Environmental Factors Affecting Microbial Production of Dimethylselenide in a Selenium‐Contaminated Sediment

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Abstract
Selenium poisoning from agricultural wastewater has been blamed for wildlife deaths and deformities at Kesterson Reservoir (Merced County, California). One approach in reducing the Se content in seleniferous sediments is based on microbial methylation of Se. This study was conducted to determine the optimum environmental conditions for volatilization of Se. A saline (> 20 dS m−1) seleniferous soil collected from Pond 4, Kesterson Reservoir was assayed for dimethylselenide (DMSe) production by incubating it for up to 120 h at 22 °C under various treatments. The DMSe was monitored by gas chromatography and identified by gas chromatography‐mass spectrometry. The conditions or additions optimum for DMSe production were: pH 8.0; moisture content, field capacity (−33 kPa); temperature, 35 °C; L‐methionine, 100 mg kg−1 soil; galacturonic acid, 3.6 g C kg−1 soil; and protein sources including casein (2.0 g C kg−1 soil) and albumin (0.05 to 2.0 g C kg−1 soil). Albumin applied to soil enhanced gaseous Se production 19.3‐fold over the unamended control. It should be possible to apply these findings in a management practice to detoxify seleniferous sediments.

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