Browsing by Department "Marine Science"

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Analysis of Sediment Particle Size from Northwest Florida Estuaries
Marine Science; TAMUG; https://hdl.handle.net/20.500.14641/665; Environmental Protection Agency
Background: A major component of the U.S. EPA SSWR 4.02A research is to understand the factors influencing benthic macrofauna communities across stressor gradients. Secliment particle size can be influencing depth to which dissolved oxygen may penetrate into the sediments, as well as influencing the distribution, settlement, and survival of benthic fauna in soft-bottom environments. US EPA needs information on the distribution of particle size in estuarine sediment samples to identify factors influencing faunal community and sediment characteristics and to develop models. This contract will cover the analysis of up to 150 sediment samples (collected from marine to freshwater regions in the Pensacola Bay Estuary system) for sediment grain size distribution. Contractor Responsibilities and Task Description: The contractor shall provide the necessary personnel, facilities and equipment for the analysis of sediment samples. Task Description: Task A: Reporting methods and quality assurance documentation The contractor shall provide to the EPA a Quality Assurance Project Plan (QAPP) or similar document reporting the analytical methods they will use and their expected data quality measures. Task B: Analysis of particle size distribution in sediments The contractor shall analyze the samples received from EPA using a laser diffraction particle size analyzer using Standard Operating Procedure for determination of sediment particle size. Appropriate standards (as outlined in the QA plan from the contractor) will be used to verify that measurements achieve appropriate accuracy and precision. Milestones: Samples will be provided by the EPA between after acceptance of the QA plan and before 12/1/2018. Contractor shall complete analyses of samples within 9 weeks of sample delivery.
Collaborative Research: Reevaluating Precipitation Extremes and Urban Flood Risk in the Wake of Hurricane Harvey
Marine Science; TAMUG; https://hdl.handle.net/20.500.14641/580; National Science Foundation
In August 2017, Hurricane Harvey produced catastrophic flooding across southeast Texas that caused over $100 billion in damages. Rainfall totals and river flows associated with Hurricane Harvey shattered records across southeast Texas, but these records span only the last ~100 years. How unusual was the flooding generated by Hurricane Harvey, and what is the likelihood of such an event occurring again? The brevity of instrumental hydrologic records currently limits our ability to precisely answer this critical question. This project will improve risk assessments for extreme precipitation and flooding in southeast Texas by extending the length of the hydrologic record back in time using geological evidence of flooding with a hydrologic model. These data will allow us to better understand the probability of an event like Hurricane Harvey occurring again, and evaluate how variations in climate and human activities affect flood risk in southeast Texas. This research will improve assessments of the risk posed by flooding, a hazard that has recent affected millions of people living in the Houston metropolitan area. The project will engage undergraduate and graduate students in research, and its findings will be disseminated to the public and decision-makers through the Center for Texas Beaches and Shores. Frequency analyses based on a century of hydrological measurements estimate that the recurrence intervals of Hurricane Harvey?s precipitation and discharge maxima approach 1,000 years (i.e., 0.1% exceedance probability), but these estimates are highly uncertain with 95% confidence intervals that span multiple orders of magnitude. The goal of this project is to reevaluate flood hazard in the Houston metropolitan area by extending the temporal range of analysis from ~100 years to ~1,000 years. To do this, we will use established techniques in paleoflood hydrology to reconstruct discharge maxima of the two rivers in southeast Texas over the last millennium, and integrate these data with a hydrologic model to evaluate the roles of natural and anthropogenic forces on regional flood hazard. These data will allow us to (a) improve assessments of the exceedance probability of Hurricane Harvey and other recent catastrophic floods in the Houston metropolitan region, (b) test for the presence of non-stationarities in flood hazard, and (c) identify the roles of climate variability and land use and land cover change in generating discharge extremes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
NSFOCE-BSF: Collaborative Research: The Role and Mechanisms of Nuclei-induced Calcium Carbonate Precipitation in the Coastal Carbon Cycle: A First In-depth Study
Marine Science; TAMUG; https://hdl.handle.net/20.500.14641/665; National Science Foundation
The formation of calcium carbonate (CaCO3) in seawater is a fundamental pathway in the marine carbon cycle. Calcium carbonate formation may occur through biological production (calcification by organisms building shells or skeletal material) or through non-biological (abiotic, or chemical) processes. Although most surface seawater in both open and coastal waters is supersaturated in calcium carbonate, several factors inhibit the abiotic production of calcium carbonate. Therefore the current paradigm is that most calcium carbonate formation in seawater is biological. However, laboratory experiments have demonstrated that addition of solid-phase particles to supersaturated seawater promotes nuclei-induced CaCO3 precipitation (NICP) by providing "seeds" for precipitation. NICP has been demonstrated in the Little Bahama Banks during events of re-suspension of CaCO3-rich sediments. Until very recently, essentially no evidence has shown that NICP occurs in typical marine systems where suspended particles have relatively low CaCO3 content. A recent study by the Israeli partners in this project provides evidence that NICP may play a significant role in the carbon budget in the Red Sea, as a result of an influx of particulate material caused by flash floods and potentially airborne dusts. Such a finding suggests that NICP may be an important CaCO3 formation pathway that has been mostly ignored in the ocean carbon cycle. The goal of this project is to conduct the first comprehensive, in-depth study to evaluate the significance of NICP in the oceans. The project is an international collaboration between U.S. and Israeli scientists, jointly funded by NSF and the U.S.-Israel Binational Science Foundation. A postdoctoral researcher whose Ph.D. work forms the foundation for this study will be supported through this project. An Israeli masters-level student and one U.S. minority undergraduate intern will be advised and trained in this project. The project will use an integrated approach to assess different mechanisms that may result in NICP, including riverine sediment input, land-derived particle influx via flash floods, bottom sediment resuspension, and atmospheric dust input. Field investigations will be done in a suite of coastal environments: the northern Red Sea, the Mississippi and Sabine River plumes and Galveston Bay in the northern Gulf of Mexico, each of which receive significant quantities of non-carbonate rich sediments. The investigators will also conduct controlled laboratory experiments to verify and extend field observations. If NICP is shown to be significant, this finding could promote a reexamination of important parts of the carbon cycle and the response of the ocean carbon system to ongoing perturbations.
