Nitrate Removal, Nitrate Removal Velocity and Denitrification In Coastal Louisiana Freshwater Wetlands.

Nitrate removal, nitrate removal velocity and denitrification rate were determined for various freshwater wetland types in the Mississippi River Coastal delta plain. Site 1 and 4 were collected from forested-tupelo dominated wetland, and site 2 and 3 were from floating emergent marsh. The nitrate removal rate was 19.454 mg N m^-2 d^-1 for site 1, 48.414 mg N m^-2 d^-1 for site 2, 46.982 mg N m^-2 d^-1 for site 3, and 48.896 mg N m^-2 d^-1 for site 4. The nitrate removal rate was in the order of site 4 > site 2 > site 3 > site 1 for the soil water columns. The removal velocity constants (k) of NO₃-N in site 1, 2, 3 and 4 were 0.4412, 1.3325, 1.4383 and 1.4270 per day, respectively. The removal velocity of nitrate in tested cores was rapid on the order of site 3 ≥ site 4 ≥ site 2 >> site 1. The maximum denitrification rate was determined using the acetylene inhibition method 1.24 mg N m^-2 d^-1 for site 1, 1.93 mg N m^-2 d^-1 for site 2, 2.24 mg N m^-2 d^-1 for site 3, and 2.78 mg N m^-2 d^-1 for site 4. The maximum denitrification rate was in the order of site 4 > site 3 > site 2 > site 1. The relative contribution of denitrification in site 1, 2, 3 and 4 were 6.35%, 3.98%, 4.77%, and 5.68% of total nitrate removal rate, respectively.