O lançamento de esgoto não tratado é um dos principais fatores que contribuem para a poluição das águas. O tratamento de esgotos, quando existente, em grande parte dos casos é insuficiente para a remoção satisfatória de poluentes, principalmente para o atendimento aos padrões legais. Dentre os diversos motivos desta ineficiência, destacam-se o desconhecimento da composição efetiva do esgoto bruto de entrada e das eficiências dos processos unitários em diferentes locais de instalação, com alterações de clima, relevo, vegetação, dentre outros. Assim como para outras atividades, os projetos de estações e a seleção dos sistemas de tratamentos de esgoto contemplam um processo trabalhoso e demorado devido à grande quantidade de variáveis que devem ser considerados. A inexistência de modelamento sistêmico para tomada de decisão em projeto relacionados ao tratamento de esgotos dificulta ainda mais este processo. No intuito de atender esta carência, o presente projeto de pesquisa propõe que se elabore uma ferramenta que auxilie a tomada de decisão para projetos de ETE's de pequeno porte, possibilitando com uma consulta rápida, a partir do fornecimento de algumas informações sobre o local de instalação e da população a ser atendida, identificar os processos mais indicados para compor a estação de tratamento. / The release of untreated sewage is a major factor that helps contributing to water pollution. The sewage treatment, if any, in most cases is insufficient for satisfactory removal of pollutants, primarily for compliance with legal standards. Among the many reasons for this inefficiency, it was highlighted the lack of effective composition of raw sewage input and efficiencies of unit processes at different installation sites, with changes in climate, topography, vegetation, among others. As for other activities, projects of stations and selection of wastewater treatment systems include a laborious and time consuming due to the large number of factors that must be considered. The absence of auxiliary systems for decision making on project related to sewage treatment complicates this process. In order to meet this need, this research project proposes to develop a tool of decision making for projects of small WTP's, allowing with a quick query, providing some information about their location and population to be served, identify the processes that best suits to compose the treatment station.

Orientadores: Francisco Sergio Bernardes Ladeira, Salvador Carpi Junior / Anexos: 2 tabelas de dados e 1 mapa "Riscos ambientais e sua distancia" / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-09T15:09:31Z (GMT). No. of bitstreams: 1 Dagnino_RicardodeSampaio_M.pdf: 5764412 bytes, checksum: 131645cec6e822cb39869ebdce2dd6a1 (MD5) Previous issue date: 2007 / Resumo: Este trabalho trata dos riscos ambientais na Bacia Hidrográfica do Ribeirão das Pedras, uma importante sub-bacia do Ribeirão das Anhumas, no Município de Campinas, Estado de São Paulo. O Ribeirão das Pedras drena águas do Distrito de Barão Geraldo e dos Bairros Santa Genebra, Jardim Costa e Silva, Alto Taquaral, Jardim Primavera e outros. Nesta bacia se localizam os campi de diversas instituições de ensino e pesquisa como a Universidade Estadual de Campinas (Unicamp) e a Pontifícia Universidade Católica de Campinas, além de diversas indústrias e estabelecimentos comerciais de grande porte. Na área da bacia, 29,7 km2, residem cerca de 36 mil habitantes, totalizando mais de 1200 hab/km2. O mapa final, elaborado com base na representação proposta por Journaux (1985), utilizou dados adquiridos em trabalhos de campo, além de outros resultados do Projeto Anhumas ¿ FAPESP. Dentre o total de 120 situações de riscos mapeadas, os maiores, em área, foram identificados como riscos relacionados ao cultivo agrícola, com a utilização de agrotóxicos e o cultivo de Organismos Geneticamente Modificados (OGM), além das situações de riscos especiais, relacionados à presença da Unicamp e do Shopping Parque D. Pedro como as principais fontes de riscos da Bacia. Ao final, são feitas sugestões de continuidade para o estudo de riscos ambientais utilizando o mapeamento participativo de riscos e a proposta de cartografia elaborada com base em Journaux (1985) / Abstract: This work deals with the environmental risks at Ribeirão das Pedras, an important subwatershed of the Ribeirão das Anhumas watershed, at Campinas, São Paulo state. The Ribeirão das Pedras drains waters of the of Barão Geraldo district and the quarters called