Trace Element Concentration and Speciation in Selected Mining-Contaminated Soils and Water in Willow Creek Floodplain, Colorado

Abstract

Long-term mining activities in the mountains around Creede, Colorado have resulted in significant contamination in soils and water in the Willow Creek floodplain. Total major and trace were determined for soils and water and sequential chemical extraction for soils. Objectives were to determine concentrations and potential reactivity of trace elements and investigate their relationship with other soil and water properties. Water trace elements showed significant variability among sites, ranging from 347 to 12108 μg/L. Relative trend showed (Zn > Sr > Ba) > (Mn > W > Cd) > (Sn > V≈Ni≈Cu > Co) > (Ag). Soil trace elements showed significant short-range spatial variability, ranging from 2819 to 19274 mg/kg. Relative trend showed (Pb≈Zn > Mn > Ba > P) > (As > Cu > Sr > V > Cd > Sb≈Ag) > (Co≈Cr > Mo≈Sn≈Ni) > (Be≈W > Se≈Hg). Predominant fractions were oxide, specifically-sorbed/carbonate bound, and residual. Water soluble and exchangeable fractions showed (Zn≈Cd) > Pb and Cd > Zn > Pb, respectively. Mobility factors for highly contaminated soils showed Cd≈Zn > Pb > Cu > As.