Phytostabilization of metals by indigenous riparian vegetation

Authors

  • Klaudia Schachtschneider 1. CSIR, Natural Resources and the Environment, PO Box 320, Stellenbosch 7599, South Africa; 2. WWF-SA PO Box 23273, Claremont 7735, Cape Town, South Africa
  • Jessica Chamier 1. CSIR, Natural Resources and the Environment, PO Box 320, Stellenbosch 7599, South Africa; 2. HySA Catalysis, University of Cape Town, Rondebosch 7701, South Africa
  • Vernon Somerset 1. CSIR, Natural Resources and the Environment, PO Box 320, Stellenbosch 7599, South Africa; 2. Cape Peninsula University of Technology, Chemistry Department, Bellville 7535, Cape Town, South Africa

DOI:

https://doi.org/10.4314/wsa.v43i2.01

Keywords:

riparian vegetation, heavy metals, acid mine drainage, phytostabilization, bioaccumulation

Abstract

Given the increasing pressure of man-made activities on riparian zones, the capacity of the riparian vegetation along the Upper Olifants River, South Africa, to phytoextract and phytostabilize aluminium (Al), manganese (Mn) and iron (Fe) from the soil was investigated. The aim of the study was to gain better understanding of the capacity of indigenous vegetation in riparian zones to immobilize metals in the soil, thereby improving river water quality and ecosystem services. Seven commonly-occurring pollution-tolerant riparian plant species were evaluated to establish their potential as bioaccumulators for Fe, Al and Mn. Species included: Cyperus haspan, Schoenoplectus corymbosus, Typha capensis, Phragmites australis, Cynodon dactylon, Cyperus marginatus and Juncus effusus, which were sampled in five riparian areas in the Upper Olifants catchment. The bioconcentration factor (BCF) for Mn was > 1 for all species investigated with a maximum of 5 for Typha capensis, which also showed the highest accumulation of Al (10.26) and Fe (7.03). The remaining species presented with Al and Fe BCF between 0.11 and 2.00, with minimal transfer from root to shoot. When measured against an ideal hypothetical buffer zone, the buffer zones under investigation varied between intact and severely compromised. Intact riparian zones showed elevated metal concentrations in the soil, yet significantly lower concentrations in the river water compared to areas with insufficient vegetative cover. A polluted riparian area overgrown by P. australis effectively phytoextracted 204 960 g/m2 Al, 204 400 g/m2 Fe and 27 887 g/m2 Mn. The two indigenous Cyperus spp. were not ideal for metal immobilization with low bioaccumulation and transfer factors as well as low biomass. High biomass and Al, Fe and Mn phytostabilizing species: P. australis, T. capensis, S. corymbosus and J. effusus, should be considered in the rehabilitation of South African buffer areas.

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Published

2017-04-20

Issue

Section

Research paper

How to Cite

Klaudia Schachtschneider, Jessica Chamier and Vernon Somerset (2017) “Phytostabilization of metals by indigenous riparian vegetation”, Water SA, 43(2 April). doi:10.4314/wsa.v43i2.01.