Geochemical evidence contained

Geochemical Evidence Contained in Sedimentary Organic Matter... 

Several lines of geochemical evidence support low to negligible concentrations of atmospheric O2 during the Archean and earliest Proterozoic, when oxygenic photosynthesis may have evolved. The presence of pyrite and uraninite in detrital Archean sediments reveals that the atmosphere in the earliest Archean contained no free O2 (Cloud, 1972). Although Archean-age detrital pyrites from South Africa may be hydrothermal in origin, Australian sediments of the Pilbara craton (3.25-2.75 Ga) contain rounded grains of... 

This case study is interesting in that one hazardous waste (acrylonitrile) was quickly rendered nonhazardous after injection, whereas another (sodium thiocyanate) showed no evidence of decomposition during the duration of the study. The implication for geochemical fate assessment is that research should focus on the compounds likely to be most resistant to decomposition or immobilization, as they will be the ones most critical in demonstrating containment in a no-migration petition. 

This chapter reviews research on the abundance of sulfur in major coal basins in the U.S., the forms of sulfur in coals, the distribution of sulfur in coal lithotypes and macerals, and the nature of sulfur-containing organic compounds in coal. Next, the origin of sulfur in coal is reviewed based on the evidence from the distribution and speciation of sulfur in peat, and from stratigraphic, isotopic, and trace element data. Finally, the origin of sulfur in coal is explained by a geochemical model. 

There are good reasons to assume that the core contains some amount of carbon, phosphorus, and sulfur. These three elements are among the 12 most common in the Earth that account for >99% of the total mass (Table 5), as based on geochemical, cosmochemical, and meteoritical evidence. Seven out of 12 of these elements (not including carbon, phosphorus, and sulfur) are either refractory or major component elements. 

---