Abstract. The current knowledge concerning mercury dry deposition is reviewed, including dry deposition algorithms used in chemical transport models (CTMs) and at monitoring sites and related deposition calculations, measurement methods and studies for quantifying dry deposition of gaseous oxidized mercury (GOM) and particulate bound mercury (PBM), and measurement studies of litterfall and throughfall mercury. Measured median GOM plus PBM dry deposition in Asia (10.7 μg m−2 yr−1) almost double that in North America (6.1 μg m−2 yr−1) due to the higher anthropogenic emissions in Asia. Measured median litterfall and throughfall mercury are 22.3 and 56.5 μg m−2 yr−1, respectively, in Asia, 12.8 and 16.3 μg m−2 yr−1 in Europe, and 11.9 and 7.0 μg m−2 yr−1 in North America. The much higher litterfall mercury than GOM plus PBM dry deposition suggests the important contribution of gaseous elemental mercy (GEM) to mercury dry deposition to vegetated canopies. Over all the regions, including the Amazon, dry deposition, estimated as the sum of litterfall and throughfall minus open-field wet deposition, is more dominant than wet deposition for Hg deposition. Regardless of the measurement or modelling method used, a factor of two or larger uncertainties in GOM plus PBM dry deposition need to be kept in mind when using these numbers for mercury impact studies.
Supplementary material to "An evaluation of European nitrogen and sulfur wet deposition and
their trends estimated by six chemistry transport models for the
period 1990–2010"
