Engineering Commons^™

A Literature Review Of Wetland Treatment Systems Used To Treat Runoff Mixtures Containing Antibiotics And Pesticides From Urban And Agricultural Landscapes, Emily R. Nottingham, Tiffany L. Messer

Biosystems and Agricultural Engineering Faculty Publications

Wetland treatment systems are used extensively across the world to mitigate surface runoff. While wetland treatment for nitrogen mitigation has been comprehensively reviewed, the implications of common-use pesticides and antibiotics on nitrogen reduction remain relatively unreviewed. Therefore, this review seeks to comprehensively assess the removal of commonly used pesticides and antibiotics and their implications for nitrogen removal in wetland treatment systems receiving non-point source runoff from urban and agricultural landscapes. A total of 181 primary studies were identified spanning 37 countries. Most of the reviewed publications studied pesticides (n = 153) entering wetlands systems, while antibiotics (n = 29) had …

Intelligent Sensors For Sustainable Food And Drink Manufacturing, Nicholas J. Watson, Alexander L. Bowler, Ahmed Rady, Oliver J. Fisher, Alessandro Simeone, Josep Escrig, Elliot Woolley, Akinbode A. Adedeji

Biosystems and Agricultural Engineering Faculty Publications

Food and drink is the largest manufacturing sector worldwide and has significant environmental impact in terms of resource use, emissions, and waste. However, food and drink manufacturers are restricted in addressing these issues due to the tight profit margins they operate within. The advances of two industrial digital technologies, sensors and machine learning, present manufacturers with affordable methods to collect and analyse manufacturing data and enable enhanced, evidence-based decision making. These technologies will enable manufacturers to reduce their environmental impact by making processes more flexible and efficient in terms of how they manage their resources. In this article, a methodology …

Characterization Of Indoor Arenas Through An Anonymous Survey, Staci Mcgill, Morgan D. Hayes, Kimberly I. Tumlin, Robert Coleman

Biosystems and Agricultural Engineering Faculty Publications

Equine farms are building both stables for the horses to live in and additional facilities to train and work horses (Kidd et al., 1997). For many of these farms, an outdoor arena that has an all-weather footing is the first working facility built. During inclement weather the ability to train in the outdoor arenas is inhibited, which in turn means the trainers, riders, and farms lose income as money is only made when horses are working, training, and competing. Indoor arenas allow for horses to continue to be worked no matter the weather conditions. The equine industry contributes a total …

An Experimental Comparison Of Simple Measurements Used For The Characterization Of Sand Equestrian Surfaces, María Alejandra Blanco, Raúl Hourquebie, Kaleb Dempsey, Peter Schmitt, Michael L. Peterson

Biosystems and Agricultural Engineering Faculty Publications

Quantitative measurements of performance parameters have the potential to increase consistency and enhance performance of the surfaces as well as to contribute to the safety of horses and riders. This study investigates how factors known to influence the performance of the surface, incorporation of a drainage package, control of the moisture control, and introduction of a geotextile reinforcement, affect quantitative measurements of arena materials. The measurements are made by using affordable lightweight testing tools which are readily available or easily constructed. Sixteen boxes with arena materials at a consistent depth were tested with the Going Stick (GS), both penetration resistance …

Development Of Predictive Equations For Thermal Conductivity Of Compost Bedding, Flávio A. Damasceno, Joseph L. Taraba, George B. Day V, Randi A. Black, Jeffrey M. Bewley, Tales J. Fernandes, Carlos E. A. Oliveira, Rafaella R. Andrade, Matteo Barbari, Patrícia F. P. Ferraz, Lorenzo Leso

Biosystems and Agricultural Engineering Faculty Publications

Among animal facilities, compost-bedded pack (CBP) barns have attracted a lot of attention from milk producers and the scientific community. Systematic investigation of the main thermal properties utilizing sawdust in CBP barns is of environmental and economic relevance. In this paper, the aim was to (a) develop predictive equations for the thermal conductivity (k) of compost bedding as a function of moisture content (MC), the degree of compaction (DC_o), and particle size (PS); and (b) investigate the links between k and depth within bedding material. Samples of compost bedding materials were collected from 42 commercial CBP …

