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Attenuation of ultraviolet radiation in mountain lakes: Factors controlling the among- and within-lake variability / Isabelle Laurion in Limnology and oceanography, 45 (6) (2000) 

Public Citation [article]  inLimnology and oceanography > 45 (6) (2000) . - 1274-1288 Titre : Attenuation of ultraviolet radiation in mountain lakes: Factors controlling the among- and within-lake variability Type de document : Imprimé Auteurs : Isabelle Laurion ; Marc Ventura ; Jordi Catalán ; Roland Psenner (1950-) ; Ruben Sommaruga Année de publication : 2000 Article en page(s) : 1274-1288 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Enjeux de conservation des lacs d'altitude Résumé : High-altitude lakes are exposed to high fluence rates of solar ultraviolet radiation (UVR; 29–400 nm) and contain low concentrations of dissolved organic carbon (DOC). While in most lowland lakes, DOC can be used to predict UV transparency with sufficient accuracy, current models fail to estimate UVR in clear alpine lakes. In these lakes, phytoplankton may contribute significantly to the UV attenuation either as particles or as a source of chromophoric dissolved organic matter (CDOM) with distinctive properties. We investigated a series of 26 lakes in the Alps and Pyrenees, situated at elevations ranging from 422 to 2,799 m above sea level and having DOC concentrations ranging from 0.2 to 3.5 mg L−1. CDOM, as measured by the absorptivity of filtered lake water, explained most of the variability in the attenuation of underwater UVR among lakes (r2 = 0.94, P < 0.001). However, within-lake variation in the UV attenuation revealed a significant contribution from phytoplankton in deeper waters (UV attenuation increasing with chlorophyll a concentration; r2 = 0.97, P = 0.002), only apparent when DOC concentrations were low (∼0.3 mg L−1). The DOC-specific absorptivity (ag*) was also important for characterizing the optical conditions in this series of lakes. Epilimnetic values of ag* were significantly lower in lakes located at high elevations (with low allochthonous CDOM inputs from the catchment), compared to lakes surrounded by trees and meadows. Moreover, ag* was generally lower in surface waters than in deeper water layers, suggesting the influence of photobleaching on UV transparency. The slope S of the exponential regression between CDOM absorptivity and wavelength did not show clear patterns, such as found in marine systems, and often presented lower values in the epilimnetic waters (in association with lower ag*). Collectively, our results suggest that in transparent alpine lakes, the dynamics of the CDOM pool and phytoplankton production will have a strong effect on temporal changes in UV underwater attenuation. Lien pérenne : DOI : 10.4319/lo.2000.45.6.1274 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=150993 Laurion, Isabelle, Ventura, Marc, Catalán, Jordi, Psenner, Roland (1950-), Sommaruga, Ruben 2000 Attenuation of ultraviolet radiation in mountain lakes: Factors controlling the among- and within-lake variability. Limnology and oceanography, 45(6): 1274-1288.

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Dust inputs and bacteria infl uence dissolved organic matter in clear alpine lakes / N. Mladenov in Nature communications, 2 (2011) 

Public Citation [article]  inNature communications > 2 (2011) . - 405 Titre : Dust inputs and bacteria infl uence dissolved organic matter in clear alpine lakes Type de document : Imprimé Auteurs : N. Mladenov ; Ruben Sommaruga ; R. Morales-Baquero ; Isabelle Laurion ; Lluis Camarero ; M. C. Diéguez ; A. Camacho ; A. Delgado ; O. Torres ; Z. Chen ; Marisol Felip ; I. Reche Année de publication : 2011 Article en page(s) : 405 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Enjeux de conservation des lacs d'altitude Résumé : Remote lakes are usually unaffected by direct human influence, yet they receive inputs of atmospheric pollutants, dust, and other aerosols, both inorganic and organic. In remote, alpine lakes, these atmospheric inputs may influence the pool of dissolved organic matter, a critical constituent for the biogeochemical functioning of aquatic ecosystems. Here, to assess this influence, we evaluate factors related to aerosol deposition, climate, catchment properties, and microbial constituents in a global dataset of 86 alpine and polar lakes. We show significant latitudinal trends in dissolved organic matter quantity and quality, and uncover new evidence that this geographic pattern is influenced by dust deposition, flux of incident ultraviolet radiation, and bacterial processing. Our results suggest that changes in land use and climate that result in increasing dust flux, ultraviolet radiation, and air temperature may act to shift the optical quality of dissolved organic matter in clear, alpine lakes. Lien pérenne : DOI : 10.1038/ncomms1411 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=150988 Mladenov, N., Sommaruga, Ruben, Morales-Baquero, R., Laurion, Isabelle, Camarero, Lluis, Diéguez, M. C., Camacho, A., Delgado, A., Torres, O., Chen, Z., Felip, Marisol, Reche, I. 2011 Dust inputs and bacteria infl uence dissolved organic matter in clear alpine lakes. Nature communications, 2: 405.

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Lakes and reservoirs as regulators of carbon cycling and climate / Lars J. Tranvik in Limnology and oceanography, 54 (6-2) (November 2009) 

Public Citation [article]  inLimnology and oceanography > 54 (6-2) (November 2009) . - 2298-2314 Titre : Lakes and reservoirs as regulators of carbon cycling and climate Type de document : Imprimé Auteurs : Lars J. Tranvik ; John A. Downing ; James B. Cotner ; Steven A. Loiselle ; Robert G. Striegl ; Thomas J. Ballatore ; Peter Dillon ; Kerri Finlay ; Kenneth Fortino ; Lesley B. Knoll ; Pirkko L. Kortelainen ; Tiit Kuster ; Soren Larsen ; Isabelle Laurion ; Dina M. Leech ; S. Leigh McCallister ; Diane M. McKnight ; John Michael Melack ; Erin Overholt ; Jason A. Porter ; Yves Prairie ; William H. Renwick ; Fabio Roland ; Bradford Sherman ; David W. Schindler (1940-2021) ; Sebastian Sobek ; Alain Tremblay ; Michael J. Vanni ; Antonie M. Verschoor ; Eddie (von) Wachenfelt ; Gesa A. Weyhenmeyer Année de publication : 2009 Article en page(s) : 2298-2314 Langues : Anglais (eng) Catégories : [LOTERRE-Biodiversité] Changement climatique [CBNPMP-Thématique] Lac d'altitude Résumé : We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments. Lien pérenne : DOI : 10.4319/lo.2009.54.6_part_2.2298 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=152304 Tranvik, Lars J., Downing, John A., Cotner, James B., Loiselle, Steven A., Striegl, Robert G., Ballatore, Thomas J., Dillon, Peter, Finlay, Kerri, Fortino, Kenneth, Knoll, Lesley B., Kortelainen, Pirkko L., Kuster, Tiit, Larsen, Soren, Laurion, Isabelle, Leech, Dina M., Leigh McCallister, S., McKnight, Diane M., Melack, John Michael, Overholt, Erin, Porter, Jason A., Prairie, Yves, Renwick, William H., Roland, Fabio, Sherman, Bradford, Schindler, David W. (1940-2021), Sobek, Sebastian, Tremblay, Alain, Vanni, Michael J., Verschoor, Antonie M., Wachenfelt, Eddie (von), Weyhenmeyer, Gesa A. 2009 Lakes and reservoirs as regulators of carbon cycling and climate. Limnology and oceanography, 54(6-2): 2298-2314.

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