Nitrogen removal by streams and rivers of the Upper Mississippi River basin

Abstract

We used stream chemistry and hydrogeomorphology data from 549 stream and 447 river sites to estimate NO 3 -N removal in the Upper Mississippi, Missouri, and Ohio Rivers. We used two N removal models to predict NO 3 -N input and removal. NO 3 -N input ranged from 0.01 to 338 kg km -1 d -1 in the Upper Mississippi River to\0.01-54 kg km -1 d -1 in the Missouri River. Cumulative river network NO 3 -N input was 98700-101676 Mg year -1 in the Ohio River, 85961-89288 Mg year -1 in the Upper Mississippi River, and 59463-61541 Mg year -1 in the Missouri River. NO 3 -N output was highest in the Upper Mississippi River (0.01-329 kg km -1 d -1 ), followed by the Ohio and Missouri Rivers (\0.01-236 kg km -1 d -1 ) sub-basins. Cumulative river network NO 3 -N output was 97499 Mg year -1 for the Ohio River, 84361 Mg year -1 for the Upper Mississippi River, and 59200 Mg year -1 for the Missouri River. Proportional NO 3 -N removal (PNR) based on the two models ranged from \0.01 to 0.28. NO 3 -N removal was inversely correlated with stream order, and ranged from \0.01 to 8.57 kg km -1 d -1 in the Upper Mississippi River to\0.001-1.43 kg km -1 d -1 in the Missouri River. Cumulative river network NO 3 -N removal predicted by the two models was: Upper Mississippi River 4152 and 4152 Mg year -1 , Ohio River 3743 and 378 Mg year -1 , and Missouri River 2277 and 197 Mg year -1 . PNR removal was negatively correlated with both stream order (r = -0.80-0.87) and the percent of the catchment in agriculture (r = -0.38-0.76).

Heavy load and high potential: anthropogenic pressures and their impacts on the water quality along a lowland river (Western Bug, Ukraine)

“…The agricultural region showed highest concentrations of nitrate, which was found to be in agreement with other agriculturally used regions (Burt et al 2011;Hill and Bolgrien 2011). Fairly low concentrations of orthophosphate, TDP and BOD 5 were observed.…”

Nitrogen surface water retention in the Baltic Sea drainage basin

“…Reduced N export can be achieved by increasing N retention in soils, sediments and biomass, reducing atmospheric and terrestrial N sources, and increasing in-stream N removal and retention processes (Hill and Bolgrien, 2011).…”

“…In later years, a number of models of different complexity have been developed for estimating surface water N retention (e.g. Billen et al, 2009;Grimvall and Stålnacke, 1996;Hejzlar et al, 2009;Hill and Bolgrien, 2011;Jung and Deng, 2011;Mayorga et al, 2010;Seitzinger et al, 2002).…”

“…Expanding human activities have had a great impact on nutrient dynamics and nutrient export from watersheds (Hill and Bolgrien, 2011;Mayorga et al, 2010). Increased population densities, food production, sewage emissions and fossil fuel combustion are among the driving forces causing increased nutrient mobilisation and alterations to hydrological systems (Mayorga et al, 2010).…”

Effect of Flow Depth and Velocity on Nitrate Loss Rates in Natural Channels1

“…Figure 5 (compare with figure 4b of Hill and Bolgrien, 2011) displays fractional removals of nitrate for the same generic 2‐km stream, across a range of depths for θ = 0.0, 0.5, and 1.0. Figures 6a and 6b display the corresponding mass decline curves as a function of streamflow travel distance, for water column depths of 0.01 and 0.1 m, respectively.…”