Mercury and Organic Carbon Relationships in Streams Draining Forested Upland/Peatland Watersheds

We determined the fluxes of total mercury (HgT), total organic carbon (TOC), and dissolved organic carbon (DOC) from five upland/peatland watersheds at the watershed outlet. The difference between TOC and DOC was defined as particulate OC (POC). Concentrations of HgT showed moderate to strong relationships with POC (R2 = 0.77) when all watersheds were grouped. Although POC only accounts for 10 to 20% of the OC transported, we estimate that it is associated with 52 to 80% of the HgT transported from the five watersheds. Total transport of HgT from the watersheds ranged from 0.70 to 2.82 µg m−2 yr−1. Watershed geometry and hydrology play important roles in determining the influence of OC on HgT transport in forested watersheds. Watershed properties such as peatland area have considerable promise as predictors for estimating HgT transport in streams draining forested watersheds in the Great Lakes States.