| In my dissertation I investigated anthropogenic perturbations of trace metal biogeochemistry and detailed interactions between human activities and natural biogeochemical cycling. I studied the fate and transport of trace metals in sedimentary, aquatic and atmospheric systems. My work is presented in three chapters and several appendices of analytical methods and data tables.; My first project examines how trace metal pollution from the abandoned Spenceville copper mine in California is chemically transformed in the water column and eventually sequestered within stream sediments. A sequential extraction procedure was performed on these stream sediments to ascertain which trace metals could be chemically re-mobilized back into the water column. Also at Spenceville, I collected samples and began a study to investigate the use of copper isotope ratios as geochemical tracer of pollution. Although this project was not completed, preliminary results of method development utilizing a multi-collector inductively-coupled plasma mass spectrometer are contained in Appendix 1. Data for my second and third projects were collected during the fourth Intergovernmental Oceanographic Commission Global Investigation of Pollutants in the Marine Environment. My second project looks at emissions of trace metals to the atmosphere over the North Pacific from industrial sources in Asia. In addition, I estimated deposition of trace metals to the surface ocean and examined the relationship between Ag and Se as geochemical tracers of pollution from coal combustion. My third project examined controls on silver distribution within the North Pacific water column, and detailed what I believe is a disruption of silver cycling caused by atmospheric contamination. The silver measurements in Chapter 3 were made by a new flow-injection method coupled to an inductively-coupled plasma mass spectrometer. This method, which is detailed in Appendix 2, decreases sample preparation time and eliminates the need for an organic extractions. Overall this dissertation examines how human activities impact the fate and transport of trace metals between and within different environmental reservoirs. |
