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Mercury and Legacy Contaminant Concentrations, Trends, Sources and Risks in the Laurentian Great Lakes: Model Development and Application.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Mercury and Legacy Contaminant Concentrations, Trends, Sources and Risks in the Laurentian Great Lakes: Model Development and Application./
作者:	Zhou, Chuanlong.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
面頁冊數:	206 p.
附註:	Source: Dissertations Abstracts International, Volume: 80-08, Section: B.
Contained By:	Dissertations Abstracts International80-08B.
標題:	Environmental Health. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10982095
ISBN:	9780438814950

Mercury and Legacy Contaminant Concentrations, Trends, Sources and Risks in the Laurentian Great Lakes: Model Development and Application.
Zhou, Chuanlong.

Mercury and Legacy Contaminant Concentrations, Trends, Sources and Risks in the Laurentian Great Lakes: Model Development and Application. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 206 p.

Source: Dissertations Abstracts International, Volume: 80-08, Section: B.

Thesis (Ph.D.)--Clarkson University, 2018.

This item must not be sold to any third party vendors.

Mercury (Hg) and other legacy contaminants, including polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichlorethane (DDTs), dieldrin, endrin, chlordane, oxychlordane, nonachlor, Mirex, and hexachlorobenzene (HCB) are being monitored in Laurentian Great Lake (GL) fish by the Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) operated by the U.S. Environmental Protection Agency (EPA). In this thesis, concentration patterns, bioaccumulation, temporal trends, potential sources, and human consumption risks of these contaminants in top predator fish (Lake Trout and Walleye) of the GL region were investigated mainly from 2004 to 2014 (maximum time span was from 1980 to 2016) as a part of GLFMSP. To appropriately interpret the measurement data for contaminant and control the concentration bias caused by the changes in lake trophic status, unique models based on non-parametric statistics, hierarchical clustering methods, and Monte-Carlo concepts were developed for bioaccumulation pattern analysis, concentration normalization (with fish age), trend test, and risk assessment. Temporal trends of fish Hg were determined from 2004 to 2015 with Kendall-Theil robust regression and a cluster-based age normalization method. When data from the GLs (except Lake Erie) are combined, a significant decreasing trend in the lake trout Hg concentrations was found between 2004 and 2015 with an annual decrease of 4.1% per year, consistent with the decline in regional atmospheric Hg emissions and water Hg concentrations. However, a breakpoint in 2010 was detected with a significant decreasing slope (-8.1% per year) before the breakpoint and no trend after the breakpoint. When the lakes are examined individually, Lakes Superior and Huron, which are dominated by atmospheric Hg inputs and are more likely than the lower lakes to respond to declining emissions from areas surrounding the GL, have significant decreasing trends with rates between 5.2 and 7.8% per year from 2004 to 2015. These declining trends appear to be driven by decreasing regional atmospheric Hg emissions although they may be partly counterbalanced by other factors, including increasing local emissions, food web changes, eutrophication, and responses to global climate change. Lakes Michigan, Erie and Ontario may have been more impacted by these other factors and their trends changed from decreasing to non-decreasing or increasing in recent years (after 2010). PBDEs were widely used as fire retardants, and their concentration trends (after fish age normalization) were determined from 1979 to 2016, which includes most of the period when PBDEs were manufactured and used in this region. Including GLFMSP, fish samples for PBDE analysis were also contributed by long-term fish monitoring programs operated by Environment and Climate Change Canada (ECCC). Trends in total concentrations of the five major PBDE congeners (BDE-47, 99, 100, 153, and 154) across all five lakes have varied over time. Significant increases were observed from 1990 to 2000 (16.3% per year). Rapidly decreasing concentrations (-19.5% per year) were found from 2000 to 2007. Since 2007, the decreasing trend has become smaller (less than -5.5% per year) and relatively unchanged from 2011 to 2015. BDE-47, the congener with the highest concentrations in lake trout, has decreased continuously (ranging from -6.7% to -16.2% per year) in all lakes except Lake Erie. This decrease can be associated with the voluntary or regulatory phase out of production and/or usage of PBDEs since 2000. However, it has been offset by recent (since 2007) increasing trends of the other four higher brominated BDE congeners, especially BDE-100 and 154 even though the production and usage of commercial penta- and octa- BDE mixtures containing primarily the five major PBDE congeners was stopped in 2004 in the U.S. and 2008 in Canada. These results indicate increasing fish uptake and bioaccumulation of higher brominated BDE congeners from prey or the environment, which may be related to the transformation of BDE-209 (not accumulated in top predator fish) to lower brominated BDE compounds in the GL environment or food web. Considering the abundance of BDE-209 in existing products and sediment in the GL region, the duration of the constant total PBDE concentration trend in GL fish could be longer than expected. For the other legacy persistent, bioaccumulative and toxic (PBT) contaminants, including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichlorethane (DDTs), dieldrin, endrin, chlordane, oxychlordane, nonachlor, Mirex, and hexachlorobenzene (HCB), concentration trends were determined from 1999-2014. Significant decreasing trends (ranging from -4.1% to -21.6% per year) were found reflecting the successful contaminant release reduction and remediation efforts in the U.S. and Canada. Generally, lower concentrations and faster decreasing trends are observed in western/northern sampling sites compared to eastern/southern sites as the former sites are generally more remote from population centers with fewer industrial activities. HCB has the slowest decreasing trend probably due to its continuous release from existing products/by-products. (Abstract shortened by ProQuest.).

