Rhizosediments of Salicornia tegetaria Indicate Metal Contamination in the Intertidal Estuary Zone

Abstract

Metal pollution is a well-known anthropogenic impact of highly developed estuaries, with dire consequences to the ecosystem. This study investigated the metal concentrations (Al, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in the sediment colonized by Salicornia tegetaria, a dominant salt marsh plant in the lower intertidal zone of the Swartkops Estuary. The samples were collected at five sites along the banks of the middle and lower reaches of the estuary, and analyzed using an Inductively Coupled Plasma-Optical Emission Spectrometer. Metal contamination was determined using established normalized baseline models. It was found that all the sites contained metal enrichment, with the estuary mouth experiencing the least enrichment. Salicornia tegetaria holds a substantial amount of anomalous metals within its rhizosediment-providing a valuable ecosystem service to a highly developed Swartkops Estuary.

The Bioconcentration and the Translocation of Heavy Metals in Recently Consumed Salicornia ramosissima J. Woods in Highly Contaminated Estuary Marshes and Its Food Risk

“…Many reasons could explain this lack of correlation regarding the absorption of heavy metals, including metal species, soil properties, and salinity [3,[111][112][113]. Other reasons could be the exclusion of metal ion uptake at root level [114], saturation in root tissues at high levels of soil concentration [1,7], transpiration rates [115], the presence of root exudates that can improve the solubility of heavy metal ions and thus enhance metal accumulation in plants, such as Pb in Salicornia europaea [116], or the interactions among metals for absorption [4].…”

“…Heavy metals are enriched in the environment by human activities such as mining, industrial and traffic emissions, untreated sewage effluents, fertilizer, pesticides, etc., reaching the soil and the sediment where they become bound [1][2][3], generating problems by their contamination of the atmosphere, water and soil that have become a global concern [4][5][6][7]. For this reason, soil contamination by heavy metals has been regulated by various organizations and public administrations, which have established maximum permitted limits for metal concentrations in order to protect the soil and the environment, normally depending on the soil's pH value.…”