Two adsorption/microcoulometric methods have been investigated for total organic halogen (TOX) in water. TOX, a proposed water-quality parameter, is a rapid, surrogate method to detect halides microcoulometrically and does not require compound identification before water quality can be judged. An XAD resin is used to concentrate organic halides that are eluted by a two-step, two-solvent procedure, followed by analysis using :chromatography or pyrolysis to convert organic halides to halide. In the granular activated carbon (GAC) method, the entire GAC-organic halide sample is pyrolyzed. TOX measurements of model compounds are comparable by both methods, but GAC was found to be superior to XAD for adsorption of chlorinated humics in drinking water and chlorinated lake water.

Many applied statistical applications face the potential problem of model contamination and measurement error. The form and degree of contamination as well as the measurement error are usually unknown and sample-specific, which brings additional challenges for researchers. In this thesis, we have proposed several Bayesian inference models to address these issues, with the application to one type of special data for allergen concentration measurement, which is called serial dilution data and is self-calibrated. In our first chapter, we address the problem of model contamination by using a multilevel model to simultaneously flag problematic observations and estimate unknown concentrations in serial dilution data, a problem where the current approach can lead to noisy estimates and difficulty in estimating very low or high concentrations. In our second chapter, we propose the Bayesian joint contamination model for modeling multiple measurement units at the same time while adjusting for differences between experiments using the idea of global calibration, and it could account for uncertainty in both predictors and response variables in Bayesian regression. We are able to get efficacy gain by analyzing multiple experiments together while maintaining robustness with the use of hierarchical models. In our third chapter, we develop a Bayesian two-step inference model to account for measurement uncertainty propagation in regression analysis when the joint inference model is infeasible. We aim to increase model inference reliability while providing flexibility to users by not restricting the type of inference model used in the first step. For each of the proposed methods, We also demonstrate how to integrate multiple model building blocks through the idea of Bayesian workflow. In extensive simulation studies, we show that our proposed methods outperform other commonly used approaches. For the data applications, we apply the proposed new methods to the New York City Neighborhood Asthma and Allergy Study (NYC NAAS) data to estimate indoor allergen concentrations more accurately as well as reveal the underlying associations between dust mite allergen concentrations and the exhaled nitric oxide (NO) measurement for asthmatic children. The methods and tools developed here have a wide range of applications and can be used to improve lab analyses, which are crucial for quantifying exposures to assess disease risk and evaluating interventions.

Atmospheric pollution in some degree has been around since time began. In recent times it has reached levels in some areas which proved to be harmful to man's health. A brief history review of these occurrences is presented. Laws have been enacted to combat this threat. A brief review of these laws is presented. Instruments for remote sensing of polluting sources are being developed to monitor ambient air quality and aid in enforcing these laws. A review of the techniques employed and the present state of the art is explored. Available instruments are presented in section III-5.

No description available.

A stochastic dynamic constituent transport model was developed, capable of simulating the operation of a water distribution system containing pumps and storage tanks, and subject to random demands and contaminant inputs. Long term operation of a hypothetical small town water supply system containing one pump station and one storage tank was simulated while the system was subjected to external contaminant inputs. Repeated simulations were made under different regimes of external contamination applied to the tank, the pump station and at system nodes, and internal contamination representing biofilm effects based on assumed relationships between flow velocities and bioflim cell detachment. Seven sampling plans representing regulatory requirements and industry practice were applied during the simulation to evaluate their ability to detect the contamination under a presence/absence criterion. The simulations were able to identify contamination patterns and provide information useful in the definition of sampling plans. Time of sampling was found to be as important as location. This was true both within the monitoring period, and particularly within the diurnal cycle of demand. Spreading samples over different days within the monitoring period rather than sampling all on one day, always improved contaminant detection. Detection by plans based on fixed times and locations were very sensitive to those times and locations. There was no best plan suitable for all situations tested. The better sampling plans were those that captured the temporal and spatial contamination patterns present in the system. No consistent advantage was noted from sampling in proportion to population served or in locating sampling nodes systematically instead of randomly. The location and timing of sampling for most plans could be improved with the knowledge of actual contamination patterns and timing provided by the model. The presence of a storage tank was found to have a strong influence on hydraulic patterns and the location and timing of contamination reaching different parts of the system. / Ph. D.

