Effect of Soil Properties on Arsenic Hyperaccumulation in Pteris Vittata and Pityrogramma Calomelanos var. Austroamericana

Abstract

Two arsenic (As) hyperaccumulators, Pteris vittata L. and Pityrogramma calomelanos var. austroamericana, were grown in As-contaminated soils of contrasting properties. Ferns were exposed to three levels of As in soil at concentrations of 0, 600 and 2400 μmol kg⁻¹ for a period of 22 weeks. Plant biomass and As concentration in fronds and roots varied significantly between the two species. At 600 μmol kg⁻¹ As level, As hyperaccumulation was not observed in both the fern species. However at the 2400 μmol kg⁻¹ As level, both the species accumulated very high levels (>1000 mg kg⁻¹) of As in fronds. Arsenic concentration and uptake in fronds of both species followed the order Kurosol (Box Hill) > Vertosol (Narrabri) > Ferrosol (Robertson). In the studied soils, P. vittata possessed higher frond biomass and As accumulation, and thus was more efficient in removing soil As than P. calomelanos var. austroamericana. Soil properties such as free Fe, clay and organic matter contents appear to have affected the bioavailability of As in the studied soils. These results show that soil properties influence the As extraction efficiency of hyperaccumulating plants and must be considered in context of the phytoextraction technology of As contaminated soils.

KEYWORDS:

• Chinese brake fern
• gold dust fern
• phytoremediation

ACKNOWLEDGMENTS

Weihong gratefully acknowledges the financial assistance from the China Scholarship Council, and the Faculty of Agriculture, Food and Natural Resources at the University of Sydney. The authors would also like to thank Nabeel Niazi for assistance with laboratory determination of bioavailable As.

Notes

^†Bioconcentration factor (the ratio of As concentrations in fern tissue to extractable As in soil).

^‡As concentration removed by fern (sum of As uptake in frond and root).

^‡†Transfer factor (the ratio of As concentration in frond to root).

^‡‡Arsenic extracted using hydroxylamine hydrochloride as the extractant (Chao and Zhou, 1983).

^†Bioconcentration factor (the ratio of As concentrations in plant tissue to extractable As in soil).

^‡Transfer factor (the ratio of As concentration in frond to root). The values are means of three replicates.

^†Arsenic extracted by hydroxylamine hydrochloride.

^‡Arsenic concentration removed by fern is calculated by the sum of As uptake in frond and root. The values are means of three replicates.