A comparison of the geochemistry of Fe–Mn coatings on pebbles and Potamopyrgus (Hydrobia) jenkinsi shells, Allen River, SW England, UK

An investigation of the chemistry of surface precipitates on stream pebbles and Potamopyrgus (Hydrobia) jenkinsi (Smith) shells has been undertaken on samples collected from a contaminated river in SW England, UK. Samples were analysed by LA-ICP-AES to evaluate the technique as a suitable method to use on small environmental samples, and to determine if the Pb/Fe and Zn/Mn ratios of the coatings on the two substrates were comparable. The ratios in the coatings are similar in these samples types, but are generally higher on the pebble samples. Results have been compared to a previous investigation of pebble coating chemistry in the river, and are shown to have the same spatial distribution but very different absolute values due to changes in environmental conditions in the river over time.