HEAVY METAL CONCENTRATIONS IN URBAN SOILS

Soils in urban areas may be contaminated with heavy metals due to the use of fertilizers, pesticides, wood preservatives, and construction materials. Soil samples were collected between October 2013 and March 2014 in Spokane, Washington in residential areas and protected urban wetlands that are home to a variety of wildlife and plant species. The area has been developed since the late 1800s, and is known to have contained orchards, lumber yards, railcar systems, and dumping grounds, but it is not registered as an action site by the EPA. Topsoil samples were collected, leached using trace metal-grade nitric acid and analyzed using an Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). The results indicate that concentrations were elevated relative to the crustal abundances for each element. For example, arsenic, lead, and cadmium concentrations were about ten, three, and two times higher in the urban soils than the crustal abundances, respectively.