Migration of pentachlorophenol and copper from a preservative treated bridge

The potential for migration of pentachlorophenol (PCP) and copper naphthenate (CuNaph) from Douglas-fir was assessed in a bridge over a stream located in Western Oregon in the United States. All rainfall runoff was collected from a portion of the bridge on 15 occasions over a 27 month period and analyzed for pentachlorophenol or copper. PCP and copper were detected at every time point. PCP concentrations ranged from 0.296 to 6.183 μg/mL, while those for copper ranged from 0.37 to 7.80 μg/mL. These data were then used to estimate PCP and Cu inputs in runoff from the entire bridge. Stream flow data were then used to predict the concentrations that would develop in the receiving stream. The results showed that runoff from the bridge would result in PCP and copper concentrations that were 500-1000 times lower than the reported levels of effect for each component. The results are discussed in the context of this location as well as other sites with lower stream flow conditions.