REU Site: Ocean and Coastal ResEArch ExperieNces for UndergraduateS (REU-OCEANUS)
Marine Science; TAMUG; https://hdl.handle.net/20.500.14641/422; National Science Foundation
A new Research Experience for Undergraduates (REU) program at Texas A&M University Galveston (TAMUG), which is located on the Texas Gulf Coast, will be established with this award. The REU Site: Ocean and Coastal Research Experiences for Undergraduates (REU-OCEANUS) will host ten participants in each summer for three years during a 10-week REU program. Students will have the opportunity to conduct independent, marine-focused research. REUs will work in active research labs, be mentored by the research faculty and use state-of-the-art scientific facilities and resources. Participating faculty mentors from the Department of Marine Biology, Department of Marine Sciences and Department of Ocean Engineering will engage REUs in ongoing diverse research topics including: Gulf of Mexico coastal wetlands response to climate change; shark feeding ecology; hydrozoan biodiversity; tsunami modeling; Texas coast paleoclimatology, sedimentology, physical/chemical oceanography and geology; Caribbean reef fish speciation; and Arctic Ocean biogeochemistry. REU students will gain skills in communicating their research by completing a research prospectus, a mock research budget and budget justification, an oral presentation, a Research Symposium oral and poster presentation, and a three-minute video abstract. The program will engage students in various enrichment activities, including research seminars given by the faculty, graduate school planning and workshops designed to enhance REU scholar success and to highlight various career options. The site will recruit students from diverse backgrounds with active recruitment efforts nationwide and at institutions serving as alliance partner institutions of the Louis Stokes Alliance for Minority Participation Programs in Texas.
Using Radioiodine Speciation to Address Environmental Remediation and Waste-Stream Sequestration Problems at the Fukushima Daiichi Nuclear Power Plant and a DOE Site
Marine Science; TAMUG; https://hdl.handle.net/20.500.14641/534; DOE - Office of Nuclear Energy
Iodine-129 is one of three key risk drivers at several DOE waste management sites. Natural organic matter (NOM) is thought to play important roles in immobilization of aqueous iodide (I-) and iodate (IO3-) in the environment, but molecular interactions between NOM and iodine species are poorly understood. In this work, we investigated iodine and carbon speciation in three humic acid (HA)-I systems using I K-edge XANES and EXAFS and C K-edge XANES spectroscopy: 1) I- in the presence of laccase (an oxidase enzyme) and a mediator, 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in pH 4 buffer, 2) I- in the presence of lactoperoxidase (LPO) and H2O2 in pH 7 buffer, 3) IO3- in pH 3 groundwater. The oxidase and peroxidase systems were less effective than the laccase-ABTS mediator system at oxidizing I- to I2 or hypoiodide (HOI), resulting in I- uptake by HA increasing from 0.4 to 2.9 mg/g in the oxidase and peroxidase systems to 13.5 mg/g in the laccase-ABTS mediator system. IO3- was abiotically reduced to I2 / HOI. Pathways for HA iodination include covalent modification of aromatic-type rings by I2 / HOI or iodine incorporation into newly formed benzoquinone species arising from oxidation of phenolic C species. This study improves our molecular understanding of NOM-iodine interaction and describes the important role that mediators may play in the enzymatic reactions between iodine and NOM. KEYWORDS: Enzyme, Humic acid, Iodine immobilization, I K-edge XANES and EXAFS, C K-edge XANES