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Phytoscreening and phytoextraction of heavy metals at Danish polluted sites using willow and poplar trees.

Algreen M, Trapp S, Rein A - Environ Sci Pollut Res Int (2013)

Bottom Line: Concentrations in wood from the highly polluted site were significantly elevated, compared to references, in particular for willow.The conclusion from these results is that tree coring could be used successfully to identify strongly heavy metal-polluted soil for Cd, Cu, Ni, Zn, and that willow trees were superior to poplars, except when screening for Ni.Extraction efficiencies were best for willows and Cd, but below 0.5% over 10 years, and below 1‰ in 10 years for all other HMs.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej building 113, DK-2800, Kongens Lyngby, Denmark, mann@env.dtu.dk.

ABSTRACT
The main purpose of this study was to determine typical concentrations of heavy metals (HM) in wood from willows and poplars, in order to test the feasibility of phytoscreening and phytoextraction of HM. Samples were taken from one strongly, one moderately, and one slightly polluted site and from three reference sites. Wood from both tree species had similar background concentrations at 0.5 mg kg(-1) for cadmium (Cd), 1.6 mg kg(-1) for copper (Cu), 0.3 mg kg(-1) for nickel (Ni), and 25 mg kg(-1) for zinc (Zn). Concentrations of chromium (Cr) and lead (Pb) were below or close to detection limit. Concentrations in wood from the highly polluted site were significantly elevated, compared to references, in particular for willow. The conclusion from these results is that tree coring could be used successfully to identify strongly heavy metal-polluted soil for Cd, Cu, Ni, Zn, and that willow trees were superior to poplars, except when screening for Ni. Phytoextraction of HMs was quantified from measured concentration in wood at the most polluted site. Extraction efficiencies were best for willows and Cd, but below 0.5% over 10 years, and below 1‰ in 10 years for all other HMs.

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Measured concentrations of Cd, Cu, Ni, and Zn in wood (willow and poplar) versus measured total concentrations in soil. Lines represent linear fit (poplar dotted); black arrows indicate usual Danish background in soil (Miljøstyrelsen 1998)
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Fig2: Measured concentrations of Cd, Cu, Ni, and Zn in wood (willow and poplar) versus measured total concentrations in soil. Lines represent linear fit (poplar dotted); black arrows indicate usual Danish background in soil (Miljøstyrelsen 1998)

Mentions: Concentrations in wood versus concentrations in soil are shown in Figs. 2 (total concentration) and S2 (easily extractable concentration in soil). Measured concentrations in wood are highest for Zn > Cu > Cd > Ni for both tree species. Except for Cu and Zn in poplar wood, concentrations in wood increase with increasing soil concentrations, and generally more in willow wood except for Ni. Table 2 shows the BCF values derived from the slopes of the linear regression between all concentrations in wood and soil, and the Y-intercept interpreted as background concentration in wood. Two of the eight linear regressions have an explained variance (R2) above 70 %; four regression coefficients are significant at an error probability of 5 %. The highest slope of the regression line between concentrations in wood and in soil was obtained for Cd, both for willows and poplars. Regressions were also made for the relation of concentration in wood to the easily extractable concentration in soil (Fig. S2, Supporting Information). Only in two (out of eight) cases, R2 improves (Cu in willows, Ni in poplars, not shown). BCF values derived with Eq. (1) from average concentrations in wood and soils at each site are only useful for test site 1. For all other sites, measured concentrations in wood are close to background. This can be seen by comparison of the Y-intercept of the BCF regressions (Table 2) with the mean concentrations in willow wood of the sites (Table 1), which are rather similar for all HM and the reference sites as well as test sites 2 and 3. Overall, willows take HM better up, and concentrations in wood show a stronger relation to those in soil. Consequently, willows are better indicators of subsurface HM than poplars.Fig. 2


Phytoscreening and phytoextraction of heavy metals at Danish polluted sites using willow and poplar trees.

Algreen M, Trapp S, Rein A - Environ Sci Pollut Res Int (2013)

Measured concentrations of Cd, Cu, Ni, and Zn in wood (willow and poplar) versus measured total concentrations in soil. Lines represent linear fit (poplar dotted); black arrows indicate usual Danish background in soil (Miljøstyrelsen 1998)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4125817&req=5

Fig2: Measured concentrations of Cd, Cu, Ni, and Zn in wood (willow and poplar) versus measured total concentrations in soil. Lines represent linear fit (poplar dotted); black arrows indicate usual Danish background in soil (Miljøstyrelsen 1998)
Mentions: Concentrations in wood versus concentrations in soil are shown in Figs. 2 (total concentration) and S2 (easily extractable concentration in soil). Measured concentrations in wood are highest for Zn > Cu > Cd > Ni for both tree species. Except for Cu and Zn in poplar wood, concentrations in wood increase with increasing soil concentrations, and generally more in willow wood except for Ni. Table 2 shows the BCF values derived from the slopes of the linear regression between all concentrations in wood and soil, and the Y-intercept interpreted as background concentration in wood. Two of the eight linear regressions have an explained variance (R2) above 70 %; four regression coefficients are significant at an error probability of 5 %. The highest slope of the regression line between concentrations in wood and in soil was obtained for Cd, both for willows and poplars. Regressions were also made for the relation of concentration in wood to the easily extractable concentration in soil (Fig. S2, Supporting Information). Only in two (out of eight) cases, R2 improves (Cu in willows, Ni in poplars, not shown). BCF values derived with Eq. (1) from average concentrations in wood and soils at each site are only useful for test site 1. For all other sites, measured concentrations in wood are close to background. This can be seen by comparison of the Y-intercept of the BCF regressions (Table 2) with the mean concentrations in willow wood of the sites (Table 1), which are rather similar for all HM and the reference sites as well as test sites 2 and 3. Overall, willows take HM better up, and concentrations in wood show a stronger relation to those in soil. Consequently, willows are better indicators of subsurface HM than poplars.Fig. 2

Bottom Line: Concentrations in wood from the highly polluted site were significantly elevated, compared to references, in particular for willow.The conclusion from these results is that tree coring could be used successfully to identify strongly heavy metal-polluted soil for Cd, Cu, Ni, Zn, and that willow trees were superior to poplars, except when screening for Ni.Extraction efficiencies were best for willows and Cd, but below 0.5% over 10 years, and below 1‰ in 10 years for all other HMs.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej building 113, DK-2800, Kongens Lyngby, Denmark, mann@env.dtu.dk.

ABSTRACT
The main purpose of this study was to determine typical concentrations of heavy metals (HM) in wood from willows and poplars, in order to test the feasibility of phytoscreening and phytoextraction of HM. Samples were taken from one strongly, one moderately, and one slightly polluted site and from three reference sites. Wood from both tree species had similar background concentrations at 0.5 mg kg(-1) for cadmium (Cd), 1.6 mg kg(-1) for copper (Cu), 0.3 mg kg(-1) for nickel (Ni), and 25 mg kg(-1) for zinc (Zn). Concentrations of chromium (Cr) and lead (Pb) were below or close to detection limit. Concentrations in wood from the highly polluted site were significantly elevated, compared to references, in particular for willow. The conclusion from these results is that tree coring could be used successfully to identify strongly heavy metal-polluted soil for Cd, Cu, Ni, Zn, and that willow trees were superior to poplars, except when screening for Ni. Phytoextraction of HMs was quantified from measured concentration in wood at the most polluted site. Extraction efficiencies were best for willows and Cd, but below 0.5% over 10 years, and below 1‰ in 10 years for all other HMs.

Show MeSH