Linking major and trace element concentrations in a headwater stream to DOC release and hydrologic conditions in a bog and peaty riparian zone

Most of the variance in the data, as revealed by Principal Component Analysis, integrated the DOM concentration pattern (element loadings > 0.8: Al, Ca, Fe, Mg, Mn, Zn, Li, Co, As, Sr, Cd, Pb, and DOC). Ca, Mg and Sr were also found to load on this principal component, suggesting that the main control on element mobilization is not DOM, but rather similar source areas and mobilization processes. The DOM-related export was driven by plant uptake, plant decomposition and the bog water level in terms of hydrologic connectivity. The differences between the bog and the riparian zone were mainly driven by different hydrologic conditions and additional elemental sources, such as mineral weathering. The export patterns of Rb, Cs, K, NO3− and SO42− were predominantly controlled by the season and plant uptake, and they were particularly exported by a surficial fast flow path. In addition to other elements, Ga, Y and Ba were enriched in the upper peat and organic soil layer, likely due to anthropogenic pollution. The specific export pattern of these latter elements indicates their predominant mobilization by the dissolution of dust particles and their subsequent mobilization by coupling to DOM.