| The spatial and temporal trends in dissolved organic matter (DOM) and mercury (Hg) in a small Precambrian Shield watershed were investigated. The concentration of dissolved organic carbon (DOC) and total mercury (THg) varied with respect to sampling site and season along a hydrologic flowpath that included throughfall, wetland inflow, wetland, wetland outflow and lake outflow. A significantly different positive regression was found between the concentrations of DOC and THg for throughfall samples when compared to the remaining watershed samples. The majority of DOC and THg was found in the 100--10 KDa molecular size range with little spatial and seasonal variation. The position and intensity of maximum DOM fluorescence was used to estimate the molecular size of DOM from samples taken along the hydrologic flowpath. The wetland inflow consisted of small molecular sized DOM, while the wetland, wetland outflow and lake outflow consisted of large molecular sized DOM. |
