Assessing the potential for metal accumulation in Salicornia neei across a latitudinal gradient

Abstract

Salt marshes are efficient traps for metals transported from coastal watersheds, where contaminants can accumulate in soils and become incorporated into biota. Halophytic vegetation plays a key role in this process, yet the extent to which dominant marsh plants reflect local contamination or contribute to metal retention remains uncertain. We examined patterns of accumulation of Cu, Cr, Ni, Pb, and Zn in the halophyte Salicornia neei across salt marshes along the southwestern Atlantic coast of Argentina. Sampling was conducted in marshes of the Bahía Blanca Estuary, San Antonio Bay, and Rawson, covering a broad latitudinal gradient and variable environmental settings. Metal concentrations were measured in soils, roots, and aerial tissues to calculate bioaccumulation (BAF) and translocation factors (TF). Soil metal levels differed among sites: the highest Pb, Cu, and Zn concentrations occurred near mining residues, while fluvial-influenced marshes showed higher Ni and Cr levels. However, these spatial patterns were not consistently reflected in plant tissues. BAF and TF indicate that S. neei primarily retains Cu and Zn in roots, supporting its role in phytostabilization. Evidence of phytoextraction was limited and restricted to Pb and Ni under specific conditions. Overall, these results suggest that while S. neei is not a reliable biomonitor of metal contamination, it may contribute to the stabilization—and occasionally extraction—of metals in marsh sediments.