title: Seasonal Variation in Floodplain Biogeochemical Processing in a Restored Headwater Stream.
abstract: Stream and river restoration activities have recently begun to emphasize the enhancement of biogeochemical processing within river networks through the restoration of river-floodplain connectivity. It is generally accepted that this practice removes pollutants such as nitrogen and phosphorus because the increased contact time of nutrient-rich floodwaters with reactive floodplain sediments. Our study examines this assumption in the floodplain of a recently restored, low-order stream through five seasonal experiments. During each experiment, a floodplain slough was artificially inundated for 3 h. Both the net flux of dissolved nutrients and nitrogen uptake rate were measured during each experiment. The slough was typically a source of dissolved phosphorus and dissolved organic matter, a sink of NO3(-), and variable source/sink of ammonium. NO3(-) uptake rates were relatively high when compared to riverine uptake, especially during the spring and summer experiments. However, when scaled up to the entire 1 km restoration reach with a simple inundation model, less than 0.5-1.5% of the annual NO3(-) load would be removed because of the short duration of river-floodplain connectivity. These results suggest that restoring river-floodplain connectivity is not necessarily an appropriate best management practice for nutrient removal in low-order streams with legacy soil nutrients from past agricultural landuse.
authors.affiliation: Biological Systems Engineering, Virginia Tech , Seitz Hall, Room 200, 155 Ag Quad Lane, Blacksburg, Virginia 24061, United States.
authors.forename: C Nathan
authors.initials: CN
authors.lastname: Jones
authors.affiliation: Biological Systems Engineering, Virginia Tech , Seitz Hall, Room 200, 155 Ag Quad Lane, Blacksburg, Virginia 24061, United States.
authors.forename: Durelle T
authors.initials: DT
authors.lastname: Scott
authors.affiliation: Civil and Environmental Engineering, Virginia Tech , Blacksburg, Virginia 24061, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Guth
authors.affiliation: Civil and Environmental Engineering, Virginia Tech , Blacksburg, Virginia 24061, United States.
authors.forename: Erich T
authors.initials: ET
authors.lastname: Hester
authors.affiliation: Biological Systems Engineering, Virginia Tech , Seitz Hall, Room 200, 155 Ag Quad Lane, Blacksburg, Virginia 24061, United States.
authors.forename: W Cully
authors.initials: WC
authors.lastname: Hession
mesh_terms: D000383:Agriculture; D017753:Ecosystem; D052918:Environmental Restoration and Remediation / Q000379:methods*; D055868:Floods; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis; D045483:Rivers; D012621:Seasons; D012987:Soil; D014768:Virginia
chemical_list: D009566:Nitrates; D012987:Soil; D010758:Phosphorus; D009584:Nitrogen