ARS | Publication request: CHALLENGES WITH PHYTOREMEDIATION OF SELENIUM-LADEN SOILS

Submitted to: Soil and Groundwater Cleanup
Publication Type: Popular Publication
Publication Acceptance Date: March 1, 1998
Publication Date: N/A

Interpretive Summary: Elevated levels of selenium have been measured in sediment at Kesterson Reservoir and have been reported to contribute to the death and deformities in waterfowl frequenting this site. As part of a remediation strategy to lower levels of soil Se, the phytoremediation of Se by canola was evaluated in sediment from Kesterson Reservoir from three different depths under greenhouse and field conditions. Canola lowered Se concentrations more effectively under greenhouse conditions than under field conditions. Concentrations of Se were most reduced near the soil surface, where soluble Se is most present and where the primary roots of canola are most present. Using canola to lower Se levels in sediment at Kesterson Reservoir will be a long-term management strategy, especially for the deeper depths.

Technical Abstract: Selenium (Se) may be present in soils and sediments in high concentrations, yet not mobile or available for plant uptake. Phytoremediation of Se by canola (Brassica napus) was evaluated in sediment from Kesterson Reservoir at three different depths (0-30, 30-60, 60-90 cm) under greenhouse and field conditions. In the greenhouse study, total soil Se concentrations at preplant ranged from 10 to 112 mg/kg. Shoot Se concentrations of canola were 182, 53, and 19 mg/kg DM in the 0-30, 30-60, and 60-90 cm depths, respectively. Percentages of Se accumulated by canola relative to total Se loss in the soil at postharvest were as high as 24%. In the field study, total soil Se concentrations were as high as 26 mg/kg soil. Field-grown canola accumulated approximately 50 mg/kg DM which accounted for less than 10% of total Se lost in the soil at postharvest. Phytoremediation of Se-laden soils under field conditions was about 50% of that observed under controlled greenhouse conditions. This relationship may be useful for prediction of field remediation operation using greenhouse generated data.