Seagrass soil archives reveal centennial-scale metal smelter contamination while acting as natural filters

The upper Spencer Gulf in South Australia hosts the world's largest single stream Pb-Zn smelter, which has caused environmental and health issues related to elevated metal concentrations in the surrounding environment. The area also has extensive seagrass meadows, occupying >4000 km2. We rec...

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Bibliographic Details
Published in:The Science of the total environment 2019-02, Vol.649, p.1381-1392
Main Authors: Lafratta, A., Serrano, O., Masqué, P., Mateo, M.A., Fernandes, M., Gaylard, S., Lavery, P.S.
Format: Article
Language:English
Subjects:
Heavy metals
Holocene
Lead isotopes
Seagrass soil deposits
South Australia
Southern Ocean
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Summary:The upper Spencer Gulf in South Australia hosts the world's largest single stream Pb-Zn smelter, which has caused environmental and health issues related to elevated metal concentrations in the surrounding environment. The area also has extensive seagrass meadows, occupying >4000 km2. We reconstructed the fluxes of heavy metals over the last ~3000 years through a multi-parameter study of the soil archives formed by the seagrass Posidonia australis. Pb, Zn and Cd concentrations increased up to 9-fold following the onset of smelter operations in the 1880s, and the stable Pb isotopic signatures confirmed the smelter has been the main source of lead pollution in the seagrass soils until present. Preliminary estimates suggest that over the past 15 years seagrass meadows within 70 km2 of the smelter accumulated ~7–15% of the smelter emissions in their soils. Here we demonstrate that seagrass meadows act as pollution filters and sinks while their soils provide a record of environmental conditions, allowing baseline conditions to be identified and revealing the time-course of environmental change. [Display omitted] •Seagrass soils provide a reliable archive of metal contamination over centennial time scales.•Pb, Zn and Cd concentrations in soil increased up to 9-fold after the onset of the Port Pirie smelter.•Pb isotopes show that the Port Pirie smelter is the main source of Pb contamination.•Seagrass meadows act as significant filters and sinks of metals in Port Pirie.•Seagrass soils are a possible source of remobilized pollution following disturbance.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2018.08.400