My project is examining whether surface carbonate precipitation acts as a sink for heavy metals from polluted source water. The site I am looking at is a tufa forming at a waste pond stream near Neilston, East Renfrewshire. Tufa is a type of limestone which forms by precipitation of calcite from calcium carbonate-saturated surface waters. Its formation can be rapid, and may preserve structures associated with seasonal climatic variations. Many trace elements can substitute for calcium in the calcite structure, and the resulting calcite can provide a record of water and environmental chemistry. I use several geochemical techniques to monitor changes in carbon and heavy metal content in the pond and stream water from which the tufa is being deposited. Should a downstream decrease of both carbon and metals be observed in water (and correlate with increase of these elements in the tufa), the results may prove beneficial for the application of carbonate-based treatment of waters affected by heavy metal pollution. Remediation of polluted waters is essential for future access to clean water as the risk of water scarcity increases hand in hand with the global water demand. In addition, this method has implications for carbon capture and storage in the context of present climate change: increased atmospheric carbon dioxide may result in reduced tufa formation, or even potentially dissolve existing tufa, releasing carbon dioxide.