| Abstract | A growing concern exists about the effects of chloride (Cl) on freshwater systems. Increasing Cl concentrations have been observed in the last few decades in several rivers and lakes, mainly in northern countries. In Italy, present levels and temporal changes of sodium (Na) and Cl in water bodies have rarely been assessed. Based on long-term data for the lakes of the subalpine district in Italy (Maggiore, Lugano, Como, Iseo, Garda), we analyzed trends affecting Cl and Na concentrations during the last 25 years, with the aim of identifying temporal changes and assessing possible causes. An in-depth analysis is presented for Lake Maggiore. Positive temporal Na and Cl trends were evident in all studied lakes, with the trends increasing since early 2000s. Data for Lake Maggiore tributaries showed a clear seasonality (higher values in winter and early spring). The NaCl used as road de-icing agent, together with Cl discharge from wastewater treatment plants, were identified as the main causes for the observed trends. Chloride concentrations in the lakes are below the threshold limit for reduced water quality and below concentrations known to harm aquatic biota. However, considering the relevance of deep subalpine lakes, representing almost 80 % of the total freshwater volume in Italy, these trends indicate an important chemical change, which warrants further analysis. |
| Text | 367168 2015 10.1007/s11356 015 5090 6 Scopus 2 s2.0 84949103710 ISI Web of Science WOS 000365816000067 Deep subalpine lakes Long term trends NaCl Water chemistry Recent trends in chloride and sodium concentrations in the deep subalpine lakes Northern Italy Rogora M.; Mosello R.; Kamburska L.; Salmaso N.; Cerasino L.; Leoni B.; Garibaldi L.; Soler V.; Lepori F.; Colombo L.; Buzzi F. CNR Institute of Ecosystem Study, L.go Tonolli 52, Verbania Pallanza, 28922, Italy; IASMA Research and Innovation Centre, Istituto Agrario di S. Michele all Adige Fondazione E. Mach, Via E. Mach 1, S. Michele all Adige, Trento, 38010, Italy; Department of Earth and Environmental Sciences, University of Milan Bicocca, Piazza della Scienza 1, Milan, 20126, Italy; University of Applied Sciences and Arts of Southern Switzerland SUPSI , Via Trevano 72, Canobbio, 6952, Switzerland; ARPA Lombardia, Dipartimento di Lecco, Via I Maggio, 21/b, Oggiono, Lecco, 23848, Italy A growing concern exists about the effects of chloride Cl on freshwater systems. Increasing Cl concentrations have been observed in the last few decades in several rivers and lakes, mainly in northern countries. In Italy, present levels and temporal changes of sodium Na and Cl in water bodies have rarely been assessed. Based on long term data for the lakes of the subalpine district in Italy Maggiore, Lugano, Como, Iseo, Garda , we analyzed trends affecting Cl and Na concentrations during the last 25 years, with the aim of identifying temporal changes and assessing possible causes. An in depth analysis is presented for Lake Maggiore. Positive temporal Na and Cl trends were evident in all studied lakes, with the trends increasing since early 2000s. Data for Lake Maggiore tributaries showed a clear seasonality higher values in winter and early spring . The NaCl used as road de icing agent, together with Cl discharge from wastewater treatment plants, were identified as the main causes for the observed trends. Chloride concentrations in the lakes are below the threshold limit for reduced water quality and below concentrations known to harm aquatic biota. However, considering the relevance of deep subalpine lakes, representing almost 80 % of the total freshwater volume in Italy, these trends indicate an important chemical change, which warrants further analysis. 22 Published version http //www.scopus.com/inward/record.url eid=2 s2.0 84949103710 partnerID=q2rCbXpz Articolo 2015_Environ_Sci_Pollut_Res_22_19013_19026.pdf Articolo in rivista Springer 0944 1344 Environmental science and pollution research international Environmental science and pollution research international Environ. sci. pollut. res. int. Environmental science and pollution research international. Environmental science and pollution research international Print Environmental science and pollution research Print ESPR Print lyudmilatodorova.kamburska KAMBURSKA LYUDMILA TODOROVA rosario.mosello MOSELLO ROSARIO michela.rogora ROGORA MICHELA |
