Thesis (M.S.)--Ohio University, June, 2005. / Title from PDF t.p. Includes bibliographical references (p. 129-135)

The aims of this study include (1) Examine the total mercury and organic mercury concentrations in the muscle and liver tissues of dolphinfish, Coryphaena hippurus that collected in Tungkang and Taitung, Taiwan, in order to understand their safety consumption by human beings due to their high trophic level in a marine ecosystem; (2) Investigate the species difference in comparison to other marine high trophic organisms, e.g. shark, tuna; (3) Look for the pattern of Hg bioaccumulation to see whether it matches the three models defined by Holsbeek et al. A total of 209 samples of Coryphaena hippurus were collected from Tungkang and Taitung. In the 34 samples from Tungkang, males and females were 11 and 23, respectively, whereas 197 samples from Taitung included 92 males and 83 females. Samples from Tungkang were investigated individually, but those from Taitung were pooled by size into 58 samples, 27 males and 24 females. The Hg levels in the samples were wet digested and determined by cold vapor atomic absorption spectrophotometer. The results showed that there was no gender and site difference in the relationship between fork length and body weight in both Tungkang and Taitung samples. The relationship was BW = 0.00005 FL2.7443. The mean and range of total and organic Hg concentrations in muscles and livers of dolphinfish were 0.138 (0.045~0.506) and 0.103 (0.009~0.388), and 0.103 (0.037~0.260) and 0.077 (0.003~0.249), respectively. These concentrations were lower than the WHO food safety level for human consumption and Hg concentrations of shark and tuna. The total Hg concentrations in the muscles were significantly higher than those in livers in both sites. However, only samples of Taitung revealed the organic Hg concentrations of muscles were higher than those of livers. Concerning the site difference, the muscle concentrations of organic Hg, and the liver concentrations of total and organic Hg in Taitung were higher than those of Tungkang. There was positive linear relationship between total and organic Hg as well as in muscle and liver. However, no significant relationship was found between the Hg concentrations and fork length/body weight. The Hg bioaccumulative model of dolphinfish was similiar with Holsbeek et al.¡¦s models. In muscle, the largest sizes of the fish contained the highest organic Hg levels. In companying with no variation of total and inorganic Hg, it looks like Type I model of Holsbeek et al.¡¦s results.

Thesis (M.S.) in Civil Engineering--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 95-100).

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 98-109).

Thesis (M.S.) in Ecology and Environmental Sciences--University of Maine, 2002. / Includes vita. Bibliography: leaves 55-61.

Mercury (Hg) has been recognized as a contaminant of global concern due to its high toxicity, as well as its ability to mobilize over long distances and biomagnify up through the food chain. The discovery of polar springtime atmospheric mercury depletion events (AMDEs) in the 1990s provides a new mechanism for enhanced atmospheric Hg deposition to the surface environment in the Arctic, yet questions remain on the process leading to AMDEs and the net contribution of AMDEs to Hg loadings to the Arctic marine ecosystem. Here we report the first systematic study of AMDEs over the open ocean conducted in the Amundsen Gulf flaw lead system from February to July 2008. A total of 31 AMDEs were observed which showed clear dependence on local sea ice environment and meteorological conditions. Enhanced concentrations of dissolved gaseous mercury were also measured in both under ice and open water conditions. Our results confirm that the sea ice environment plays a large role in Hg dynamics in the Arctic Ocean.

Mercury (Hg) has been recognized as a contaminant of global concern due to its high toxicity, as well as its ability to mobilize over long distances and biomagnify up through the food chain. The discovery of polar springtime atmospheric mercury depletion events (AMDEs) in the 1990s provides a new mechanism for enhanced atmospheric Hg deposition to the surface environment in the Arctic, yet questions remain on the process leading to AMDEs and the net contribution of AMDEs to Hg loadings to the Arctic marine ecosystem. Here we report the first systematic study of AMDEs over the open ocean conducted in the Amundsen Gulf flaw lead system from February to July 2008. A total of 31 AMDEs were observed which showed clear dependence on local sea ice environment and meteorological conditions. Enhanced concentrations of dissolved gaseous mercury were also measured in both under ice and open water conditions. Our results confirm that the sea ice environment plays a large role in Hg dynamics in the Arctic Ocean.

Mercury occurs naturally in the environment and is released by human activities. Mercury exists in gaseous, liquid, and solid phases, and all phases are of importance when fate s effects of mercury in terrestrial, fresh and marine water, and atmospheric environments. Mercury can be transformed to a highly toxic form of methylmercury. Humans are exposed to the toxicity of methylmercury by eating fish. Methylmercury is bioaccumulated up the food chain by transfer of residues of methylmercury in smaller organisms that are food for larger organisms in the chain. This sequence of process results in higher concentrations in organisms at higher levels in the food chain with human at the top of the food chain. This study is an evaluation of chemical speciation and biological processes that govern mercury distribution and transformation among three environmental media: atmosphere, water, and sediments. Understanding speciation of mercury and biological processes of methylmercury transformation plays an important part in toxicity and exposure of mercury to living organisms. Speciation also influences transport of mercury within and between environmental media while biological processes of methylmercury transformation influence methylmercury production and its transport to the biological communities. Study also covers the demethylation process that can convert methylmercury to inorganic mercury species. Demethylation and methylation processes therefore may occur in parallel further complicating the assessment of mercury fate in the environment. The study will provide integrated fundamental pathways of mercury species transformation through chemical and biological pathways and will contribute to an understanding of fate and transport of mercury species in environmental media. It will also provide a foundation for a state- and region-wide examination of mercury monitoring and control strategies.

Thesis (Ph. D.)--University of Maryland, 1998. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1997. / Includes bibliographical references.