Arctic aerosols at Barrow AK from 16 March to 7 May 1986 were sampled and studied for natural aerosols or natural aerosol components as well as pollutants using ion chromatography and proton induced X-ray emission analyses, and a modified principal component analysis receptor model, absolute principal component analysis (APCA). Natural organic acids were found in the aerosols at high concentrations and were likely due to low temperature condensation of acid vapors. By APCA, 20% of non-sea salt sulfate was found to come from oxidation of marine emitted organo-sulfur compounds by means of the tracer methanesulfonate. 80% of sulfate was found in the form of NH$\sb4$HSO$\sb4$. Pollutant coal combustion aerosols, determined from their chemical composition as condensate from gaseous precursors, were found and were traced back to northern Europe during a major haze event by synoptic meteorological studies. Similarly, sea salt aerosols were present and were traced back to either the Beaufort Sea or the remote North Pacific. Dust particles were present in the Arctic throughout the sampling period. Bromine was found to exist in aerosol particles not related to these aerosol components. The size distributions of these aerosol components were obtained by applying APCA to 8 cascade impactor stages, and indicated (1) the sea salt particles were aged and were consistently enriched in chlorine; (2) the dust particles were probably due to long range transport of eolian dust and had absorbed sulfur gases; (3) the coal combustion pollutants were due to gaseous phase condensation; and (4) bromine on particles was due to absorption of bromine gases. Aerosol bromine was found to vary inversely with ozone concentration changes during both day and night time, but only when very low aerosol nitrate was present. When nitrate levels were high, ozone followed the variation in nitrate, / indicating a pollution origin. Movements of ozone-depleted air and ozone-rich air apparently caused very large in situ ozone concentration fluctuations, but the excess bromine-ozone anticorrelation argues for a chemical interaction between them. / Source: Dissertation Abstracts International, Volume: 50-12, Section: B, page: 5681. / Major Professor: John Widmer Winchester. / Thesis (Ph.D.)--The Florida State University, 1989.

Peats and organic-rich soils are a key part of the global carbon (C) cycle due to their sequestration and storage of atmospheric C as organic matter. Atmospheric deposition as a result of human activities has led to increased inventories of lead (Pb) and mercury (Hg) in UK peats and organic-rich soils. Ombrotrophic peat bogs, which receive all their nutrients and pollutants from the atmosphere, provide a historic record of Pb and Hg deposition within their solid phase. Organic-rich forest soil systems can also act as sinks for anthropogenic Pb but vertical transport of Pb can distort these temporal records. The long-term outlook may, however, be affected by processes which lead to decomposition of organic matter e.g. drying out of peatlands and soils due to climatic change, since these may release Pb into the aqueous phase and volatile Hg to the atmosphere. The associations and speciation of Pb and Hg within peats and organic-rich soils are not well understood but are key to understanding both the potential for release of these pollutants into other environmental compartments and the risks to ecosystems and human health posed by such a release. Investigation of 4 sites in central Scotland showed that, depending on vertical depth, ~40-99% of Pb in ombrotrophic peat was in association with large (0.22 μm – 100 kDa) humic molecules. Near-surface regions where intact plant material had not yet undergone complete humification showed the lowest proportion of Pb-humic association. Historical Pb deposition was retained to similar degrees across each site with recorded inventories to 1986 of 0.340-0.561 g m-2. However, perturbation of the 206Pb/207Pb isotope ratio profile at Glentress forest indicated that limited migration of petrol-sourced Pb may be occurring. Similarly, perturbation of the 210Pb profile at Auchencorth Moss, in addition to discrepancies in the apparent time period in which peak Pb deposition occurred, indicated that Pb may also be subject to migration within this ombrotrophic system. With respect to Hg, between-site differences in speciation were observed. For example, Hg2+ represented < 25% of the total Hg species in the top 10 cm of solid phase ombrotrophic peat but > 50% of the total in forest soil. In contrast, aqueous phase Hg was entirely in the inorganic form across all sites. The occurrence of a solid phase [Hg] peak in layers corresponding to the ~1955 height of coal burning, in addition to the narrow range of peatland Hg inventories to 1950 (2.20-3.23 g m-2) provide evidence that Hg deposition records may be maintained in organic-rich systems to a greater degree than previously assumed. Differences observed in the associations of Pb and the speciation of Hg between the surface vegetation of ombrotrophic bogs and the underlying peat suggests that plants play an integral role in the biogeochemical behavior and sequestration of Pb and Hg in these terrestrial systems.

