Environmental Chemistry Commons^™

Evaluating Seasonal Nutrient Fluxes In Emerging And Eroding Wetlands Of The Louisiana Delta Plain, Kiran Upreti

LSU Doctoral Dissertations

Deltaic wetlands can ameliorate high NO₃^- loads via denitrification, a dominant NO₃^- reduction pathway in inland and coastal habitats. Dissimilatory Nitrate Reduction to Ammonia (DNRA), in contrast to denitrification, conserves N within the system and has been found to be favored over denitrification with increase in salinity and temperature. There are no studies in the Louisiana Deltaic plain with simultaneous estimation of denitrification and DNRA. Increased P availability has been shown to increase denitrification so it is essential to understand P biogeochemistry when studying N cycle. Here, we evaluated net denitrification using N₂:Ar and …

Lake Sediment Analysis At Heron Haven Nature Center, Erik Lato

UNO Student Research and Creative Activity Fair

Understanding the chemical composition of a wetland sanctuary lakebed can help us understand how recent developments may have changed the chemical composition. Due to recent dredging by the U.S. Army Corps of Engineers and previous research on water composition at Heron Haven, the goal of this project was to determine the chemical composition as a function of sediment depth. The concentration of seven different metals and nutrients were analyzed in terms of depth. The aluminum, iron, and phosphate concentrations had no real discernible concentration change as a function of depth. There is some hint of a steady increase of manganese …

Seasonal Origins Of Soil Water Used By Trees, Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, Gregory R. Goldsmith

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Rain recharges soil water storages and either percolates downward into aquifers and streams or is returned to the atmosphere through evapotranspiration. Although it is commonly assumed that summer rainfall recharges plant-available water during the growing season, the seasonal origins of water used by plants have not been systematically explored. We characterize the seasonal origins of waters in soils and trees by comparing their midsummer isotopic signatures (δ2H) to seasonal isotopic cycles in precipitation, using a new seasonal origin index. Across 182 Swiss forest sites, xylem water isotopic signatures show that summer rain was not the predominant water source …

Carbohydrate Polymers As Controlled Release Devices For Pesticides, Soma Chakraborty, Maria Cleofe Neri-Badang

Chemistry Faculty Publications

Controlled release technology addresses problems associated with excessive use of toxic agricultural chemicals. This paper reviews the studies on the use of carbohydrate polymers as controlled release matrices for pesticides. Alginates, starch and its derivatives, chitosan, carboxymethylcellulose and ethylcellulose are some of the natural polymers discussed in this review. The advantages and disadvantages of these polymeric systems as well as the factors that affect pesticide release are presented. A discussion on the polymers’ encapsulation efficiency and release profile is also included, which will aid future researchers in identifying the suitable formulation for controlled release of pesticides. Combination of two polymers, …

Potential Degradation Of Hexabromocyclododecane (Hbcdd) In Sediments: Stereoisomer Specific Reaction Of Hbcdd With Reduced Sulfur Species Or Fe(Ii) Bound To Iron Oxides, Xianmiao Zhang

Dissertations, Theses, and Capstone Projects

The individual degradation rates of the three dominant stereoisomers (alpha, beta, gamma) of hexabromocyclododecane (HBCDD) with bisulfide and polysulfides were investigated at pH 9-10 in methanol/water solutions at two different temperatures (25 °C and 40 °C). alpha-HBCDD reacts significantly slower than beta-HBCDD and gamma-HBCDD. It was also observed that the reaction of HBCDD with polysulfides is faster than with bisulfide. For the reaction of HBCDD with bisulfide, the experiments were performed in 20% water/80% methanol, 50% water/50% methanol and 80% water/20% methanol at 40 °C. It was determined that the solvent polarity affects the reaction and the second-order rate constants …

