Phyto (In)Stabilization of Elements

Abstract

The effects of plants (corn, soybean, and sunflower) and fertilizer on mobility of more than 60 elements were assessed in a greenhouse experiment. Unplanted columns with the same soil served as controls. Half the columns received fertilizer and all columns were watered at the same rate. At the end of the experiment, the columns were watered to mimic a rainstorm event such that water drained from the bases of the columns, which was collected and analyzed for element content. Soil from between the roots of the plants was also collected and the water-extractable fraction determined. It was expected that (1) more mobile elements, as measured by water extraction, would be leached from the soils at a higher rate compared to less mobile elements, (2) plants would immobilize most elements, but that some would be immobilized, and (3) that this would depend on plant species. The results led to the following conclusions: plants cause metal mobility to vary over a wide range for a specific soil and do mobilize some elements (e.g., Th) while immobilizing others (e.g., U). The effects depended on plant species for some elements. Water-extractable fractions of elements do not predict mobility.

KEY WORDS:

• phytostabilization
• metal
• leaching

ACKNOWLEDGEMENTS

This study was funded by the North Dakota Agriculture Experiment Station/NDSU College of Science and Mathematics small grants program and North Dakota INBRE (http://ndinbre.org).

Thanks to Mr. Jim Wieland of Goldmark Realty, and Mr. Tim Berntson, Farm Manager of the property, for allowing access to the field for collection of soil for the experiment. Also thanks to Jordan Wein, Matthew Green, Sharmila Sunwar and LaToya Kissoon and other members of the Wet Ecosystem Research Group (www.ndsu.edu/werg) for their assistance at various stages of this project.