Mercury (Hg) is a contaminant of global concern due to its long-range atmospheric transport and high toxicity. The focus of this research is on the role of the forest canopy in the accumulation, and delivery of Hg to the soil Hg pool. Particular focus is on the role of atmospheric speciation of Hg on deposition. An urban-rural gradient was examined from Mississauga to Dorset, Ontario, to determine the role of locally emitted Hg: RGM, and PM on deposition. [GEM] was measured to be similar at both sites, and [PM] and [RGM] were greater in the urban location. Seasonal accumulation of Hg on foliar surfaces was dominated by GEM, and similar at the urban (8.74 ng cm-2) and rural (9.80 ng cm-2) locations. Increased [PM] and [RGM] at the urban location resulted in a transient upper canopy Hg pool, and throughfall enrichment at the urban site.

Mercury (Hg) is a contaminant of global concern due to its long-range atmospheric transport and high toxicity. The focus of this research is on the role of the forest canopy in the accumulation, and delivery of Hg to the soil Hg pool. Particular focus is on the role of atmospheric speciation of Hg on deposition. An urban-rural gradient was examined from Mississauga to Dorset, Ontario, to determine the role of locally emitted Hg: RGM, and PM on deposition. [GEM] was measured to be similar at both sites, and [PM] and [RGM] were greater in the urban location. Seasonal accumulation of Hg on foliar surfaces was dominated by GEM, and similar at the urban (8.74 ng cm-2) and rural (9.80 ng cm-2) locations. Increased [PM] and [RGM] at the urban location resulted in a transient upper canopy Hg pool, and throughfall enrichment at the urban site.

Abstract The concentration of mercury vapour in ambient air is routinely determined using specialised instruments. As an economical alternative, actively pumped Hopcalite sorbent tubes can be used to trap atmospheric mercury, which is subsequently analysed by cold vapour atomic absorption spectroscopy. Plant materials are also readily available in most regions and can be analysed to obtain information on time averaged atmospheric mercury levels. Lichen and tree bark samples were collected in the cities of Pretoria and Witbank, dried and acid digested with subsequent cold vapour atomic absorption spectroscopy. Average mercury concentrations ranging from 74 to 193 μg.kg-1 were found in lichens from three Pretoria suburbs, whilst average Hg levels of 228 μg.kg-1 were determined in lichens collected in Witbank. The average mercury concentration in tree bark was consistently lower than in lichens, with concentrations between 28 and 72 μg.kg-1 determined in samples from three Pretoria suburbs and 75 μg.kg-1 determined in samples taken in Witbank. This study is the first in South Africa to determine mercury levels in lichens and tree bark. Average total gaseous mercury concentrations in ambient air at the three Pretoria suburban sites, as determined by a semi-continuous spectroscopic method using Hopcalite sampling, ranged between 1.6 and 2.5 ng.m-3, while an average of 1.7 ng.m-3 was measured in Witbank over the sampling interval.

Thesis (Ph. D.)--Washington State University, August 2006. / Includes bibliographical references.

Thesis (Ph. D.)--Lehigh University, 2006. / Includes vita. Includes bibliographical references (leaves 257-274).

Thesis (Ph. D.)--University of Nevada, Reno, 2005. / "December 2005." Includes bibliographical references. Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm.

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

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

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.