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ABSTRACT: The Siam weed, Chromolaena odorata (L.) King & Robinson, Family Asteraceae, was found to be a new Pb hyperaccumulator by means of field surveys on Pb soil and hydroponic studies. Plants from field collection accumulated 1377 and 4236mgkg(-1) Pb in their shoots and roots, respectively, and could tolerate soil Pb concentrations up to 100000 mgkg(-1) with a translocation factor of 7.62. Very low concentrations of Cd and Zn were found in plants collected from the field. Under nutrient solution culture condition, C. odorata from the contaminated site (CS) and from non-contaminated site (NCS) grew normally with all three metals (Pb, Cd, Zn) supplied. However, the relative growth rates of all treated plants decreased with increased metal concentrations. The percentage uptakes of Pb, Cd, and Zn by C. odorata increased with increasing metal concentrations. Pb concentration in shoots and roots reached its highest values (1772.3 and 60655.7mgkg(-1), respectively) at a Pb supply level of 10mgl(-1). While the maximum concentrations of Cd (0.5mgl(-1)) in shoots and roots of C. odorata were 102.3 and 1440.9mgkg(-1), and the highest concentrations of Zn (20mgl(-1)) were 1876.0 and 7011.8mgkg(-1), respectively. The bioaccumulation coefficients of Pb and Cd were greater than 1000. These results confirm that C. odorata is a hyperaccumulator which grows rapidly, has substantial biomass, wide distribution and has a potential for the phytoremediation of metal contaminated soils.
Chemosphere 06/2007; 68(2):323-9. · 3.21 Impact Factor
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ABSTRACT: Bo Ngam lead mine soils contain high concentrations of lead (up 1% total Pb) and low amounts of organic matter and major nutrients (N, P, K). A glasshouse study was conducted to compare growth performance, metal tolerance and metal uptake by two grasses, Thysanolaena maxima (Roxb.) O. Kuntze and four ecotypes of Vetiveria zizanioides (L.) Nash, syn. Chrysopogon zizanioides (L.) Roberty (three from Thailand: Surat Thani, Songkhla and Kamphaeng Phet, and one from Sri Lanka) and to study the effects of pig manure (20% and 40% w/w) and inorganic fertilizer (75 and 150 mg kg(-1)) amendments to this lead mine soil. The results showed that both T. maxima and V. zizanioides (Surat Thani and Songkhla) could tolerate high Pb concentrations in soil (10750 mg kg(-1)) and had very good growth performance. Application of pig manure increased electrical conductivity (EC) and reduced DTPA-extractable Pb concentration in the soils. Pig manure application improved the growth of vetiver, especially at 20%, application dosage. Vetiver had the highest biomass. T. maxima could not tolerate high EC values. The uptake by roots and transport of Pb to shoots of both species was reduced when soils were amended with pig manure. Application of inorganic fertilizer did not improve growth of vetiver but did improve that of T. maxima. Fertilizer application did not have any great influence on the Pb uptake in vetiver while T. maxima took up more Pb as a result of the fertilizer enhancing its biomass yield. Both species transported low Pb concentrations to shoots (8.3-179 mg kg(-1)) and accumulated higher concentrations in roots (107-911 mg kg(-1)). In summary, both species may be species well suited for phytostabilization in tropical lead mine areas.
Chemosphere 02/2007; 66(1):45-53. · 3.21 Impact Factor
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ABSTRACT: A field survey of terrestrial plants growing on Bo Ngam lead mine area, Thailand, was conducted to identify species accumulating exceptionally high concentrations of lead. Plant and soil samples were collected from five areas. Lead concentrations in surface soil ranged from 325 to 142,400 mg/kg. The highest lead concentration in soil was found at the ore dressing plant area and lowest at a natural pond area. In different areas, the concentrations of lead in plants were different when comparing various study sites. A total of 48 plant species belonging to 14 families were collected from five sampling sites. Twenty-six plant species had lead concentrations more than 1000 mg/kg in their shoots. Three species (Microstegium ciliatum, Polygala umbonata, Spermacoce mauritiana) showed extremely high lead concentrations in their shoots (12,200-28,370 mg/kg) and roots (14,580-128,830 mg/kg).
Environmental Pollution 12/2006; 144(2):681-8. · 3.75 Impact Factor
