Physical Sciences and Mathematics Commons^™

Modeling Overdraft-Driven Nitrate Transport In Shallow Wells For Mitigation And Scenario Planning, Jonathan Cronk

Department of Biological Systems Engineering: Dissertations and Theses

In Nebraska, average nitrate concentrations in groundwater have doubled since 1974, making water quality management more important than ever. As droughts, heat waves, and floods become more common climate events, understanding their impacts will be necessary to make informed management decisions. Emerging literature describes that drought correlates to an increase in the concentration of nitrate-N at domestic and irrigation wells, however the relative contributions of the mechanisms thought to be responsible is currently unknown.

This research assessed the impact of recharge and pumping rate changes as two mechanisms affecting nitrate-N concentration during drought, assessed the relationship between well depth and …

Importance Of Snowmelt On Soil Nitrate Leaching To Groundwater – A Model Study, Sahila Beegum, Arindam Malakar, Chittaranjan Ray, Daniel D. Snow

Nebraska Water Center: Faculty Publications

The movement of nitrate to surface water bodies during snow accumulation and melting has been extensively studied, but there are only limited studies on the influence of snow processes on nitrate leaching to groundwater. The present study investigated the impact of snow processes on nitrate leaching to groundwater based on a simulation modeling approach using HYDRUS-1D. HYDRUS-1D model has a temperature threshold-based snow model in addition to water, solute, and heat simulation components. The snow component in HYDRUS-1D was previously not applied to snow simulation studies since the method does not consider a detailed physical and process-based representation of snow …

Labile Carbon And Soil Texture Control Nitrogen Transformation In Deep Vadose Zone, Lidong Li, Jordan Shields, Daniel D. Snow, Michael Kaiser, Arindam Malakar

Daugherty Water for Food Global Institute: Faculty Publications

Understanding transient nitrogen (N) storage and transformation in the deep vadose zone is critical for controlling groundwater contamination by nitrate. The occurrence of organic and inorganic forms of carbon (C) and nitrogen and their importance in the deep vadose zone is not well characterized due to difficulty in sampling and the limited number of studies. We sampled and characterized these pools beneath 27 croplands with different vadose zone thicknesses (6–45 m).We measured nitrate and ammonium in different depths for the 27 sites to evaluate inorganic N storage. We measured total Kjeldahl nitrogen (TKN), hot-water extractable organic carbon (EOC), soil organic …

Source Apportionment And Health Risk Assessment Of Nitrate In Foothill Aquifers Of Western Ghats, South India, Banajarani Panda, S. Chidambaram, Daniel D. Snow, Arindam Malakar, Dhiraj Kr Singh, L. Ramanathan

Nebraska Water Center: Faculty Publications

The present research reports the level of nitrate (NO₃^-), associated health risks and possible sources of contamination in groundwater from south India. Many samples (32%) are above or approaching the recommended level of NO₃^- for safe drinking water. The correlation analysis indicates different sources of NO₃^- contamination in different regions rather than a common origin. The isotopic measurements provide information about potential nitrogen sources contributing NO₃^- to the groundwater. Based on isotope analysis, the sources of NO₃^- in the groundwater of this region are likely to be from (a) …

Occurrence And Potential Transformation Pathways Of Nitrogen Species In The Intermediate Vadose Zone, Jordan Shields

School of Natural Resources: Dissertations, Theses, and Student Research

Nebraska is a large agricultural producing state with a heavy reliance on groundwater resources and nitrogen fertilizer application to maintain output. Poor management, such as excessive fertilizer application, improper timing, and over irrigation can lead to contamination of groundwater. Nitrate is the leading groundwater contaminant in Nebraska and chronic consumption at medium to high concentrations leads to adverse health effects. Nitrate, a highly soluble anion, is present in the root zone in numerous forms and undergoes biogeochemical transformations before being leached through the profile. In order to predict the timing and quantity of nitrate contamination in groundwater, researchers study the …

Nitrate Dynamics And Source Within Nested Watersheds Of An Agricultural Stream, Nebraska, Usa, Galen Richards

