Fossil Organic Carbon Research Articles

Carbonaceous Aerosol Sources in Rio de Janeiro

Aerosol carbon concentrations, organic / elemental speciation, and carbon isotopic composition data (13C/12C ratios and 14C content) are reported from the second Rio de Janeiro Aerosol Characterization Study (RIO-JACS II), along with supplemental meteorologic and inorganic aerosol data. These data and their diurnal and weekday / weekend variability are used to identify sources of carbonaceous aerosols in the urban Rio air basin. Specifically, contributions from biogenic sources, anthropogenic emissions (principally transportation sources), and sugar cane-derived alcohol-fueled vehicular emissions to aerosol carbon levels in Rio are estimated from measurements of carbon-14, organic and elemental carbon, and 13C/12C isotopic composition in total aerosol samples collected at two ambient Rio sites and in a heavily traveled tunnel. The major source of elemental (soot) carbon appears to be diesel vehicles, but secondary sources of both biogenic and fossil organic aerosol carbon are indicated.

Petroleum Pollutants in Surface and Groundwater as Indicated by the Carbon-14 Activity of Dissolved Organic Carbon

The (14)C activity of dissolved organic carbon (DOC) can be used to distinguish between the fossil organic carbon due to petrochemical effluents and modern organic carbon due to domestic wastes and natural decaying organic matter. Rivers polluted by petrochemical effluents show varying amounts of depression of the DOC (14)C activity, reflecting concentrations of (14)C-deficient fossil carbon of as much as about 40 percent of the total DOC.