CZNET-REU PROJECTS AND MENTORS

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2024

Short project description: Water drives watershed-scale processes that ecosystems are dependent on. Despite this importance, hydrologists are still working to understand how water is stored and transmitted in the shallow subsurface—in a region known as the Critical Zone—and how water moves from groundwater to surface water to trees. For example, what causes variations in water stores and tree resilience across a landscape? The objective of this project is to identify how geophysics can be used to answer these types of questions. The CZREU students will collect and analyze data in the field with Professor Singha, a postdoc, and a graduate student in Colorado. This project will include field work as well as time in the computer lab at Colorado School of Mines.

Skills/experiences desired: The CZREU students should have an interest in hydrology, geochemistry, and/or geophysics, and enjoy working outdoors. Due to the field components of this research, the students should be physically able to conduct in field work. This includes working at a high elevation site that sits at 9,500 feet above sea level, hiking multiple miles in a day through uneven terrain, carrying a field pack with equipment/supplies, and working in varying weather conditions such as rain or cold temperatures. Prior coding experience in Matlab, R, or Python would be helpful, but coding tutoring will be provided if the students do not have previous experience with coding languages.

Short project description: Our goal is to develop dust "fingerprints" that can be used to trace dust from source to sink. We hypothesize that different landuse types will yield dust with distinct geochemical or microbiological signatures that may be used for tracing studies. Over the past two years we have collected over 200 dust samples from sites across the state of Utah representing potential dust emissions from agriculture, oil & gas development, playas, degraded rangeland, and alluvial fans. We have calculated seasonal dust fluxes using dust masses from each site, but we have not started on the laboratory work for the samples. Two CZREU students will work with a PhD student and faculty mentor to perform the laboratory analyses for these samples, interpret the results, and begin to prepare a manuscript on the dataset. The lab work will include DNA/RNA extractions and sequencing, acid leaching for geochemical analysis, and mineralogy. The large datasets generated from the lab analyses will be analyzed by advanced statistical methods. The students will also visit the field sites to collect additional data and to gain an appreciation of the field areas.

Skills/experiences desired: Background in geochemistry and/or microbiology. Lab experience is a plus.

  • CZ Cluster(s): CINet

  • Location: University of Illinois at Urbana-Champaign with fieldwork in the Sangamon River basin

  • Mentor(s): Dr. Bruce Rhoads

Short project description: Intensive management of agricultural landscapes in the upper midwestern United States has resulted in increased rates of water runoff and soil erosion. Although these effects are well-documented, the influence of increased amounts of runoff and soil erosion on the sediment dynamics of river systems are rather poorly understood, especially temporal variation in these dynamics. Recent work has focused on relating sediment concentrations to discharge within the upper Sangamon River basin of Illinois, an intensively managed agricultural watershed. This work has shown that sediment concentrations exhibit substantial variation between rising and falling limbs of flow events, even for the same discharge. This effect produces large amounts of scatter in relationships between sediment concentration and discharge. The CZREU student will work with sediment concentration data as well as detailed flow data collected by the U.S. Geological Survey to explore whether information on flow velocity, which for the same discharge can vary during rising and falling limbs of flow events, can help account for scatter in the relationship between discharge and sediment concentration. Through field and laboratory work, the student will learn how river sediment and flow data are collected and analyzed. The student will work within a team environment at the University of Illinois consisting of faculty/scientist mentors as well as graduate students and undergraduates working with these mentors.

Skills/experiences desired: Education that includes coursework in hydrology and/or geomorphology, data analysis skills, desire or experience to participate in fieldwork. Experiences in hydrology or geomorphology.

  • CZ Cluster(s): CINet

  • Location: University of Illinois at Urbana-Champaign with fieldwork within 30 minutes of the University

