Phytoextraction of selenium from soils irrigated with selenium-laden effluent

Abstract

This two-part study compared the efficacy of different plant species to extract Se from soils irrigated with Se-laden effluent. The species used were: Brassica napus L. (canola), Brassica juncea Czern L. and Coss (Indian mustard), and Hordeum vulgare L. (barley). In Study 1 we irrigated the plants with a saline effluent containing 0.150 mg Se L−1, while in Study 2, the same species were planted in a saline soil selenized with 2 mg Se L−1. Plants were simultaneously harvested 120 days after planting. In Study 1, there were only slight effects of treatment on dry matter (DM) yield. Plant Se concentrations averaged 21 μg Se g−1DM for the Brassica species, and 4.0 μg Se g−1 DM for barley. Total Se added to soils via effluent decreased by 40% for Brassica species and by 20% for barley. In Study 2, total DM decreased for all species grown in saline soils containing Se. Plant Se concentrations averaged 75 μg g−1 DM for Brassica species and 12 μg Se g−1 DM for barley. Total Se added to soils prior to planting decreased by 40% for Brassica species and up to 12% for barley. In both studies, plant accumulation of Se accounted for at least 50% of the Se removed in soils planted to Brassica and up to 20% in soils planted to barley. Results show that although the tested Brassica species led to a significant reduction in Se added to soil via use of Se-laden effluent, additional plantings are necessary to further decrease Se content in the soil.