Distribution and speciation of arsenic in two top predator fish species from lake Nahuel Huapi

JUNCOS, R.; ARCAGNI, M.; RIZZO, A.; ARRIBÉRE, M.A.; BRIZIO, P.; ABETE, M.C.; SQUADRONE, S.; RIBEIRO GUEVARA, S.

Córdoba

Congreso; VI Congreso Argentino de la Sociedad de Toxicología y Química Ambiental; 2016

Arsenic (As) is an environmental contaminant, from natural and anthropogenic origin. Volcanic eruptions are recognized sources of As to freshwaters. The bioavailability, bioaccumulation, and toxicity of As depends on its chemical form. We analyzed different tissues from two fish species with different feeding habits: native creole perch (Percichthys trucha) and introduced rainbow trout (Oncorhynchus mykiss), from lake Nahuel Huapi, recently impacted by a volcanic eruption. The objective of this study was to determine total As concentrations (As) and species in tissues of top predator fish species from an oligotrophic lake in volcanic area. Fishes were sampled at two sites: close to Puyehue Cordón Caulle volcanic complex (BR site) and farthest from the volcano (DH site), using gillnets. As in fish organs were determined by Instrumental Neutron Activation Analysis (INAA). Arsenic speciation was analyzed in muscles through high-performance liquid chromatography (HPLC) coupled with ICP-MS. The pattern of As accumulation in perch organs was: kidney (1.4-3.9 µg g-1 DW) = liver (1-3.9 µg g-1 DW)> gill (0.9-2.6 µg g-1 DW)> muscle 0.2-1.8 µg g-1 DW). Perch exhibited significantly higher As than the same organs from rainbow trout: kidney (0.2-1.2 µg g-1 DW) liver (0.3-0.9 µg g-1 DW)> gill (0.2-1.2 µg g-1 DW) muscle (0.1-0.9 µg g-1 DW). As in perch organs and rainbow trout muscle were higher in individuals captured closest to the volcano (BR) than in DH, with the inverse pattern in rainbow trout kidney. No variations in As were observed in rainbow trout liver or gills regarding sampling site. As species detected in fish muscle were arsenobetaine (AB) and in lower proportion dimethylarsenate (DMA). Mean AB fraction in perch (34%) was higher than in trouts (19%), being higher in DH site (43%). On the contrary, DMA fraction in rainbow trouts from DH (10%) was higher than in perchs from both sites (6 and 4%) and higher than trouts from BR (5%). These results are consistent with most works that indicate that AB is a significant part of the overall As in sea and freshwater fish. Habitat, diet differences, and volcano proximity may explain the observed differences in total As and As species between the two fish species. However, speciation analysis should be performed in other tissues and also prey to confirm these assumptions. This investigation will contribute to the study of As dynamics and metabolism in fish inhabiting waters impacted by natural As sources.