To evaluate the effects of anthropogenic alteration of the Chesapeake Bay (CB) watershed since European settlement, the historical progression of eutrophication and anoxia in the mesohaline region of CB was reconstructed. Lipid biomarker and carbon and nitrogen stable isotopic and elemental composition of CB surficial sediments were examined seasonally in order to identify the present sources of organic matter to CB sediments and the processes controlling their distribution. Temporal variability in surficial sediment composition could be linked to seasonal changes in phytoplankton community composition and biomass while spatial variation was dominated by the delivery of alloclithonous versus autochthonous sources of organic matter. Three cores (3 to 4.5 m in length) collected from the mesohaline region of Chesapeake Bay were dated using a combination of tools including 210Pb and 137Cs radioisotopes, anthropogenic Pb and pollen indices. Enrichments in the carbon and nitrogen isotopic signature of sediments of all three cores deposited between 1790 and 1915 indicated enhanced primary productivity and nitrogen recycling, respectively. at the same time, increases in the flux of total organic carbon (TOC) and episodic enrichments (relative to TOC) of algal and bacterially-derived lipid biomarker compounds signaled a change in the sources of OM to the sediments. More extreme change occurred after the 1915's with further isotopic enrichments, a 1.5 to 2.5-fold increase in TOC deposition and 2 to 5-fold enrichments in algal and bacterially-derived lipid biomarker compounds. No change in the contribution of terrestrially-derived OM was indicated in any of the cores. Changes in sulfur speciation identified the initial occurrence of anoxia/hypoxia in 1790 at the deepest site (26 m) and in 1929 at a 15 m depth site. An examination of both qualitative evidence and quantitative models of degradation indicates that diagenesis cannot account for the observed increases in the total amount and labile quality of OM deposited during the 19th and 20th century in CB. Using diagenetic models, it is estimated that both algal and bacterial production has increased by 100 to 200% relative to pre-Colonial times with a temporal progression similar to the history of anthropogenic alteration of the watershed.

No description available.

The Pariette Wetlands was constructed to provide wildlife habitat in an arid environment. Elevated levels of selenium (Se) have been detected in water, soil, and biota. Selenium concentrations have ranged from below detection limit to four times the water quality criterium limit. Here we report on three interrelated research topics: 1) selenium mass balance and flux in water, 2) selenium accumulation, concentration and volatilization of water and plant tissues; and 3) selenium sorption by upland and wetlands soils. 1) Mass balance and mass water flux of selenium for the Pariette Wetlands were studied. A comparison of inlet and outlet Se fluxes was used to determine the mass of Se stored. Selenium concentrations were higher at the inlet (2.1-16.3 μg L-1) than at the outlet (2.0-14.0 μg L-1). The average amount of Se retention and/or loss was 75%. 2) Elevated levels of selenium (Se) in water, soil, and biota of the Pariette Wetlands, Utah. Twelve sample sites were selected to determine the spatial and temporal variation of Se accumulation, concentration and volatilization. At the inlet, concentrations of waterborne Se during low-flow period (winter) were significantly higher than concentrations during high-flow irrigation season (summer). Se concentrations in water at the outlet were lower during the high-flow period ranging from. In contrast, plant tissue Se concentration was lower at the inlet and higher at the outlet. Selenium volatilization results indicated that there were spatial and temporal differences among samples sites. 3) The physical and chemical properties were compared for two soils in the Pariette Draw of Utah. It appears that Se mobility is associated with the distribution of soluble salts. We surmise that soluble Se is regulated by the solubility of a sodium selenate sulfate coprecipitate.. Knowledge gained about the mass balance, storage of Se, and the associated biogeochemical processes in water, plants, and soils that contribute to the accumulation or loss of Se in the wetlands will be beneficial to future land management decisions to minimize the impact of Se exposure to wildlife.

No description available.

Graduation date: 2002

The purpose of this thesis is to provide a first look at the spatial and temporal distributions of dissolved organic material (DOM) off the Oregon coast of North America. While this paper is not a comprehensive examination of these distributions, several patterns are identified as promising candidates for continued research. Most of the data presented was acquired during a strong El Nino event. The DOM data is presented as dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) and is accompanied by temperature, salinity, nitrate plus nitrite (N+N), ammonium, silicate, chlorophyll, total organic carbon (TOC), particulate organic carbon (POC), total nitrogen (TN), total organic nitrogen (TON), and zooplankton biomass measurements. During July 1997, we examined the distribution of DOM in the surface waters off the Oregon and Southern Washington coasts. Eleven east-west transects were sampled from nearshore waters to 190km offshore. DOC concentrations as high as 180 iM were observed in the Columbia River plume. Patterns in the DOC distribution were also associated with upwelling regions, an offshore coastal jet, and an oligotrophic water mass in the northern portion of our study area. Beginning with the July 1997 study and continuing until July 1998, samples were collected on weekly and seasonal time scales at station NH-05, located 9km offshore from Newport, Oregon. Various problems have limited our seasonal comparisons, but we were able to collect high quality data depicting the changes in organic matter partitioning during a phytoplankton bloom and its decline during a two month period from mid-July through mid-September in 1997. During the bloom, POC increased dramatically, but DOC decreased. Possible explanations for this decrease and for changes in the C/N ratio of the DOM during the bloom are explored. Suggestions for future research are presented in the final chapter. / Graduation date: 2000

Graduation date: 2003

Thesis (MSc)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.