RESUMEN

Fly ash is predominately the inorganic byproduct of coal combustion for electrical power generation. It is composed of aluminosilicates with Fe, Mg, K, and Ca forming submicron to 100 µm spheres and amorphous particles. During combustion trace elements are incorporated into the heterogenous fine particles that can pose risks to the environment and human health. This study combines optical, rock magnetic, and geochemical analyses of fly ash originating from Appalachian coal to develop an integrated suite of environmental coal ash tracers. The non-magnetic portion of power plant fly ash has higher abundance of clear spheres and clear amorphous particles, combined with enrichment of As, B, Th, Ba, Li, Se, Cd, Pb, and Tl. The magnetic fraction is enriched in opaque and orange spheres and Cu, U, V, Mo, Cr, Ni, and Co. Plerospheres occur in either fraction. We investigated ash-bearing fluvial sediment from Emory-Clinch River system that was impacted by the instantaneous TVA spill in 2008 and Hyco Lake in North Carolina that was contaminated by chronic releases of fly ash since 1964. Five years after the TVA spill, most ash in the riverbed reflects one population with trace element concentrations proportional to percent total ash. This relationship does not hold for As and Se, volatile elements associated with the outer surface of clear spheres, which are affected by river transport. At Hyco Lake, small clear and opaque spheres correlate with trace elements released from storage ponds. The combination of trace elements, fly ash morphology and rock magnetism provides a powerful set of tools to assess the distribution of ash and potential impact on the environment. We conclude that dispersal of fly ash to the aquatic environment, especially small clear and opaque spheres, should be avoided in favor of dry landfills.

RESUMEN

An estimated 229,000 m(3) of coal fly ash remains in the river system after dredging to clean-up the 2008 Tennessee Valley Authority (TVA) spill in Kingston, Tennessee. The ash is heterogeneous with clear, orange and black spheres and non-spherical amorphous particles. Combustion produces iron oxides that allow low field magnetic susceptibility (χ(LF)) and percent frequency dependent susceptibility (χ(FD)%) to be used to discriminate between coal fly ash and sediments native to the watershed. Riverbed samples with χ(LF) greater than 3.0 × 10(-6) m(3)/kg, have greater than 15% ash measured by optical point counting. χ(LF) is positively correlated with total ash, allowing ash detection in riverbed sediments and at depth in cores. The ratio of ash sphere composition is altered by river transport introducing variability in χ(LF). Measurement of χ(LF) is inexpensive, non-destructive, and a reliable analytical tool for monitoring the fate of coal ash in this fluvial environment.

Asunto(s)

Ceniza del Carbón/química , Monitoreo del Ambiente/métodos , Contaminantes Químicos del Agua/química , Liberación de Peligros Químicos , Ceniza del Carbón/análisis , Restauración y Remediación Ambiental , Magnetismo , Ríos , Tennessee , Contaminantes Químicos del Agua/análisis , Contaminación Química del Agua/estadística & datos numéricos

RESUMEN

Growth in colonial organisms by iteration of modules inherently provides for an increase in available morpho-ecospace relative to their solitary relatives. Therefore, the interpretation of the functional or evolutionary significance of complexity within groups that exhibit modular growth may need to be considered under criteria modified from those used to interpret complexity in solitary organisms. Primary modules, corresponding to individuals, are the fundamental building blocks of a colonial organism. Groups of primary modules commonly form a second-order modular unit, such as a branch, which may then be iterated to form a more complex colony. Aspects of overall colony form, along with their implications for ecology and evolution, are reflected in second-order modular (structural) units to a far greater degree than by primary modular units (zooids). A colony generated by modular growth can be classified by identifying its second-order modular (structural) unit and then by characterizing the nature and relationships of these iterated units within the colony. This approach to classifying modular growth habits provides a standardized terminology and allows for direct comparison of a suite of functionally analogous character states among taxa with specific parameters of their ecology.