Historical trend of ecological risk caused by copper sediment in Quintero Bay, Chile, associated with a copper smelter and refinery.

Abstract

The Ventanas copper smelter began its activities in Quintero Bay in 1960, and it is estimated that it has released around 152 tons of copper per year into the waters of the bay since then. The increasing copper concentrations in the sediments exceed international standards and pose a potential danger for marine fauna. The object of this work carries out a present and historical ecological risk assessment of copper concentrations in the marine sediment of Quintero Bay. Copper concentration profiles in sediments from the bay were studied to compare present concentration data with a chronological estimate obtained using the 210Pb excess activity age model. A protective value of HC₅ of 338 mg kg-1 and a PNEC of 33.8 mg kg-1 were estimated. The results showed a background concentration before 1964 with no ecological risk (30.3 mg kg-1; RQ < 1); subsequently, the concentration was found to increase from 45.2 mg kg-1 in 1964 to a maximum of 85.4 mg kg-1 in 1990, with RQ values between 1.3 and 2.5. Concentrations in sediments over the period 1997-2022 presented maximum values between 70 and 283.6 mg kg-1. The ecological risk characterization showed that all sites presented a risk to biodiversity (RQ > 1), with a probability of occurrence of 0.44-77.56 %. This research highlights the need to develop quality standards that consider the sensitivity of local species, and to use the ecological risk assessment methodology to support business management and reduce the environmental impact in industrial areas such as Quintero.