Nutrient over-enrichment is a critical driver of harmful cyanobacterial blooms world-wide. Point sources of nutrients have long been identified as management targets, while diffuse, non-point sources (e.g., agricultural sources, and onsite septic systems) are more challenging to assess and manage for nutrient reductions. In North Carolina, nitrogen levels have increased over time in many freshwater and estuarine systems, and atmospheric deposition of nitrogen has also increased, resulting in nitrogen hot spots; these are often associated with areas that have highly clustered confined animal operations. In addition to emissions to the airshed, these sources of nutrients can result in substantial hydrologic export of both nitrogen and phosphorus, particularly after extreme rainfall events mobilize nutrients stored in waste lagoons, pastures, and croplands. This session will bring together research that has been done in the Carolinas related to nutrient source assessments, including atmospheric deposition, monitoring of surface waters where nutrient levels have increased and phytoplankton blooms have developed, and nutrient management approaches. We also welcome submissions from researchers from a variety of disciplines (remote sensing, monitoring, modeling, etc.), who are working in other places where nutrient hot spots and climate interactions are impacting water quality and the formation of harmful blooms.
Lead Organizer: Diane Lauritsen, LIMNOSCIENCES (ddlauritsen@comcast.net)
Co-organizers:
Lorrayne Miralha, Ohio State University (miralha.1@osu.edu)
Daniel Obenour, North Carolina State University (drobenou@ncsu.edu)
Nathan Hall, University of North Carolina-Chapel Hill (nshall@email.unc.edu)
Astrid Schnetzer, North Carolina State University (aschnet@ncsu.edu)
Presentations
02:30 PM
SPATIOTEMPORAL ASSESSMENT OF ATMOSPHERIC DEPOSITION SURROUNDING ANIMAL FARMS IN THE UNITED STATES (9726)
Primary Presenter: Lorrayne Miralha, The Ohio State University (miralha.1@osu.edu)
Concentrated Animal Feeding Operations (CAFOs) have expanded in the U.S. to address efficiencies in livestock production. These operations tend to cluster in space, and processes such as atmospheric deposition can partially explain significant increases in nutrients found in waterbodies surrounding these intensified agricultural systems. Nationwide, CAFO-clustered watersheds have shown greater concentrations of precipitation NH4 (0.10 mg/l greater on average) and NO3 (0.60 mg/) than CAFO-dispersed watersheds (p< 0.05). When comparing CAFO-clustered watersheds in NC and the trends in NH4 and NO3, we observed that watersheds with a higher density of CAFOs displayed an increasing trend in NH4 over time, while no trend was observed in NH4 for watersheds with a lower density of CAFOs. A shallow natural seepage lake located in a nitrogen hot spot has seen increases in pH and total nitrogen over a similar time period. The spatial patterns revealed in this study may be used to understand how watershed-targeted management has worked to prevent nutrient pollution from nonpoint sources and bring insights into the role of CAFOs in freshwater nutrient pollution and algal bloom expansion in the US.
02:45 PM
USING MACHINE LEARNING TO INVESTIGATE THE ROLE OF CAFO EXPANSION ON NUTRIENT POLLUTION TRENDS IN EASTERN NORTH CAROLINA (8780)
Primary Presenter: Colleen Brown, University of North Carolina Wilmington (cnb6822@uncw.edu)
Agriculture and wastewater practices are major contributors to nutrient loading and coastal eutrophication issues globally. The lower Cape Fear River basin in eastern North Carolina, USA, is particularly affected, with one of the highest densities of livestock production facilities, known as concentrated animal feeding operations (CAFOs), in the world. Long-term water quality monitoring by the Lower Cape Fear River Program revealed chronic nutrient and fecal bacteria pollution and increased trends over the past 20 years with hotspots in CAFO-dense watersheds. While swine CAFO density has remained stable since the 1990s, poultry CAFOs have rapidly expanded, yet long-term geospatial data for poultry CAFOs was unavailable. The growth of the poultry CAFO industry is a high priority research need to understand the impacts on water quality and human health in this already CAFO-dense area. A machine-learning image classification model was developed to identify and quantify poultry CAFOs constructed in North Carolina over the past 20 years using public aerial imagery from the National Agricultural Imagery Program and processed with Google Earth Engine and Google Colaboratory. Combined with long-term water quality data, the resulting dataset fills a critical data gap and provides a framework for assessing the long-term impact of CAFOs on water quality. The findings demonstrate the utility of machine learning for monitoring pollution sources and provides insights for environmental management and policy decisions in the region.
03:00 PM
INFLUENCE OF RAINFALL AND IRRIGATION EVENTS ON NUTRIENT DYNAMICS IN DAIRY FARMS (8754)
Primary Presenter: Justice Osuoha, Monash University (justice.osuoha@monash.edu)
Nutrient runoff from dairy farms is a well-known driver of eutrophication. While prior research on nutrient dynamics in agricultural systems has primarily focused on catchment scales, often overlooking localised nitrogen processing hotspots, our study investigates nutrient transformations at the farm scale, hypothesising that his approach will offer deeper insights into improved nutrient management strategies. We measured nutrient concentrations (nitrate and ammonium) and isotopes (δ15N-NO3−, δ18O-NO3−, δ15N-NH4+) in farms’ runoff during rainfall and irrigation events. Significant variations of δ15N-NO3− in the farms’ runoff (-6.8 -23 ‰) compared to input (-3.8 to 7.1‰) strongly suggest that nutrients were being altered within the pasture before leaving the farm. Low δ15N-NO3− (as low as -6.8‰) in some runoff and manure samples (-3.8‰) were consistent with nitrification, while increases of δ15N-NO3− (23 ‰) suggested active denitrification. Very low δ15N-NH4+ (as low as -10‰) coincident with moderate to high δ15N-NO3− (4.6 – 14‰) suggested dissimilatory nitrate reduction to ammonium (DNRA) was a significant process. Even during rainfall, significant isotope fractionation occurred, indicating complex transformations despite short water residence times. As such, the use of nitrogen isotopes to trace nitrogen sources should be undertaken with a detailed understanding of likely fractionation processes. This can help shed light on the times and locations of nitrogen transformation and loss processes to help improve management practices.