  • Mentor(s): Dr. Allison Goodwell

Short project description: Plants uptake water from soil moisture at different depths. In an intensively managed landscape, soil moisture dynamics depend on soil characteristics, crop types that have different root structures and water use efficiencies, management practices such as planting and harvesting, and weather and climate conditions. It is a challenge to disentangle how these factors drive variability in soil moisture, and how this variability leads to differences in vegetation health. In the proposed project, the CZREU student will explore critical zone processes, specifically related to soils, in the near-surface environment based on flux tower data and management-induced reactive zone (MIRZ) experiments that are being conducted for the CINet project. The student will analyze data from these sites to address questions about how soil moisture variability is a function of the study site, vegetation characteristics, measurement depth, and environmental conditions. Research questions to be addressed may include “what types of rainfall events lead to soil moisture increases at different depths, and how does this depend on previous conditions?”, and “how does soil moisture through a growing season link to vegetation greenness”? This project will also involve participating in related summer CINet field work efforts near the University of Illinois and becoming familiar with instrumentation at several sites. The student will work within a team environment at the University of Illinois consisting of faculty/scientist mentors as well as graduate students and undergraduates working with these mentors. Specifically, the student will be co-mentored by Allison Goodwell (Prairie Research Institute, UIUC), Ashlee Dere (University of Nebraska), Jennifer Druhan (UIUC), and Brian Saccardi (postdoctoral researcher, Prairie Research Institute), and will participate in field work along with another undergraduate researcher advised by Bruce Rhoads (UIUC).

Skills/experiences desired: Some experience with data analysis and/or programming ideal, not absolute requirement

  • CZ Cluster(s): Coastal

  • Location: University of Maryland, College Park, with fieldwork on the Eastern Shore of Maryland, Delaware and Virginia

  • Mentor(s): Dr. Kate Tully

Short project description: Coastal forests and agricultural fields along the Eastern seaboard are converting to salt marshes as a result of two driving mechanisms: slow processes (e.g., sea-level rise) and fast processes (e.g., storm surges and tides). The flooding and salinization associated with these processes drive landscape changes that are affected by feedback among coupled hydrological, ecological, geomorphological, and biogeochemical processes. The occurrence of these mechanisms and the nature of their feedbacks, which differ between forested and agricultural land, determine the rate and extent of landscape transformation and the associated changes in elemental stores and fluxes in the coastal critical zone (CZ). The CZREU students will join the Coastal Critical Zone Network (CZN), a collaborative, multi-disciplinary research project that investigates the effects of salinization and flooding on marsh migration into forested and agricultural lands on the Delmarva Peninsula. Students will participate in research that helps to address one of our four major topical areas: hydrology, ecology, geomorphology or biogeochemistry. Research questions and projects will be tailored to fit each individual student’s interest and level of research experience.

Skills/experiences desired: A background in biogeochemistry or chemistry will be useful for this internship. Must love getting your hands dirty (and possibly losing a boot in the mud).

Short project description: Nutrient availability in soils is often considered a potentially limiting factor to plant and microbial growth, so the ability to accurately measure the true availability of important nutrients like Nitrogen (N) and Phosphorus (P) is important to our understanding of Plant-Microbe-Soil interactions. To measure nutrient availability, soils are typically shaken in a salt solution, and the nutrients dissolved in the solution are measured - this represents the “available” pool of nutrients that are in the soil water or loosely adsorbed to the soil surface. Some nutrients, such as P can be bound more strongly to soil particles, contained within organic molecules, or bound to other elements that make them more difficult to access. This can result in nutrient ions being re-absorbed to soil or forming complexes that are filtered out after a sample is shaken, thus underestimating the availability of these nutrients in the soil. The CZREU student will be working with PhD candidate Dylan Stover under the mentorship of Dr. Jennie McLaren to determine the amount of re-adsorption of soil phosphate that happens during the extraction process with dryland soils, and whether this differs among different pools of phosphate (e.g., phosphate that needs enzymes to access vs. water soluble P). This project will involve field collection of soils from the site of a nutrient addition experiment in the Jornada Experimental Range, New Mexico. The student will gain experience with different extraction techniques, and learn high-throughput soil nutrient analysis techniques using a microplate reader.

Skills/experiences desired: None essential. Basic lab skills preferred

Short project description: Formation of carbonate in soil (pedogenic carbonate) results in emission of CO2, and therefore can play a role in greenhouse gas levels and climate change. Pedogenic carbonates form in natural drylands worldwide, and have been studied intensively, including morphology, deposition mechanisms and accumulation rates. Pedogenic carbonate develops when dissolved bicarbonate and calcium react to form calcite, carbon dioxide and water:

2HCO3- + Ca2+ → CaCO3(s) + CO2(g) + H2O Rxn (1)

The release of CO2 to the atmosphere by this process has not been extensively measured, partially because this is a small flux due to the slow accumulation rates of pedogenic carbonates. However, when natural ecosystems are converted to agricultural fields in drylands, soils are intensively irrigated which leads to elevated soil salinity. Similarly, irrigation delivers significant amounts of Ca2+ and HCO3- to these soils continuously. This enhances both pedogenic carbonate formation and soil-atmosphere CO2 emission. To date, only a few studies have measured the associated emission flux of CO2 in such agricultural settings. The CZREU student will explore the spatial and temporal variability and the dominant controls of such abiotic CO2 efflux. They will have the opportunity to work with a variety of soil sensors, carry out soil/gas/water sample collection and characterization, and statistical and spatial data analysis, as well engage in education and outreach activities.

