Occurrence and air-water diffusive exchange legacy persistent organic pollutants in an oligotrophic north Patagonian lake

• Published in: Environmental research 2022-03, Vol.204 (Pt B), p.112042-112042, Article 112042
• Main Authors: Luarte, Thais, Tucca, Felipe, Nimptsch, Jorge, Woelfl, Stefan, Casas, Gemma, Dachs, Jordi, Chiang, Gustavo, Pozo, Karla, Barra, Ricardo, Galbán-Malagón, Cristóbal
• Format: Article
• Language: English
• Subjects: Air Pollutants - analysis; Air-water exchange; Environmental Monitoring; Lakes; Legacy pollutants; North patagonian lakes; Persistent Organic Pollutants; Pesticides; Pesticides - analysis; Polychlorinated Biphenyls - analysis; South America; Water; Water Pollutants, Chemical - analysis
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2021.112042

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. •We determined levels of Persistent Organic Pollutants in the atmosphere and water of a North Patagonian Lake.•Persistent organic pollutant levels were higher in the dissolved phase than in the gas phase.•Net volatilization of hexachlorocyclohexane isomers, apart from β-HCH, predominated.•Polychlorinated biphenyls volatilize from the oligotrophic during the present study.