55,991 Works

Influence of Land Use and Storm Events on Dissolved Organic Matter Quantity and Quality in the Jordan Lake Watershed

Urbanization of inland watersheds is occurring at faster rate in the Southeastern United States compared to the national average. The integrated response of surface waters to changes in their catchments over time is poorly understood. Given that terrestrially-derived dissolved organic matter (DOM) plays numerous roles in biogeochemical processes important for water quality, DOM represents a terrestrial-aquatic linkage that is particularly susceptible to changes in watershed land use. Thus, this study examined spatial and temporal patterns...

Impact of Organic Carbon Removal on Cancer Risks Posed by Drinking Water Chlorination

The US Environmental Protection Agency is currently proposing regulations to further limit the concentrations of disinfection by-products in drinking water distribution systems. Certain disinfection by-products have been indicted as potential carcinogens in both toxicological and epidemiological studies. One important strategy for reducing by-product concentrations in water distribution systems is to limit the amount of organic carbon, a by-product precursor, at the point of disinfection. According to the regulatory impact analysis, over 4,000 surface water utilities...

Effects of Instillation of Residual Oil Fly Ash on Cardiac, Pulmonary, and Thermoregulatory Parameters in Spontaneously Hypertensive Rats

Epidemiological studies have reported a robust correlation between levels of ambient particulate matter (PM) and the incidence of morbidity and mortality, particularly among persons with cardiopulmonary disease. While similar effects have been demonstrated in animals, the mechanism(s) by which these effects are mediated are unresolved. To further investigate this phenomenon, the effects of ROFA (a model emission PM) were examined in Spontaneously Hypertensive (SH) rats (a susceptible disease model). Rats were surgically implanted with radiotelemeters...

Evaluation of Pre-Ozonation and Enhanced Coagulation for Control of Disinfection By-Products in Drinking Water

This project evaluated the impact pre-ozonation and enhanced coagulation for the control halogenated disinfection byproducts (DBPs) in drinking water. In 1998, the U.S. Environmental Protection Agency (USEPA) promulgated Satge One of the Disinfectants/Disinfection Byproducts (D/DBP) Rule to reduce levels of potentially carcinogenic chemicals that form following chlorination. As part of the D/DBPRule, the USEPA constructed a 3x3 enhanced coagulation matrix mandating utilities to meet or exceed total organic carbon (TOC) removal percentages prior to chlorination....

Evaluation of Methodology For Analysis of Organic Contaminants in Soil

Analytical methods for analysis of organic contaminants in soil were investigated. Two methods were evaluated for reproducibility, applicability to field site monitoring, and usefulness with common pollutants. An ultrasonic solvent extraction method was found to show promise for analysis of semivolatile organic contaminants. The method compared favorably with established techniques in terms of extraction efficiency and rapidity. An adaptation of the Grob Closed-Loop Stripping (CLS) Method was developed for analysis of volatile organics in soil....

A Vehicular Portal Monitor

A NaI monitoring system was assembled and installed to provide radiological surveillance of refuse trucks destined for the sanitary landfill at Brookhaven National Laboratory. The performance of the system was tested by obtaining count rates for various gamma reference sources placed in the bed of a pickup truck parked over the detector. The system's sensitivity was documented for the various sources counted in a stationary truck as well as in a truck moving over the...

Air Quality as a Factor in the Pathogenesis of Asthma

Air quality plays an important role in the increased prevalance of asthma observed in industrialized countries. Recent advances in the study of asthma provide further information on how air pollution affects asthmatics. In this survey of current literature, air pollutants have been loosely categorized according to their location in the environment (occupational, outdoor, indoor). In relation to asthma, these air pollutants have been classified according to their deposition in the lung and their ability to...

Using A Tracer Gas Technique to Evaluate Laboratory Hood Effectiveness

Animal researchers and pathologists who perform necropsies on animals may be exposed to significant concentrations of formaldehyde vapor. Because of complaints of respiratory and eye irritation, nausea, headaches, and recent animal data that suggests formaldehyde may be a carcinogen, several types of hoods have been used to control the process. A partial enclosure hood designed to control this process was evaluated using a tracer gas, sulfur hexafluoride, to determine the minimal operating conditions necessary to...

Evaluation of an Inhalation Device to be Used in Cystic Fibrosis Research

Powder aerosols are being considered as treatment for patients with Cystyic Fibrosis because powders can deliver amiloride hydrochloride directly to airway surfaces more quickly and easily than is possible when the drug is administered in solution. The goals of this research were: 1) to increase the fraction of respirable amiloride hydrochloride mass generated, 2) to remove larger, non-respirable particles from the aerosol before inhalation, and 3) to assess the effectiveness of these aerosol generation techniques...

