Hydrology and cycling of nitrogen and phosphorus in Little Bean Marsh: A remnant riparian wetland along the Missouri River in Platte County, Missouri, 1996–97

Abstract

The lack of concurrent water-quality and hydrologic data on riparian wetlands in the Midwestern United States has resulted in a lack of knowledge about the water-quality func tions that these wetlands provide. Therefore, Little Bean Marsh, a remnant riparian wetland along the Missouri River, was inves tigated in 1996 and 1997 primarily to determine the magnitude and character of selected water-quality benefits that can be pro duced in such a wetland and to identify critical processes that can be managed in remnant or restored riparian wetlands for amelioration of water quality.

Pre‐ and post‐impoundment nitrogen in the lower Missouri River

“…The large change in N speciation from particulate N to nitrate in the lower Missouri River is likely the result of: (1) the large increase in nitrate from agriculture that occurred after impoundment; (2) the removal and isolation of flood‐plain wetlands that have been shown to have large nitrate‐removal capacities through denitrification (Blevins, ); (3) the decrease in suspended‐sediment concentrations of 70 to 80% that occurred after the construction of large upstream reservoirs (Blevins, ), which trap nearly all particulate‐organic N; and (4) the increase in urban populations and the advent of modern sewage treatment that convert some organic‐N to nitrate. Remnant riparian wetlands along the lower Missouri River have been shown to effectively remove nitrate from small tributaries and runoff just before entering the Missouri River (Blevins, ) through denitrification and settling of particulate N. Consequently, the restoration and creation of new wetlands through ongoing governmental programs could provide a potential reduction of nitrate‐N concentrations if these wetlands are constructed with appropriate depths, retention times, hydroperiods, and flow routing.…”

Geomorphic Controls on Floodplain Connectivity, Ecosystem Services, and Sensitivity to Climate Change: An Example From the Lower Missouri River

“…We then used a range of areal estimates of denitrification rates to calculate minimum and maximum likely bounds on denitrification. The low value used is 8 mg N*m −2 *day −1 determined for an episodically inundated Mississippi River floodplain (Hurst et al., 2016) and the high value used is 300 mg N*m −2 *day −1 measured in a shallow, permanent oxbow lake in the Missouri River floodplain (Blevins, 2004). Notably, Blevins (2004) considered the floodplain lake to be NO ‐3 limited, indicating that potential denitrification rates could be higher than measured.…”

“…A main finding in our analysis is the importance of recognizing how the current state of channel geomorphic responses to channelization and impoundment propagate to affect floodplain connectivity. The most common , 1994, -2004, (Aulenbach et al, 2007.…”

“…a Hurst et al (2016). b Blevins (2004). response to impoundment and engineering of large rivers is incision due to loss of bed load and/or increase in slope from channelization, and in some cases aggregate mining (Gibson & Shelley, 2020;Schmidt & Wilcock, 2008;Williams and Wolman, 1984).…”

Trees at work: economic accounting for forest ecosystem services in the U.S. South

“…Hydrological functions of forested wetlands may include flood mitigation or short-term surface water storage; and to a lesser extent than forested wetlands in other regions of the United States, they abate storm damages and recharge groundwater (National Research Council 1995, Walbridge 1993. Biogeochemical processes of wetlands include the transformation and cycling of elements and retention and removal of dissolved substances and thereby the improvement of surface, subsurface, and groundwater quality (Blevins 2004, National Research Council 1995.…”