Uptake and partitioning of metals in the Australian saltmarsh halophyte, samphire (Sarcocornia quinqueflora)

Little is known regarding potential uptake of metals in Australian saltmarsh flora, thus the current study endeavored to examine patterns of Zn, Cu, Pb and Cd uptake and partitioning in the dominant saltmarsh halophyte, Samphire (Sarcocornia quinqueflora), across three contaminated estuaries in New South Wales, Australia. Average sediment concentrations ranged from 62 to 764 μg/g for Zn, 20–52 μg/g for Cu, 27–311 μg/g for Pb and 0.45–1.90 μg/g for Cd across estuaries. Lake Macquarie was the most contaminated estuary, with the Hunter River estuary and Sydney Olympic Park exhibiting intermediate levels of sediment metal contamination. Bioconcentration factors for metal uptake from sediment to roots were ≥ 1 (except for Cu). Translocation within the plant was low for most metals, with apparent barriers to transport identified at the root: non-photosynthetic stem interface for Zn, Cu, Pb and Cd, and at the non-photosynthetic stem: photosynthetic stem transition for Pb and Cd. All metals accumulated in roots with increasing sediment exposure, and lower soil organic matter predicted greater Pb and Cu uptake to roots. Further, increases in sediment pH predicted greater Cd root accumulation. However, transport was regulated to the non-photosynthetic stem for Zn, and to the PS stem for Zn and Pb. In terms of employing S. quinqueflora as a bioindicator, all root metals, and Pb and Cd in non-photosynthetic stem tissue exhibited relationships with sediment metal loads, though high variability made their predictive ability limited.