Examinando por Autor "Pozo, Karla"

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    Ítem
    Levels of persistent organic pollutants (POPs) in the Antarctic atmosphere over time (1980 to 2021) and estimation of their atmospheric half-lives
    (Copernicus Publications, 2023-07-19) Luarte, Thais; Gómez-Aburto, Victoria A.; Poblete-Castro, Ignacio; Castro-Nallar, Eduardo; Hunneus, Nicolas; Molina-Montenegro, Marco; Egas, Claudia; Azcune, Germán; Pérez-Parada, Andrés; Lohmann, Rainier; Bohlin-Nizzetto, Pernilla; Dachs, Jordi; Bengtson-Nash, Susan; Chiang, Gustavo; Pozo, Karla; Galbán-Malagón, Cristóbal J.
    Persistent organic pollutants (POPs) are synthetic compounds that were intentionally produced in large quantities and have been distributed in the global environment, originating a threat due to their persistence, bioaccumulative potential, and toxicity. POPs reach the Antarctic continent through long-range atmospheric transport (LRAT). In these areas, low temperatures play a significant role in the environmental fate of POPs, retaining them for a long time due to cold trapping by diffusion and wet deposition, acting as a net sink for many POPs. However, in the current context of climate change, the remobilization of POPs that were trapped in water, ice, and soil for decades is happening. Therefore, continuous monitoring of POPs in polar air is necessary to assess whether there is a recent re-release of historical pollutants back to the environment. We reviewed the scientific literature on atmospheric levels of several POP families (polychlorinated biphenyls - PCBs, hexachlorobenzene - HCB, hexachlorocyclohexanes - HCHs, and dichlorodiphenyltrichloroethane - DDT) from 1980 to 2021. We estimated the atmospheric half-life using characteristic decreasing times (TD). We observed that HCB levels in the Antarctic atmosphere were higher than the other target organochlorine pesticides (OCPs), but HCB also displayed higher fluctuations and did not show a significant decrease over time. Conversely, the atmospheric levels of HCHs, some DDTs, and PCBs have decreased significantly. The estimated atmospheric half-lives for POPs decreased in the following order: 4,4' DDE (13.5 years) > 4,4' DDD (12.8 years) > 4,4' DDT (7.4 years) > 2,4' DDE (6.4 years) > 2,4' DDT (6.3 years) > α-HCH (6 years) > HCB (6 years) > 3-HCH (4.2 years). For PCB congeners, they decreased in the following order: PCB 153 (7.6 years) > PCB 138 (6.5 years) > PCB 101 (4.7 years) > PCB 180 (4.6 years) > PCB 28 (4 years) > PCB 52 (3.7 years) > PCB 118 (3.6 years). For HCH isomers and PCBs, the Stockholm Convention (SC) ban on POPs did have an impact on decreasing their levels during the last decades. Nevertheless, their ubiquity in the Antarctic atmosphere shows the problematic issues related to highly persistent synthetic chemicals. © 2023 Thais Luarte et al.
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    Ítem
    Occurrence and air-water diffusive exchange legacy persistent organic pollutants in an oligotrophic north Patagonian lake
    (Academic Press Inc., 2022-03) Luarte, Thais; Tucca, Felipe; Nimptsch, Jorge; Woelfl, Stefan; Casas, Gemma; Dachs, Jordi; Chiang, Gustavo; Pozo, Karla; Barra, Ricardo; Galbán-Malagón, Cristóbal
    In this study, the occurrence and diffusive air-water exchange of POPs in Panguipulli Lake (39°42′S-72°13′W), an oligotrophic lake located in northern Patagonia (Chile), were determined. Air and water samples were collected between March and August 2017 (autumn-winter) and analyzed for concentrations of OCPs (α-HCH, β-HCH, γ-HCH and HCB) and PCBs (PCB-28,-52,-101,-118,-153,-158,-180) using gas chromatography coupled with an electron capture detector. The direction of air-water exchange direction was evaluated using a fugacity approach (ƒw ƒa−1), and net diffusive exchange fluxes (FAW, ng m−2 d−1) were also estimated. Total ∑4OCP levels in air ranged from 0.31 to 37 pg m−3, with a maximum for β-HCH, while Σ7PCB levels ranged from 3.05 to 43 pg m−3. The most abundant congener was PCB-153, accounting for 60% of the total PCBs in air. Surface water ∑4OCPs measured in this study ranged from 1.01 to 3.9 pg L−1, with γ-HCH predominating, while surface water Σ7PCB levels ranged from 0.32 to 24 pg L−1, with PCB-101, PCB-118, and PCB-153 presenting the highest levels. Diffusive air-water exchanges of HCB, α-HCH, γ-HCH and PCBs in the form of volatilization from the lake to air predominated; in contrast, for β-HCH net deposition dominated during the sampling period. Estimates suggested faster microbial degradation in the dissolved phase compared to atmospheric degradation for all analyzed POPs. Overall, these results could indicate that the oligotrophic lakes of northern Patagonia act as a secondary source of atmospheric POPs, mainly PCBs and some OCPs. This study is a first attempt to understand the occurrence of POPs in air and water, as well as their dynamics in oligotrophic lakes in the southern hemisphere. © 2021