Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1995
Publication Date: N/A
Interpretive Summary: Typical soils of the westside of the central valley in California are high in salinity and high in natural-occurring selenium (Se). Decades of excessive irrigation on these soils have contributed to the solubilization and eventual movement of salts including Se, throughout the soil profile. Researchers have suggested using plants to lower Se concentrations by plant tuptake. These plants might be grown to maximize Se accumulation in aerial organs that could be harvested, removed from the site, and disposed of elsewhere. It is, however, necessary to identify salt-tolerant species for this phytoremediation strategy. Thus canola, kenaf, tall fescue, and birdsfoot trefoil were evaluated for their ability to accumulate Se under increasing salt regimes; 1, 5, 10, and 20 dS/m. Within any given salt treatment, canola accumulated the highest concentrations of Se, followed by birdsfoot trefoil, kenaf, and tall fescue. Increasing salt levels reduced the accumulation of Se in kenaf (>50%) while the other species were less affected (<20%). Planting plant species that tolerate high saline soils and accumulate Se may be useful in lowering soil Se concentrations in saline soils of the westside of the central valley. Using phytoremediation in conjunction with water management strategies may reduce the amount of soluble Se entering drainage water that will eventually need to be treated or disposed.
High levels of natural-occurring Se are often found in conjunction with salinity in central California. Plant species considered for use in phytoremediation of Se-laden soils must therefore be salt tolerant. Selenium accumulation and soil Se removal was evaluated under greenhouse conditions for the following plant species: Brassica napus (canola), Hibiscus cannabinus (kenaf), Festuca arundinacea (tall fescue), and Lotus corniculatus (birdsfoot trefoil). Treatments consisted of growing each species in soil containing 2 mg Se/kg soil and one of the respective salt treatments; 1, 5, 10, or 20 dS/m (EC) for 90 d. Shoot and root dry matter yield of kenaf was most significantly affected (P<0.001) by the highest salt treatment and tall fescue the least. Canola accumulated the most selenium (up to 315 mg Se/kg DM) and tall fescue the least (7 mg Se/kg DM). Total soil Se concentrations were significantly (P<0.05) lower for all plant species, irrespective of salt treatment. Canola was, however, the most effective for lowering soil Se levels. Using phytoremediation in conjunction with water management may be a practical stategy for managing Se in saline soils.