Santa Genebra, Jardim Costa e Silva, Alto Taquaral, Jardim Primavera and other quarters. In this basin is located universities, as the State University of Campinas (Unicamp) and the Pontifical University Catholic of Campinas, and big industries and commercial establishments. In this watershed live 36 thousand inhabitants, in one area like 29,7 km2, totalizing more than 1200 hab/km2. The final map, elaborated on the basis of the representation proposal for Journaux (1985), used data collected in fieldwork, and additional results of the Anhumas Project - FAPESP. Amongst the total of 120 mapped risk situations, the biggest, in area, was identified a risks related to plantation with agro-toxics and the culture of genetically modified organism (GMO). Moreover, the presence of the Unicamp and Dom Pedro Shopping, classified as special situation of risk, are related as the main sources of risks of the watershed. At the end, suggestions are made for the continuity of using the participatory risk mapping and the cartography elaborated on the basis of Journaux (1985) in other environmental risk studies / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia

M.Sc. / Pollution of the earth is presently one of the most important environmental issues of the world and various attempts, including creation of public awareness have been initiated over the past few years to address this situation. There is especially a global concern about the progressive pollution of valuable freshwater systems which most organisms, including humans, are reliant upon. This includes South Africa's aquatic ecosystems, many of which have been degraded over the past few decades. The Olifants River in Mpumalanga is one of the most threatened river systems in South Africa. It is impacted by various anthropogenic activities, particularly mining in the upper catchment, and urbanisation, industrial and agricultural activities in the upper and lower catchments. Previous investigations have shown that these activities are responsible for the degradation of this river system. The broad objective of this study was to obtain data on water and sediment quality, as well as bioaccumulation of metals in fish via monitoring of the Olifants River. It formed part of a major study concerned with the experimental investigation of lethal and sub-lethal effects of metals on fish physiology, supported by a field investigation into the water quality and metal contamination of the biotic and abiotic components of the Olifants River system. Physico-chemical properties of the water as well as the concentrations of some metals (Al, Fe, Cu, Zn, Ni, Mn, Pb & Cr) in the water and sediment were seasonally investigated. The extent of bioaccumulation of these metals in selected organs/tissues (muscle, gills, liver & skin) of Oreochromis mossambicus and Clarias gariepinus from Loskop Dam (upper catchment) and Mamba Weir, Kruger National Park (lower catchment) was also investigated. High levels of various macro-constituents and metals were detected at many sites in the study area and in many cases they exceeded the guideline limits set for aquatic ecosystems. Localities 2, 3, 6, 8, 10, 12 and 17 were observed to be severely impacted (see Chapter 9- Table 9.1) by elevated concentrations of pollutants influencing variables such as TDS and sulphates. This confirms that these sites are being impacted by mining. This was further confirmed by low pH-values at localities 3, 5, 8, 9, 10 and 12 which indicate on acid mine drainage originating from the many coal mines in the upper catchment of the Olifants River. Nutrient enrichment (elevated levels of phosphates, nitrates and nitrites) occurred at many sites in the catchment but in particular at localities 3, 4, 6, 10, 11, 14, 15 and 17. Point source pollution from sewage treatment works and non-point sources from agricultural runoff and informal settlements are the main contributors to these elevated levels of nutrients. The Selati River, impacted in particular by elevated phosphate levels, is the main contributor to the high nutrient levels detected at locality 17. It is evident from the evaluation of the metal concentrations in the water and sediment (Table 9.2) that most of the sites in the Olifants River catchment are being impacted by metal pollution. Oreochromis mossamhicus and C gariepinus sampled at selected sites in the Olifants River accumulated selected metals in the following order; Fe>Zn>Al>Cr>Ni>Pb>Mn>Cu. Levels were generally high in the liver and