03:15 PM
The North Carolina Coastal Plain: A Hotspot for Increasing Nutrient Pollution (8853)
Tutorial/Invited: Invited
Primary Presenter: Michael Mallin, University of North Carolina - Wilmington (mallinm@uncw.edu)
The North Carolina Coastal Plain is dominated by a series of 2nd to 5th order blackwater streams and rivers. These watersheds host over 9 million head of swine and hundreds of millions of chickens and turkeys being raised in CAFOs, or concentrated animal feeding operations. These types of industrial livestock operations dispel animal waste into the environment with no secondary treatment. While swine numbers have stayed steady for the past two decades, poultry abundance has increased dramatically. A 22-year data set collected by the Lower Cape Fear River Program at UNC Wilmington was analyzed for trends at 29 stations. The analysis showed significantly increasing nitrate at 18 stations, increasing total nitrogen at 14 stations, increasing total phosphorus at 20 stations, and increasing fecal coliform bacteria at 17 stations. A separate NCDEQ analysis indicated increasing organic nitrogen at numerous sites in North Carolina. Targeted sampling at a CAFO – rich watershed found chronically high nutrient and fecal bacteria concentrations in receiving streams. Besides the high amounts of waste from swine sprayfields and poultry litterfields entering the land and waterscapes, the soils in this region are porous and water tables high, making movement to the water table rapidly. Thus, streams are subject to both overland runoff and polluted groundwater inputs. Despite the lower Cape Fear River and estuary on the 303(d) list for waters impaired by hypoxia, there are no legal non-point runoff controls in agricultural lands in this large watershed.
03:30 PM
MESOCOSMS IN MITIGATION STUDIES - FROM WASTE TO RESOURCE: RECYCLING OLIVE OIL WASTEWATER AND BYPRODUCTS FOR SUSTAINABLE AGRICULTURE IN THE MEDITERRANEAN REGION (9421)
Primary Presenter: Jens Nejstgaard, IGB - Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin-Berlin, Brandenburg, Germany (jens.nejstgaard@igb-berlin.de)
The Mediterranean region faces great challenges, including water scarcity, rising energy costs, and unsustainable agricultural practices that lead to soil degradation and lower productivity. In the Mediterranean, the olive oil industry is one of the most important agricultural productions, but also one of the most polluting. By-products such as olive mill wastewater (OMWW) and olive pomace (OP) have chemical compositions that makes their management and disposal difficult. To solve current environmental problems related to agricultural practices and offer technical innovations, the multidisciplinary project CYCLOLIVE (www.cyclolive.eu), involving nine partner institutions from Morocco, Spain, Tunisia, Jordan, Turkey, Italy, France, and Germany, has been funded under the PRIMA international partnership. The aim of the project is to integrate the reCYCLing of by-products of OLIVE oil extraction for sustainable agricultural practices in the Mediterranean region, i.e. from waste to resource. Here, we describe how we construct mesocosm facilities and conduct experiments to test the effects of discharging treated and untreated OMWW on aquatic ecosystems, as well as the implementation and testing of cost-effective irrigation control systems. These activities will provide information to integrate OMWW treatment and OP recycling, as well as renewable energy strategies into practical and innovative solutions that are easy to use, environmentally friendly, cost-effective, and sustainable, thus contributing to the European Green Deal, which aims to achieve climate neutrality by 2050.
03:45 PM
EVALUATING THE INFLUENCE OF ONSITE WASTEWATER TREATMENT SYSTEMS ON STREAM NITROGEN CONCENTRATIONS IN A PIEDMONT WATER SUPPLY WATERSHED, FALLS LAKE, NC (9204)
Primary Presenter: Mike O'Driscoll, East Carolina University (odriscollm@ecu.edu)
In the southeastern Piedmont region, the majority of lakes are manmade reservoirs, and the growing population is heavily reliant on these for water supplies. Falls Lake, North Carolina, a multi-use reservoir in the Research Triangle region, is experiencing nutrient-related impairment. Recent efforts have improved estimates of various nutrient inputs, however, assessments of nutrient inputs from onsite wastewater treatment systems (OWTS or septic systems) are limited. This research focused on the influence of OWTS wastewater inputs on baseflow stream nitrogen concentrations in the Falls Lake watershed. Sites were selected in (26) sub-watersheds across a gradient of septic system density (0-2.3 systems/ha). Baseflow stream water N concentration and streamflow data were collected monthly (2020-2021) along with additional N-15 in nitrate samples. Median annual nitrate-N (0.78 mg/l) and total dissolved nitrogen (TDN: 1.67 mg/l) concentrations were elevated for the sub-watersheds with high densities (>1 system/ha) of septic systems relative to a sewered control watershed (nitrate-N: 0.25 mg/l, TDN: 1.35 mg/l). Stream nitrate concentrations and N-15 in nitrate had positive correlations with septic system density, indicating an influence of onsite wastewater contributions to stream nitrogen concentrations. The highest stream TDN concentrations were observed in sub-watersheds in the Triassic Basin region of the watershed, where poorly drained soils are common, suggesting that soils and hydrogeologic setting can influence onsite wastewater nitrogen contributions to streams.
SS34B - Reducing Nutrient Inputs to Coastal and Inland Waters: How Hard Can It Be?
Description
Time: 2:30 PM
Date: 31/3/2025
Room: W205CD