Mercurio en cuencas Andino-Patagónicas: evaluación de su dinámica atmosférica, especiación, fuentes y reguladores climáticos. XXII Congreso Argentino de Toxicología (ATA)

DIÉGUEZ, M.C.; GARCIA, P.E.

BUENOS AIRES

Congreso; XXII CONGRESO ARGENTINO DE TOXICOLOGIA; 2021

ASOCIACIÓN ARGENTINA DE TOXICOLOGIA

Mercury (Hg) is a global pollutant that can reach remote regions of the globe through atmospheric transport. Hg is toxic in many forms, however, the organic species methylmercury (CH3Hg, produced in soils, sediments and natural waters from inorganic Hg, is a dangerous neurotoxin that poses serious risks to humans and wildlife with fish-based diets. CH3Hg is differentially bioaccumulated due to its lipophilic nature and passes from basal organisms to higher trophic levels of aquatic food chains, bioconcentrating along food chains. In the absence of point sources, atmospheric deposition is the most important source of Hg (mostly as Hg2+) to catchments and thus, one of the drivers of its dynamics in different environmental compartments. In Nahuel Huapi National Park (NHNP, Patagonia, Argentina) moderate to high total Hg levels (THg) have been detected in natural waters, lake sediments and aquatic biota of NHNP, with a recognized hot-spot at the western sector of the Park, close to an active volcanic area (Puyehue Cordón Caulle). The origin of Hg has been related to major historical inputs from volcanic eruptions and forest fires through lake sediment studies. This work aims at analyzing the dynamics of atmospheric Hg levels and speciation in NHNP, using long-term records of Hg0 (GEM), Hg2+ (GOM) and Particle Bound Hg2+ (PBM) between 2012-2019 at the EMMA station (Global Mercury Observation System) in Bariloche. Atmospheric Hg monitoring was performed using a Cold Vapor Atomic Fluorescence (CVAF) equipment Tekran 2537B suited with speciation units, providing GEM, GOM and PBM data. Hg and concurrent meteorological data was analyzed applying multivariate statistics in order to evaluate climate drivers of Hg dynamics. Hg dynamics and source contribution was evaluated through Hysplit trajectories (HBT) and Potential Source contribution (PSCF) models. In the studied period, GEM ranged between 0.21 and 1.47 ng m-3 displaying higher day-time levels, and, increased concentrations in spring-summer (0.95 ± 0.13 ng m-3 and 0.88 ± 0.15 ng m-3, respectively) compared to winter-autumn (0.85 ± 0.16 ng m-3 and 0.80 ± 0.15 ng m-3). GOM varied between 0.42 and 37.2 pg m-3 (4.61 ± 4.00 pg m-3) and PBM ranged from 0.42 to 20.1 pg m-3 (3.74 ± 3.41 pg m-3), showing higher levels in autumn-summer. Westerly winds, temperature, humidity and UV radiation affected GEM, GOM and PBM levels. HBT and PSCF indicated: i- influence of long-range transport determining low GEM, GOM and PBM levels brought by clean Pacific-borne air masses from W and SW, and, ii- the influence of short-range transport from the NW, W and SW causing eventual increases in GOM and PBM levels, coinciding with the local influences of forest fires and volcanic activity in the region.