Riparian zone effects on in-stream nutrient cycling in the Fox River Basin, WI, USA

Session: Beyond the Edge of the Field: Mitigating the Impacts of Nutrient Pollution on HABs (3)

Rebecca Kreiling, United States Geological Survey, [email protected]
Lynn Bartsch, USGS, [email protected]
Patrik Perner, United States Geological Survey, [email protected]
Enrika Hlavacek, United States Geological Survey, [email protected]
Victoria Christensen, USGS, [email protected]

Abstract

Land cover type is an important driver of nutrient concentrations in rivers and can influence in-stream sediment nutrient cycling.  In 2018, we evaluated nitrogen and phosphorus cycling at 28 stream sites with either an agricultural riparian zone, forested riparian zone, or wetland riparian zone.  Sites were sampled in May, June, and August.  All sampling periods experienced above normal streamflow.  Maximum surface water nitrogen and phosphorus concentrations occurred in June and August, respectively, at sites with agricultural riparian zones and coincided with highest rates of denitrification and nitrification.  The forested sites had the highest equilibrium phosphorus concentrations (EPC₀) in May.  These sites had sandier substrates which typically increases EPC₀.  The EPC₀ values were similar among all the sites during June and August.  Phosphorus saturation ratios were comparable among all the sites during the three sampling episodes.  In the Fox River Basin, riparian zone type has a potential to influence sediment nutrient cycling indirectly through effects on surface water nutrient concentrations.