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Bench-Scale Investigation Of Mercury Phytoremediation By Water Hyacinths (Eichhornia crassipes) In Heavily Contaminated Sediments
Citation:
Lehocky, P. L., R. L. Fimmen, R. Darlington, V. Lai, B. Sass, S. Chattopadhyay, AND P. M. RANDALL. Bench-Scale Investigation Of Mercury Phytoremediation By Water Hyacinths (Eichhornia crassipes) In Heavily Contaminated Sediments. Presented at Battelle 10th International In Situ and On-Site Bioremediation Conference, Baltimore, MD, May 05 - 08, 2009.
Impact/Purpose:
To investigate water hyacinths (Eichhornia crassipes) for their ability to assimilate Hg and MeHg into plant biomass, in both aquatic and sediment-associated forms over a 68-day hydroponic study.
Description:
Phytoremediation has the potential to be implemented at mercury (Hg) and methylmercury (MeHg) contaminated sites. Water hyacinths (Eichhornia crassipes) were investigated for their ability to assimilate Hg and MeHg into plant biomass, in both aquatic and sediment-associated forms, over a 68-day hydroponic study. Previous investigations have demonstrated the promise of Hg assimilation as a potential remediation technique under specific laboratory conditions (Skinner, 2007). The suitability of Eichhornia crassipes to assimilate both Hg and MeHg was evaluted under differing PO4 concentrations (0.0 mg-PO4/L, 2.5 mg-PO4/L, 12.5 mg-PO4/L, and 22.5 mg-PO4/L) light intensities (94 Lux and 976 Lux) and sediment:aqueous phase contamination ratios. Because aquatic rhizospheres have the ability to enhance MeHg formation (Acha, 2005), MeHg levels in water, sediment and Eichhornia crassipes roots and shoots were also measured. Mercury and MeHg were found to concentrate preferentially in the roots of Eichhornia crassipes with little translocation to the shoots or leaves of the plant, result consistent with studies from similar macrophytes (Skinner, 2007; Gupta, 1998). Sediments were found to be the major sink for Hg as they were able to sequester Hg, making it non-bioavailable for water hyacinth uptake (plant tissue concentrations of ~10,000 mg-Hg/kg dry plant biomass and ~1,000 mg MeHg/kg in the absence of sediments and ~2,000 mg-Hg/kg and <200 mg-MeHg/kg in the presence of sediments). We observed an optimum PO4 concentration (2.5 mg-PO4/L) at which Hg and MeHg uptake is enhanced (~3X greater Hg and MeHg uptake compared to 0.0 mg-PO4/L, 12.5 mg-PO4/L or 22.5 mg-PO4/L conditions). Increasing light intensity served to enhance the translocation of both Hg and MeHg. Assimilation of Hg and MeHg into the biomass of water hyacinths represents a potential means for remediation of contaminated waters and sediments under the appropriate conditions.
URLs/Downloads:
Phytoremediation of Mercury and Methylmercury Contaminated Sediments by Water Hyacinth (Eichhornia crassipes) (PDF, NA pp, 132 KB, about PDF)Conference Program
