| Abstract | Rock-glacier sediment transfer and ice melting can impact surface waters located downstream. However, there is a lack of knowledge on the influence of rock-glacier dynamics on the geochemical, hydrochemical, and ecological characteristics of adjacent impounded surface waters. In the Col d'Olen area (Long-Term Ecological Research site, NW Italian Alps), an intact rock glacier terminates into a pond and solute-enriched waters originating from the rock glacier flow into the pond through a subsurface hydrological window. In this study, we performed geophysical and ground surface temperature measurements. Moreover, we sampled soils and sediments in different compartments of the investigated rock-glacier - pond system and we further sampled benthic invertebrates in the pond. Cold ground thermal regime, ground-ice presence, and coarse debris cover on the rock glacier together with its lithology (serpentinites) influence the rock-glacier geochemistry and ecology with respect to surrounding areas. Pond geochemistry is affected by transfer of trace-metal-enriched fine-grained debris and meltwaters from the rock glacier. Enhanced bioavailability of serpentinite-associated trace metals was proved, with concentrations of Ni and Cr in benthic invertebrates up to 384 and 110 mg kg-1 d.w., respectively, potentially exerting toxic effects on pond biota. The advancing movement of the rock glacier not only has delivered sediments to the pond, but it has progressively filled the valley depression where the pond is located, creating a dam that could have modified the level of impounded water. This process likely constituted a sediment trap in which serpentinitic rock-glacier sediments could be deposited at the pond bottom, with related geochemical and ecological implications. This study illustrates the importance of rock glaciers in influencing the characteristics of downstream freshwater bodies and highlights the need to improve our knowledge about climate-change-related impacts of rock-glacier dynamics on alpine headwaters. |
| Text | 423855 2020 10.1016/j.catena.2020.104700 Soil Weathering Rock glacier Lacustrine sediments Alps LTER A rock glacier pond system NW Italian Alps Soil and sediment properties, geochemistry, and trace metal bioavailability N.Colombo ab C.Ferronato cd L. Vittori Antisari d L.Marziali e F.Salerno e S. Fratianni b M. E. D Amico a A. Ribolini f D. Godone g S. Sartini h L. Paro i U. Morra di Cella j M. Freppaz a a Department of Agricultural, Forest and Food Sciences, University of Turin, Grugliasco, Italy b Department of Earth Sciences, University of Turin, Turin, Italy c Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy d Department of Agricultural and Food Sciences, University of Bologna, Bologna, Italy e CNR IRSA National Research Council Water Research Institute , Brugherio, Italy f Department of Earth Sciences, University of Pisa, Pisa, Italy g CNR IRPI National Research Council Research Institute for Geo Hydrological Protection , Turin, Italy h So.Ge.T, Lucca, Italy i Department of Natural and Environmental Risks , Arpa Piemonte, Turin, Italy j Department of Climate Change , Arpa Valle d Aosta, Aosta, Italy Rock glacier sediment transfer and ice melting can impact surface waters located downstream. However, there is a lack of knowledge on the influence of rock glacier dynamics on the geochemical, hydrochemical, and ecological characteristics of adjacent impounded surface waters. In the Col d Olen area Long Term Ecological Research site, NW Italian Alps , an intact rock glacier terminates into a pond and solute enriched waters originating from the rock glacier flow into the pond through a subsurface hydrological window. In this study, we performed geophysical and ground surface temperature measurements. Moreover, we sampled soils and sediments in different compartments of the investigated rock glacier pond system and we further sampled benthic invertebrates in the pond. Cold ground thermal regime, ground ice presence, and coarse debris cover on the rock glacier together with its lithology serpentinites influence the rock glacier geochemistry and ecology with respect to surrounding areas. Pond geochemistry is affected by transfer of trace metal enriched fine grained debris and meltwaters from the rock glacier. Enhanced bioavailability of serpentinite associated trace metals was proved, with concentrations of Ni and Cr in benthic invertebrates up to 384 and 110 mg kg 1 d.w., respectively, potentially exerting toxic effects on pond biota. The advancing movement of the rock glacier not only has delivered sediments to the pond, but it has progressively filled the valley depression where the pond is located, creating a dam that could have modified the level of impounded water. This process likely constituted a sediment trap in which serpentinitic rock glacier sediments could be deposited at the pond bottom, with related geochemical and ecological implications. This study illustrates the importance of rock glaciers in influencing the characteristics of downstream freshwater bodies and highlights the need to improve our knowledge about climate change related impacts of rock glacier dynamics on alpine headwaters. 194 Published version https //doi.org/10.1016/j.catena.2020.104700 Articolo in rivista Elsevier Science 0341 8162 Catena Cremling. Catena Cremling. Catena Cremling. Catena. Cremling. Catena Amsterdam Cremling. Catena Giessen Cremling. danilofrancescostefano.godone GODONE DANILO FRANCESCO STEFANO franco.salerno SALERNO FRANCO laura.marziali MARZIALI LAURA TA.P05.010.001 Tecniche e tecnologie per il monitoraggio dei parametri che caratterizzano le evoluzioni morfologiche di alvei e versanti instabili. DTA.AD003.141.001 Sviluppo sistemi monitoraggio innovativi |
