One of the world’s largest smelters has been operating since 1889 in Port Pirie (South Australia), contaminating the environment and affecting human health. The 110 km² of seagrass meadows adjacent to the smelting site can act as a sink of this pollution. However, their role as pollution filters and traps remains poorly understood. Here we quantified the magnitude of Pb, Zn and Cd emissions sequestered by Posidonia australis meadows since 1889. The metal pollution record contained within seagrass soil cores sampled across the region showed that smelting operations contaminated the entire area, with decreasing metal sequestration by seagrass with increasing distance from discrete points of contamination. The meadows accumulated a total stock of ~1,300 t of Pb, ~3,450 t of Zn, and ~90 t of Cd since 1889. By comparing the accumulated metal stocks since 1999 with the reported smelter emissions for the same period, we estimated that seagrasses sequestered ~20% of Pb, and ~50% of Zn and Cd cumulative emissions. The findings showed that seagrass can play a significant role as long-term sinks of metal pollution in highly contaminated environments. Conservation efforts should prioritize these seagrass meadows to avoid the potential release of pollutants following habitat loss, which could turn seagrasses from a sink to a source of pollution.

Primary Presenter: Anna Lafratta, Edith Cowan University (a.lafratta@ecu.edu.au)

Authors:

Oscar Serrano, Centre d'Estudis Avançats de Blanes (CEAB)  (oserrano@ceab.csic.es)

Pere Masqué, International Atomic Energy Agency (IAEA)  (p.masque-barri@iaea.org)

Milena Fernandes, South Australia Water Corporation (SA WATER)  (milena.fernandes@sawater.com.au)

Sam Gaylard, South Australian Environment Protection Authority  (sam.gaylard05@gmail.com)

Paul Lavery, Edith Cowan University  (p.lavery@ecu.edu.au)

Anna Lafratta, Edith Cowan University  (a.lafratta@ecu.edu.au)