Accumulation and interactions of trace elements in tadpoles of Dendropsophus minutus (Peters, 1872) (Anura: Hylidae) in natural and soybean monoculture areas from Central Brazil

Abstract

The contamination of natural ecosystems by trace elements represents a growing environmental concern, particularly in regions under agricultural expansion. In the Brazilian Cerrado, soybean monocultures contribute to soil and water contamination through agrochemicals containing potentially toxic elements. Amphibians, especially tadpoles, are highly sensitive to such disturbances and are thus recognized as reliable bioindicators of environmental quality. This study investigated the accumulation and interaction of eight metals (As, Ba, Cd, Cr, Cu, Hg, Pb, and Zn) in Dendropsophus minutus tadpoles collected from soybean cultivation areas and a preserved site on Cerrado biome, in Cezarina municipality, State of Goiás, Central Brazil. A total of 20 tadpoles were collected, equally divided between case and control areas, and analysed after the acid digestion of the whole tadpole, through inductively coupled plasma optical emission spectrometry (ICP-OES). Tadpoles from soybean areas exhibited significantly higher concentrations of As, Ba, Cd, Cr, Cu, Pb, and Zn compared with those from the preserved site, while Hg did not differ significantly, suggesting low environmental mobility or absence in local inputs. The most critical increases were detected for Cd, Cu, and Pb, with values exceeding those of the control site by 6371.7%, 13841.9%, and 1108.1%, respectively. Statistical analyses revealed strong positive correlations, notably Pb with Ba, Cd, Cr, and Cu, in addition to interactions involving Cd–Cr, Cd–Cu, Cr–Cu, and Zn–As. These associations suggest synergistic accumulation, with potential to intensify physiological stress in amphibians, including oxidative damage and developmental impairments.