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Constructed treatment wetlands are a common practice for filtering nitrogen from agricultural sub-surface (i.e. tile) drainage in the Midwest. Wetland size recommendations typically depend on watershed size, but little is known about the effectiveness of wetlands with a pooled area as small as 0.11 ha combined with a high infiltration rate and sub-surface treatment. A small, edge-of-field wetland treating tile drainage from a 10.1-ha row-crop field was constructed in 2013 adjacent to Elm Creek in Martin County, MN. The water, nitrate‑nitrogen (NO3−-N), and phosphorus (P) budgets were determined for 2013 to 2016. The wetland received an annual average of 12.6 m drainage water, 185 kg NO3−-N, and 1.3 kg total phosphorus (TP) each of the four years of this study. It removed 67% of the input NO3−, but TP removal was inconclusive. The majority of NO3− was removed in the shallow groundwater flow after it infiltrated from the surface. Approximately 3.2 kg-P ha−1 yr−1 was removed by harvesting the vegetation in the wetland. Therefore, it can be concluded that NO3− removal in the shallow groundwater and TP removal through vegetation harvest were the primary means of removing each nutrient.
Brad A. Gordon; Christian Lenhart; Heidi Peterson; Joshua Gamble; John Nieber; Dean Current; Ashley Brenke. Reduction of nutrient loads from agricultural subsurface drainage water in a small, edge-of-field constructed treatment wetland. Ecological Engineering 2021, 160, 106128 .
AMA StyleBrad A. Gordon, Christian Lenhart, Heidi Peterson, Joshua Gamble, John Nieber, Dean Current, Ashley Brenke. Reduction of nutrient loads from agricultural subsurface drainage water in a small, edge-of-field constructed treatment wetland. Ecological Engineering. 2021; 160 ():106128.
Chicago/Turabian StyleBrad A. Gordon; Christian Lenhart; Heidi Peterson; Joshua Gamble; John Nieber; Dean Current; Ashley Brenke. 2021. "Reduction of nutrient loads from agricultural subsurface drainage water in a small, edge-of-field constructed treatment wetland." Ecological Engineering 160, no. : 106128.
Nutrient loads in fresh and coastal waters continue to lead to harmful algal blooms across the globe. Historically, floodplains—low-lying areas adjacent to streams and rivers that become inundated during high-flow events—would have been nutrient deposition and/or removal sites within riparian corridors, but many floodplains have been developed and/or disconnected. This review synthesizes literature and data available from field studies quantifying nitrogen (N) and phosphorus (P) removal within floodplains across North America and Europe to determine how effective floodplain restoration is at removing nutrients. The mean removal of nitrate-N (NO3−-N), the primary form of N in floodplain studies, was 200 (SD = 198) kg-N ha−1 year−1, and of total or particulate P was 21.0 (SD = 31.4) kg-P ha−1 year−1. Based on the literature, more effective designs of restored floodplains should include optimal hydraulic load, permanent wetlands, geomorphic diversity, and dense vegetation. Floodplain restorations along waterways with higher nutrient concentrations could lead to a more effective investment for nutrient removal. Overall, restoring and reconnecting floodplains throughout watersheds is a viable and effective means of removing nutrients while also restoring the many other benefits that floodplains provide.
Brad A. Gordon; Olivia Dorothy; Christian F. Lenhart. Nutrient Retention in Ecologically Functional Floodplains: A Review. Water 2020, 12, 2762 .
AMA StyleBrad A. Gordon, Olivia Dorothy, Christian F. Lenhart. Nutrient Retention in Ecologically Functional Floodplains: A Review. Water. 2020; 12 (10):2762.
Chicago/Turabian StyleBrad A. Gordon; Olivia Dorothy; Christian F. Lenhart. 2020. "Nutrient Retention in Ecologically Functional Floodplains: A Review." Water 12, no. 10: 2762.
Reed canary grass (Phalaris arundinacea L.) is an invasive, cool‐season grass commonly dominating wetlands with high nutrient loads. Its impact on nitrogen removal via denitrification in wetlands is unknown. Most studies of denitrification in treatment wetlands have focused on the effects of physical or chemical variables and not on the effects of plant roots on the soil environment. The purpose of this study was to measure effects of plant type on denitrification rates in typical wetland soils of the midwestern United States by comparing wet prairie mix, switchgrass‐dominated, and reed canary grass plant communities. Nitrate (NO3−) removal and other parameters were measured in miniature wetlands, or mesocosms, containing each plant community transplanted from a small agricultural treatment wetland in southern Minnesota. Quantitative polymerase chain reaction analysis was used to quantify the total bacteria population (measured with 16S rRNA genes) and denitrifying gene abundance (measured with nosZ genes) from the rhizosphere of each plant community. The wet prairie mix mesocosms on average removed the most NO3− in each test (p = .01 and .08). Whereas the wet prairie mix removed the most NO3− from the surface water (p < .01), reed canary grass removed more from the subsurface (p < .01). Ratios of denitrifying to total bacteria were higher in the wet prairie mix than in the other communities’ root zones (p < .05). Results suggest that reed canary grass invasion could reduce denitrification in wetlands, especially during the spring and fall when it is growing but other plants are dormant.
