SFS Annual Meeting

5/24/2018  |   14:00 - 14:15   |  310 A

1997-2017: TWENTY YEARS OF RIPARIAN ZONE RESEARCH: WHERE TO NEXT? Riparian zones have been used for water quality management with respect to nitrate (NO3-) in subsurface flow and total phosphorus (TP), sediments, and pesticides in overland flow for decades. Only recently has the dynamics of soluble reactive phosphorus (SRP), mercury (Hg), emerging contaminants, and greenhouse gas fluxes (GHG: N2O, CO2, CH4) been examined in riparian zones. For this talk, we show that riparian zones are overall efficient at reducing emerging contaminants in subsurface flow and only function as hot spots of methylmercury production in the landscape when dominated by Hg rich wet organic soils. However, riparian zones do not provide consistent benefits with respect to SRP removal or GHG emissions. More research should be conducted on how various practices, including stream restoration, subsurface drainage, two-stage ditches, beaver dam analogues, denitrification bioreactors and permeable reactive barriers, artificial wetlands, or short rotation forestry crops impact riparian water and air quality functions. Riparian zone benefits should also be discussed not only with respect to water and air quality, but also with respect to water quality or air quality tradeoffs associated with riparian zone management in a multi-contaminants / multi-use landscape context.

Philippe Vidon (Primary Presenter/Author), The State University of New York College of Environmental Science and Forestry, pgvidon@esf.edu;


Molly Welsh (Co-Presenter/Co-Author), The State University of New York College of Environmental Science and Forestry, mkwelsh@syr.edu;


Yasaman Hassanzadeh (Co-Presenter/Co-Author), SUNY-ESF, ythassan@syr.edu;


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5/24/2018  |   14:15 - 14:30   |  310 A

LIMITS AND LOCATION OF DENITRIFICATION AT CATCHMENT SCALES: CAN HYPORHEIC AND RIPARIAN REMOVAL SOLVE DIFFUSE NUTRIENT POLLUTION? Protecting or restoring stream corridors is a common approach for improving water quality. Riparian and hyporheic zones support high rates of nutrient retention and removal but represent only a small portion of the total catchment volume. Determining the relative importance of stream corridors in attenuating catchment-scale nutrient fluxes requires quantifying nutrient removal in more distal and deep catchment components, which remains a challenge. Here we present case studies integrating data from 45 locations across France and the U.S. We used multi-tracer methods to quantify the rate and total amount of denitrification at the catchment scale, including partitioning near surface (riparian and hyporheic) from deep (aquifer) denitrification. We calibrated water residence time, reaction times, and location of reactive zones using concentrations and isotopes of carbon, nitrogen, oxygen, and sulfur species, and anthropogenic dissolved gases (CFCs and SF6). We found that aquifer denitrification made up a substantial portion of catchment-level nitrogen attenuation at most sites. Without this “deeper” understanding of where and when denitrification occurs, it will not be possible to constrain the role of stream corridors in catchment nutrient budgets.

Benjamin Abbott (Primary Presenter/Author), Brigham Young University, Department of Plant and Wildlife Sciences, benabbott@byu.edu;


Tamara Kolbe (Co-Presenter/Co-Author), Swedish University for Agricultural Science, Uppsala, Sweden, tamara.kolbe@slu.se;


Jean-Raynald de Dreuzy (Co-Presenter/Co-Author), Université de Rennes, CNRS, Géoscience Rennes - UMR 6118, 35000 Rennes, France, jean-raynald.de-dreuzy@univ-rennes1.fr;


Camille Vautier (Co-Presenter/Co-Author), Université de Rennes, CNRS, Géoscience Rennes - UMR 6118, 35000 Rennes, France, camille.vautier@univ-rennes1.fr;


Jean Marçais (Co-Presenter/Co-Author), Université de Rennes, CNRS, Géoscience Rennes - UMR 6118, 35000 Rennes, France, jean.marcais@univ-rennes1.fr;


Zahra Thomas (Co-Presenter/Co-Author), UMR SAS, AGROCAMPUS OUEST, INRA, 35000 Rennes, France, zahra.Thomas@agrocampus-ouest.fr;