ISBN: 9780438814950Subjects--Topical Terms:

578282
Environmental Health.
Subjects--Index Terms:

Age normalization

Mercury and Legacy Contaminant Concentrations, Trends, Sources and Risks in the Laurentian Great Lakes: Model Development and Application.
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To appropriately interpret the measurement data for contaminant and control the concentration bias caused by the changes in lake trophic status, unique models based on non-parametric statistics, hierarchical clustering methods, and Monte-Carlo concepts were developed for bioaccumulation pattern analysis, concentration normalization (with fish age), trend test, and risk assessment. Temporal trends of fish Hg were determined from 2004 to 2015 with Kendall-Theil robust regression and a cluster-based age normalization method. When data from the GLs (except Lake Erie) are combined, a significant decreasing trend in the lake trout Hg concentrations was found between 2004 and 2015 with an annual decrease of 4.1% per year, consistent with the decline in regional atmospheric Hg emissions and water Hg concentrations. However, a breakpoint in 2010 was detected with a significant decreasing slope (-8.1% per year) before the breakpoint and no trend after the breakpoint. When the lakes are examined individually, Lakes Superior and Huron, which are dominated by atmospheric Hg inputs and are more likely than the lower lakes to respond to declining emissions from areas surrounding the GL, have significant decreasing trends with rates between 5.2 and 7.8% per year from 2004 to 2015. These declining trends appear to be driven by decreasing regional atmospheric Hg emissions although they may be partly counterbalanced by other factors, including increasing local emissions, food web changes, eutrophication, and responses to global climate change. Lakes Michigan, Erie and Ontario may have been more impacted by these other factors and their trends changed from decreasing to non-decreasing or increasing in recent years (after 2010). PBDEs were widely used as fire retardants, and their concentration trends (after fish age normalization) were determined from 1979 to 2016, which includes most of the period when PBDEs were manufactured and used in this region. Including GLFMSP, fish samples for PBDE analysis were also contributed by long-term fish monitoring programs operated by Environment and Climate Change Canada (ECCC). Trends in total concentrations of the five major PBDE congeners (BDE-47, 99, 100, 153, and 154) across all five lakes have varied over time. Significant increases were observed from 1990 to 2000 (16.3% per year). Rapidly decreasing concentrations (-19.5% per year) were found from 2000 to 2007. Since 2007, the decreasing trend has become smaller (less than -5.5% per year) and relatively unchanged from 2011 to 2015. BDE-47, the congener with the highest concentrations in lake trout, has decreased continuously (ranging from -6.7% to -16.2% per year) in all lakes except Lake Erie. This decrease can be associated with the voluntary or regulatory phase out of production and/or usage of PBDEs since 2000. However, it has been offset by recent (since 2007) increasing trends of the other four higher brominated BDE congeners, especially BDE-100 and 154 even though the production and usage of commercial penta- and octa- BDE mixtures containing primarily the five major PBDE congeners was stopped in 2004 in the U.S. and 2008 in Canada. These results indicate increasing fish uptake and bioaccumulation of higher brominated BDE congeners from prey or the environment, which may be related to the transformation of BDE-209 (not accumulated in top predator fish) to lower brominated BDE compounds in the GL environment or food web. Considering the abundance of BDE-209 in existing products and sediment in the GL region, the duration of the constant total PBDE concentration trend in GL fish could be longer than expected. For the other legacy persistent, bioaccumulative and toxic (PBT) contaminants, including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichlorethane (DDTs), dieldrin, endrin, chlordane, oxychlordane, nonachlor, Mirex, and hexachlorobenzene (HCB), concentration trends were determined from 1999-2014. Significant decreasing trends (ranging from -4.1% to -21.6% per year) were found reflecting the successful contaminant release reduction and remediation efforts in the U.S. and Canada. Generally, lower concentrations and faster decreasing trends are observed in western/northern sampling sites compared to eastern/southern sites as the former sites are generally more remote from population centers with fewer industrial activities. HCB has the slowest decreasing trend probably due to its continuous release from existing products/by-products. (Abstract shortened by ProQuest.).
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