Influence Of Speed, Ground Surface And Shoeing Condition On Hoof Breakover Duration In Galloping Thoroughbred Racehorses, Kate Horan, James Coburn, Kieran Kourdache, Peter Day, Dan Harborne, Liam Brinkley, Henry Carnall, Lucy Hammond, Michael L. Peterson, Sean Millard, Thilo Pfau

Biosystems and Agricultural Engineering Faculty Publications

Understanding the effect of horseshoe–surface combinations on hoof kinematics at gallop is relevant for optimising performance and minimising injury in racehorse–jockey dyads. This intervention study assessed hoof breakover duration in Thoroughbred ex-racehorses from the British Racing School galloping on turf and artificial tracks in four shoeing conditions: aluminium, barefoot, aluminium–rubber composite (GluShu) and steel. Shoe–surface combinations were tested in a randomized order and horse–jockey pairings (n = 14) remained constant. High-speed video cameras (Sony DSC-RX100M5) filmed the hoof-ground interactions at 1000 frames per second. The time taken for a hoof marker wand fixed to the lateral hoof wall to …

Quantifying Hydrologic Pathway And Source Connectivity Dynamics In Tile Drainage: Implications For Phosphorus Concentrations, Saeid Nazari, William I. Ford, Kevin W. King

Biosystems and Agricultural Engineering Faculty Publications

Flowpathways and source water connectivity dynamics are widely recognized to affect tile-drainage water quality. In this study, we developed and evaluated a framework that couples event-based hydrograph recession and specific conductance end-member mixing analysis (SC-EMMA) to provide a more robust framework for quantifying both flow pathway dynamics and source connectivity of drainage water in tile-drained landscapes. High-frequency (30-min) flow and conductivity data were collected from an edge-of-field tile main located in northwestern Ohio, and the newly developed framework was applied for data collected in water year 2019. Multiple linear regression (MLR) analysis was used to evaluate the impact of pathway-connectivity …

What About The Rest Of Them? Fatal Injuries Related To Production Agriculture Not Captured By The Bureau Of Labor Statistics (Bls) Census Of Fatal Occupational Injuries (Cfoi), Bryan Weichelt, Erika Scott, Rick Burke, John Shutske, Serap Gorucu, Wayne T. Sanderson, Murray Madsen, Emily Redmond, Dennis J. Murphy, Risto Rautiainen

Biosystems and Agricultural Engineering Faculty Publications

Surveillance of injuries in production agriculture is necessary to inform stakeholders about workplace hazards and risks in order to improve and advance injury prevention policies and practices for this dangerous industry. The most comprehensive fatal injury surveillance effort currently in the United States is the Bureau of Labor Statistics (BLS) Census of Fatal Occupational Injuries (CFOI), which covers occupational fatalities in all U.S. industries, including production agriculture. However, this surveillance does not include many categories of fatalities that occur during agricultural work or on production agriculture worksites. To better capture the human cost of production agriculture, the authors of this …

Creating A Field-Wide Forage Canopy Model Using Uavs And Photogrammetry Processing, Cameron Minch, Joseph S. Dvorak, Joshua J. Jackson, Stuart Tucker Sheffield

Biosystems and Agricultural Engineering Faculty Publications

Alfalfa canopy structure reveals useful information for managing this forage crop, but manual measurements are impractical at field-scale. Photogrammetry processing with images from Unmanned Aerial Vehicles (UAVs) can create a field-wide three-dimensional model of the crop canopy. The goal of this study was to determine the appropriate flight parameters for the UAV that would enable reliable generation of canopy models at all stages of alfalfa growth. Flights were conducted over two separate fields on four different dates using three different flight parameters. This provided a total of 24 flights. The flight parameters considered were the following: 30 m altitude with …

Biodegradable Cellulose Film Prepared From Banana Pseudo-Stem Using An Ionic Liquid For Mango Preservation, Binling Ai, Lili Zheng, Wenqi Li, Xiaoyan Zheng, Yang Yang, Dao Xiao, Jian Shi, Zhanwu Sheng

Biosystems and Agricultural Engineering Faculty Publications

The excessive use and disposal of plastic packaging materials have drawn increasing concerns from the society because of the detrimental effect on environment and ecosystems. As the most widely used fruit packing material, polyethylene (PE) film is not suitable for long-term preservation of some tropical fruits, such as mangos, due to its inferior gas permeability. Cellulose based film can be made from renewable resources and is biodegradable and environmental-friendly, which makes it a promising alternative to PE as a packaging material. In this study, cellulose film synthesized from delignified banana stem fibers via an ionic liquid 1-Allyl-3-methylimidazolium chloride ([AMIm][Cl]) were …

