Heavy metal compartmentalisation in salt marsh and seagrass of the urbanised Swartkops estuary, South Africa

Marelé A Nel; Janine B Adams; Gletwyn Rubidge; Lucienne R D Human

doi:10.1016/j.marpolbul.2023.115007

Heavy metal compartmentalisation in salt marsh and seagrass of the urbanised Swartkops estuary, South Africa

Mar Pollut Bull. 2023 Jul:192:115007. doi: 10.1016/j.marpolbul.2023.115007. Epub 2023 May 15.

Authors

Marelé A Nel¹, Janine B Adams², Gletwyn Rubidge³, Lucienne R D Human⁴

Affiliations

¹ DSI/NRF Research Chair: Shallow Water Ecosystems, Nelson Mandela University, Summerstrand South Campus, Gqeberha, South Africa; South African Environmental Observation Network (SAEON) Elwandle Coastal Node Nelson Mandela University, Ocean Sciences Campus, 4 Gomery Avenue, Summerstrand, Gqeberha 6031, South Africa; Department of Botany, Nelson Mandela University, Summerstrand, South Campus, PO Box 77 000, Gqeberha 6031, South Africa.
² DSI/NRF Research Chair: Shallow Water Ecosystems, Nelson Mandela University, Summerstrand South Campus, Gqeberha, South Africa; Department of Botany, Nelson Mandela University, Summerstrand, South Campus, PO Box 77 000, Gqeberha 6031, South Africa.
³ Department of Chemistry, Nelson Mandela University, Summerstrand North Campus, PO Box 77 000, Gqeberha 6031, South Africa.
⁴ South African Environmental Observation Network (SAEON) Elwandle Coastal Node Nelson Mandela University, Ocean Sciences Campus, 4 Gomery Avenue, Summerstrand, Gqeberha 6031, South Africa; Department of Botany, Nelson Mandela University, Summerstrand, South Campus, PO Box 77 000, Gqeberha 6031, South Africa. Electronic address: lucienne.human@saeon.ac.za.

PMID: 37196376
DOI: 10.1016/j.marpolbul.2023.115007

Abstract

Wetland plants are naturally exposed to high metal concentrations, and often have mechanisms to prevent metal toxicity. This study compared metal concentrations in seagrass (Zostera capensis) and salt marsh (Spartina maritima, Salicornia tegetaria) - to determine their niche as metal sinks. Samples were collected in each season over a year at five sites in the estuary and analysed using a Total X-Ray Fluorescence (TXRF) spectrometer. Spartina maritima and S. tegetaria accumulated in their roots, and displayed little translocation to leaves (BCF = 1-14; TF_[leaf/root] < 1). Contrastingly, Z. capensis showed high uptake to its leaves (TF_[leaf/root] = 1-8; Mn, Zn, Cr, Pb, Ni, Cu). Spartina maritima and S. tegetaria were identified as good phytostabilisers (BCF > 1, TF_[leaf/root] < 1). Compartmentalization was unique to each species, and considering their ecosystem service importance, more plant species should be analysed to estimate their ecological value for management purposes.

Keywords: Heavy metals; Phytoremediation; Sink; TXRF; Wetland.

MeSH terms

Biodegradation, Environmental
Ecosystem
Environmental Monitoring
Estuaries
Metals, Heavy* / analysis
Plants
Poaceae
South Africa
Wetlands*

Substances

Metals, Heavy