The efficacy of indoor environment evaluation is, in part, a function of the reliability and validity of the different measures used. This thesis presents results of a study, conducted in a building without known problems, which compares the reliability and validity of sensory comfort components from three well-known survey questionnaires. A review of literature reveals that sensory comfort theory draws upon many disciplines including, hedonics, psychometrics, and olfaction theory. The fundamental domains thermal, air quality, lighting, and acoustics and their dimensions are identified. The conceptual model integrates these theories underlying human response to sensory comfort. The research questions involved in the selection of survey questionnaires are explored by examining sixteen indoor environment survey questionnaires. A meta-evaluation reveals that these questionnaires have three major functions, proactive, reactive, and re-evaluative studies. Finally, the methods used to analyze survey questionnaires for reliability and validity are examined. An analysis of variance shows that the order in which questions were presented did not affect responses. The reliability of the measures tested ranged from poor to good. Examination of content and face validity by expert and untrained judges demonstrates inconsistencies in common or accepted meanings of the measures considered in evaluating the indoor environment. Analysis of construct validity indicates that not all survey questionnaire variables were categorized under their expected dimensions. Contrary to advice found in the literature, this thesis suggests that the practice of combining items from different questionnaires is problematic. Finally, in buildings with known problems we can expect a relatively high degree of reliability and validity. However, the utility of such questionnaires in inventorying and assessing buildings without known problems will prove to be questionable. / Master of Urban and Regional Planning

Two mathematical models (TASS and PT AEDA2) were applied to the study of long-term interactions of air pollution stress and forest growth and yield. TASS was previously developed to examine the dynamics and yield of Douglas-fIr, and PTAEDA2 was previously developed to examine individual tree growth and stand development in loblolly pine plantations. Differential levels of pollution stress were incorporated into TASS through the reduction of the input variables photosynthetic efficiency and average needle retention. Reductions of photosynthetic efficiency included 0, 7.5, and 15 percent, while average needle retention was reduced 0 and 1 year. These reductions were distributed evenly over each of the five most current years' needles. Percentage volume reductions of 0, 17.3, 4.4, 23.1, 16.0, and 32.4 were obtained as results from six TASS scenarios. Given these percentage volume reductions, several levels of crown ratio reduction (0, 5, 10, 12, 15, and 22 percent) were applied to PTAEDA2 in order to determine the crown ratio reductions necessary to cause the same percentage volume reductions obtained from TASS. Results indicate that crown ratio reductions of 0, 5, 10, 12, 15, and 22 caused total volume reductions of 0, 6.3, 14.9, 18.7, 22.6, and 33.3 percent. These results are not intended to be final quantitative answers to the question of possible volume reductions due to air pollution impacts. However, they do offer insights to the possible effects of air pollution stress on forests. / Master of Science

A bench study was conducted to compare two membrane filter techniques for their efficiency in recovering fecal coliforms exposed to selected heavy metals. The effects on recovery by increasing time and metal concentration were also examined. The recovery methods employed included the standard membrane filter technique (S-MF) and a modified membrane filter technique (M-MF)~ which consisted of a lactose agar overlay and a five-hour preincubation at 35 C. The heavy metals Cd, Cr, Pb, and Zn were examined, each at two concentrations, to evaluate their effect on the recovery of the I. coli test organism, after exposure for 6, 24, and 48 hours. A statistical analysis of the data found the recoveries obtained by the M-MF to be significantly greater (.0001 level) than those of the S-MF, in all cases. Time was also found to significantly effect recovery, with recoveries decreasing as time increased. A significant difference was also found between the effects of the heavy metals tested and the concentrations of metals was likewise found to significantly effect recovery, with decreased recoveries being obtained at the high concentration of each metal. / Master of Science

