Total atmospheric mercury fluxes in Southern South America: seasonal dynamics recorded in the GMOS Station EMMA (Nahuel Huapi National Park, Patagonia, Argentina)

DIÉGUEZ, MC; GARCÍA, PE

Roma

Workshop; GMOS (Global Mercury Observation System, Unión Europea FP7). Data quality assurance and quality control. Software QA/QC=data validation.; 2014

CONSIGLIO NAZIONALE DELLE RICERCHE ITALIA

In North Patagonia several studies have reported high levels of mercury (Hg) in  deep ultraoligotrophic lakes belonging to the Nahuel Huapi catchment, Nahuel Huapi National Park (NHNP). NHNP limits at the west with an active volcanic region with highly frequent eruptive events that impact east of the Andes due to the predominant westerly winds. Volcanic activity and atmospheric transport across the Andes have been proposed as the source of Hg to locations east of the cordillera. Mining, industry and other potentially polluting activities are not developed within the Park, thus levels of Hg recorded in the atmosphere may be considered as natural. In contrast with the increasing evidence of mercury concentration and fractionation within lakes, the identification and measurement of the potential sources of mercury, atmospheric and precipitation Hg fluxes is at its starting point. This investigation provides the first evidence of atmospheric Hg fluxes in NHNP, obtained by continuous monitoring of gaseous elemental mercury (GEM) at the EMMA station (Bariloche, 41° 7´43.82"S, 71°25´11.89"W, at 803 m a.s.l) belonging to the Global Mercury Observation System (GMOS). Measurements of GEM consist of desorbed Hg detected by cold vapor atomic fluorescence spectrometry at 253.7 nm using a Hg vapor analyzer Tekran 2537B, within a 5 min time frame, from October 2012 to October 2013. Raw GEM data was sorted out and validated in the frame of the quality control and quality assurance procedures (QC/QA). GEM ranged between 0.22 and 1.33 ng m-3, with a mean annual concentration of 0.90 ± 0.14 ng m-3 of GEM. The highest GEM concentration (1.14 ng m-3) was recorded during the austral spring (October 2012) while lower concentrations (0.83 ng m-3) were measured during fall (April 2013). From spring towards fall, GEM concentrations showed a decreasing pattern until April 2013. Afterwards a slight increase was recorded and, from May to October GEM concentrations fluctuated between 0.9 and 1 ng m-3. The largest GEM variability was found from January 2013 to April 2013, indicating a greater dynamism likely due to pronounced day-night differences, characterized by lower GEM concentrations at night (<1 ng m-3) and higher levels during daytime (above 1.5 ng m-3). So far, GEM records at EMMA station resemble background concentrations, comparable to levels found in Antarctica and remote South Hemisphere locations.