Florentina Moatar (Co-Presenter/Co-Author), INRAE, florentina.moatar@inrae.fr;


Luc Aquilina (Co-Presenter/Co-Author), Université de Rennes, CNRS, Géoscience Rennes - UMR 6118, 35000 Rennes, France, luc.aquilina@univ-rennes1.fr;


Thierry Labasque (Co-Presenter/Co-Author), Université de Rennes, CNRS, Géoscience Rennes - UMR 6118, 35000 Rennes, France, thierry.labasque@univ-rennes1.fr;


Jay Zarnetske (Co-Presenter/Co-Author), Department of Earth and Environmental Sciences, Michigan State University, jpz@msu.edu;


Christophe Lécuyer (Co-Presenter/Co-Author), Laboratoire de Géologie de Lyon (LGL-TPE), UMR CNRS 5276, Université Claude Bernard Lyon 1, Villeurbanne, France, christophe.lecuyer@univ-lyon1.fr;


Gilles Pinay (Co-Presenter/Co-Author), CNRS, gilles.pinay@ens-lyon.fr;


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5/24/2018  |   14:30 - 14:45   |  310 A

SYNTHESIZING RIPARIAN CONTROLS ON NITRATE EXPORT IN FORESTED AND URBAN TEMPERATE CATCHMENTS Catchment scale nitrogen export depends on the spatial and temporal heterogeneity of transformation and transport processes along flowpaths. Detailed study of nitrogen biogeochemistry in a temperate forested watershed in the Piedmont physiographic province has shown that denitrification occurring in narrow portions of the riparian zone (comprising less than 1% of catchment area) dominate denitrification fluxes at the watershed scale. However, such riparian zone processes are difficult to transfer to other watersheds, particularly to an urban watershed that has vastly different drivers of spatial and temporal heterogeneity. Long-term (20 years) of streamflow and stream nitrogen in both forested and urban catchments data show marked differences in seasonal timing and hydrologic controls in stream export patterns between sites. This work combines 3 years of high frequency in-stream data and high resolution spatial data to estimate riparian controls on the timing and magnitude of stream nitrogen fluxes in an urban watershed. We present an evolving conceptual model spanning terrestrial through aquatic ecosystem controls and integrates hydrologic, geomorphic, and ecologic perspectives.

Claire Welty (Co-Presenter/Co-Author), University of Maryland Baltimore County, weltyc@umbc.edu;


Jon Duncan (Primary Presenter/Author), Penn State University, jmduncan@psu.edu;


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5/24/2018  |   14:45 - 15:00   |  310 A

EFFECTS OF FLOODPLAIN RESTORATION ON NITROGEN AND PHOSPHORUS DYNAMICS IN AGRICULTURAL WATERSHEDS Excess nitrogen and phosphorus in receiving waters is associated with high nutrient inputs in watersheds that are unsustainably and intensively managed for agriculture uses. The majority of export occurs during high flows that mobilize dissolved nutrients as well as sediment and associated pollutants. In undeveloped watersheds, floodplains intercept this flood pulse creating optimal conditions for physical and biological retention to occur. Anoxic conditions in saturated soils promote denitrification but can also release phosphorus from sorption sites that are maintained under oxic conditions. We are investigating nitrogen, phosphorus, and carbon dynamics in restored riverine floodplains using the Wabash River as a model system. Hydrodynamic modeling and daily flow frequency analysis shows that part of the floodplain is inundated 10% of the year and the entire floodplain is inundated 2% of the year on average. At the event scale, flood connectivity controls inputs and reducing conditions, which together influence nutrient dynamics. The spatial distribution of flooding is also reflected in structural (e.g. soil nutrient content) and functional (e.g. denitrification) patterns. Covariance between inundation, soil properties and denitrification suggests that connectivity plays a strong role in controlling the distribution of floodplain function.

