modern ecosystems if it becomes methylated. Hence, it is crucial to locate legacy IHg sources, understand the processes and environments that convert IHg to MMHg, and determine whether this MMHg is still entering food webs. In chapter 2, Hg isotopic compositions are used to link Hg discharges from a former chlor-alkali plant to Hg in contaminated sediments and lower trophic biota in the St. Clair River. This project is a good example of a setting where Hg isotopes successfully delineated Hg sources and demonstrated that a legacy Hg source (decades old) is still entering the food web. Chapter 3 presents a more complex system where multiple Hg sources converge and mix. Because the isotopic compositions of Hg-contaminated sediments from the historically industrialized St. Lawrence River fell within the range of documented industrial Hg isotopic signatures, they were not able to distinguish between various industrial sources, such as chloralkali and paper and pulp industries, due to the mixing and similarity of the isotopic compositions of the sources. However, Hg isotopes support how pervasive industrial Hg contamination is in the region. Chapter 5 delves into the atmosphere-terrestrial cycling of Hg, particularly the isotopic fractionation as plants uptake and adsorb Hg from the atmosphere. Because Hg isotopes are now an important tool to delineate and quantify sources and deposition pathways to forest soils, which are one of the largest sinks of Hg, I investigated the consistency of the atmosphere-vegetation Hg isotopic offsets between and within different plant species, as this is a crucial variable in isotopic modelling. In a Canadian boreal-deciduous mixed forest (Limberlost Forest and Wildlife Reserve), offsets were reasonably consistent between and within species. This dissertation demonstrates the utility of Hg isotopes in source characterization and quantification, but also highlights some of the limitations of using Hg isotopes.

English

ISBN: 9798342756815Subjects--Topical Terms:

539092
Geochemistry.
Subjects--Index Terms:

Mercury

Understanding Sources and Cycling of Mercury in Terrestrial and Aquatic Ecosystems Using Mercury Stable Isotopes /
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520 $a Mercury (Hg) is a trace metal pollutant that is a neurotoxin, found in both inorganic (IHg: Hg0 , Hg2+) and the more toxic organo-metallic (e.g., monomethylmercury, MMHg) forms. Both historically and currently, IHg was/is released into aquatic ecosystems through industrial and mining activities, where it can be transformed into MMHg, that bioaccumulates in food webs and poses risks to both humans and wildlife. Legacy Hg pollution can still pose a threat to modern ecosystems if it becomes methylated. Hence, it is crucial to locate legacy IHg sources, understand the processes and environments that convert IHg to MMHg, and determine whether this MMHg is still entering food webs. In chapter 2, Hg isotopic compositions are used to link Hg discharges from a former chlor-alkali plant to Hg in contaminated sediments and lower trophic biota in the St. Clair River. This project is a good example of a setting where Hg isotopes successfully delineated Hg sources and demonstrated that a legacy Hg source (decades old) is still entering the food web. Chapter 3 presents a more complex system where multiple Hg sources converge and mix. Because the isotopic compositions of Hg-contaminated sediments from the historically industrialized St. Lawrence River fell within the range of documented industrial Hg isotopic signatures, they were not able to distinguish between various industrial sources, such as chloralkali and paper and pulp industries, due to the mixing and similarity of the isotopic compositions of the sources. However, Hg isotopes support how pervasive industrial Hg contamination is in the region. Chapter 5 delves into the atmosphere-terrestrial cycling of Hg, particularly the isotopic fractionation as plants uptake and adsorb Hg from the atmosphere. Because Hg isotopes are now an important tool to delineate and quantify sources and deposition pathways to forest soils, which are one of the largest sinks of Hg, I investigated the consistency of the atmosphere-vegetation Hg isotopic offsets between and within different plant species, as this is a crucial variable in isotopic modelling. In a Canadian boreal-deciduous mixed forest (Limberlost Forest and Wildlife Reserve), offsets were reasonably consistent between and within species. This dissertation demonstrates the utility of Hg isotopes in source characterization and quantification, but also highlights some of the limitations of using Hg isotopes.
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653 $a Aquatic ecosystems
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