3 Results
3.1 Hg in ecosystem components
Surficial soils sampled from the four stream sites in 2012 had mean concentrations of total Hg ranging from 62 to 164 ng/g dry weight (dw) (Table 2). Mean MeHg in soils ranged from 1.6 to 2.9 ng/g dw, representing 1.0% to 2.6% of total Hg. Total Hg in soil correlated well with percent mass loss on ignition (LOI), a surrogate measure of organic matter content (r2 = 0.92; Fig. 2, upper panel). The slope between total Hg and LOI in GRPO soils was more than 3-fold that for soils sampled in 2012 from five other park units in the western Great Lakes region and from the Experimental Lakes Area in northwestern Ontario (K. Rolfhus, unpublished data).