Brad A. Gordon; Christian Lenhart; Timothy M. LaPara. A comparison of nitrate removal and denitrifying bacteria populations among three wetland plant communities. Journal of Environmental Quality 2019, 49, 210 -219.
AMA StyleBrad A. Gordon, Christian Lenhart, Timothy M. LaPara. A comparison of nitrate removal and denitrifying bacteria populations among three wetland plant communities. Journal of Environmental Quality. 2019; 49 (1):210-219.
Chicago/Turabian StyleBrad A. Gordon; Christian Lenhart; Timothy M. LaPara. 2019. "A comparison of nitrate removal and denitrifying bacteria populations among three wetland plant communities." Journal of Environmental Quality 49, no. 1: 210-219.
Treatment wetlands are increasingly needed to remove nitrate from agricultural drainage water to protect downstream waters, such as the Gulf of Mexico. This project sought to develop a new edge-of-field treatment wetland, designed to remove nitrate-nitrogen and enhance phosphorus removal by plant harvest and to monitor its effectiveness. A 0.10 ha wetland was designed and installed to treat subsurface drainage flow from farmland in southwestern Minnesota, USA, in 2013, and monitored for three years by recording flow, nitrate-nitrogen, total phosphorus (TP) and soluble orthophosphorus (OP) input to and output from the wetland. Prior to construction, a level-pool routing, mass balance approach with DRAINMOD flow inputs was used to predict nitrate removal efficiency. Nitrate load removal averaged 68% over three years, nearly matching model predictions. However, most denitrification occurred in the sub-soil of the wetland rather than in surface flow as predicted. Phosphorus removal was approximately 76% over three years, and phosphorus removed by plant uptake exceeded inflow mass in the third year. The edge-of-field design has potential as a cost-effective method to treat field outflows because agricultural landowners can adopt this treatment system with minimal loss of productive farmland. The wet-prairie vegetation and shallow depth also provide the opportunity to remove additional phosphorus via vegetative harvest.
Christian Lenhart; Brad Gordon; Joshua Gamble; Dean Current; Nikol Ross; Lydia Herring; John Nieber; Heidi Peterson. Design and Hydrologic Performance of a Tile Drainage Treatment Wetland in Minnesota, USA. Water 2016, 8, 549 .
AMA StyleChristian Lenhart, Brad Gordon, Joshua Gamble, Dean Current, Nikol Ross, Lydia Herring, John Nieber, Heidi Peterson. Design and Hydrologic Performance of a Tile Drainage Treatment Wetland in Minnesota, USA. Water. 2016; 8 (12):549.
Chicago/Turabian StyleChristian Lenhart; Brad Gordon; Joshua Gamble; Dean Current; Nikol Ross; Lydia Herring; John Nieber; Heidi Peterson. 2016. "Design and Hydrologic Performance of a Tile Drainage Treatment Wetland in Minnesota, USA." Water 8, no. 12: 549.
Christian F Lenhart; Bruce N Wilson; Bradley Gordon. Factors impacting the variability of effectiveness of agricultural best management practices (BMPs) in Minnesota. 2016 10th International Drainage Symposium 2016, 1 -8.
AMA StyleChristian F Lenhart, Bruce N Wilson, Bradley Gordon. Factors impacting the variability of effectiveness of agricultural best management practices (BMPs) in Minnesota. 2016 10th International Drainage Symposium. 2016; ():1-8.
Chicago/Turabian StyleChristian F Lenhart; Bruce N Wilson; Bradley Gordon. 2016. "Factors impacting the variability of effectiveness of agricultural best management practices (BMPs) in Minnesota." 2016 10th International Drainage Symposium , no. : 1-8.
Brad Gordon; Paul E. Rothrock; Paul Labus. Testing the use of best professional judgment to create biological benchmarks for habitat assessment of wetlands and oak savannas in northwestern Indiana. Ecological Indicators 2016, 60, 410 -419.
AMA StyleBrad Gordon, Paul E. Rothrock, Paul Labus. Testing the use of best professional judgment to create biological benchmarks for habitat assessment of wetlands and oak savannas in northwestern Indiana. Ecological Indicators. 2016; 60 ():410-419.
Chicago/Turabian StyleBrad Gordon; Paul E. Rothrock; Paul Labus. 2016. "Testing the use of best professional judgment to create biological benchmarks for habitat assessment of wetlands and oak savannas in northwestern Indiana." Ecological Indicators 60, no. : 410-419.