Effects of episodic exposures have gained attention as the regulatory focus of the Clean Water Act has shifted away from continuous-flow effluents. Standardized laboratory toxicity tests require that exposure be held constant. However, this approach may not accurately predict organism responses in the field following episodic exposures such as those associated with rain-driven runoff events or accidental pollutant discharge. Using a modified version of the 7-day short-term chronic test recommended by the US Environmental Protection Agency, Ceriodaphnia dubia were exposed to copper or cadmium for durations ranging from 1 minute to 24 hours. In addition, adult reproductive recovery and effects on second generation individuals was assessed following select copper exposures. Finally, cadmium exposures were compared in reconstituted hard water (RHW) and municipal treated wastewater effluent (TWE). Following exposure, organisms were transferred to clean RHW or TWE and maintained for the remainder of the test. No- and lowest observed effect concentrations (NO- and LOECs) increased logarithmically with respect to logarithmic decreases in duration regardless of metal, endpoint or water type. Effective concentrations of cadmium however, were usually higher than those of copper, especially in TWE. LOECs for C. dubia survival following 24-hour and 5-minute exposures to copper were 116 and 417 µg/L, respectively. LOECs for fecundity were 58 and 374 µg/L, respectively. Neonate production of first generation adult C. dubia appeared to recover from pulsed copper exposure upon examination of individual broods. Cumulative mean neonate production however, showed almost no signs of recovery at exposure durations ≥3 hours. Pulse exposure to copper also resulted in diminished fecundity of unexposed second generation individuals. Such effects were pronounced following parental exposure for 24 hours but lacking after parental exposures ≤3 hours. LOECs for C. dubia survival following 24-hour and 5-minute exposures to cadmium in RHW were 44 and 9000 µg/L, respectively. LOECs for fecundity were 16 and 5000 µg/L, respectively. In TWE, LOECs for C. dubia survival were 83 and >10,000 µg/L, respectively. LOECs for fecundity in TWE were 48 and 7000 µg/L, respectively. Runoff pollution is site and event specific, however, data presented herein may be useful as a predictive tool under various conditions.

Economic and ecological processes interact with one another over both spatial and temporal dimensions.This dissertation explores four socio-ecological systems where space crucially matters for both economic and ecological outcomes. In the first chapter, a windborne chemical dictates the diffusion in space of a new agricultural technology. The second chapter dissects the notion of landscape complexity to find which of its components matter for the intensity of insect pressure in agriculture, and thus the use of insecticides. In the third chapter, the location of participants in an environmental program seeking to curb deforestation points to additionality problems and anticipates the lack of measurable effects of the program. Knowing where crops are grown and temperatures less well-suited for their thriving is key to identifying in chapter four the effects of weather fluctuations on asylum applications into the European Union. The spatial dimension tends to be hard to apprehend and overlooked, but those four pieces together stress that space matters in the study of sustainable development.

Thesis (DTech (Environmental Health))--Cape Peninsula University of Technology, 2011. / This study was aimed to provide baseline information about the environmental levels of selected PBDEs (BDE 28, 47, 100, 99, 154, 153, 183 & 209) and BB 153 in different matrices, including wastewater treatment plants' effluent, sludge, landfill leachate, river water and bottom sediment samples from different locations within the City of Cape Town. The monitoring of these contaminants was carried out bi-monthly over an extended period of 12 months beginning from April 2010 to March 2011. In this study, a total of 63, 168, 312, 93 and 108 samples for leachate, wastewater treatment plant (WWTP) sludge, effluent, river water and bottom sediment, respectively were collected from three landfill sites, four WWTPs and two rivers within the City of Cape Town. The aqueous matrices were extracted using a liquid-liquid extraction technique. The extraction of both sediment and sludge samples were performed using mechanical shaking and soxhlet extraction techniques, respectively. Extract obtained were further purified using multi-layer silica gel column chromatographic technique. The routine analysis of these target compounds was carried out using a gas chromatograph equipped with an electron capture detector (GC-µECD). However, the structural elucidation of these compounds was performed with a gas chromatography-time of flight-mass spectrometry (GC-TOF-MS) instrument.

