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Factors Controlling Fluxes Of Volatile Sulfur Compounds In Sphagnum Peatlands, William Zamboni De Mello
Factors Controlling Fluxes Of Volatile Sulfur Compounds In Sphagnum Peatlands, William Zamboni De Mello
Doctoral Dissertations
Exchange of DMS and OCS between the surface of Sphagnum peatlands and the atmosphere were measured with dynamic (S-free sweep air) and static enclosures. DMS emission rates determined by both methods were comparable. The dynamic method provided positive OCS flux rates (emission) for measurements performed at sites containing Sphagnum. Conversely, data from the static method indicated that OCS was consumed from the atmosphere.
Short and long-term impacts of increased S deposition on fluxes of volatile S compounds (VSCs) from Sphagnum peatlands were investigated in a poor fen (Mire 239) at the Experimental Lakes Area, Ontario, Canada. Additional experiments were conducted …
Isotope Geochemistry And Paleobiology Of The Devils Lake Basin, North Dakota, Robert Mulvihill Lent
Isotope Geochemistry And Paleobiology Of The Devils Lake Basin, North Dakota, Robert Mulvihill Lent
Doctoral Dissertations
Devils Lake is located in one of the largest closed basins in the northern prairies. Water and sediment samples were collected to characterize present and past hydrologic and climatic conditions in the basin.
Precipitation in North Dakota exhibits a wide range of stable isotopic compositions. Precipitation samples clustered along two segments of the meteoric water line, illustrating the strong seasonal component of precipitation. Low deuterium excess in summer precipitation was indicative of higher relative humidity of the air masses originating over the Gulf of Mexico. High deuterium excess in winter precipitation is similar to the values found at Canadian stations …
Geochronology And Geochemistry Of The Basement Orthogneisses Of The Araguaia Belt, Brazil, Candido A Veloso Moura
Geochronology And Geochemistry Of The Basement Orthogneisses Of The Araguaia Belt, Brazil, Candido A Veloso Moura
Doctoral Dissertations
Orthogneisses representing the basement rocks of the Araguaia belt (AB), Brazil, are exposed in the core of dome-like structures. Gneisses of trondhjemitic, tonalitic, and granodioritic (TTG) composition constitute the Colmeia Complex, while augen gneiss, of granitic composition, is termed Cantao Gneiss (CG). An Archean age is suggested for the TTG gneisses, although the available Rb-Sr ages for these rocks range between 1.8 and 2.6 Ga. A Rb-Sr age of 1.77 Ga for the CG is interpreted either as a crystallization age or a resetting age.
Geochronological and geochemical studies of the orthogneisses of five of these dome-like structures of the …