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Trace metals (Sb, As, Br, Cs, Co, Cr, Ag and Hg), rare earth elements (Ce, Eu, La, Lu, Sm, Tb and Yb), and Sc. were analysed in suspended load and in two sediment cores from Lake Nahuel Huapi, Nahuel Huapi National Park, Patagonia, Argentina, by using Instrumental Neutron Activation Analysis. The core activity profiles of 210Pb and 137Cs were measured to estimate the age of the sediments. Silver was enriched in the upper layers of both cores, and correlated with the strong growth of the population of Bariloche City in the last 50 yr. Concentrations are higher in the core sampled near Bariloche, and indicate some transport in the water body. Silver concentrations measured in the suspended load were 4.58±0.36 and 3.46±0.40 ìg g−1 in the southern margin of the lake, near San Carlos de Bariloche City, whereas in the northern margin the concentrations were 1.68±0.18 and 1.88±0.23 ìg g−1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase above base line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base line values. The metalloids antimony and arsenic show little variation with regard to base line concentration. Noticeable, the mercury contents found in the suspended load. 210Pb and 137Cs were measured to estimate the age of the sediments. Silver was enriched in the upper layers of both cores, and correlated with the strong growth of the population of Bariloche City in the last 50 yr. Concentrations are higher in the core sampled near Bariloche, and indicate some transport in the water body. Silver concentrations measured in the suspended load were 4.58±0.36 and 3.46±0.40 ìg g−1 in the southern margin of the lake, near San Carlos de Bariloche City, whereas in the northern margin the concentrations were 1.68±0.18 and 1.88±0.23 ìg g−1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase above base line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base line values. The metalloids antimony and arsenic show little variation with regard to base line concentration. Noticeable, the mercury contents found in the suspended load. ±0.36 and 3.46±0.40 ìg g−1 in the southern margin of the lake, near San Carlos de Bariloche City, whereas in the northern margin the concentrations were 1.68±0.18 and 1.88±0.23 ìg g−1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase above base line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base line values. The metalloids antimony and arsenic show little variation with regard to base line concentration. Noticeable, the mercury contents found in the suspended load. ±0.18 and 1.88±0.23 ìg g−1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase above base line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base line values. The metalloids antimony and arsenic show little variation with regard to base line concentration. Noticeable, the mercury contents found in the suspended load.210Pb and 137Cs were measured to estimate the age of the sediments. Silver was enriched in the upper layers of both cores, and correlated with the strong growth of the population of Bariloche City in the last 50 yr. Concentrations are higher in the core sampled near Bariloche, and indicate some transport in the water body. Silver concentrations measured in the suspended load were 4.58±0.36 and 3.46±0.40 ìg g−1 in the southern margin of the lake, near San Carlos de Bariloche City, whereas in the northern margin the concentrations were 1.68±0.18 and 1.88±0.23 ìg g−1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase above base line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base line values. The metalloids antimony and arsenic show little variation with regard to base line concentration. Noticeable, the mercury contents found in the suspended load. ±0.36 and 3.46±0.40 ìg g−1 in the southern margin of the lake, near San Carlos de Bariloche City, whereas in the northern margin the concentrations were 1.68±0.18 and 1.88±0.23 ìg g−1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase above base line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base line values. The metalloids antimony and arsenic show little variation with regard to base line concentration. Noticeable, the mercury contents found in the suspended load. ±0.18 and 1.88±0.23 ìg g−1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase above base line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base line values. The metalloids antimony and arsenic show little variation with regard to base line concentration. Noticeable, the mercury contents found in the suspended load. Keywords: 137Cs dating, heavy metals, Instrumental Neutron Activation Analysis, Lake Nahuel Huapi, 210Pb dating, sediment contamination Huapi, 210Pb dating, sediment contamination

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