gills, while much lower levels were detected in the skin and muscle tissues. Gill tissue is in direct contact with the aqueous environment and therefore gives a good indication of the extent of exposure. Skin tissues usually contained relatively low levels of metals (except for Zn). Although muscle tissues usually accumulated low metal concentrations it is an important tissue to monitor in bioaccumulation studies as it can lead to metal poisoning if contaminated muscle tissues are consumed by humans. Adult specimens were mostly sampled and within this range there was a slight decrease in Cu, Al, Fe, Ni, Mn and Cr concentrations with increasing age. Temporal variation in metal accumulation by fish possibly occurred due to variations in metal concentrations in the water and sediment at a locality. These differences were caused by seasonal variation in climatical conditions (eg. rainfall, temperature), as well as temporal fluctuations of pollutant inputs into the river system. Aquatic organisms at both localities 15 (Loskop Dam) in the upper catchment and 17 (Mamba weir, Kruger National Park) in the lower catchment are at present being chronically exposed to elevated levels of the investigated metals, compared to both the control site and results in literature. The impact of the highly polluted Selati River in the lower catchment was evident in the difference between metal concentrations detected in fish at locality 17, and at locality 19 (Phalaborwa Barrage) upstream of the Olifants-Selati confluence. The present study clearly indicates that the Olifants River is subjected to various sources of pollution which could be detrimental to the health of this aquatic ecosystem. It is recommended (see Chapter 9) that a multi-disciplinary approach including a biomonitoring programme, should be followed to ensure a sustainable freshwater ecosystem.

D.Phil. / The entire Olifants . River Catchment is subjected to increasing afforestation, agricultural, domestic, mining, industrial, irrigation and urbanisation activities. These activities have a profound effect on the water quality of the river and its tributaries. This is cause for concern for the water users in the upper catchment, and because the Kruger National Park, one of its downstream water users, is extremely dependent on water of a satisfactory quality to sustain its various ecosystems. It is therefore vitally important to determine to what extent activities in the Upper Catchment of the Olifants River (Mpumalanga), especially in the Witbank and Middelburg areas, influence the water quality of the river. Point sources of pollution in the upper reaches include mining and industrial activities as well as water care works located at various points along the river. These were addressed in a Water Research Commission Project (No. 608/1/97) titled "Lethal and sublethal effects of metals on the physiology of fish: An experimental approach with monitoring support". Although sixteen localities were chosen for the initial project, this study only focussed around the metal ecotoxicology at two localities (Steenkool Spruit and Witbank Dam) in the upper catchment and the effect of metals (copper and zinc) on fish blood physiology. In aquatic ecosystems water quality is an important variable and full assessment of water quality, of Steenkool Spruit (locality 3) and Witbank Dam (locality 7), included evaluation of the chemical, physical and biological characteristics at each of the localities. Water and sediment samples were collected seasonally during the study period, February 1994 to May 1995, and the chemical and physical water quality variables were measured. During the study period three metal bioaccumulation indicator species, Labeo umbratus, Clarias gariepinus and Labeo capensis, were captured from which tissue (gills, liver, muscle and skin) samples were collected. These samples as well as water and sediment samples, were analysed for aluminium, chromium, copper, iron, manganese, nickel, lead and zinc concentrations, using atomic absorption spectrophotometry. In the past routine monitoring of chemical and physical water quality characteristics left scientists and managers with a sizeable pool of data which is often difficult but not impossible to interpret. To standardise and summarise this collection of data an aquatic toxicity index (ATI), WATER2 was developed by Wepener et at (1992). The present study attempted to expand and refine WATER2, which has resulted in the establishment of a new ATI, RAUWater.