Light Scattered by Particles on Reflective Surfaces

This report describes an analytical approach to light scattering from particles resting on reflective surfaces. The phenomenon of light scattering from particle-deposited surfaces depends on the optical characteristics of the particle, the surface, and the coated film individually and the combined optical effects among these three. Mie theory was used to compute scattering from the particle while ray tracing was used to estimate the influence of the surface. Four paths have been analyzed: (1) back...

Methicillin Resistant Staphylococcus aureus in Gyms: Evaluation of Swabbing-Based Sampling Methodologies and the Levels of MSSA/MRSA on Environmental Surfaces within Recreational Exercise Facilities

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging infectious bacterial pathogen which is a leader in the causes of nosocomial infections. Overtime, this pathogen has transitioned from association primarily with healthcare settings to association with community-acquired infections (CA-MRSA) as well. As CA-MRSA prevalence has risen, its outbreaks have been linked to common environmental sources; prompting interest in the environment as a potential means of its dissemination. To investigate this risk in gyms, four types of sampling...

Are Wastewater Treatment Residuals Applications The Major Source Of Perfluorienated Compounds (PFC) Contamination? An Analysis of Two Counties in The Cape Fear River Basin, North Carolina

An initial database of wastewater sludge application is built to test whether wastewater sludge application is the major source of Perfluorinated Compounds (PFC) contamination in Cape Fear River Basin. A Land use regression (LUR) model is framed to analyze the association between wastewater sludge applications and PFC contamination based on three approaches: Euclidean distances, River distances, and Flows. The wastewater sludge application database covers a 10-year time period consisting of 2001-2002 and 2004-2011, and two...

Studies in Oxidative Chemistry: Oxidation of Benz[a]anthracene Using a Synthetic Porphyrin Catalyst to Model Cytochrome P-450

Oxidations of the PAH benz[a]alanthracene were carried out using m-chloroperoxybenzoic acid as monooxygen donor and the 2,6-chlorotetraphenyl-substituted iron porphyrin as catalyst. These reactions were performed in two different modes. The first used the oxoferryl porphyrin cation radical as direct oxidant, essentially allowing only one turnover of catalyst, whereas the second used the high-valent complex in a multi-turnover, catalytic mode. Phenoxathiin hexachloroantimonate was used as a model one-electron oxidant to compare its product profile to the...

Concentration and Molecular Detection of Norwalk Virus and other Viruses in Water

Norwalk Virus (NV) and other human enteric viruses in fecally contaminated waters pose a human health risk that is inadequately characterized due to the limitations of current virus detection methods. Standard methods for virus concentration from water using electropositive adsorbent filters have not been tested for NV recovery because there is no convenient infectivity assay system and because the beef extract (BE/G) used to elute the adsorbed viruses inhibits virus detection by reverse transcriptase-polymerase chain...

Impact of District-level Managerial Training of Kenya of Government Officials on the Scale-up of Community-Led Total Sanitation

Many organizations in the water, sanitation, and hygiene (WaSH) sector educate and train local stakeholders in order to increase the effectiveness and efficiency of their WaSH interventions. A key challenge has been measuring how well these training contribute to WaSH improvements and scale-up. I used a conceptual framework to evaluate a community-led total sanitation (CLTS) management training program in Kenya. Interviews guide were administered to 52 government officials in Kenya from June 2013 through July...

A Comparison of Speciation Methods on Environmentally Isolated, Sediment Associated Aeromonas using Matrix Assisted Laser Desorption/Ionization Mass Spectrometry and Three Housekeeping Genes

Background: The taxonomy of Aeromonas is complex and has confounded researchers for years. Over the past twenty years, technological advances have allowed researchers to attempt to clarify the taxonomy through genetic and proteomic techniques. Several of these advances include PCR amplification and sequencing of numerous housekeeping genes and small sub-unit ribosomal DNA (16SrDNA) in order to determine the small taxonomic differences between the species in the genus Aeromonas. Another method that has recently been employed...

Computer Modeling of Contaminant Jet Flow into Local Exhaust Hoods

A computer model was developed and coded in BASIC topredict the streamline that a jet of gaseous sulfur hexafluoride will follow in the flow field of a flanged circular exhaust hood (FCH). This approximate solution is based on the vector addition of a modified potential flow solution for the FCH, and a jet flow solution. The assumptions underlying the equations describing jet flow are those of the Prandtl mixing length hypothesis. The computer program generates...

