a. 2009 mean water column dissolved MeHg (±SE, surface & deep water; 3–4 m) plotted against mean sediment pore water MeHg (0–6 cm) (LIS MeHg from Schartup et al., 2015), b. NY/NJ Harbor (Hammerschmidt et al., 2008; Balcom et al., 2008), Hudson R. ETM (Heyes et al., 2004) and Delaware R. ETM (Gosnell et al., 2015-submitted) mean (±SE, surface & deep water) dissolved MeHg plotted against mean sediment pore water MeHg.