Viscosities, Diffusion Coefficients, And Mixing Times Of Intrinsic Fluorescent Organic Molecules In Brown Limonene Secondary Organic Aerosol And Tests Of The Stokes–Einstein Equation, Dagny A. Ullmann, Mallory L. Hinks, Adrian M. Maclean, Christopher Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Sergey A. Nizkorodov, Saeid Kamal, Allan K. Bertram

Physics Faculty Publications and Presentations

Viscosities and diffusion rates of organics within secondary organic aerosol (SOA) remain uncertain. Using the bead-mobility technique, we measured viscosities as a function of water activity (a_w) of SOA generated by the ozonolysis of limonene followed by browning by exposure to NH₃ (referred to as brown limonene SOA or brown LSOA). These measurements together with viscosity measurements reported in the literature show that the viscosity of brown LSOA increases by 3–5 orders of magnitude as the aw decreases from 0.9 to approximately 0.05. In addition, we measured diffusion coefficients of intrinsic fluorescent organic molecules within brown …

Effect Of Dissolved Salts On The Physiochemical Properties Of Deep Eutectic Solvents, Eleanor Haeska, Megan Radtke

The Journal of Undergraduate Research

Green chemistry seeks to make chemical procedures safer, improve reaction efficiency, and utilize environmentally safe reagents. Deep eutectic solvents (DES) have recently become of great interest due to their eco-friendly nature and functionality as solvent for various chemical processes. One key characteristic of DES is their conductive nature and depressed melting point. This project sought to determine the effect of the addition of aqueous solutions of halides on the conductivity of two selected types of DES. Also assessed were the polarity and viscosity of the DES. It can be concluded that aqueous halides had no measureable effect on the conductivity …

Increased Perchlorate In The Environment Following The 1600 C.E. Huaynaputina Volcanic Eruption, Joseph Gibson, Amanda Shea

The Journal of Undergraduate Research

Perchlorate is an environmental contaminant that can have adverse health effects on humans. Although our knowledge about how natural perchlorate is formed is very limited, volcanic eruptions are believed to play an important role. An ice core obtained from Summit Station, Greenland was used to study the effects of the Huaynaputina eruption on the amount of perchlorate in the environment. The section of ice core sampled was determined to span the years 1594 through 1610. The results indicate that the Huaynaputina eruption caused a temporary but significant increase in the amount of perchlorate in the atmosphere.

Toward The Impact Of Particulate Matter On Human Health: Evaluation Of Fluorescent Environmentally Persistent Free Radical (Epfr) Surrogates, Ansonia Badgett

LSU Doctoral Dissertations

Environmentally persistent free radicals (EPFRs)—a newly discovered pollutant associated with particulate matter (PM)—form during combustion and thermal processes, such as the incineration of hazardous waste. Various chlorine- and hydroxy-substituted benzenes chemisorb on the surface of metal oxides (e.g., NiO, CuO, and Fe₂O₃) and then form EPFRs, stabilized radical species, as the result of the transfer of electrons between the adsorbate and the metal ion of the metal oxide. Previous studies have shown direct correlations between ultra-fine (d < 0.1 mm) particulate matter (PM_0.1) exposure and adverse pulmonary health effects. PM_0.1 has the potential …

Facile Synthesis Of A Tailored-Designed Au/Pt Nanoanode For Enhanced Formic Acid, Methanol, And Ethylene Glycol Electrooxidation, Yaser M. Asal Mr., Islam M. Al-Akraa Dr, Ahmad M. Mohammad Prof

Chemical Engineering

The recent revolution in nanoscience and global energy demand have motivated research in liquid fuel cells (LFCs) due to their enhanced efficiency, moving flexibility, and reduced contamination. In line with this advancement, a glassy carbon (GC) electrode was modified with platinum (PtNPs) and gold (AuNPs) nanoparticles to fabricate a nanosized anode for formic acid, methanol, and ethylene glycol electrooxidation (abbreviated, respectively, to FAO, MO, and EGO), of the key anodic reactions of LFCs. The deposition sequence of the catalyst’s layers was important where the Au/Pt/GC electrode (in which PtNPs were directly deposited onto the GC surface followed by AuNPs—surface coverage …