Effects Of Racing Surface And Turn Radius On Fatal Limb Fractures In Thoroughbred Racehorses, Michael L. Peterson, Wayne T. Sanderson, Nurlan Kussainov, Sarah Jane Hobbs, Patti Miles, Mary C. Scollay, Hilary M. Clayton

Biosystems and Agricultural Engineering Faculty Publications

North American Thoroughbred racing is conducted on three types of surfaces—dirt, turf, and synthetic. The tracks are oval, and races are run counterclockwise. The loading on right and left limbs is expected to differ as a function of turn radius, banking, surface, and gait asymmetry. Hind limbs and forelimbs also have different functions related to propulsion and turning, respectively. This study uses the Equine Injury Database for race starts from 1 January 2009 through 31 December 2014, to compare injury rates across participating North American racetracks. The data are limited to catastrophic injuries in which horses died or were euthanized …

Modeling And Prioritizing Interventions Using Pollution Hotspots For Reducing Nutrients, Atrazine And E. Coli Concentrations In A Watershed, Olufemi Abimbola, Aaron Mittelstet, Tiffany L. Messer, Elaine Berry, Ann Van Griensven

Biosystems and Agricultural Engineering Faculty Publications

Excess nutrients and herbicides remain two major causes of waterbody impairment globally. In an attempt to better understand pollutant sources in the Big Sandy Creek Watershed (BSCW) and the prospects for successful remediation, a program was initiated to assist agricultural producers with the implementation of best management practices (BMPs). The objectives were to (1) simulate BMPs within hotspots to determine reductions in pollutant loads and (2) to determine if water-quality standards are met at the watershed outlet. Regression-based load estimator (LOADEST) was used for determining sediment, nutrient and atrazine loads, while artificial neural networks (ANN) were used for determining E. …

Mathematical Modelling And Numerical Simulation Of Mass Transfer During Deep-Fat Frying Of Plantain (Musa Paradisiacal Aab) Chips (Ipekere), James Abiodun Adeyanju, John Oluranti Olajide, Emmanuel Olusola Oke, Akinbode A. Adedeji

Biosystems and Agricultural Engineering Faculty Publications

This study developed a mathematical model following the fundamental principles of mass transfer for the simulation of the oil and moisture content change during the Deep-Fat Frying of plantain (ipekere) chip. The explicit Finite Difference Technique (FDT) was used to conduct a numerical solution to the consequential governing equation (partial differential equation) that was used to describe the mass transfer rate during the process. Computer codes that were computed in MATLAB were used for the implementation of FDT at diverse frying conditions. Samples of the plantain were cut into portions of 2 mm thickness, and these sliced portions …

Literature Review: Global Neonicotinoid Insecticide Occurrence In Aquatic Environments, Josephus F. Borsuah, Tiffany L. Messer, Daniel D. Snow, Steve D. Comfort, Aaron R. Mittelstet

Biosystems and Agricultural Engineering Faculty Publications

Neonicotinoids have been the most commonly used insecticides since the early 1990s. Despite their efficacy in improving crop protection and management, these agrochemicals have gained recent attention for their negative impacts on non-target species such as honeybees and aquatic invertebrates. In recent years, neonicotinoids have been detected in rivers and streams across the world. Determining and predicting the exposure potential of neonicotinoids in surface water requires a thorough understanding of their fate and transport mechanisms. Therefore, our objective was to provide a comprehensive review of neonicotinoids with a focus on their fate and transport mechanisms to and within surface waters …

3d Cfd Analysis Of Natural Ventilation In Reduced Scale Model Of Compost Bedded Pack Barn For Dairy Cows, Flávio A. Damasceno, Joseph L. Taraba, George B. Day V, Felipe A. O. Vega, Keller S. O. Rocha, Randi A. Black, Jeffrey M. Bewley, Carlos E. A. Oliveira, Matteo Barbari