M.Sc. / The catchment area of the Olifants River has, over a number of years, been exposed to extensive mining, agriculture and urbanisation activities in the Witbank-Middelburg and Phalaborwa regions which has largely contributed to the deterioration of water quality. Of major concern is the influence anthropogenic activities have on the aquatic ecosystem of the Olifants River within the Kruger National Park and how me health of fish residing In these waters is affected. To determine fish health, a biological monitoring method, the Health Assessment Index (H41), was tested for the first time In South Africa. Four surveys were conducted at Mamba and Balule In the Olifants River, Kruger National Park during 1994 (February, May, July and November). An additional survey was conducted in February 1995 at Loskop Dam. Samples of water and sediment were taken for analysis of metals and physical and chemical water parameters. A maximum of 20 Clarias gariepinus fish were sampled at each location. Evaluation of the fish was done according to guidelines set in the HAI and parasite population composition (prevalence, abundance, mean intensity) was determined. Organ and tissue samples including gills, liver, muscle and skin were analysed for the bioaccumulation of chromium, copper, Iron, manganese, nickel, lead, strontium and zinc, using atomic absorption spectrophotomeby. Metal concentrations in the water at Mamba and Balule were within guideline limits, whereas concentrations at Loskop Dam were above guidelines. As reflected by the application of the Aquatic toxicity Index, Loskop Dam presented with the poorest water quality followed by Mamba then Balule. It was found that certain physical and chemical variables namely fluoride, potassium, sulphate and total dissolved solids concentrations at Mamba and Balule were relatively high, particularly during drier months. Metals accumulated in organs and tissues, with the highest concentrations In the gills followed by the liver, skin and muscle. The discriminant analysis, utilising metal bloaccumulation, discriminates between water quality at Mamba and Balule, revealing a 100 % classification probability for each survey. Values obtained In the application of the HAI indicated that variables with good predictor accuracy were plasma protein, all parasites, endoparasites, liver, white blood cell counts, ectoparasites, skin, fins and gills. The discriminant function for the HAI generally Indicated variables similar to those exhibiting high predictor accuracy. The discriminant function showed relatively low classification probability for each survey. In case 1, where separate endo- and ectoparasite variables were Included in the determination of me discriminant function, probability for me entire study ranged between 47.5 % and 84.2 %. In case 2, where endo- and ectoparasite variables were given a refined score rating system, probability ranged between 62.5 % and 100 %. The low classification probability Indicates either the Importance of repetitive testing for this technique or a total departure from it. Results showed that fish populations with higher HAI values are found in water of poorer quality (Mamba), while healthier fish populations i.e. with lower RAI values are found In water of better quality (Balule). Parasite data shows a similar tendency by indicating that ectoparasites are abundant in water of higher quality, while endoparasftes increase in water of poorer quality. The HAI reflects the condition of fish populations in relation to their aquatic environment, therefore, the HA/ gives an indication of water quality and should be used as a first level screening tool. If complemented by a parasite survey, distinguishing between endoand ectoparasites, the results from the HAI will be enhanced.

Made available in DSpace on 2017-06-01T18:20:28Z (GMT). No. of bitstreams: 1 dissertacao_roberto_cesar.pdf: 1051704 bytes, checksum: 01800777eccdcbca21a49c5a3a0b2da5 (MD5) Previous issue date: 2008-06-10 / The objective of this study was to evaluate the conditions for modeling the pollution of a river by an effluent from laundry and dying industries. Samples were collected from this treated effluent in the city of Toritama, Pernambuco and in the Capibaribe river before and after the effluent launch. Temperature, pH, color, turbidity, sedimented solids, electrical conductivity, nitrogen (ammonium, nitrite and nitrate), dissolved oxygen, chemical oxygen demand, biochemical oxygen demand, bacteria counting pattern and coliforms (total and thermotolerant) were analyzed. The results of temperature, pH, color, turbidity and sedimented solids from the industrial effluent did not interfere in the water quality of the Capibaribe river. The high electrical conductivity due to the excess of salts in this effluent was one of the parameters responsible for the ecological imbalance. The absence of dissolved oxygen in the treated effluent was one of the factors that did not help the selfdepuration of water. The launch of organic material in the Capibaribe river water with low concentrations of dissolved oxygen was confirmed by the high biochemical oxygen demand. The high bacteriological contamination detected also contribuited for the water pollution. The non sustainability of the river in the period of drought and the difficulty of