Concentration and Speciation of Arsenic, Chromium, and Copper in the Soil System Adjacent to Chromated Copper Arsenate Treated Lumber Fence Posts.

Arsenic (As), Chromium (Cr), and Copper (Cu) are ubiquitous in soils as a result of anthropogenic and geogenic processes.  The fate of As, Cr, and Cu in the environment is largely governed by their speciation, which is influenced by soil physiochemical properties.  This study investigated the influence of soil physiochemical properties and landscape position on As, Cr, and Cu concentration and speciation in soils adjacent to Chromated Copper Arsenate (CCA) treated lumber fence posts.  Three soil series (Maury silt loam, Donerail silt loam, and Newark silt loam) with different landscape positions and drainage classes (summit, well drained; mid slope, moderately well drained; and toe slope, somewhat poorly drained, respectfully) were investigated.  Concentration gradients were constructed for each soil profile by acquired surface and subsoil samples.  Speciation and mapping of the metals was determined using synchrotron x-ray absorption spectroscopy.  Concentration gradients showed elevated As and Cu adjacent to the three fence posts, which decreased with increasing distance from the posts. As and Cu leaching occurred to a greater extent than Cr, which was not elevated with respect to the background concentration. In addition, As and Cu had higher concentrations in the surface soil samples than the subsoil samples possibly due to enhanced weathering of the CCA treated posts at the surface. Concentrations of As, Cr, and Cu were similar among the Maury and Donerail silt loam, however, they were closer to the background concentration in the Newark silt loam, a partially hydric soil, indicating mobility of the metals. Overall, the use of CCA treated lumber as a metal source can help determine how soil properties influence mobility and speciation of As, Cr, and Cu across the soil landscape.