Air Concentrations of Gaseous Elemental Mercury and Vegetation–Air Fluxes within Saltmarshes of the Tagus Estuary, Portugal

In situ air concentrations of gaseous elemental mercury (Hg(0)) and vegetation–atmosphere fluxes were quantified in both high (Cala Norte, CN) low-to-moderate (Alcochete, ALC) Hg-contaminated saltmarsh areas the Tagus estuary colonized by plant species Halimione portulacoides (Hp) Sarcocornia fruticosa (Sf). Atmospheric Hg(0) ranged between 1.08–18.15 ng m−3 CN 1.18–3.53 ALC. CN, most levels occurred during nighttime, while opposite was observed at ALC, suggesting that photoreduction not driving contaminated site. Vegetation–air low ALC from −0.76 to 1.52 m−2 (leaf area) h−1 for Hp −0.40 1.28 Sf. higher Hg plants, ranging −9.90 15.45 −8.93 12.58 Mercury flux results considered less reliable due large fast variations ambient Hg(0), which may have been influenced emissions nearby chlor-alkali plant, or historical contamination. Improved experimental setup, influence local seasonal activity plants must be when assessing vegetation–air areas.