ABSTRACT
In Vietnam, industrial, agricultural and commercial activities have led to significant contamination of soils and waterways with Arsenic (As), which have caused adverse health effects to humans exposed to this toxic element. Several techniques have been employed to remediate As contaminated soils and water such as: soil washing, solidification, vitrification, electrokinetic treatment, precipitation, filtration and ion exchange. However, these engineering methods have limitations as they are more applicable to small-scale intensive utilisation due to requirements for technical maintenance, high costs, unenvironmental friendliness (spreading contamination through air and water). Phytoremediation is an emerging technique which uses hyperaccumulating plants, e.g., Pteris vittata L. (Chinese bake fern), to extract toxic metals and metalloids (e.g., As) from contaminated soils (Maria et al. 2008). The efficiency of this technique, however, is influenced by factors such as soil properties, contaminant depth, climatic conditions, and phyto-availability of As that are essential for effective plant uptake (removal) from contaminated soils. Arbuscular Mycorrhizal Fungi (AMF) form a symbiotic association with native plant roots. This symbiosis may enhance resistance to metal toxicity, nutrient acquisition, metal bioavailability, and consequently metal uptake (removal) (Bell et al. 2003). Heavy metals are
3 RESULTS AND DISCUSSION
Despite the harsh conditions (highly acidic and high heavy metal content), both species were able to grow well in both soils containing total As concentrations of 500 and 1270 mg/kg, respectively. In general, Pteris vittata produced much more biomass than the Pittyrogramma calomelanos (Table 2). Prior inoculation of AFM into soils significantly increased plant biomass from 30 to 50% in comparison with the plants grown in uninoculated soils (Table 2). This suggested the survival and subsequent colonisation of AFM with the two native fern species was effective in this environment. This is of great significance in mined land rehabilitation as AMF is often absent in soils after mining activities.
