Trace metal leaching behavior studied through the use of parametric modeling of water borne soil particles fractionated with a split-flow thin cell.
Leaching of particle-bound metals affects the ability of settling ponds and other engineered structures to remove metallic pollutants, and leaching behavior is related to particle size. In this investigation, water borne soil particles were leached and fractionated with a split-flow thin cell, and the metal loadings were quantified as a function of particle size. For comparison of the metal-loading curves, different empirical modeling procedures were investigated to convert the data to a precise functional form suitable for quantitative comparison of changes in differential loading as a function of particle size. Results of this investigation are presented for a soil sample before and after leaching caused by simulated acid rain conditions. Following simulated acid rain leaching, the shape of the differential distribution curves change, and these changes reflect the particle size mediated leaching behavior. For the soil used in this demonstration, simulated acid rain leaching shifted the differential loading toward larger particle sizes, and the magnitude of the shift varied significantly among the metals. Because settling rate decreases as the square of particle size, this could potentially affect management decisions for settling ponds receiving these particles. The high precision afforded by the analysis allows the development of insight into the leaching mechanisms through comparing "partial" acid rain leaching with "total recoverable" leaching by EPA Method 3050.
Magnuson
Matthew L
ML
United States Environmental Protection Agency, National Risk Management Research Laboratory, Water Supply and Water Resources Division, Cincinnati, Ohio 45268, USA. Magnuson.Matthew@epa.gov
Kelty
Keith C
KC
Kelty
Catherine A
CA
D015258:Acid Rain; D004738:Engineering; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D008962:Models, Theoretical; D010316:Particle Size; D012989:Soil Pollutants / Q000032:analysis*; D012995:Solubility; D014872:Water Movements
D015258:Acid Rain; D019216:Metals, Heavy; D012989:Soil Pollutants