Trace elements in sediments and plankton from two high-altitude lakes in a volcanic area from North Patagonia, Argentina

Abstract

This study analyzes the distribution of nine potentially toxic trace elements (arsenic, antimony, bromine, cobalt, chromium, mercury, rubidium, selenium, and zinc) in sediments and plankton from two small mesotrophic lakes in a non-industrialized area impacted by the Caviahue-Copahue volcanic complex (CCVC). The two lakes have different plankton community structures and received different amounts of pyroclastic material after the last CCVC eruption. Trace element concentrations of surface sediments differed between lakes, according to the composition of the volcanic ashes deposited in the lakes. The size of organisms was the principal factor influencing the accumulation of most trace elements in plankton within each lake, being trace element concentrations generally higher in the microplankton than in the mesozooplankton. The planktonic biomass in the shallower lake was dominated by small algae and copepods, while mixotrophic ciliates and different-sized cladocerans dominated the deeper lake. These differences in the community structure and species composition influenced the trace element bioaccumulation, especially in microplankton, while habitat use and feeding strategies seem more relevant in mesozooplankton bioaccumulation. This work contributes to the scarce records of trace elements and their dynamics in plankton from freshwater ecosystems impacted by volcanic activity.

Keywords: Lacustrine sediments; Phytoplankton; Trace elements; Volcanic activity; Zooplankton.