determining the flow because of dams in the stretch examined, were determining factors that haltered the development of a methodology to identify the type of the mathematic model that should be applied in this study. The disorderly occupation of laundry and dying industries on the banks of the river and the lack of sanitation in the region were the factors that characterized the diffuse pollution. Thus, the construction of a model to simulate the environmental impact of the effluents from the laundry and dying industries was not feasible. The conditions for this investigation did not offer minimal resources needed for the modeling of the River in Toritama. There is a need for a survey of data in small portions of the Rio so that the experimental results can be evaluated and interpreted, targeting the development of a model that could assist in the management of water resources in the region / O objetivo deste trabalho foi avaliar as condições para modelagem da poluição de um rio não perene por efluente de lavanderia e tinturaria industriais. Foram coletadas amostras do efluente tratado no município de Toritama, Pernambuco e do rio Capibaribe a montante e a jusante do lançamento desse efluente. Foram analisados: temperatura, pH, cor, turbidez, sólidos sedimentáveis, condutividade elétrica, nitrogênio (amônia, nitrito e nitrato), oxigênio dissolvido, demanda química de oxigênio, demanda bioquímica de oxigênio, contagem padrão de bactérias e coliformes totais e termotolerantes. Os resultados de temperatura, pH, cor, turbidez e sólidos sedimentáveis do efluente industrial não interferiram na qualidade da água do rio Capibaribe. A condutividade elétrica elevada devido ao excesso de sais existentes no efluente de lavanderia e tinturaria industriais foi um dos parâmetros responsável pelo desequilíbrio ecológico. A ausência de oxigênio dissolvido nesse efluente tratado foi um fator que desfavoreceu a autodepuração da água. O lançamento de matéria orgânica na água do rio Capibaribe, com baixa concentração de oxigênio dissolvido foi confirmado pelos valores elevados da demanda bioquímica de oxigênio. Os valores elevados de contaminação bacteriológica detectados também contribuíram para a poluição da água. A não perenidade do rio no período de estiagem e a dificuldade de determinar a vazão devido à existência de barragens no trecho analisado, foram fatores que dificultaram o desenvolvimento de uma metodologia para identificar o tipo de modelo matemático que deveria ser aplicado no referido estudo. A ocupação desordenada da região por Empresas desse segmento nas margens do Rio e a falta de saneamento básico nessa região foram os fatores que caracterizaram a poluição difusa. Então, a construção de um modelo para simular o impacto ambiental por efluente de lavanderia e tinturaria industriais foi inviável. As condições de investigação não ofereceram recursos mínimos necessários para a modelagem da água do rio Capibaribe em Toritama. Há necessidade de um levantamento de dados em pequenos trechos do Rio para que os resultados experimentais possam ser avaliados e interpretados, visando à elaboração de um modelo que possa auxiliar na gestão dos recursos hídricos da região

Marshy soil and sediment samples were collected during dry and rainy seasons within Warri, and Agbarho, 20km away as control. Levels of 16 USEPA priority Polycyclic Aromatic Hydrocarbons PAHs were determined using GC-FID. Source prediction analysis was also done. The study was in Niger Delta region, Nigeria from January to March and June to August 2012 in dry and wet seasons. Benzo(a)pyrene had highest total concentration of 3.302mg/kg and mean value of 1.651mg/kg in dry season soil samples. However, sediment samples had highest levels for total concentration of PAHs of 19.362mg/kg and mean of 4.840mg/kg for both dry and rainy seasons within Warri. PAHs concentration was higher in dry than rainy seasons for soil and sediment samples. Source prediction analysis revealed that PAHs in sediments for dry season were pyrolytic while rainy seasons were petrogenic sources. For soils, the dry season was mixed sources while the rainy season was petrogenic. / Environmental Science / M. Sc. (Environmental Science)

Heavy metal pollution in water and soil is a serious concern to human health and the associated environment. Some heavy metals have bio-importance but the bio-toxic effects of many of them in human health are of great concern. Hence, there was a need for proper understanding of the concentration levels of these heavy metals in ground water and soil around the community residing in the vicinity of the defunct mine. Mining has become prominent in this area because of the existence of copper lodes, veins and veinlets. It was therefore necessary to assess these selected metals associated with copper mining as their concentration has a tendency to affect the environment and human health. The objective of this study was to establish the levels of lead (Pb)-zinc (Zn)-copper (Cu)-arsenic (As)-nickel (Ni) metals in ground water and soil associated with an old copper mine in the vicinity of the township and to compare them with the South African and international standards in order to safeguard the health of the community using such water for drinking purpose. Clean sampling plastic bottles were used to