Biosystems and Agricultural Engineering Faculty Publications

Compost bedded pack (CBP) barns have been receiving increased attention as an alternative housing system for dairy cattle. To create a satisfactory environment within CBP barns that promotes a good composting process, an adequate air movement and minimal temperature fluctuations throughout the building are required. Therefore, a study based on compost barn structure model employing techniques of dimensional analysis for naturally ventilated buildings was developed. Three-dimensional computational fluid dynamic (CFD) simulations of compost barns with different ridge designs and wind direction, along with the visual demonstration of the impact on airflow through structure were performed. The results showed that the …

Recent Advances In Reducing Food Losses In The Supply Chain Of Fresh Agricultural Produce, Daniel I. Onwude, Guangnan Chen, Nnanna Eke-Emezie, Abraham Kabutey, Al Fadhl Yahya Al Khaled, Barbara Sturm

Biosystems and Agricultural Engineering Faculty Publications

Fruits and vegetables are highly nutritious agricultural produce with tremendous human health benefits. They are also highly perishable and as such are easily susceptible to spoilage, leading to a reduction in quality attributes and induced food loss. Cold chain technologies have over the years been employed to reduce the quality loss of fruits and vegetables from farm to fork. However, a high amount of losses (≈50%) still occur during the packaging, transportation, and storage of these fresh agricultural produce. This study highlights the current state-of-the-art of various advanced tools employed to reducing the quality loss of fruits and vegetables during …

Classifying Reflectance Targets Under Ambient Light Conditions Using Passive Spectral Measurements, Ali Hamidisepehr, Michael P. Sama, Joseph S. Dvorak, Ole O. Wendroth, Michael D. Montross

Biosystems and Agricultural Engineering Faculty Publications

Collecting remotely sensed spectral data under varying ambient light conditions is challenging. The objective of this study was to test the ability to classify grayscale targets observed by portable spectrometers under varying ambient light conditions. Two sets of spectrometers covering ultraviolet (UV), visible (VIS), and near−infrared (NIR) wavelengths were instrumented using an embedded computer. One set was uncalibrated and used to measure the raw intensity of light reflected from a target. The other set was calibrated and used to measure downwelling irradiance. Three ambient−light compensation methods that successively built upon each other were investigated. The default method used a variable …

Reach-Scale Model Of Aquatic Vegetation Quantifies N Fate In A Bedrock-Controlled Karst Agroecosystem Stream, Nolan Lewis Bunnell, William I. Ford, Alex W. Fogle, Joseph L. Taraba

Biosystems and Agricultural Engineering Faculty Publications

In-stream fate of nutrients in karst agroecosystems remains poorly understood. The significance of these streams is recognized given spring/surface water confluences have been identified as hotspots for biogeochemical transformations. In slow-moving streams high in dissolved inorganic nutrients, benthic and floating aquatic macrophytes are recognized to proliferate and drastically impact nutrient fate; however, models that quantify coupled interactions between these pools are limited. We present a reach-scale modeling framework of nitrogen dynamics in bedrock-controlled streams that accounts for coupled interactions between hydrology, hydraulics, and biotic dynamics and is validated using a multi-year, biweekly dataset. A fluvial N budget with uncertainty was …

Characterization And Enzyme Engineering Of A Hyperthermophilic Laccase Toward Improving Its Activity In Ionic Liquid, Joseph Craig Stevens, David W. Rodgers, Claire Dumon, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Ionic liquids (ILs) are organic salts molten at room temperature that can be used for a wide variety of applications. Many ILs, such as 1-ethyl-3-methylimidazolium acetate ([C₂C₁Im][OAc]), have been shown to remove a significant fraction of the complex biopolymer lignin from biomass during pretreatment. Valorizing lignin via biological pathways (e.g., enzymes) holds promise but is limited by the low biocompatibility of many ILs used for pretreatment. The discovery of thermostable enzymes and the application of enzyme engineering techniques have yielded biocatalysts capable of withstanding high concentrations of ILs. Converting lignin from a waste product to value-added …

Effect Of Substrate Characteristics On The Growth And Sporulation Of Two Biocontrol Microorganisms During Solid State Cultivation, Ga Young Lee, Wenqi Li, Ulalo M. Chirwa, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Biocontrol agents are a group of naturally occurring organisms capable of interrupting the lifespan and suppressing the propagation of disease organisms. The use of biocontrol agents offers an environment-friendly and sustainable solution to the synthetic agrochemicals. In this study, we investigated parboiled rice and millets as substrates for spore production of two model biocontrol microorganisms (Bacillus pumilus and Streptomyces griseus) under solid state cultivation (SSC) conditions. The effects of cultivation parameters such as initial moisture content, water activity, and cultivation time on microbial growth and spore production were studied. Furthermore, texture profile analysis was performed to test the …