School of Natural Resources: Dissertations, Theses, and Student Research

Nitrate concentrations have been increasing throughout the globe, primarily due to heightened agricultural activity. Nitrate concentrations in Bazile Creek, located in Northeastern Nebraska, have been steadily rising since the early 2000s. Groundwater nitrate concentrations within the Bazile Creek watershed are high (> 10 mg/L nitrate-N), and there is strong connectivity between groundwater and surface water systems. This study aimed to better understand temporal nitrate concentration variability within the watershed through sampling tributaries and the main channel during baseflow conditions. Nitrate source was also investigated though the use of dual δ¹⁵N and δ¹⁸O nitrate isotopes, with samples …

Environmental Fate And Microbial Effects Of Monensin, Lincomycin, And Sulfamethazine Residues In Soil, Matteo D'Alessio, Lisa M. Durso, Daniel N. Miller, Brian Woodbury, Chittaranjan Ray, Daniel D. Snow

Nebraska Water Center: Faculty Publications

The impact of commonly-used livestock antibiotics on soil nitrogen transformations under varying redox conditions is largely unknown. Soil column incubations were conducted using three livestock antibiotics (monensin, lincomycin and sulfamethazine) to better understand the fate of the antibiotics, their effect on nitrogen transformation, and their impact on soil microbial communities under aerobic, anoxic, and denitrifying conditions. While monensin was not recovered in the effluent, lincomycin and sulfamethazine concentrations decreased slightly during transport through the columns. Sorption, and to a limited extent degradation, are likely to be the primary processes leading to antibiotic attenuation during leaching. Antibiotics also affected microbial respiration …

The Impact Of Land Use On Nitrate-N Movement And Storage In The Vadose Zone Of The Hastings’ Whpa, Craig Adams

School of Natural Resources: Dissertations, Theses, and Student Research

Nebraska has one of the largest agricultural economies in the United States and relies heavily on irrigation and fertilizer application to maintain crop yields. Over-irrigation and continuous application of nitrogen (N) in many areas has led to accumulation of nitrate-N in soils and sediments throughout the state’s vadose zone. Because nitrate-N is both persistent and mobile, groundwater concentrations in many areas of Nebraska and other agriculturally intensive states are increasing. Nitrate-N contamination of public and private drinking water supplies that utilize groundwater are of particular concern. Vadose zone sampling is an important method for rapidly assessing the effect of changing …

Modeling Vulnerability Of Groundwater To Pollution Under Future Scenarios Of Climate Change And Biofuels-Related Land Use Change: A Case Study In North Dakota, Usa, Ruopu Li, James W. Merchant

School of Natural Resources: Faculty Publications

Modeling groundwater vulnerability to pollution is critical for implementing programs to protect groundwater quality.Most groundwater vulnerability modeling has been based on current hydrogeology and land use condi- tions. However, groundwater vulnerability is strongly dependent on factors such as depth-to-water, recharge and land use conditions thatmay change in response to future changes in climate and/or socio-economic condi- tions. In this research, a modeling framework, which employs three sets of models linked within a geographic information system (GIS) environment, was used to evaluate groundwater pollution risks under future climate and land use changes in North Dakota. The results showed that areas with …

Occurrence Of Sulfonamide Antimicrobials In Private Water Wells In Washington County, Idaho, Usa, Angela L. Batt, Daniel D. Snow, Diana S. Aga

Nebraska Water Center: Faculty Publications

County (Weiser, Idaho) were collected to assess the impact of a nearby confined animal feeding operation (CAFO) on the quality of the local groundwater. All six samples were found contaminated by two veterinary antimicrobials, sulfamethazine (at concentrations from 0.076 to 0.22 μg/l) and sulfadimethoxine (at concentrations from 0.046 to 0.068 μg/l). These groundwater samples also contained elevated concentrations of nitrate and ammonium. Three of the sampled wells have nitrate levels that exceeded the maximum contaminant level set by the US Environmental Protection Agency for drinking water, with nitrate concentration as high as 39.1 mg/l. All but one well showed nitrate, …