Biomonitoring of metals using plants and fish species after a mining spill: the case of the Sonora river, Northwestern Mexico

Abstract

Aquatic ecosystems are under constant pressure from anthropogenic activities, which frequently release many contaminants that may have adverse impacts. In August 2014, a spill of 40 000 m³ of acid solution occurred in the Sonora River Basin (SRB), which contained elevated levels of metal(loid)s. These elements are persistent in the environment and may have adverse health effects on organisms. In this study, the impact of the spill on the accumulation of metals was evaluated in SRB, using two plants and three fish species. Organisms were collected from sites affected by the spill and from sites not affected by the spill. The samples were analyzed for Al, Cu, Fe, Mn, Pb, and Zn contents. The levels of all elements in the organisms at all sites exhibited spatial and seasonal variations, without discernible patterns. In most cases, metal accumulations were similar between sites affected and not affected by the spill. However, Pb levels in fish exceeded international regulations, implying risks associated with consuming these species. Some positive correlations were determined between Pb and other metals, which may indicate that they occur in similar routes of exposure and/or are linked to the same minerals. Although there were no defined metal accumulation patterns between affected and non-affected sites by the spill, the studied species were useful for determining metal exposure in the two ecosystems investigated.