Celena Alford (Co-Presenter/Co-Author), Purdue University, alford5@purdue.edu;


Alex Johnson (Co-Presenter/Co-Author), Purdue University, john1963@purdue.edu;


Siddharth Saksena (Co-Presenter/Co-Author), Purdue University, ssaksena@purdue.edu;


Venkatesh Merwade (Co-Presenter/Co-Author), Purdue University, vmerwade@purdue.edu;


Gregory Noe (Co-Presenter/Co-Author), U.S. Geological Survey, gnoe@usgs.gov;


Sara McMillan (Primary Presenter/Author), Iowa State University, swmcmill@iastate.edu;


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5/24/2018  |   15:00 - 15:15   |  310 A

THE EFFECT OF FLOODPLAIN CREATION ON SOIL PROCESSES IN AGRICULTURAL CHANNELS In the agricultural Midwest, subsurface drainage allows excess water to drain into agricultural channels, which flows into rivers and streams transporting excess nutrients downstream. The construction of an inset floodplain within agricultural channels enhances sedimentation of particulate nutrients and sediment, provides stable conditions for vegetation to establish, increases rates of microbial activity, and promotes denitrification. We collected sediments from floodplains of two-stage channels and naturally forming floodplain benches in conventional channels to determine the effect of floodplain creation on nutrient dynamics. We measured potential denitrification rates using bottle assays and net denitrification and respiration measurements via membrane inlet mass spectrometry (MIMS) seasonally. Respiration rates and organic matter fractions were higher in the inset floodplains for all seasons, but denitrification rates showed no difference. Nutrient processing rates were most dependent on local environmental conditions, particularly organic matter, background water chemistry, and sediment grain size. This suggests that site-specific conditions may dictate the impact of floodplain creation on water quality. However, because of the increase in biologically active surface area, the net effect on water quality is greater for the two-stage channels.

Sara McMillan (Co-Presenter/Co-Author), Iowa State University, swmcmill@iastate.edu;


Alex Johnson (Co-Presenter/Co-Author), Purdue University, john1963@purdue.edu;


Amanda Limiac (Co-Presenter/Co-Author), Purdue University, montgom8@purdue.edu;


Celena Alford (Primary Presenter/Author), Purdue University, alford5@purdue.edu;


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5/24/2018  |   15:15 - 15:30   |  310 A

THE LONGITUDINAL IMPLICATIONS OF ABRUPT RIPARIAN CHANGES: A CASE STUDY FROM BRAZIL Contemporary riparian corridors are often a patchwork of croplands, pastures, and forests that often have discrete boundaries. We hypothesized that abrupt riparian boundaries would be blurred in the stream channel due to downstream transport and transformation, effectively creating downstream 'shadows' of the upstream riparian conditions. To test this hypothesis, we sampled sites along 1050m of a headwater stream that traversed a discrete transition from forest to pasture. We quantified canopy cover, sediment size, and algal and invertebrate standing stocks at each site. A threshold modeling approach was used to examine the displacement of these variables downstream of the transition. Alternative models were tested and inverse estimation was applied to describe shifts in each variable. We observed a rapid, sigmoidal shift in canopy cover downstream of the forest boundary. Downstream increases in chlorophyll-a concentrations and grazing invertebrates were less abrupt and significantly displaced downstream relative to changes in canopy cover. Invertebrate abundance and richness decreased downstream of the forest to pasture transition and continued to change over the entire pasture reach. We discuss how these results can be used to quantitatively link the value of riparian restoration to its longitudinal dimension.

Steven Thomas (Primary Presenter/Author), University of Alabama, sathomas16@ua.edu;


Rafael Feijó de Lima (Co-Presenter/Co-Author), University of Montana, rfeijod@clemson.edu;


Flavia Tromboni (Co-Presenter/Co-Author), University of Nevada, Reno, ftromboni@unr.edu;


Eduardo F. Silva-Júnior (Co-Presenter/Co-Author), Universidade do Estado do Rio de Janeiro, eduardobioadventure@gmail.com ;


Timothy P. Moulton (Co-Presenter/Co-Author), Universidade do Estado do Rio de Janeiro, moulton.timothy@gmail.com;


Eugenia Zandona (Co-Presenter/Co-Author), Universidade do Estado do Rio de Janeiro, eugenia.zandona@gmail.com;


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