Volcanic rocks typically have only low to moderate arsenic concentrations, none-the-less, elevated levels of arsenic in ground waters have been associated with pyroclastic and volcaniclastic rocks and sediments in many parts of the world. The potential for arsenic leaching from these deposits is particularly problematic as they often comprise important water-bearing units in volcanic terrains. However, the role that chemical and mineralogical variations play in controlling the occurrence and mobility of arsenic from pyroclastic rocks is largely unexplored. This study uses chemical and X-ray diffraction data to characterize and classify 49 samples of ash-flow tuffs, and 11 samples of tuffaceous sediments. The samples exhibit a range of devitrification and chemical weathering. Total and partial digestion, and water extractions of samples are used to determine the total, environmentally available, and readily leachable fractions of arsenic present in all tuff samples. Leaching experiments were also performed with buffered solutions to determine the influence of elevated pH levels on arsenic mobility. The 49 tuff samples have a mean arsenic content of 7.5 mg kg-1, a geometric mean arsenic content of 4.8 mg kg-1, a median arsenic content of 5.2 mg kg-1, and a maximum arsenic concentration of 81 mg kg-1. The mean and median values are 2.8 - 4.4x the average crustal abundance of 1.7 mg kg-1 (Wedepohl, 1995), and consistent with previously reported values for volcanic glasses and felsic volcanic rocks (Onishi and Sandell, 1955; Wedepohl, 1995), although the maximum arsenic content is higher than previously reported (e.g., Casentini et al., 2010; Fiantis et al., 2010; Nobel et al., 2004). In addition, the arsenic concentrations of tuffs were found to be highly heterogenous, both between and within individual units, and in some cases, individual outcrops. Results of whole rock and leachate analyses indicate that there is no significant difference in the total arsenic content of tuffs as a result of devitrification or weathering, but both devitrified and weathered tuffs contain higher levels of environmentally available arsenic than unweathered glassy tuffs. Glassy tuffs did not produce any readily leachable arsenic, while individual devitrified and weathered tuffs both generated aqueous concentrations that exceeded regulatory limits after 18 hours. Leaching of weathered tuffs produced higher levels of arsenic at high (~9-11) pH than in tests conducted at circum-neutral pH. Devitrified and glassy tuffs showed no increase in leachable arsenic with increasing pH. The results of this study indicate that devitrification and weathering processes determine the host phases, degree of adsorption, and overall mobility of arsenic from ash-flow tuffs. Tuffs that have undergone different types of alteration are likely to have different host phases of arsenic, and different mechanisms that mobilize arsenic into the environment. Potential host phases and mobility mechanisms are discussed, and a conceptual model of arsenic behavior in ash-flow tuffs is proposed.

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Over the past two decades, an increasing amount of research has been directed toward climatic influences on behavior and the built environment. The evidence from this research has lead to the development of recommended site interventions to improve energy performance in individual buildings and to mitigate extreme climate conditions in exterior public spaces in order to make these environments more comfortable."Comfort", as a measure of performance, is usually based upon one of the many indices of thermal comfort. These indices, however, have been developed specifically for use in indoor environments and were later readapted for exterior environments. Previous research has begun to show that standards designed for and developed in interior settings, are not necessarily applicable for use in exterior environments where climate is only partially controllable and behavior is less defined. Early preliminary studies have shown that considerable activity will occur outside of the boundaries formally established as “comfortable” by any particular thermal index. In contradiction to the traditional thermal performance measures that determine specific climatological conditions to support a particular behavior, this research uses two bio-comfort charts and a thermal indexing equation to establish what specific behaviors will occur under particular climate profiles. This study takes an annual record of regional and site specific climate data and applies it to existing comfort prediction models to ascertain if such applications are legitimate and if these applications are capable of predicting the frequency and duration of observed social behavior in an outdoor urban setting. / Master of Landscape Architecture

A naturalistic method (concealed video camera) on the Library Plaza at Virginia Tech has been used successfully to document the climate-behavior relationships in outdoor space. Analysis of the data reveals that each climatic factor had certain types of relationships with outdoor human behaviors, and that it might be possible to predict the amount of outdoor activity occurring on the plaza under a specific climate profile. Due to the lack of previous research and data similar to our observations, we experienced some difficulties in comparing the results with previous research and in doing systematic analysis. The individual climate factors such as temperature, relative humidity, wind velocity, solar radiation, and the composite climate index, the Index of Thermal Stress, were analyzed to find a relationship with outdoor behavior. Graphic and statistical methods were used to analyze observation data. As the temperature on the plaza increased, there was a strong tendency for people to extend their time of stay on the plaza. But the temperature did not seem to have any strong relationship with the number or percentage of people who stayed on the plaza. Relative humidity appeared to have a negative correlation with the frequency of stationary behavior, but almost no relationship with average duration of stationary people. This finding conflicts with Givoni who reported that variations in relative humidity between 30% and 85% were almost imperceptible and at temperatures above 25°C, the influence of humidity on the response became gradually more apparent (Givoni,1981). Most of our observations were done under the temperature range of 0° ~ 25°C with a relative humidity of 30 ~ 85%. Under our observational condition (wind velocity less than 24 Km/hr), wind velocity had the strongest relationship with the frequency of stationary behavior. As the wind speed increased, the number and percentage of stationary people decreased almost linearly. Thus, wind velocity is a determining factor and the lower wind velocity is an impetus that induces people outdoors to pause or rest. The relationship between air velocity and the average duration of stationary people had a slightly negative correlation. The negative correlation was understandable, but, because it was negligibly weak, there was no meaningful relationship. Solar radiation did not appear to be an important factor for inducing people outside to stay on the plaza. But this study showed that the greater the solar radiation, the longer people stayed. The mean of the Index of Thermal Stress of Fall data was -139.268 and that of spring was 14.40. Therefore, in Fall, it was probable that people felt cold stress while in spring people were more likely to be comfortable. In Fall observations, the I.T.S. had a stronger relationship with frequency and duration of outdoor stationary behaviors than any single climatic factor. As the I.T.S. increased(in other words, as the cold stress decreased), more people stayed on the plaza and people tended to stay longer periods of time under the weather conditions in the fall of Southwestern Virginia. But, in spring observations, the relationships were much weaker than Fall observation. It was found that I.T.S. seemed to show a strong relationship between climate and outdoor behaviors if the I.T.S. values of data were completely negative or completely positive. / Master of Landscape Architecture