Skills/experiences desired: Experience working/living in desert environments

2023

Short project description: Stream water quality and sediment fluxes are strongly influenced by watershed topography, bedrock type, soil thickness, and floodplain morphology. In the Urban Fall Zone watersheds, soils are deeper under hillslopes than near the streams, which greatly influences storage and delivery of water, solutes, nutrients, and sediment to streams. The REU student will visit potential field sites, develop ideas, and work both individually and with our research group to characterize stream/floodplain morphology, subsurface soil-bedrock characteristics, and monitor sediment or solute transport in urbanized Fall Zone watersheds. The student will have the opportunity to develop an independent project that combines field data on soil thickness (from seismic data) and field data on channel morphology with GIS topographic data to evaluate changes in critical zone structure as a function of position relative to the stream profile and urban structures. The student may focus on stream channels, floodplains, wetlands, hillslope sites, or some combination of these. Characterization of floodplain and channel morphology will be conducted using field and remotely sensed methods. Sediment transport projects could use both sensor and field data to monitor transport of coarse and fine sediment fractions. The student will be able to collaborate with scientists and students at UMD who are working with the Coastal CZ project and potentially develop collaborative projects with both research groups.

Short project description: Human activities in urban systems have left a legacy of chemical contamination. This novel “cocktail” of chemicals can disrupt a wide range of CZ processes. These disruptions not only can identify crucial risks to humans in regions with dense populations, they also allow fundamental insight into how all critical zones work. The REU associated with the Urban CZC at the University of Pittsburgh will examine patterns of metals in urban soils and evaluate implications for the CZ. The focus will be on the fundamental question: “How do patterns of human activity create consistent, predictable patterns of chemical anomalies in soils?” which can be examined in both directions. The student may identify patterns in time or space from rich data archives and spend their time examining potential human forcings that dictate the pattern. Or, they may be fascinated by the biogeochemical implications of specific human or urban processes and design a field sampling and lab analysis campaign to characterize how these patterns develop. The investigations could take place both within a Cluster site or across Cluster sites along the Fall Zone from Philadelphia to Raleigh.. Previous undergraduate work has used a field X-Ray Fluorescence spectrometer to map soil metal concentrations at fine scales in green infrastructure installations, reanalyzed a water sample archive collected from urban streams, and evaluated the interactions between groundwater chemistry and storm water fluxes.

Short project description: Water drives watershed-scale processes that ecosystems are dependent on. Despite this importance, hydrologists are still working to understand how water is stored and transmitted in the shallow subsurface—in a region known as the Critical Zone—and how changing precipitation inputs impact water availability and the transport of contaminants. The objective of this work is to identify how: 1) groundwater storage varies throughout watersheds, 2) variation in storage impacts water quality and/or tree productivity, and 3) climate change will alter storage dynamics. The REU student will gain experience using hydrological and geophysical tools, and will gather data such as flow rates, solute concentrations, and electrical resistivity to work on for their final project. The student will work closely with their Mines mentors to analyze the data. This project will include field work in Colorado as well as time in the computer lab at Colorado School of Mines.

Short project description: The aim of this research is to determine the effects of aeolian dust transport on the biogeochemistry of lake systems, focusing on the impacts on the lake microbiome. Previous work has shown a significant change in the lake microbiome following dust addition, but little research has assessed the long-term viability of the microbial communities that arise. The REU student will design an investigation characterizing the lake microbiome before and after dust addition. By examining both DNA and RNA, the student will be able to observe not only which species are present, but also which species remain viable over time. Dust samples can be collected from the region immediately surrounding the Great Salt Lake and applied to water samples from the Great Salt Lake, Utah Lake, and Deer Creek Reservoir. Dust addition experiments and lab work will be carried out over the summer.