collect water from five water boreholes being used at present. Water samples were filtered using membrane filtration set LCW (0.45 μm). The samples were digested sequentially with different procedures for the total metal concentration. Concentrations of four metals commonly associated with Cu mining were examined at five different water boreholes which are used for drinking and industrial purposes. Flame Atomic Absorption Spectrophotometer (Perkin Elmar S/n 000003F6067A, Singapore) was used to analyze metals in water samples at Eskom Ga-Nala Laboratory: pH, electrical conductivity and turbidity were analyzed using an auto titrator meter (AT- 500,Japan), conductivity meter (Cole-parmer® YO-19601-00) and turbidity meter (AL 250TIR, Agua lytic, German) respectively. Soil samples were collected from the selected areas where human health is of a serious concern, and a hand held auger drill was used to recover samples, while shovels were used to prepare the sampling area. The samples were sieved up to 63.0 μm particle size and digested with aqua-regia. Flame Atomic Absorption Spectrophotometer (Model: AA400; Year: 2008; Manufacturer: Perkin Elmer; Germany; Serial no: 201S6101210) was used at the University of Venda Laboratory to analyze soil from the study area for possible heavy metal contamination due to the defunct Cu mine in the area. v The results showed variation of the investigated parameters in water samples as follows: pH, 6.0 to 7.51; EC, 70.0 to 96.40 μS/cm and turbidity, 1.05 to 4.56 NTU. The mean concentration of the metals increased in the followed order: Pb<Cu<As<Ni. Ni is the most abundant in the ground water determined with value of (6.49 μg/g). The observations have confirmed that most ground water contains an appreciable quantity of Ni. The mean value of As in water is (4.20 to 4.84 μg/g), Pb and Cu have (2.13 to 2.58 μg/g) and (1.52 to 2.52 μg/g) respectively. For soil samples, the mean concentration of the metals increased in the following order: Pb<Cu<Zn<As<Ni. Pb ranged from (0.023 to 0.036 μg/g) followed by Cu (0.28 to 0.45 μg/g) then Zn (0.026 to 0.053 μg/g), the mean range of As in soil ranged from (0.054 to 0.086 μg/g). However, some studies show much higher contamination of As from the natural sources and Ni with (0.057 to 0.144 μg/g) lastly. Accumulation of heavy metals in soil is of concern due to their toxic effects on human and animals. The quality of ground water from the five boreholes studied was satisfactory with turbidity (T), electrical conductivity (EC) and heavy metals (HM’s) below the WHO limit. The water therefore may, according to the WHO Standards be safely used as a drinking water. The concern lies on pH which was slightly (0.5) below the standard. There is a serious need to monitor the ground water which is now used for drinking purposes. This study revealed that heavy metal pollution in soil from the abandoned Cu mine in Musina is a threat to the health of the community. Although pollution was between medium and low in the contamination index, it is therefore important for the Musina Municipality or mine owner of Musina (TVL) Development Co Ltd copper mine to advocate possible remedial actions which will safeguard the environment and human health. The tailing at Musina’s old Cu mine have high pH and they lack normal soil stabilization processes, as a result the tailing does not develop a good plant cover. Pollution of the ground water resources is also evident in the study area where there is seepage or ingress of polluted water to the underground aquifers. Small-scale mining in Musina is causing further degradation to the environment but it supports the South African Waste Hierarchy by promoting the reuse and recycling of the tailing and mine dumps for the production of bricks. Mine workers are exposed to the above mentioned toxic heavy metals daily. Medicine will not help stop the poisoning. The only way to stop the metal poisoning is to stop being exposed to the heavy metals. / Environmental Sciences / M. Sc. (Environmental Management)

The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better characterizing biogenic VOCs (BVOCs) and thus SOA precursors. This work presents measurements of BVOCs collected during two field campaigns and analyzed using GC×GC/TOFMS. The first campaign, the Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS), took place in a Ponderosa pine forest in Colorado. The second campaign, Particle Investigations at a Northern Ozarks Tower: NOx, Oxidant, Isoprene Research (PINOT NOIR) Study, was conducted in the Ozark region of Missouri. Tens to hundreds of BVOCs were quantified in each set of samples, including primary emissions, atmospheric oxidation products, stress indicators and semi-volatile leaf surface compounds. These findings highlight that there is a largely uncharacterized diversity of BVOCs in ambient samples. Our findings demonstrate that GC×GC can distinguish between compounds with the same molecular weight and similar structures, which have highly variable potentials for production of SOA (Lee et al., 2006). This work represents some of the first analysis of ambient BVOCs with this technology, which is anticipated to contribute greatly to characterization of atmospheric SOA precursors and ultimately, regional and global modeling of SOA and fine particulate matter.

