Geochemical evidence of pollutants from coalfired generating stations in late Pleistocene palaeosols in the Dalijia Shan, northwestern China
Surface palaeosols in two tills and a diamicton from an area in northwestern China were analysed for geochemical pollutants. Elevated levels of Br, As and Sb indicate that pollution from coal-burning and/or coal-fired electricity generating stations is delivered by aeolian transport into palaeosols dating from the last glaciation. Because the climate in the field area is sub-humid (precipitation <760 mm) the relative movement of soluble elements in palaeosols dating from early and late stades of the last glaciation is not expected to be high. The glacial and aeolian parent materials of the palaeosols indicate differences that are probably related to their source areas and to the incorporation of geochemical pollutants.
Trace impurities in Canadian oil-sands, coals and petroleum products and their fate during extraction, up-grading and combustion
National energy programs for the next two decades entail increased total consumption of fossil fuels in general and, in particular of portable fuels extracted from oil sands and shales and from lower quality coals. Improved fuel-upgrading and combustion technologies are recognized to be vital for minimizing environmental degradation caused by continental and global acid-rain precipitation from fossil-fuel impurities. A further consideration, however, is the fate of those trace-element co-contaminants of acid-rain such as heavy metals, which are present at lower concentrations (10−4–10−7) but may also be of environmental significance when 107 to 109 tons·y−1 are utilized on several continents. In this laboratory, INAA procedures have been adapted for the determination of 25–30 trace impurities in a variety of fuels and extracts including: S, V and Al, As, Ba, Br, Ca, Ce, Cl, Co, Cr, Dy, Eu, Fe, Hf, K, La, Mn, Na, Rb, Sb, Sc, Sm, Th, Ti, U. Samples were obtained of typical Canadian pumped crudes, and from several Canadian oil-sands and coal deposits (mostly bituminous and subbituminous) both in their natural states and after stages of extraction and upgrading. Also analyzed were fuels derived from them and the residues resulting from their refining and combustion. InAA of all fossil fuel extracts including light oils, viscous bitumen and such organic fluids could be performed under the same conditions as the parent substances: crude oils, oil-sands and coals, without any special sample preparation. Although no standard samples are routinely required because of the 1–2% long-term flux stability of the reactor, accuracy checks were performed periodically by reference to NBS-1632A standard coal and atomic absorption standard dilute solutions. Results obtained for the NBS coal SRM and the BAM flyash sample (1978) are also given. A wide range of trace impurities determined in the Canadian fossil fuels included some of those which are of particular significance in Canadian coals and their ashes (a STM standard ashing method). The ‘inorganic’ traces can also be grouped according to their fate during static combustion at 750°C.
Determination of 18 trace elements in petroleum and its derivatives by neutron activation with a small nuclear reactor
Non-destructive neutron activation has been used to analyze 6 different samples of crude oil and heating oil, from Western Canada and Venezuela. These samples were irradiated with thermal neutrons for 2, 30 and 240 min in the SLOWPOKE reactor and the concentrations of 18 trace and minor elements (Al, As, Br, Cl, Co, Dy, Eu, Fe, I, La, Mn, Mo, Ni, Na, S, Se, Sm and V) ranging from 0.6 ppb to 2.24% have been measured. Eleven elements (As, Br, Co, Cl, Fe, Mo, Mn, Na, Ni, S and V) were determined in the fuel oil (SRM-1634) obtained from the National Bureau of Standards and were found to be in good agreement with the values certified by NBS