Recent trace element contamination in a rural crater lake, NW Mexico

Abstract

Lakes provide a wide range of ecosystem services, which are challenged by multiple anthropogenic pressures. Santa María del Oro crater lake is in a rural environment and it is of interest for global change studies and as a natural resource to sustain the economy of local communities. The temporal trends of trace element (As, Co, Cr, Cu, Ni, Pb, V, and Zn) concentrations over the past century were assessed by analyzing four 210 Pb-dated sediment cores, under the hypothesis that the recent development of anthropogenic activities has promoted increasing trace element inputs reflected as sediment contamination. Data were analyzed within three periods: pre-1900s (from which background levels were carefully estimated), pre-1950, and post-1950. Trace element provenance was ascertained through a chemometric approach. Most trace element concentrations varied narrowly within the past ~100 years, accounting from null Co, V, and Zn enrichment, to minor Cr, Cu, and Ni enrichment in a few sections of the three cores collected from the deepest locations, within the hypolimnion) and Pb (in the shallowest core). Conversely, As enrichment in the deep cores reached moderately severe levels within the post-1950 period. Cobalt, Pb, V, and Zn input to the lake was related to terrigenous sources; Pb enrichment was mainly anthropogenic (the shallow coring site is close to human settlements); Cu and Cr variability are mostly the result of