| Title | Decadal trends in water chemistry of Alpine lakes in calcareous catchments driven by climate change |
| Abstract | High mountain lakes are considered sensitive indicators of the effects of natural and anthropogenic drivers, including atmospheric deposition and climate change. In this study, we assess long-term trends in the chemistry of a group of high altitude lakes in the Western Alps, Italy, lying in bedrock with a relevant presence of basic, soluble rocks. An in-depth investigation was performed on two key-sites (Lakes Boden Inferiore and Superiore) for which continuous chemical data are available for a period of 30 years. A group of 10 additional lakes in the same area was also considered; these lakes were sampled at the end of the ice-free period during irregular surveys in the period 1980-2017. Water samples were analysed for the main chemical variables, including pH, electrical conductivity, major ions (Ca, Mg, Na, K, HCO, Cl, SO, NO) and algal nutrients (phosphorus and nitrogen compounds, reactive silica). A steep increase in conductivity and ion concentrations was detected at the key-sites: conductivity increased from 40-45 to 60-70 µS cm over the period 1984-2017; sulphate concentrations more than doubled over the same period (from 50-60 to 120-180 µeq L) and base cations increased from 400-500 to 600-750 µeq L. An increase in the solute content was also detected in the survey lakes (average conductivity from 39 ± 20 to 57 ± 23 µS cm). The analysis of meteorological data revealed a significant increase of air temperature (0.019 °C y over the period 1950-2017), mainly in spring and summer (0.033 °C y), and a decrease of snow cover depth and duration. Meteo-climatic drivers were identified as the responsible for the chemical changes occurred in the lakes. Climate-driven effects on weathering rates were mainly indirect and occurred by affecting the flow paths of water at both surface and subsurface level. Cryosphere modification (reduced snow cover and permafrost thawing) also played a role. |
| Source | Science of the total environment 708 |
| Keywords | BiogeochemistryLong-term trendsMountain lakesPermafrostWeathering |
| Journal | Science of the total environment |
| Editor | Elsevier, Lausanne ;, Paesi Bassi |
| Year | 2020 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.scitotenv.2019.135180 |
| Authors | Rogora, M.; Somaschini, L.; Marchetto, A.; Mosello, R.; Tartari, G. A.; Paro, L. |
| Text | 420918 2020 10.1016/j.scitotenv.2019.135180 Scopus 2 s2.0 85076623954 Biogeochemistry Long term trends Mountain lakes Permafrost Weathering Decadal trends in water chemistry of Alpine lakes in calcareous catchments driven by climate change Rogora, M.; Somaschini, L.; Marchetto, A.; Mosello, R.; Tartari, G. A.; Paro, L. ARPA Piemonte; Istituto di Ricerca sulle Acque, Italy High mountain lakes are considered sensitive indicators of the effects of natural and anthropogenic drivers, including atmospheric deposition and climate change. In this study, we assess long term trends in the chemistry of a group of high altitude lakes in the Western Alps, Italy, lying in bedrock with a relevant presence of basic, soluble rocks. An in depth investigation was performed on two key sites Lakes Boden Inferiore and Superiore for which continuous chemical data are available for a period of 30 years. A group of 10 additional lakes in the same area was also considered; these lakes were sampled at the end of the ice free period during irregular surveys in the period 1980 2017. Water samples were analysed for the main chemical variables, including pH, electrical conductivity, major ions Ca, Mg, Na, K, HCO, Cl, SO, NO and algal nutrients phosphorus and nitrogen compounds, reactive silica . A steep increase in conductivity and ion concentrations was detected at the key sites conductivity increased from 40 45 to 60 70 µS cm over the period 1984 2017; sulphate concentrations more than doubled over the same period from 50 60 to 120 180 µeq L and base cations increased from 400 500 to 600 750 µeq L. An increase in the solute content was also detected in the survey lakes average conductivity from 39 ± 20 to 57 ± 23 µS cm . The analysis of meteorological data revealed a significant increase of air temperature 0.019 °C y over the period 1950 2017 , mainly in spring and summer 0.033 °C y , and a decrease of snow cover depth and duration. Meteo climatic drivers were identified as the responsible for the chemical changes occurred in the lakes. Climate driven effects on weathering rates were mainly indirect and occurred by affecting the flow paths of water at both surface and subsurface level. Cryosphere modification reduced snow cover and permafrost thawing also played a role. 708 Published version http //www.scopus.com/record/display.url eid=2 s2.0 85076623954 origin=inward Articolo in rivista Elsevier 0048 9697 Science of the total environment Science of the total environment Sci. total environ. rosario.mosello MOSELLO ROSARIO aldo.marchetto MARCHETTO ALDO michela.rogora ROGORA MICHELA gabriele.tartari TARTARI GABRIELE TA.P02.031.002 Impatti dei cambiamenti climatici sugli ecosistemi remoti |
