Fig. 3.

Regional trends for 1990 to 2013 in atmospheric Hg⁰ concentrations (A–D) and Hg^II wet deposition (E and F). Observations for individual years are shown as squares with linear regression as solid line. The dashed line is the trend from the GEOS-Chem simulation using our revised anthropogenic emissions inventory for 1990 and 2010 (Table 2). The data are averaged regionally across the sites in Table 1 for the free troposphere (A), North America (B and E), Western Europe (C and F), and high northern latitude regions (D) (vertical bars show the SDs). Regression coefficients (slope ± SE) and number of sites (n) are given (Insets). The SE of modeled trend is calculated based on the uncertainty range of the emission inventory (Table 2). North American atmospheric Hg⁰ concentrations are from the CAMNet (https://www.ec.gc.ca/natchem) and AMNet (nadp.sws.uiuc.edu/amn) networks and the Experimental Lakes Area, Canada. North American Hg^II wet deposition is from the MDN (nadp.sws.uiuc.edu/mdn). Observations in Western Europe are from the EMEP network (www.emep.int). High-latitude sites include Alert, Canada and Zeppelin, Norway, and three sites above 60° N from the EMEP network.