The loading rate analysis found efficient nutrient
removal at low loading rates, but removal efficiency
decreased rapidly with increasing loading
rate. Richardson and Nichols (1985) reviewed a
number of wetland wastewater treatment systems
and found similar results. The nutrient loading
rates reported here were lower for corresponding
removal efficiencies for total phosphorus and total
nitrogen than those reported by Richardson and
Nichols (1985). This difference may be due to
chemical differences between wastewater and Mississippi
River water, and physiological differences
of the receiving wetlands. The trend of low removal
efficiency at high loading rates may be caused
by shorter residence times of water in the estuary
during high loading rates, allowing less time for
biogeochemical processes to occur.