Non-Destructive Technologies For Detecting Insect Infestation In Fruits And Vegetables Under Postharvest Conditions: A Critical Review, Akinbode A. Adedeji, Nader Ekramirad, Ahmed Rady, Ali Hamidisepehr, Kevin D. Donohue, Raul T. Villanueva, Chadwick A. Parrish, Mengxing Li

Biosystems and Agricultural Engineering Faculty Publications

In the last two decades, food scientists have attempted to develop new technologies that can improve the detection of insect infestation in fruits and vegetables under postharvest conditions using a multitude of non-destructive technologies. While consumers' expectations for higher nutritive and sensorial value of fresh produce has increased over time, they have also become more critical on using insecticides or synthetic chemicals to preserve food quality from insects' attacks or enhance the quality attributes of minimally processed fresh produce. In addition, the increasingly stringent quarantine measures by regulatory agencies for commercial import-export of fresh produce needs more reliable technologies for …

Development And Preliminary Evaluation Of An Integrated Individual Nozzle Direct Injection And Carrier Flow Rate Control System For Pesticide Applications, Joe D. Luck, Scott A. Shearer, Michael P. Sama

Biosystems and Agricultural Engineering Faculty Publications

Direct injection systems for agricultural spray applications continue to present challenges in terms of commercialization and adoption by end users. Such systems have typically suffered from lag time and mixing uniformity issues, which have outweighed the potential benefits of keeping chemical and carrier separate or reducing improper tank-mixed concentration by eliminating operator measurements. The proposed system sought to combine high-pressure direct nozzle injection with an automated variable-flow nozzle to improve chemical mixing and response times. The specific objectives were to: (1) integrate a high-pressure direct nozzle injection system with variable-flow carrier control into a prototype for testing, (2) assess the …

Performance Validation Of A Multi-Channel Lidar Sensor: Assessing The Effects Of Target Height And Sensor Velocity On Measurement Error, Surya S. Dasika, Michael P. Sama, L. Felipe Pampolini, Christopher B. Good

Biosystems and Agricultural Engineering Faculty Publications

The objective of this study was to determine the effects of sensor velocity and target height above ground level on height measurement error when using a multi-channel LiDAR sensor. A linear motion system was developed to precisely control the dynamics of the LiDAR sensor in an effort to remove uncertainty in the LiDAR position and velocity while under motion. The linear motion system allowed the LiDAR to translate forward and backward in one direction parallel to the ground. A user control interface was developed to operate the system under different velocity profiles and to log LiDAR data synchronous to the …

Thermal Comfort In Heated-And-Ventilated-Only Warehouses, Christian Taber, Donald G. Colliver

Biosystems and Agricultural Engineering Faculty Publications

Building energy codes and standards contain minimum requirements that provide a path to energy efficient buildings and building systems. ASHRAE/IES Standard 90.1 and the International Energy Conservation Code (IECC) are the main national building code models in the United States. Both Standard 90.1 and the IECC are updated on three-year cycles with the goal of reducing building energy consumption.

Linking Lignin Source With Structural And Electrochemical Properties Of Lignin-Derived Carbon Materials, Wenqi Li, Yan Zhang, Lalitendu Das, Yikai Wang, Mi Li, Namal Wanninayake, Yunqiao Pu, Doo Young Kim, Yang-Tse Cheng, Arthur J. Ragauskas, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Valorization of lignin to high-value chemicals and products along with biofuel production is generally acknowledged as a technology platform that could significantly improve the economic viability of biorefinery operations. With a growing demand for electrical energy storage materials, lignin-derived activated carbon (AC) materials have received increasing attention in recent years. However, there is an apparent gap in our understanding of the impact of the lignin precursors (i.e., lignin structure, composition and inter-unit linkages) on the structural and electrochemical properties of the derived ACs. In the present study, lignin-derived ACs were prepared under identical conditions from two different lignin …