Characterizing The Effects Of Environmental Stressors On The Photosynthetic Capacity Of Chlorella Vulgaris, Amanda Louise Smythers

Theses, Dissertations and Capstones

Chlorella vulgaris is a unicellular green algae grown throughout the world. Due to its multiple trophic modes as well as its ability to maintain high rates of growth under adverse conditions, it has been of global interest for use in ecological contamination studies, biofuel feedstock optimization, and studies of photosynthetic electron transfer. Using a wide-range of methods for physiological and photosynthetic characterization, the studies within seek to further extend the usefulness of C. vulgaris in a variety of environmentally important studies. Once the protocols were optimized specifically for this alga, they could be applied in both ecologically relevant and biodiesel …

Detecting Cyanobacteria Toxins: The Human Health Impact Of An Environmental Problem, Lillian E. Naimie

Honors Theses

Cyanobacteria blooms are a growing concern in the world, as they can form a dense and sometimes toxin scum on water bodies. This paper will outline and discuss the environmental conditions that produce cyanobacteria bloom with a focus on the toxins produced by blooms and specifically the detection of these toxins through two analytical methods. Of the various toxins cyanobacteria are capable of producing, this paper will focus on microcystins and BMAA, a family of hepatotoxins and a specific neurotoxin respectively. The two analytical methods discussed are liquid chromatography coupled mass spectrometry and ELISA kit techniques. The advantages and drawbacks …

Recent Trends In Stratospheric Chlorine From Very Short‐Lived Substances, Ryan Hossaini, Elliot Atlas, Sandip S. Dhomse, Martyn P. Chipperfield, Peter F. Bernath, Anton M. Fernando, Jens Mühle, Amber A. Leeson, Stephen A. Montzka, Wuhu Feng

Chemistry & Biochemistry Faculty Publications

Very short‐lived substances (VSLS), including dichloromethane (CH₂Cl₂), chloroform (CHCl₃), perchloroethylene (C₂Cl₄), and 1,2‐dichloroethane (C₂H₄Cl₂), are a stratospheric chlorine source and therefore contribute to ozone depletion. We quantify stratospheric chlorine trends from these VSLS (VSLCl_tot) using a chemical transport model and atmospheric measurements, including novel high‐altitude aircraft data from the NASA VIRGAS (2015) and POSIDON (2016) missions. We estimate VSLCl_tot increased from 69 (±14) parts per trillion (ppt) Cl in 2000 to 111 (±22) ppt Cl in 2017, with >80% delivered to …

Shelf Inputs And Lateral Transport Of Mn, Co, And Ce In The Western North Pacific Ocean, Peter L. Morton, William M. Landing, Alan M. Shiller, Amy Moody, Thomas D. Kelly, Michael Bizimis, John R. Donat, Eric H. De Carlo, Joseph Shacat

Chemistry & Biochemistry Faculty Publications

The margin of the western North Pacific Ocean releases redox-active elements like Mn, Co, and Ce into the water column to undergo further transformation through oxide formation, scavenging, and reductive dissolution. Near the margin, the upper ocean waters enriched in these elements are characterized by high dissolved oxygen, low salinity, and low temperature, and are a source of the North Pacific Intermediate Water. High dissolved concentrations are observed across the Western Subarctic Gyre, with a rapid decrease in concentrations away from the margin and across the subarctic-subtropical front. The particulate concentrations of Mn, Co, and Ce are also high in …

Phosgene In The Upper Troposphere And Lower Stratosphere: A Marker For Product Gas Injection Due To Chlorine-Containing Very Short Lived Substances, Jeremy J. Harrison, Martyn P. Chipperfield, Ryan Hossaini, Christopher D. Boone, Sandip Dhomse, Wuhu Feng, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

