Nitrate Removal from Floodwater Overlying Flooded Soils and Sediments1
- R. M. Engler and
- W. H. Patrick2
The floodwater NO3− removal rate of intermittently-flooded fresh water swamp soils and continuously-flooded saline marsh soils of southern Louisiana was quantitatively characterized in a laboratory study. Of the two areas studied, the marsh area was the more effective sink for NO3− contaminated waters with an average initial removal rate of 9.15 ppm N/day. After correcting for the rate of NO3− diffusion, the microbial NO3− removal rate was calculated to be 7.64 ppm N/day. The swamp soil had a removal rate of 4.38 ppm N/day. The microbial NO3− removal rate for this area, after correcting for diffusion, was 2.50 ppm N/day. Studies on samples of floodwater separated from the soil showed the active site of microbial NO3− reduction to be the soil-water interface or within the soil, but not in the floodwater. Additions of organic matter to a mineral soil flooded for rice (Oryza sativa L.) culture decreased the thickness of the aerobic-anaerobic zone at the soil-water interface and increased the rate of NO3− reduction.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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