This dissertation consists of three essays in the field of environmental economics. The first chapter provides the first causal evidence that hostile activities online lead to physical violence. Given the recently documented relationship between pollution and social media, I exploit exogenous variation in local air quality as the first step to instrument for online aggression. In an event study setting, I find volatile organic compounds (VOCs) increase by 7% when refineries experience unexpected production outages. Together with higher air pollution, I find more aggressive behaviors both online and offline, as well as worse health outcomes near refineries. A one standard deviation increase in surrounding VOCs leads to 0.16 more hate crimes against Black people and 0.23 more hospital visits per thousand people each day. Second, I consider how emotional contagion spreads through social networks. On days with pollution spikes, surrounding areas see 30% more offensive and racist tweets and 12% more crimes; those geographically distant but socially networked regions also see offensive and racist tweets increase by 3% and more crimes by 4.5%. Nationally, overlooking spillovers would underestimate crime effects of pollution by 24%. My findings highlight the consequences of social media hostility and contribute to the public debate on cyberspace regulation. The second chapter, which is coauthored with Andrew Wilson, analyzes the relationship between weather and railway accidents. Rail thermal expansion and contraction are key considerations in rail design and construction; rail operators and rolling stock may likewise exhibit vulnerability to temperature changes. We quantify the sizes of these effects by leveraging a comprehensive dataset of railway malfunctions in the United States spanning 1997-2019. We find that both heat and cold cause elevated rates of railway malfunctions, with relatively larger increases in the number of incidents leading to a casualty as well as the number of injuries and deaths resulting from these incidents. We find that exposure to daily temperatures averaging over 30°C (86°F) leads to a 16% increase in the number of rail malfunctions, a 13% increase in the number of incidents leading to a casualty, and 18% and 36% increases injuries and deaths-effects net of any operational adjustments made to mitigate these effects. Further, while we also find that warmer locations exhibit a weaker relationship between heat and railway malfunctions, we find no evidence that companies are learning, year-over-year, how to reduce accidents. Finally, we note that effects of heat are strongest for derailments (versus other types of malfunctions) and freight trains (versus passenger trains). Our findings highlight the vulnerability of the railway system to the climate. The number of injuries and deaths associated with weather exposure-especially in comparison to operators' reported private costs of equipment failure-suggests a role for enhanced rail safety regulations and adaptation funding to protect critical heat-exposed infrastructure. The third chapter, which is a joint work with Douglas Almond and Muye Ru, explores the impact of federal policy rollback on methane leakage. Improvements in satellite measurement enable independent assessment of regulatory and climate policy. In August 2020, the Trump Administration lifted Obama-era requirements that oil and gas firms detect and repair methane leaks. We merge geo-identified data from the European TROPOMI (satellite instrument) to the specific locations of the US oil and gas infrastructure. Using a difference-in-differences design, we find a prompt increase in US methane emissions following the summer 2020 rollback. The number of high-methane emission events from the oil and gas sector more than doubled after the rollback relative to the coal sector, which did not experience the same regulatory rollback. While the oil and gas industry claims it faces a persistent, profit-making incentive to stem natural gas leaks and emissions, we find a large and nimble response by industry to changes in federal policy. Public policies that reduce methane externalities are critical given that global methane concentrations are rising at an increasing rate.