Arsenic species in an arsenic hyperaccumulating fern, Pityrogramma calomelanos: a potential phytoremediator of arsenic-contaminated soils
Kevin Francesconi a,U , Pornsawan Visoottivisethb, Weeraphan Sridokchanb, Walter Goessler c
Institute of Biology, Uni¨ ersity of Southern Denmark, 5230 Odense M, Denmark b Department of Biology,Mahidol Uni¨ ersity, Bangkok 10400, Thailand c Chemistry Institute, Karl-Franzens Uni¨ ersity Graz, 8010 Graz, Austria Received 10 February 2001; accepted 12 April 2001
Abstract The fern Pityrogramma calomelanos is a hyperaccumulator of arsenic that grows readily on arsenic-contaminated soils in the Ron Phibun district of southern Thailand. P. calomelanos accumulates arsenic mostly in the frondsŽup to 8350 g As gy1 dry mass. while the rhizoids contain the lowest concentrations of arsenic Ž88 310 g As gy1 dry mass.. The arsenic species in aqueous extracts of the fern and soil were determined by high performance liquid chromatography coupled to an inductively coupled plasma mass spectrometer ŽHPLC-ICPMS. which served as an arsenic speciﬁc detector. Only a small part of the arsenic Ž6.1 12%.in soil was extracted into water, and most of this arsenic Ž) 97%. was present as arsenate. The arsenic in the fern rhizoids was approximately 60% water-extractable, 95% of which was present as arsenate. In contrast, arsenic in the fern fronds was readily extracted into water Ž86 93%. and was present mainly as arsenite Ž60 72%. with the remainder being arsenate. Methylarsonate anddimethylarsinate were detected as trace constituents in only two fern samples. Preliminary estimates of phytoremediation potential suggest that P. calomelanos might remove approximately 2% of the soil arsenic load per year. With due consideration to the type of arsenic compounds present in the fern, and their water-solubility, the option of disposing high arsenic ferns at sea is raised for discussion. 2002Elsevier Science B.V. All rights reserved.
Keywords: Arsenic; Hyperaccumulator; Fern; Pityrogramma calomelanos; Phytoremediation; HPLC-ICPMS
Corresponding author. Tel.: q45-65502447; fax: q45-65930457. E-mail address: email@example.com ŽK. Francesconi..
0048-9697r02r$ - see front matter 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 4 8 - 9 6 9 7 Ž 0 1 . 0 0 8 5 4 - 3
28K. Francesconi et al. r The Science of the Total En¨ ironment 284 (2002) 27 35
1. Introduction Although the acute toxicity of arsenic has been known since antiquity, it is only in more recent times that chronic effects have been reported. Arsenic is now a proven human carcinogen, with cancers related to arsenic in drinking water reported in Taiwan, Argentina, Chile, and Bangladesh ŽAnon,1999.. Arsenic is commonly found in the earth’s crust Žapprox. 3 mg As kgy1 . where it is often associated with sulﬁde minerals ŽCullen and Reimer, 1989.. Oxidation of sulﬁde minerals can release large quantities of arsenic into solution, into underground aquifers for example where it can contaminate drinking water ŽAnon, 1999.. Arsenic is also a waste product from the mining of metals, in particulartin, and many areas have been contaminated by tin mining activities. One such area is the Ron Phibun district, in the Nakorn Si Thammarat province of southern Thailand. The site is part of the south-east Asian tin belt, an area that has a 100-year history of bedrock and alluvial mining. Consequently, soil and water in the Ron Phibun region are grossly contaminated with arsenic ŽWilliams et al.,1996.. The use of both surface and groundwater as sources of water for domestic use in Ron Phibun raises signiﬁcant human health concerns. A survey conducted in 1988 conﬁrmed approximately 1000 cases of arsenic-related skin disorders ŽChoprapawon and Rodcline, 1997.. Remediation options for Ron Phibun such as translocation of high arsenic contaminated soil have been considered but the cost is very...