Arsenic Speciation of Runoff from CCA-Treated Decks

Motivation Does the profile imply that all As is captured by upper soil layers?

Experimental Set-up sandy soil, 2 ft deck gravel rainwater runoff collection vessel Infiltrating rainwater precipitation

Avg. As Conc mg/L (CCA-treated deck) mg/L (untreated deck) Runoff

Soil Below Deck Soil below untreated deck < 1 mg/kg Primary As Species in Soil were As(V) ~ 95% As(III) ~ 5%

Day As species concentration (ug/L) As(III) As(V) Total As untreated deck, 2 – 3 ug/L Infiltration

Summary  As was found in deck runoff at an average of 730 ug/L. Maximum of 8000 ug/L.  As was found in predominantly surface soil layers.  Soil concentrations increase with age of deck.  As was found at elevated levels in waters that infiltrate below 2 feet of sand.