Seasonal patterns of atmospheric mercury in tropical South America as inferred by a continuous total gaseous mercury record at Chacaltaya station (5240 m) in Bolivia

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Koenig , A M , Magand , O , Laj , P , Andrade , M , Moreno , I , Velarde , F , Salvatierra , G , Gutierrez , R , Blacutt , L , Aliaga , D , Reichler , T , Sellegri , K , Laurent , O , Ramonet , M & Dommergue , A 2021 , ' Seasonal patterns of atmospheric mercury in tropical South America as inferred by a continuous total gaseous mercury record at Chacaltaya station (5240 m) in Bolivia ' , Atmospheric Chemistry and Physics , vol. 21 , no. 5 , pp. 3447-3472 . https://doi.org/10.5194/acp-21-3447-2021

Title: Seasonal patterns of atmospheric mercury in tropical South America as inferred by a continuous total gaseous mercury record at Chacaltaya station (5240 m) in Bolivia
Author: Koenig, Alkuin Maximilian; Magand, Olivier; Laj, Paolo; Andrade, Marcos; Moreno, Isabel; Velarde, Fernando; Salvatierra, Grover; Gutierrez, Rene; Blacutt, Luis; Aliaga, Diego; Reichler, Thomas; Sellegri, Karine; Laurent, Olivier; Ramonet, Michel; Dommergue, Aurelien
Other contributor: University of Helsinki, INAR Physics
Date: 2021-03-05
Language: eng
Number of pages: 26
Belongs to series: Atmospheric Chemistry and Physics
ISSN: 1680-7316
DOI: https://doi.org/10.5194/acp-21-3447-2021
URI: http://hdl.handle.net/10138/328815
Abstract: High-quality atmospheric mercury (Hg) data are rare for South America, especially for its tropical region. As a consequence, mercury dynamics are still highly uncertain in this region. This is a significant deficiency, as South America appears to play a major role in the global budget of this toxic pollutant. To address this issue, we performed nearly 2 years (July 2014-February 2016) of continuous high-resolution total gaseous mercury (TGM) measurements at the Chacaltaya (CHC) mountain site in the Bolivian Andes, which is subject to a diverse mix of air masses coming predominantly from the Altiplano and the Amazon rainforest. For the first 11 months of measurements, we obtained a mean TGM concentration of 0 :89 +/- 0 :01 ngm(-3), which is in good agreement with the sparse amount of data available from the continent. For the remaining 9 months, we obtained a significantly higher TGM concentration of 1 :34 +/- 0 :01 ngm(-3), a difference which we tentatively attribute to the strong El Nino event of 2015-2016. Based on HYSPLIT (Hybrid SingleParticle Lagrangian Integrated Trajectory) back trajectories and clustering techniques, we show that lower mean TGM concentrations were linked to either westerly Altiplanic air masses or those originating from the lowlands to the southeast of CHC. Elevated TGM concentrations were related to northerly air masses of Amazonian or southerly air masses of Altiplanic origin, with the former possibly linked to artisanal and small-scale gold mining (ASGM), whereas the latter might be explained by volcanic activity. We observed a marked seasonal pattern, with low TGM concentrations in the dry season (austral winter), rising concentrations during the biomass burning (BB) season, and the highest concentrations at the beginning of the wet season (austral summer). With the help of simultaneously sampled equivalent black carbon (eBC) and carbon monoxide (CO) data, we use the clearly BB-influenced signal during the BB season (August to October) to derive a mean TGM = CO emission ratio of (2.3 +/- 0.6 x 10(-7) ppbvTGM ppbv (-1)(CO), which could be used to constrain South American BB emissions. Through the link with CO2 measured in situ and remotely sensed solarinduced fluorescence (SIF) as proxies for vegetation activity, we detect signs of a vegetation sink effect in Amazonian air
Subject: 1171 Geosciences
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