Browsing by Author "Dellapenna, Timothy"

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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.
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.
Sediment Study of Addicks and Barker Reservoirs, Houston, TX
Marine And Coastal Environmental Science; TAMUG; https://hdl.handle.net/20.500.14641/665; DOD-Army-Corps of Engineers
2. Background a. Addicks and Barker Reservoirs The Galveston District has managed and monitored Addicks and Barker Reservoirs in West Houston since 1949 (their completion). During that time there has been sediment influx into the reservoirs that has resulted in sedimentation within the reservoirs. The amount of sediment is largely unknown as is its exact location. Only recently has survey technology been adequate to measure this influx, however a general lack of historical survey data, and environmental influences such as subsidence has ruled out surveying to establish a baseline. The combined area of the reservoirs is ~26,000 acres. The quantification of the sedimentation rates will be conducted through the use of 239+240Pu geochronology. b. 239+240Pu geochronology-Short Review 239+240Pu geochronology is a recent addition to the suite of short-lived and environmental radio-isotopes used for geochronology of recently deposited sediments. It is a bomb produced isotope and its application is comparable to 137Cs, but with the added advantage that it can be used on sand dominated sediments. In marine sediments, Kuelh et al. (2012) established that accurate sedimentation rates could be determined using plutonium isotopic geochronology in two independent sites. One site in New Zealand where Cs isotopic geochronology had failed previously and one site in Kitty Hawk North Carolina. Fig. 2 below is a graph taken from Kuelh et al. (2012) documenting their results in the N.C site. Additionally, they demonstrated its utility off of Galveston Island in sand dominated sediments.