SREL Reprint #2720




Mass loading of nickel and uranium on plant surfaces: application of laser ablation-ICP-MS

Tracy Punshon1,2, Brian P. Jackson2, Paul M. Bertsch2, and Joanna Burger1

1Consortium for Risk Evaluation with Stakeholder Participation, Environmental and Occupational Health
Sciences Institute, Division of Life Sciences, Rutgers University, 604 Allison Road,
Piscataway, NJ 08854, USA
2The University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA

Abstract: Transport of contaminated sediments from a former radiological settling pond results in the deposition of U and Ni in the Lower Tims Branch (LTB) (Aiken, SC, USA). Uranium is unavailable for plant uptake, but elevated U and Ni concentrations associated with foliage of understory plants suggested mass loading. Mass loading of contaminated soil on Andropogon elliottii Chapman (Poaceae) was investigated using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The technique allows for rapid quantitative elemental depth profiling. Fresh washed and unwashed leaves (n = 5) from the contaminated area were compared with those from an uncontaminated area, analysing Ni and U at ten randomly chosen points on each leaf. Nickel and U concentrations differed significantly between washed and unwashed leaves from LTB. Particles on unwashed leaves measured up to 300 µm in diameter, and were enriched with U. Uranium was detected on the surface of the leaf, whereas Ni was detected within leaf tissues. In unwashed LTB leaves, Ni and U concentrations did not significantly differ in areas with and without visible particles, suggesting that there were much smaller particles, indistinguishable at x 100 magnification, which contributed to the overall metal burden. Washing removed the majority of the Ni and U on the surface, but residual U and Ni was detected. Irregularities in the leaf surface, such as scars from herbivory contained elevated U concentrations despite a washing step, presumably from trapping soil particles. Laser ablation ICP-MS revealed that mass loading makes a significant contribution to the contaminant burden of understory plants at LTB.

SREL Reprint #2720

Punshon, T., B. P. Jackson, P. M. Bertsch, and J. Burger. 2004. Mass loading of nickel and uranium on plant surfaces: application of laser ablation-ICP-MS. Journal of Environmental Monitoring 6:153-159.

To request a reprint