A Wind Tunnel for Measuring Selenium Volatilization under Field-Like Conditions
- R. S. Dungan,
- A. Stork and
- W. T. Frankenberger *
A wind tunnel was developed to measure the loss of volatile selenium (Se) from soil under field-like conditions. The wind tunnel consisted of a volatilization chamber made of Plexiglas (2.4 m long × 0.8 m wide × 1.2 m high), which was set above a stainless steel lysimeter (0.5 m2 surface area × 0.8 m deep). High air exchange rates (avg. 700 air changes h−1) were used to simulate field-like environmental conditions inside the wind tunnel. To monitor the fate and transport of the Se, radiolabeled 75Se as sodium selenite (Na275SeO3) was incorporated into the top 5 cm of soil. Volatile Sc was trapped on activated carbon filters and measured directly using gamma counting. A 135-d bare-soil experiment was carried out, during which 2.7% of the Se was released through volatilization without added C. The average flux rate of gaseous Se was 17 mg m−2 h−1, with a high of 72 mg m−2 h−1 occurring on Day 6. After 135 d, 59 and 34% of the 75Se was located in the 0 to 5 and 5 to 10 cm soil layers, respectively. A total of 84.5% of all applied 75Se was recovered. The purpose of this study was to improve estimates on Se volatilization from seleniferous soils and help close the gap between previous laboratory and field experiments.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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