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. 1. Introduction The measurement of the total extractable pool of trace elements has been commonly used to assess the environmental levels or background amounts of trace elements in soils and water [1–7]. Selective fractionations or “geochemical partitioning” have been used to evaluate the potential reactivity of these elements [8–11] and are widely used in soil pollution studies, providing qualitative evidence about trace element reactivity and indirectly of their bioavailability [12–15]. Trace element bioavailability in soils is a complex phenomenon, affected by many factors such as total concentration, pH, organic matter, clay, and redox conditions [7, 16–20]. Trace element toxicity in waters is strongly affected by site-specific water quality factors such as pH, hardness, and other dissolved constituents [21, 22]. An assessment of trace element fate, bioavailability, and transport (e.g., surface and groundwater) is required in order to predict potential contamination and impact upon soil and water quality. Historic mining activities in the mountains around Creede, Colorado, began around 1889 and continued until 1985. Underground mining of silver and base metals has resulted in Zn and Cd contamination of ground and surface water in and along the broad floodplain of Willow Creek below Creede [23]. Willow Creek, a tributary to the Rio Grande, is polluted from drainage from various mine adits and rock piles upstream of Creede and by leachates from a gravel-capped
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