Abstract: Phosgene in the atmosphere is produced via the degradation of carbon tetrachloride, methyl chloroform, and a number of chlorine‐containing very short lived substances (VSLS). These VSLS are not regulated by the Montreal Protocol even though they contribute to stratospheric ozone depletion. While observations of VSLS can quantify direct stratospheric source gas injection, observations of phosgene in the upper troposphere/lower stratosphere can be used as a marker of product gas injection of chlorine‐containing VSLS. In this work we report upper troposphere/lower stratosphere measurements of phosgene made by the ACE‐FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) instrument and compare with results …

Spatial Patterns Of Particulate Organic Carbon Concentrations And Isotopic Signatures Across A Salinity Gradient In A River Dominated Estuary, Lauren E. Alvaro, John C. Lehrter, Mai Fung

Gulf and Caribbean Research

No abstract provided.

Spatial Fingerprinting Of Biogenic And Anthropogenic Volatile Organic Compounds In An Arid Unsaturated Zone, Christopher T. Green, Wentai Luo, Christopher H. Conaway, Karl B. Haase, Ronald J. Baker

Chemistry Faculty Publications and Presentations

Subsurface volatile organic compounds (VOCs) can pose risks to human and environmental health and mediate biological processes. Volatile organic compounds have both anthropogenic and biogenic origins, but the relative importance of these sources has not been explored in subsurface environments. This study synthesized 17 yr of VOC data from the Amargosa Desert Research Site in Nevada with the goal of improving understanding of spatial and temporal variations that distinguish sources of VOCs from a landfill and from ambient sources including biogenic VOCs (bVOCs). Gas samples were collected from 1999 to 2016 from an array of shallow sample points (0.5- and …

Pursue Undergraduate Research Journal Volume 2 (Issue 1) 2019

Pursue: Undergraduate Research Journal

The scholarly journal, “PURSUE: Undergraduate Research Journal” (ISSN 2473-6201), provides undergraduates an avenue to publish their original research abstracts and articles in the following areas: psychology, sociology, biology, chemistry, physics, engineering, computer science, mathematics, humanities, agriculture, architecture, health, business, and education (this list is not exclusive).

The original research articles included in this journal are peer reviewed and selected by the journal’s Editorial Board. The review process allows undergraduate researchers to receive feedback from notable scientists in their field of study and teach them about the publication process. Publication of their work will not only inform the scientific community; it …

Effect Of Carbonaceous Nanoparticles On Naturally Occurring Iron Reduction By Carboxylates, Ashleen Reddy

All Master's Theses

The emission of ambient particulate matter (PM) is regulated by many institutions due to the detrimental effects on health, environment and climate; yet many underlying mechanisms of PM reactivity are still not well understood. In the current study, the effect of carbonaceous nanoparticles (CNPs), contained within ultrafine PM (particle diameter ≤ 100 nm), is investigated on naturally occurring processes that increase the abundance of bioavailable iron. Enhancing iron bioavailability (i) increases primary productivity of iron-limited microorganisms, affecting the carbon cycle and global climate, and (ii) increase toxicity of inhaled particles through the associated production of reactive oxygen species (ROS). Specifically, …

Seasonal Soil Carbon Fluxes In Transitioning Agricultural Soils In Central Washington State: Relations To Land-Use, Environmental Factors And Soil Carbon-Nitrogen Characteristics, Brandon Kautzman

All Master's Theses

Changing agricultural land-use practices to increase soil carbon sequestration contributes to climate change mitigation and improved food security by moving CO₂ from the atmosphere into soil as soil organic carbon (SOC). In 2016, a farm in Thorp, Washington, Spoon Full Farm, began converting land historically farmed using conventional methods of tillage and synthetic fertilizers to conservation farming methods with direct seeding and organic soil amendments with a goal of sequestering carbon in the soil. This project evaluates relationships of soil CO₂ respiration and net ecological exchange (NEE) with land-use types, seasonal environmental factors (air temperature, relative humidity, soil …