Fractionation And Characterization Of Lignin Streams From Unique High-Lignin Content Endocarp Feedstocks, Wenqi Li, Kirtley Amos, Mi Li, Yunqiao Pu, Seth Debolt, Arthur J. Ragauskas, Jian Shi

Biosystems and Agricultural Engineering Faculty Publications

Background: Lignin is a promising source of building blocks for upgrading to valuable aromatic chemicals and materials. Endocarp biomass represents a non-edible crop residue in an existing agricultural setting which cannot be used as animal feed nor soil amendment. With significantly higher lignin content and bulk energy density, endo-carps have significant advantages to be converted into both biofuel and bioproducts as compared to other biomass resources. Deep eutectic solvent (DES) is highly effective in fractionating lignin from a variety of biomass feedstocks with high yield and purity while at lower cost comparing to certain ionic liquids.

Results: In the present …

A Low-Cost Method For Collecting Hyperspectral Measurements From A Small Unmanned Aircraft System, Ali Hamidisepehr, Michael P. Sama

Biosystems and Agricultural Engineering Faculty Publications

Small unmanned aircraft systems (UAS) are a relatively new tool for collecting remote sensing data at dense spatial and temporal resolutions. This study aimed to develop a spectral measurement platform for deployment on a UAS for quantifying and delineating moisture zones within an agricultural landscape. A series of portable spectrometers covering ultraviolet (UV), visible (VIS), and near-infrared (NIR) wavelengths were instrumented using a Raspberry Pi embedded computer that was programmed to interface with the UAS autopilot for autonomous data acquisition. A second set of identical spectrometers were fitted with calibrated irradiance lenses to capture ambient light during data acquisition. Data …

Physio-Chemical And Functional Properties Of Nine Proso Millet Cultivars, Manjot Singh, Akinbode A. Adedeji, Dipak Santra

Biosystems and Agricultural Engineering Faculty Publications

Evaluation of the postharvest properties of nine proso millet cultivars was carried out to determine their physical and engineering properties, which are very useful for designing appropriate systems for process operations such as sorting, drying, heating, cooling, and milling. Nine cultivars of proso millet comprising waxy and non-waxy types, namely Cope, Earlybird, Huntsman, Minco, Plateau, Sunrise, Rise, Dawn, and Panhandle, were obtained from the Panhandle Research and Extension Center, University of Nebraska, Scottsbluff. Results showed significant (p < 0.05) differences in their physical properties, such as sphericity, volume, bulk density, porosity, and angle of repose, which ranged from 0.86 to 0.91, from 3.94 to 5.14 mm³, from 765.49 to 809.67 kg m^-3, from 42.49% to 44.20%, and from 22.98° to 25.74°, respectively. The cultivars were …

Stored Grain Pack Factor Measurements For Soybeans, Grain Sorghum, Oats, Barley, And Wheat, Rumela Bhadra, Mark E. Casada, Aaron P. Turner, Michael D. Montross, Sidney A. Thompson, Samuel G. Mcneill, Ronaldo G. Maghirang, Josephine M. Boac

Biosystems and Agricultural Engineering Faculty Publications

Grain and oilseed crops stored in bins undergo compaction due to overbearing pressure of the grain inside the structure. Thus, volume measurements of grain in bins need to be combined with the amount of packing (usually called pack factor) in addition to the initial density so that the mass in the structure can be calculated. Multiple pack factor prediction methods are in use in the grain industry, but they have only been validated in the literature and compared with field data for corn and hard red winter wheat. Predictions from WPACKING, the program in ASABE Standard EP413.2, and two standard …

Assessing Intra-Event Phosphorus Dynamics In Drainage Water Using Phosphate Stable Oxygen Isotopes, William Ford Iii, Mark R. Williams, Megan B. Young, Kevin W. King, Eric Fischer

Biosystems and Agricultural Engineering Faculty Publications

Quantifying fluxes and pathways of dissolved reactive phosphorus (DRP) in tile-drained landscapes has been hampered by a lack of measurements that are sensitive to P fate and transport processes. One potential tool to help understand these dynamics is the oxygen isotope signature of phosphate (δ¹⁸O_PO4); however, its potential benefits and limitations are not well understood for intra-event dynamics at the field scale. The objectives of this study were to quantify intra-event variability of δ¹⁸O_PO4 signatures in tile drainage water and assess the efficacy of δ¹⁸O_PO4 to elucidate mechanisms and flow …