Quantifying excess heavy metal concentrations in drainage basins using conservative mixing models

High concentrations of heavy metals and other pollutants in river sediments can have detrimental effects on the ecosystem humans. The composition throughout drainage basins therefore provides important information for environmental monitoring. An obvious first step using sediment compositions monitoring is to quantify natural baseline concentrations. Once baselines been quantified, it straightforward compare them observations identify excesses generated by, example, anthropogenic inputs. In this study a new strategy mapping element along rivers from discrete geochemical upstream presented. We demonstrate our approach case Clyde basin western Scotland, UK. First, continuous are simple forward models that conservatively mix source region networks. 1185 measurements elemental first-order streams used parameterise region. calculated then compared measured at 60 localities main channel river. For range major trace elements (e.g., Mg, Sr, K, Mn), downstream close agreement with predicted by conservative mixing models. However, some metal (Pb, Cu, Zn) tend exceed Therefore, second part calculates areas required match observed Pb, Cu Zn inverse ‘unmix’ utilising, again, model. Model resolution determined spatial distribution data. Resultant easily be estimate excesses. tentatively suggest input equivalent annual fluxes 9.7, 1.5 5.7 t (106 g) Zn, respectively.