Exposure to ground-level ozone (O₃), which forms secondarily in the atmosphere, intensifies the risk of respiratory and cardiovascular diseases. Effective mitigation strategies require understanding the spatiotemporal variability of O₃ precursors, including nitrogen oxides (NOx) and volatile organic compounds (VOCs), as well as O₃ formation photochemistry. This thesis examines the concentrations of trace gases closely related to O₃ production, specifically nitrogen dioxide (NO₂, the dominant component of NOx) and formaldehyde (HCHO, a proxy for VOC reactivity), as well as photochemical conditions. I investigate how these factors differ on high-O₃ days, change diurnally, and respond to the temporal resolution of anthropogenic emissions. The focus is on the summer of 2018 due to the availability of trace gas retrievals from the TROPOspheric Monitoring Instrument (TROPOMI) and in situ measurements from field campaigns. I first investigate New York City (NYC) and the Baltimore/Washington D.C. area, where high O₃ levels frequently occur in summer. On high-O₃ days (when the maximum daily 8-hour average (MDA8) O₃ exceeds 70 ppb), tropospheric vertical column densities (VCDTrop) of HCHO and NO₂ increase in urban centers. The HCHO/NO2 VCDTrop ratio, proposed as an indicator of local surface O₃ production sensitivity to its precursors, generally rises due to a more pronounced increase in HCHO VCDTrop. This suggests a shift toward a more NOx-sensitive O₃ production regime that could enhance the effectiveness of NOx controls on the highest O₃ days. As retrievals of tropospheric trace gases from Low Earth Orbit (LEO) satellites like TROPOMI are limited to one overpass per day (early afternoon), I then analyze spatial variability in HCHO and NO₂ concentration diurnal patterns and connect changes in column densities with surface concentrations. Diurnal HCHO patterns indicate the impact of temperature-dependent VOC emissions, while a bimodal surface NO₂ pattern reflects diurnal patterns of local anthropogenic NOx emissions and boundary layer dynamics. Column concentration peaks generally occur about four hours after surface concentration peaks (morning for NO2 and midday for HCHO), highlighting the challenge of relating column densities to health-related surface concentrations. I also explore how the temporal resolution of anthropogenic emissions influences air pollution levels and diurnal variations. Surface NOx and O3 concentrations show different spatial patterns of change when switching from daily mean to hourly varying nitric oxide emissions. In urban areas of both the western and eastern CONUS, adding hourly NO emissions increases daytime emissions, leading to O₃ decreases, indicating NOx-saturated O₃ chemistry. In the western CONUS, monthly mean surface NO₂ increases, while in the eastern CONUS, characterized by shorter NO₂ lifetimes, NO₂ decreases. These sensitivities highlight the importance of accounting for diurnal changes when inferring emissions from concentrations. This thesis advances our understanding of O₃-NOx-VOC air pollution by exploring variations in both surface and column conditions across urban-rural gradients. It integrates in situ measurements, space-based observations, and modeling techniques and assesses advanced modeling tools for future applications. These findings support the future applications of geostationary satellite retrievals for continuous trace gas observation throughout daylight hours, supplementing the once-a-day LEO satellite data used in this thesis, with implications such as aiding source attribution and targeting cost-effective control measures for O₃ mitigation.

The suitability of the open, stirred-jar technique as a method to estimate oxygen-uptake due to degradation of organic waste and nitrification by suspended microbes was studied. With this procedure, both the concentration of waste and the reaeration rate can be set to values similar to those expected in the stream. Thus, the conditions in the jars resemble the deoxygenation process in the stream more closely than the BOD-bottle test. There is no need of assuming any particular type of kinetic behavior, because the procedure gives directly an oxygen-uptake curve. Long lags before nitrification were observed. In most experiments, the oxygen-uptake rate during the nitrification stage increased slowly, resembling a first-order increasing or autocatalytic behavior. When a waste with a low COD:TKN ratio was used, the oxygen-uptake rate was constant and low, resembling zero-order kinetics. The results showed that accurate estimates of oxygen-uptake can be obtained with the open stirred-jar test. The oxygen-uptake patterns include variations in the oxygen-uptake rate that are smoothed out when the classical BOD-bottle test and the first-order model are used. / M.S.