Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and Photodegradation
In shallow aquatic environments, sediment is a significant source of monomethylmercury (MMHg) for surface water (SW). High-altitude aquatic ecosystems are characterized by extreme hydro-climatic constraints (e.g., low oxygen and high UV radiation). We studied, during two seasons, the diel cycles of...
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MDPI AG
2020-11-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/10/21/7936 |
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| author | Stéphane Guédron Dario Achá Sylvain Bouchet David Point Emmanuel Tessier Carlos Heredia Stéfany Rocha-Lupa Pablo Fernandez-Saavedra Marizol Flores Sarah Bureau Israel Quino-Lima David Amouroux |
| author_facet | Stéphane Guédron Dario Achá Sylvain Bouchet David Point Emmanuel Tessier Carlos Heredia Stéfany Rocha-Lupa Pablo Fernandez-Saavedra Marizol Flores Sarah Bureau Israel Quino-Lima David Amouroux |
| author_sort | Stéphane Guédron |
| collection | DOAJ |
| description | In shallow aquatic environments, sediment is a significant source of monomethylmercury (MMHg) for surface water (SW). High-altitude aquatic ecosystems are characterized by extreme hydro-climatic constraints (e.g., low oxygen and high UV radiation). We studied, during two seasons, the diel cycles of MMHg in SW and sediment porewaters (PW) of Lake Uru Uru (3686 m a.s.l, Bolivia) contaminated by urban and mining activities. Our results show that diel changes in SW MMHg concentrations (up to 1.8 ng L<sup>−1</sup>) overwhelm seasonal ones, with higher MMHg accumulation during the night-time and the dry season. The calculation of MMHg diffusive fluxes demonstrates that the sediment compartment was the primary source of MMHg to the SW. Most MMHg efflux occurred during the dry season (35.7 ± 17.4 ng m<sup>−2</sup> day<sup>−1</sup>), when the lake was relatively shallow, more eutrophicated, and with the redoxcline located above the sediment–water interface (SWI). Changes in MMHg accumulation in the PWs were attributed to diel redox oscillations around the SWI driving both the bacterial sulfate reduction and bio-methylation. Finally, we highlight that although MMHg loading from the PW to the SW is large, MMHg photodegradation and demethylation by microorganisms control the net MMHg accumulation in the water column. |
| first_indexed | 2024-03-10T15:00:01Z |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-10T15:00:01Z |
| publishDate | 2020-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-9644f0b3700f45ca8a980bc68b9c99992023-11-20T20:16:43ZengMDPI AGApplied Sciences2076-34172020-11-011021793610.3390/app10217936Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and PhotodegradationStéphane Guédron0Dario Achá1Sylvain Bouchet2David Point3Emmanuel Tessier4Carlos Heredia5Stéfany Rocha-Lupa6Pablo Fernandez-Saavedra7Marizol Flores8Sarah Bureau9Israel Quino-Lima10David Amouroux11Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble, FranceUnidad de Calidad Ambiental (UCA)—Instituto de Ecología—Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, casilla, 3161 La Paz, BoliviaUniv. de Pau et des Pays de l’Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l’Environnement et les Matériaux, Pau, FranceUnidad de Calidad Ambiental (UCA)—Instituto de Ecología—Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, casilla, 3161 La Paz, BoliviaUniv. de Pau et des Pays de l’Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l’Environnement et les Matériaux, Pau, FranceUnidad de Calidad Ambiental (UCA)—Instituto de Ecología—Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, casilla, 3161 La Paz, BoliviaUnidad de Calidad Ambiental (UCA)—Instituto de Ecología—Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, casilla, 3161 La Paz, BoliviaUnidad de Calidad Ambiental (UCA)—Instituto de Ecología—Universidad Mayor de San Andrés, Campus Universitario de Cota Cota, casilla, 3161 La Paz, BoliviaLaboratorio de Hidroquímica—Instituto de Investigaciones Químicas—Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, casilla, 3161 La Paz, BoliviaUniv. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble, FranceLaboratorio de Hidroquímica—Instituto de Investigaciones Químicas—Universidad Mayor de San Andrés, Campus Universitario de Cota-Cota, casilla, 3161 La Paz, BoliviaUniv. de Pau et des Pays de l’Adour, E2S UPPA, CNRS, IPREM, Institut des Sciences Analytiques et de Physico-chimie pour l’Environnement et les Matériaux, Pau, FranceIn shallow aquatic environments, sediment is a significant source of monomethylmercury (MMHg) for surface water (SW). High-altitude aquatic ecosystems are characterized by extreme hydro-climatic constraints (e.g., low oxygen and high UV radiation). We studied, during two seasons, the diel cycles of MMHg in SW and sediment porewaters (PW) of Lake Uru Uru (3686 m a.s.l, Bolivia) contaminated by urban and mining activities. Our results show that diel changes in SW MMHg concentrations (up to 1.8 ng L<sup>−1</sup>) overwhelm seasonal ones, with higher MMHg accumulation during the night-time and the dry season. The calculation of MMHg diffusive fluxes demonstrates that the sediment compartment was the primary source of MMHg to the SW. Most MMHg efflux occurred during the dry season (35.7 ± 17.4 ng m<sup>−2</sup> day<sup>−1</sup>), when the lake was relatively shallow, more eutrophicated, and with the redoxcline located above the sediment–water interface (SWI). Changes in MMHg accumulation in the PWs were attributed to diel redox oscillations around the SWI driving both the bacterial sulfate reduction and bio-methylation. Finally, we highlight that although MMHg loading from the PW to the SW is large, MMHg photodegradation and demethylation by microorganisms control the net MMHg accumulation in the water column.https://www.mdpi.com/2076-3417/10/21/7936monomethylmercurywater–sediment interfacediel and seasonal cyclesphotodegradation |
| spellingShingle | Stéphane Guédron Dario Achá Sylvain Bouchet David Point Emmanuel Tessier Carlos Heredia Stéfany Rocha-Lupa Pablo Fernandez-Saavedra Marizol Flores Sarah Bureau Israel Quino-Lima David Amouroux Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and Photodegradation Applied Sciences monomethylmercury water–sediment interface diel and seasonal cycles photodegradation |
| title | Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and Photodegradation |
| title_full | Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and Photodegradation |
| title_fullStr | Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and Photodegradation |
| title_full_unstemmed | Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and Photodegradation |
| title_short | Accumulation of Methylmercury in the High-Altitude Lake Uru Uru (3686 m a.s.l, Bolivia) Controlled by Sediment Efflux and Photodegradation |
| title_sort | accumulation of methylmercury in the high altitude lake uru uru 3686 m a s l bolivia controlled by sediment efflux and photodegradation |
| topic | monomethylmercury water–sediment interface diel and seasonal cycles photodegradation |
| url | https://www.mdpi.com/2076-3417/10/21/7936 |
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