You are here:
TRACE METAL LEACHING BEHAVIOR STUDIED THROUGH THE USE OF PARAMETRIC MODELING OF WATER BORNE SOIL PARTICLES FRACTIONATED WITH A SPLIT-FLOW THIN CELL
Citation:
Magnuson*, M L., K. C. Kelty*, AND C A. Kelty*. TRACE METAL LEACHING BEHAVIOR STUDIED THROUGH THE USE OF PARAMETRIC MODELING OF WATER BORNE SOIL PARTICLES FRACTIONATED WITH A SPLIT-FLOW THIN CELL. ENVIRONMENTAL ENGINEERING SCIENCE.
Description:
Removal of pollutant-laden particles via engineered structures such as settling ponds is one goal of storm water management. Leaching of metals as a function of particle size affects the ability of settling ponds to remoe the polluted particle. In this investigation, water borne soil particles were leached, fractionated with a split-flow thin cell, and the metal loadings were quantified with inductively coupled plasma-atomic emission spectrometry. For comparison of these curves, different empirical modeling procedures were investigated to convert the data to a precise functional form. This expression could be used mathematically for purposes of 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 eifferential 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 towards smaller 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. To gain insight into the leaching mechanisms, the "partial" leaching due to acid rain conditions was compared to the "total recoverable" leaching by EPA Method 3050, which subjects the sample to more harsh, acidic conditions. The "total recoverable" leaching by EPA Method was plotted against the "partial leaching" caused by simulated acid rain. A linear regression resulted in a p-value for the slope of 0.03, indicating low correlation and suggesting that similarity in the leaching mechanism might not be very significant. On the other hand, the "total recoverable" leached metals from Method 3050 were plotted against a shift in the differential loading revealed using the parametric data analysis. This suggests that changes in the composition of the particles as a function of size may have a greater influence on the effect of simulated acid rain on this soil.