Short project description: Pedogenic carbonates form in soils in natural drylands worldwide, and have been studied intensively, including morphology, deposition mechanisms and accumulation rates. Pedogenic carbonate develops because dissolved bicarbonate (HCO2-) and calcium (Ca2+) react to form calcite (CaCO3), carbon dioxide (CO2) and water (H2O):

2HCO3- + Ca2+ → CaCO3(s) + CO2(g) + H2O Rxn (1)

These pedogenic carbonates can range from 1 to 93% CaCO3 in carbon accumulation zones in drylands. Pedogenic carbonates have been shown to complex with phosphorus (P) present in dryland soils, rendering most P unavailable for plant and microbial access and use. Consequently, plants and microbes have adapted P-acquisition strategies including root exudates and extracellular enzymes to access this mineral-bound P. However, it is unclear whether pedogenic carbonates play a significant role in immobilizing P and how pedogenic carbonate quantities impact this P immobilization. The REU student will design an investigation to look at pools of soil P availability along a gradient of pedogenic carbonate to determine whether there exists a correlation between carbonates and P availability. Measurements of organic and inorganic pools could identify the most important sources of P for plant and microbial communities along the carbonate gradient.

Short project description: The Coastal Critical Zone Network is a collaborative, multi-disciplinary research project that investigates the effects of salinization and flooding on marsh migration into forested and agricultural lands on the Delmarva Peninsula. Coastal forests and agricultural fields are converting to salt marshes as a result of two driving mechanisms: slow processes (e.g., sea-level rise) and fast processes (e.g., storm surges and tides). The flooding and salinization associated with these processes drive landscape changes that are affected by feedback among coupled hydrological, ecological, geomorphological, and biogeochemical processes. The occurrence of these mechanisms and the nature of their feedbacks, which differ between forested and agricultural land, determine the rate and extent of landscape transformation and the associated changes in elemental stores and fluxes in the coastal CZ. The REU student will participate in research that helps to address a question in one of our four major topical areas: hydrology, ecology, geomorphology or biogeochemistry. The student will identify their specific research question based on their interest and design a project that fits their level of research experience.

  • CZ Cluster(s): CINet
  • Location: University of Illinois at Urbana-Champaign, Champaign, IL
  • Mentor(s): Dr. Bruce Rhoads

Short project description: Intensive management of agricultural landscapes in the upper midwestern United States has resulted in increased rates of water runoff and soil erosion. Although these effects are well-documented, the influence of increased amounts of runoff and soil erosion on the sediment dynamics of river systems are rather poorly understood, especially spatial or temporal variation in these dynamics. The REU student will examine temporal and spatial variations in sediment dynamics in the upper Sangamon River basin of Illinois, an intensively managed agricultural watershed where event-scale data on river sediment fluxes are being collected at multiple locations throughout the watershed. The student will work with these data to characterize how sediment concentrations and loads vary over time at particular sampling locations and over space between different sampling locations. The student also can explore how temporal and spatial variations of sediment flux may be related to controlling factors, such as storm characteristics, seasonality of land cover, and geomorphic or vegetation attributes of riparian corridors. Through field and lab training, the student will learn how river sediment data are collected and analyzed.

Short project description: In the Anthropocene, the Earth system is experiencing transitions that are unprecedented in human history. Potential and ongoing ecosystem state changes threaten billions of individuals, highlighting the need to better understand the factors that determine ecosystem recovery or transition in the face of overlapping disturbances. This project seeks to characterize the recovery of watersheds affected by mega fire (extensive and severe wildfires >400km2) and various land-uses in a semiarid region. The research will take advantage of four years of data from an extensive and high frequency hydrochemical sensor network in central Utah. Because of the high level of spatiotemporal resolution, the REU student will be able to use complex systems tools (e.g., self-organizing maps, agent-based models, and neural networks) to address questions such as: 1) How does mega fire affect river flow and chemistry for different ecosystem types during postfire recovery? 2) How do various human disturbances (e.g., impermeable surfaces, grazing, irrigated crops, and water extraction) influence river flow and chemistry? 3) How does weather variability (e.g., extreme precipitation events and multi-year droughts) modulate links between wildfire, human disturbance, and hydrochemistry? And 4) How coupled are terrestrial and aquatic successional trajectories? The student will join Professor Abbott and graduate students in a campaign to collect and analyze data at hundreds of field sites near Provo, UT. The student’s project will include fieldwork, lab processing, and advanced data analysis.

Contact Information

Questions about applications or the program should be directed to the CZNet-REU Program Coordinator, Veronica Sosa Gonzalez.

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