Abstract
A gravity core (220 cm depth) was collected to investigate the geochemistry, enrichment, and pollution of trace metals in anoxic sediments from San Simon Bay, an ecosystem of high biological productivity in the northwest of Spain. A five-step sequential extraction procedure was used. The Cu, Pb, and Zn contents decreased with depth, with maximum values in the top layers. Ni and Zn were bound to pyrite fractions, while Cd and Pb were associated with the most mobile fractions. The analyzed metals were associated with the fractions bound to organic matter, mainly with the strongly bound to organic matter fraction. High Cd and Cu values were observed. The fractionation showed a high mobility for Cd (28.3–100%) and Pb (54.0–70.2%). Moreover, the pollution factor and the geoaccumulation index reflected a high contamination for Pb and a moderate contamination for Cu and Zn in the superficial layers, pointing to a possible ecotoxicological risk to organisms in San Simon Bay.
Highlights
Trace metals occur naturally in the environment, differing in contents along the Earth’s crust [1,2], but presenting a surprisingly consistent background in sediments [3]
With the purpose of assessing trace metals contents in sediments and their contamination degree, this study considers the distribution of Cadmium (Cd), Copper (Cu), Minerals 2020, 10, 826; doi:10.3390/min10090826
Cadmium was a difficult element in estimating background values due to its high mobility and participation in post-depositional processes, only a rough estimation is provided by previous works
Summary
Trace metals occur naturally in the environment, differing in contents along the Earth’s crust [1,2], but presenting a surprisingly consistent background in sediments [3]. The human delivery of some trace metals to the coastal environment, putting coastal ecosystems under stress, represents a current issue of concern. This is due to their persistence, potential toxicity, mobility, and ability to be incorporated and accumulated in food chains, with important implications for risk assessment, public health, and contamination management [7,8,9,10,11]. Trace metal pollution is related to a deterioration of water quality and/or accumulation in plants and animals [12,13,14], being incorporated into sediments as one of their reservoirs [15,16]
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