Stephen Reid and Stuart Z. Cohen
Environmental & Turf Services, Inc.
EPA's Science Advisory Board, among others, has expressed concern that the frequently used TCLP test has been misapplied in many situations. A more appropriate test to assess lead mobility in soils from active shooting ranges is the Synthetic Precipitation Leaching Procedure (SPLP; EPA 1312). However, the SPLP test is significantly more costly and time consuming than the total lead analysis. Therefore we evaluated total soil lead and SPLP lead analytical results from five east coast shooting ranges (n=27) to develop a predictive relationship based on commonly analyzed, inexpensive parameters. Soil textures and pH varied from sand to clay loam and from 4.6 to 7.1, respectively. Lead sources were bullets and shot. The most optimal predictive relationship was obtained from the equation, -log SPLP Pb = 2.28 pH - 0.209 pH2 + 0.0902 CEC - 2.50 x 10-5 Pb - 6.23, where SPLP Pb = lead concentration (ppm) from the SPLP test; CEC = cation exchange capacity (meq/100gm); and Pb = total soil lead (ppm). For this relationship, R2 = 0.730 and the standard error of the estimate (SEE) = 0.349. This regression equation is acceptable considering the diversity in the soils and the lead concentrations. The nonlinear relationship between SPLP Pb and pH is nearly identical to what was presented by Sauvé et al. (1997) at this conference and subsequently published (SSSAJ 62, 618 - 621, 1998). The relationship was not significantly improved with the addition of sand, clay, and dissolved organic matter as independent variables (R2 = 0.754, SEE = 0.369). This regression equation can be useful for reducing, but not eliminating, SPLP analyses in east coast shooting range studies. More soil analyses from a broader range of locations would be desirable to improve its applicability, as well as test and improve its reliability.
*Poster presented October, 2000 at the 15th Annual International Conference on Contaminated Soils & Water -- University of Massachusetts at Amherst