Sunday, November 4, 2007 - 4:00 PM
11-6

Zinc concentrations along a transect near a power-line tower in San Luis Obispo, CA.

David Guerena, Christopher Appel, Craig Stubler, Maribel Alvarado, Brendan Richart, Nathanael Sheean, Preston Skeath, Kelly Steffan, and John Yeo. California Polytechnic State University, California Polytechnic State University, Earth & Soil Sciences Dept., San Luis Obispo, CA 93407

Galvanized steel structures are potential sources of zinc contamination in soils. Zinc contamination from the weathering of galvanized structures can result in elevated soil Zn levels, potentially causing plant and animal toxicity (e.g ruminants). Few studies can be found documenting this occurrence. Plant and soil (total and bioavailable) zinc levels were determined around a power line tower on the Cropley soil series in San Luis Obispo, CA. Total Zn was determined using US EPA method 3050a (HNO3/H2O2 digestion). Bioavailable Zn was determined using US EPA method 1311 (HC2H3O2 at pH 4.93). Samples were taken along a transect following the prevailing wind. Weathering of the Zn coating of the galvanized structure resulted in translocations of Zn into the soil adjacent to the tower. Average total soil zinc levels under the power tower was 151.65 mg Zn kg-1 soil, 3 times as great as average zinc levels of uncontaminated soils. Total soil (39.06 - 475.71 mg Zn kg-1 soil) and plant Zn levels (13.50 - 61.06 mg Zn kg-1 plant) were greatest under the power tower and decreased with distance from the tower. Total plant Zn levels were higher downwind than upwind; this trend was not evident in total soil Zn. Total plant Zn increased with increasing total soil and TCLP Zn. However, this trend was poorly correlated. As zinc is relatively immobile in the soil, the elevated levels found were due to contamination from the galvanized structure. Total Zn soil levels were lower in the subsoil (68.57 mg Zn kg-1) relative to the topsoil (268.81 mg Zn kg-1). Zinc from galvanized structures can be translocated into the soil at levels known to result in toxicity to plants and animals.