Abstract
A 15-year dataset from the Clark Fork River (CFR) was used to examine the influence of mine waste remediation on Cu concentrations in resident biota (Hydropsyche) and bed sediment. Copper concentrations declined in Hydropsyche and bed sediment after the onset of remediation in the upper 30 Km of the CFR (Reach A). Detection of remediation response downstream at 85 Km (Reach B) and 130 - 190 Km (Reach C) was confounded by the significant positive relationship between bioaccumulation and stream discharge. To date, temporal patterns associated with remediation cannot be detected in Reach B or C. In order to understand how contamination levels in Reach C might be influenced by upstream remediation efforts, site-to-site correlations in temporal metal trends were evaluated. The expectation was that the strength of the spatial relationship would be a function of distance. Correlations between adjacent stations showed the strength of station-to-station connections and identified temporal similarities in patterns of metal occurrence. Between 60-75% of adjacent stations were significantly linked, suggesting that events upstream usually affected the next downstream station. Adjacent sites showing no temporal correlation may indicate a spatial disconnect in the upstream signal. Site-specific influence in metal concentrations over large spatial scales was observed when temporal patterns in downstream stations were significantly correlated to an upstream station, identifying sites which may be major sources of metal. For example, sediment Cu concentrations between 5 -10 Km were significantly correlated with concentrations at five out of seven stations along the 185 Km segment, and may be indicative of spatially extensive upstream-downstream linkages.
Start Date
1-4-2005 10:20 AM
End Date
1-4-2005 10:40 AM
Document Type
Presentation
Effects of Mine Remediation over Large Spatial and Temporal Scales
A 15-year dataset from the Clark Fork River (CFR) was used to examine the influence of mine waste remediation on Cu concentrations in resident biota (Hydropsyche) and bed sediment. Copper concentrations declined in Hydropsyche and bed sediment after the onset of remediation in the upper 30 Km of the CFR (Reach A). Detection of remediation response downstream at 85 Km (Reach B) and 130 - 190 Km (Reach C) was confounded by the significant positive relationship between bioaccumulation and stream discharge. To date, temporal patterns associated with remediation cannot be detected in Reach B or C. In order to understand how contamination levels in Reach C might be influenced by upstream remediation efforts, site-to-site correlations in temporal metal trends were evaluated. The expectation was that the strength of the spatial relationship would be a function of distance. Correlations between adjacent stations showed the strength of station-to-station connections and identified temporal similarities in patterns of metal occurrence. Between 60-75% of adjacent stations were significantly linked, suggesting that events upstream usually affected the next downstream station. Adjacent sites showing no temporal correlation may indicate a spatial disconnect in the upstream signal. Site-specific influence in metal concentrations over large spatial scales was observed when temporal patterns in downstream stations were significantly correlated to an upstream station, identifying sites which may be major sources of metal. For example, sediment Cu concentrations between 5 -10 Km were significantly correlated with concentrations at five out of seven stations along the 185 Km segment, and may be indicative of spatially extensive upstream-downstream linkages.