Acceleration of selenium volatilization in seleniferous agricultural drainage sediments amended with methionine and casein

Phytoremediation is potentially effective for managing excessive selenium (Se) in drainage sediment residing in the San Luis Drain in central California. This 2-year field study examined the feasibility of amending drainage sediment (containing 4.78 μg Se g−1) with methionine and casein to enhance volatilization without or with vegetation of Sporobolus airoides. Results show that without organic amendments, rates of Se volatilization were less than 25 μg m−2 d−1 in all plots. After amending the sediment with 71.4 mg methionine kg−1 soil, Se volatilization rates were 434 ± 107 μg m−2 d−1 in vegetated plots and 289 ± 117 μg m−2 d−1 in irrigated bare plots. With the amendment of 572 mg casein kg−1 soil, rates increased to 346 ± 103 μg m−2 d−1 in irrigated bare plots and to 114 ± 55 μg m−2 d−1 in vegetated plots. Both methionine and casein promoted biological remediation of Se via volatilization most effectively during the warmest months.