Genotyping F+ RNA Coliphages by Hybridization with Oligonucleotide Probes

F-specific RNA coliphages are prevalent in sewage and other fecal wastes of humans and animals. There are four antigenically distinct serogroups of F+ RNA coliphages and those predominating in humans (groups II and III) differ from those predominating in animals (groups I and IV). Hence, it may be possible to distinguish between human and animal wastes by serotyping F+ RNA coliphage isolates. Because serotyping requires scarce antiserum reagents, we investigated genotyping of F+ RNA coliphages...

Effect of Combustion Temperature on the Atmospheric Stability of Polybrominated Dibenzo-p Dioxins and Dibenzofurans

The incineration of materials containing polybrominated diphenyl ether (PBDPE) flame retardants can potentially lead to the formation of polybrominated dibenzo-p-dioxins and furans (PBDDs and PBDFs). Some of these compounds may exhibit toxicities similar to those of their chlorinated analogues. Little is known about the atmospheric stability of PBDDs and PBDFs. In this study PBDDs and PBDFs produced from the combustion of polyurethane foam containing 4.4% PBDPEs were injected into outdoor teflon film chambers and aged...

Sensitivity of the SRBC PFC Assay vs. Eliza for Detection of Immunosuppression by TCDD and TCDD-like Congeners

The splenic antibody plaque-forming cell (PFC) assay to sheep red blood cells (SRBC) is considered to be one of the most sensitive assays for detection of immunosuppression, and traditionally has been used in immunotoxicity testing. However, an enzyme-linked immunosorbent assay (ELISA) (Temple et al., 1993), is gaining popularity as a more convenient and less expensive alternative. The PFC assay quantifies the number of anti-SRBC producing plasma cells in the spleen, while the ELISA measures SRBC-specific...

The Built Environment, Spatial Variation in Fine Particulate Matter Concentrations, and Attributable Mortality: A Scenario-Based Land Use Regression Approach

A land use regression model is calibrated to predict annual average PM[25] concentrations throughout the Triangle Region. A risk assessment model is used to predict attributable all-cause mortality from exposure to predicted concentrations. Two alternative land development scenarios are compared to current conditions in terms of air quality and health impacts. This study finds that compact development alone is not an effective intervention to reduce all-cause mortality attributable to fine particulate matter in urban areas;...

Comparison of Mean Constituent Residence Time (MCRT) from Fluoride Tracer Studies and Water Age from Epanet Modeling of Distribution Systems

Epanet is a hydraulic and water quality model that includes calculation of Water Age, a parameter that relates to the residence of water in the DS. Locations with long Water Age are of interest because they also may experience deterioration in water quality. The Mean Constituent Residence Time (MCRT) is an alternative to Water Age that is simpler because it can be measured from the response to a fluoride tracer test in the DS and...

The Characterization of Linear Alkylbenzene Sulfonate Biodegradation Products by Estuarine Microbial Communities

A common observation in studies of linear alkylbenzene-sulfonates (LAS) biodegradation is plateau. This research was performed to examine the nature of the LAS biodegradation plateau phenomenon. Plateau of linear C12-Alkylbenzosulfonates (C12-LAS) biodegradation in Calico Creek water samples was repeated as in previous studies. The residue of degradation samples was characterized by GC/MS. Significant amounts of undegraded C12-LAS isomers were detected in these samples. Isomers with the benzene ring attached to the central carbons of the...

Assessment of DNA Copy Number Alterations in Mouse and Human Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a prevalent human cancer with rising incidence worldwide. Human HCC is typically associated with chronic liver inflammation and cirrhosis, which is typically the consequence of toxic insults, disturbances in metabolism, or viral infection. To better understand the pathogenesis of liver cancer, we studied molecular mechanisms in the development of HCC using a human-relevant mouse model of fibrosis-associated hepatocarcinogenesis. Because the increased incidence of liver tumors in this model was associated with...

Performance Testing of Carbon Adsorption Diffusion Barrier Canisters

Radon is a naturally occurring, radioactive, inert gas that is one of the nuclides emitted in the uranium-238 (238U) radioactive decay series. Upon its decay, radon produces additional radioactive elements which are referred to as radon progeny. Present throughout the environment, radon-222 (222Rn) accounts for 55% of the total radiation dose to the United States population. Concern has grown over the effects of 222Rn exposures because of the increased lung cancer potential from breathing radon...

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