Contaminated sediment dynamics in peatlandheadwater catchments

Purpose Despite substantial research into Pb storage inpeatlands, formal description of the mechanisms of contaminated sediment mobilisation is limited. This study explores the controlling factors of contaminated sediment dynamics in an eroding peatland in the Peak District National Park, UK. Materials and methods This study uses the Pb contamination stored near the peat’s surface as a fingerprint to trace contaminatedsediment dynamics in three severely degraded headwatercatchments. A field portable XRF analyser was used acrossa range of catchment surfaces to examine patterns of contaminant storage and release. Results and discussion Lead concentrations varied greatly over a small spatial scale. Erosion is exposing high concentrationsof Pb on interfluve surfaces (up to 1660 μg g−1), andsubstantial amounts of reworked contaminated material (up to 1010 μg g−1) are stored on other catchment surfaces (gully walls and floors). A variety of factors have been shown to significantly control Pb release and storage in this environment, including wind action, aspect, and gully depth. Vegetation also plays an important role in retaining sediment-bound heavy metals within contaminated peat catchments