Long term variations of PCB in the water of a river in relation to precipitation and internal sources

PCB concentration in the water of a south Swedish river was followed for 2 years. The concentration of the pollutants varied seasonally, approaching levels in precipitation at high water discharge. Principal component analysis (PCA) revealed that PCB congener distribution in river water at high flow was similar to that found in precipitation. At low water discharge, and coinciding with high water temperatures during summer, concentration of PCB increased. The relationships indicated desorption of PCB from sediment, a conclusion supported by PCA of the congener distribution in the sediment and water. The results, consequently, revealed two sources of PCB to river water, atmospheric dominance during high flow and internal, sediment recycling during low flows explaining seasonal variation.