The sea–air exchange of mercury (Hg) in the marine boundary layer of the Augusta basin (southern Italy): Concentrations and evasion flux

• Published in: Chemosphere (Oxford) 2013-11, Vol.93 (9), p.2024-2032
• Main Authors: Bagnato, E., Sproveri, M., Barra, M., Bitetto, M., Bonsignore, M., Calabrese, S., Di Stefano, V., Oliveri, E., Parello, F., Mazzola, S.
• Format: Article
• Language: English
• Subjects: air; Air Pollutants - analysis; Air pollution; Applied sciences; Atmosphere - chemistry; Atmospheric composition; Atmospheric mercury concentrations; Atmospheric pollution; Augusta basin; Basins; data collection; Environmental Monitoring; Exact sciences and technology; Exchange; Flux; Gaseous elemental mercury; Italy; Marine; Marine boundary layer; mercury; Mercury (metal); Mercury - analysis; Mercury evasion flux; Natural water pollution; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Pollution sources; Seasons; Seawater - chemistry; Seawaters, estuaries; Sea–air evasion; sediments; Water Pollutants, Chemical - analysis; Water treatment and pollution; winter
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2013.07.025

•The Hg evasion flux in the Augusta basin marine boundary layer was examined.•The human activity has influenced in the past the marine Hg cycle in the Augusta Bay.•The release of Hg from the Augusta Bay is a source of pollution for the Mediterranean. The first attempt to systematically investigate the atmospheric mercury (Hg) in the MBL of the Augusta basin (SE Sicily, Italy) has been undertaken. In the past the basin was the receptor for Hg from an intense industrial activity which contaminated the bottom sediments of the Bay, making this area a potential source of pollution for the surrounding Mediterranean. Three oceanographic cruises have been thus performed in the basin during the winter and summer 2011/2012, where we estimated averaged Hgatm concentrations of about 1.5±0.4 (range 0.9–3.1) and 2.1±0.98 (range 1.1–3.1) ngm−3 for the two seasons, respectively. These data are somewhat higher than the background Hgatm value measured over the land (range 1.1±0.3ngm−3) at downtown Augusta, while are similar to those detected in other polluted regions elsewhere. Hg evasion fluxes estimated at the sea/air interface over the Bay range from 3.6±0.3 (unpolluted site) to 72±0.1 (polluted site of the basin) ngm−2h−1. By extending these measurements to the entire area of the Augusta basin (∼23.5km2), we calculated a total sea–air Hg evasion flux of about 9.7±0.1gd−1 (∼0.004 tyr−1), accounting for ∼0.0002% of the global Hg oceanic evasion (2000 tyr−1). The new proposed data set offers a unique and original study on the potential outflow of Hg from the sea–air interface at the basin, and it represents an important step for a better comprehension of the processes occurring in the marine biogeochemical cycle of this element.