Metal enrichment evolution in marine sediments influenced by oxygen-deficient waters in a mineral loading zone, Atacama, Chile (27° S).

This study examines metal concentrations in sediments under the influence of the oxygen minimum zone of the SE-Pacific and the anthropogenic impact following industrialization in Caldera Bay (27° S), which is one of the main ore-loading ports in operation from 1849. 210Pb and the CRS dating method were employed to estimate the age in two sediment cores sectioned at 1 cm. Metal concentrations from selected samples suggested clear impacts of industrial activities after ∼1860 on Cu, and moderate impacts on Fe, Pb, and Zn. Further, authigenic enrichment of nutrient type and redox-sensitive elements (Ni, Cd, Mo, and V) in ancient times was observed. This enrichment was related to low oxygen at the bottom and high productivity. As this condition varies over time, it could result in erroneous estimations of preindustrial values. Overall, we highlight the impact of natural processes on metal distribution in marine sediments during environmental assessments and regulations.