The orange lines are research flight tracks of the NOMADSS aircraft campaign (out of Smyrna, Tennessee, United States). The red triangles and numbers in them show the locations and names of the 11 rural/remote NADP AMNet sites. The three ship cruise routes in the Northwest Atlantic are shown in blue lines. The thick blue line for the ship cruise during August 2008 (denoted as AUG08) represents the route in the coastal Gulf of Maine where mercury observations are influenced by anomalously high freshwater input (see details in the Discussion section).