Arsenic Contamination of Soils in Providence, Rhode Island

Nathaniel Harlow
Bachelor's of Science in Environmental Science
May 2002

Residential and agricultural properties are at risk of arsenic contamination due to the widespread application of arsenical pesticides during the 20th century. This study describes arsenic contamination of four sites in a residential neighborhood in Providence, Rhode Island. Subsurface core and surface soil samples were collected and analyzed for arsenic and lead concentrations using Graphite Atomic Absorption Spectrometry and Inductively Coupled Plasma Atomic Emission Spectrometry. Analyses revealed elevated concentrations of arsenic in all four sites, up to two orders of magnitude over the Rhode Island residential standard for arsenic in soil (1.7 ppm). Arsenic and lead concentrations were strongly correlated. Concentrations varied with depth and peaked at between 6-12cm. Lead-to-arsenic ratios in the core samples were similar to that ratio in lead arsenate, a commonly used pesticide. Rhode Island regulations define historical contamination as a release that must be investigated and perhaps remediated, and thus discourage further investigation of the extent of arsenic contamination.