The sulfate deposition flux produced in the nominal model is compatible with estimates of the amount of sulfates on Mars. The nominal range (1.0–1.7 wt.% SO4) is consistent with 1.3 wt.% soluble sulfate measured at the Phoenix landing site (Kounaves et al., 2010b). The estimates also compare well with an average ∼6.8 wt.% sulfur as SO3 (2.7 wt.% S) in global soil inferred from elemental abundances measured at various locations on Mars by Spirit, Opportunity, Pathfinder, and Viking Landers. We can also compare the average sulfur content in the top few tens of centimeters of the soil of ∼4.4 wt.% inferred from Gamma Ray Spectrometer measurements (King and McLennan, 2010). The agreement between model results and data suggest that 0.1% of the terrestrial volcanic gas flux is a good estimate for the volcanic emission rate on Mars 1–2 Ga if soil salts derive from volcanic input.
global soil
SO4
1.0–1.7 wt.%
wt.%
soil
soluble sulfate
1.3 wt.%
wt.%
global soil
SO3
average ∼6.8 wt.%
wt.%
global soil
S
2.7 wt.%
wt.%
soil
top few tens of centimeters
centimeters
soil
average sulfur content
∼4.4 wt.%
wt.%
terrestrial volcanic gas flux
0.1%
%