Repository for Oil and Gas Energy Research (ROGER)

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A thorough understanding of produced water (PW) quality is critical to advance the knowledge and tools for effective PW management, treatment, risk assessment, and feasibility for beneficial reuse outside the oil and gas industry. This study provides the first step to better understand PW quality to develop beneficial reuse programs that are protective of human health and the environment. In total, 46 PW samples from unconventional operations in the Permian Basin and ten surface water samples from the Pecos River in New Mexico were collected for quantitative target analyses of more than 300 constituents. Water quality analyses of Pecos River samples could provide context and baseline information for the potential discharge and reuse of treated PW in this area. Temporal PW and river water quality changes were monitored for eight months in 2020. PW samples had total dissolved solids (TDS) concentrations ranging from 100,800–201,500 mg/L. Various mineral salts, metals, oil and grease, volatile and semi-volatile organic compounds, radionuclides, ammonia, hydraulic fracturing additives, and per- and polyfluoroalkyl substances were detected at different concentrations. Chemical characterization of organic compounds found in Pecos River water showed no evidence of PW origin. Isometric log-ratio Na-Cl-Br analysis showed the salinity in the Pecos River samples appeared to be linked to an increase in natural shallow brine inputs. This study outlines baseline analytical information to advance PW research by describing PW and surrounding surface water quality in the Permian Basin that will assist in determining management strategies, treatment methods, potential beneficial reuse applications, and potential environmental impacts specific to intended beneficial use of treated PW.

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Epidemiologic studies have observed elevated health risks in populations living near unconventional oil and gas development (UOGD). In this narrative review, we discuss strengths and limitations of UOG exposure assessment approaches used in or available for epidemiologic studies, emphasizing studies of children’s health outcomes.

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Understanding emissions of methane from legacy and ongoing shale gas development requires both regional studies that assess the frequency of emissions and case studies that assess causation. We present the first direct measurements of emissions in a case study of a putatively leaking gas well in the largest shale gas play in the United States. We quantify atmospheric methane emissions in farmland >2 km from the nearest shale gas well cited for casing and cementing issues. We find that emissions are highly heterogeneous as they travel long distances in the subsurface. Emissions were measured near observed patches of dead vegetation and methane bubbling from a stream. An eddy covariance flux tower, chamber flux measurements, and a survey of enhancements of the near-surface methane mole fraction were used to quantify emissions and evaluate the spatial and temporal variability. We combined eddy covariance measurements with the survey of the methane mole fraction to estimate total emissions over the study area (2,800 m2). Estimated at ∼6 kg CH4 day–1, emissions were spatially heterogeneous but showed no temporal trends over 6 months. The isotopic signature of the atmospheric CH4 source (δ13CH4) was equal to −29‰, consistent with methane of thermogenic origin and similar to the isotopic signature of the gas reported from the nearest shale gas well. While the magnitude of emissions from the potential leak is modest compared to large emitters identified among shale gas production sites, it is large compared to estimates of emissions from single abandoned wells. Since other areas of emissions have been identified close to this putatively leaking well, our estimate of emissions likely represents only a portion of total emissions from this event. More comprehensive quantification will require more extensive spatial and temporal sampling of the locations of gas migration to the surface as well as an investigation into the mechanisms of subsurface gas migration. This work highlights an example of atmospheric methane emissions from potential stray gas migration at a location far from a well pad, and further research should explore the frequency and mechanisms behind these types of events to inform careful and strategic natural gas development.

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The association between hydraulic fracturing and human development is not well understood. Several studies have identified significant associations between unconventional natural gas development and adverse birth outcomes; however, geology and legislation vary between regions.To examine the overall association between residential proximity to hydraulic fracturing sites and adverse birth outcomes, and investigate whether well density influenced this association.This population-based retrospective cohort study of pregnant individuals in rural Alberta, Canada, took place from 2013 to 2018. Participants included reproductive-aged individuals (18-50 years) who had a pregnancy from January 1, 2013, to December 31, 2018, and lived in rural areas. Individuals were excluded if they lived in an urban setting, were outside of the age range, or were missing data on infant sex, postal code, or area-level socioeconomic status.Oil and gas wells that underwent hydraulic fracturing between 2013 to 2018 were identified through the Alberta Energy Regulator (n = 4871). Individuals were considered exposed if their postal delivery point was located within 10 km of 1 or more wells that was hydraulically fractured during 1 year preconception or during pregnancy.Outcomes investigated were spontaneous and indicated preterm birth, small for gestational age, major congenital anomalies, and severe neonatal morbidity or mortality.After exclusions, the sample included 26 193 individuals with 34 873 unique pregnancies, and a mean (SD) parental age of 28.2 (5.2) years. Small for gestational age and major congenital anomalies were significantly higher for individuals who lived within 10 km of at least 1 hydraulically fractured well after adjusting for parental age at delivery, multiple births, fetal sex, obstetric comorbidities, and area-level socioeconomic status. Risk of spontaneous preterm birth and small for gestational age were significantly increased in those with 100 or more wells within 10 km.Results suggest that individuals who were exposed to hydraulic fracturing within pregnancy may be at higher risk of several adverse birth outcomes. These results may be relevant to health policy regarding legislation of unconventional oil and gas development in Canada and internationally.

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Natural gas production from the Appalachian region has reached record levels, primarily due to the rapid increase in development of unconventional oil and gas (UOG) resources. In 2020, over 65,000 conventional wells reported natural gas production; however, this only represented 5% of the total natural gas produced. The remaining 95% of natural gas production can be attributed to 3,901 UOG wells. There has been a wide body of research on disturbance trends related to unconventional development in the region; however, there is limited characterization of disturbance related to production of conventional oil and gas (COG) or research that details energy production in relation to land disturbance. This study compares land disturbance from COG and UOG development as well as energy production. Land disturbance related to COG and UOG development was assessed for wells drilled during 2009–2012. Production data were summarized for the same wells during the period of 2009–2020. The average area disturbed for COG pads was 0.82 ha while UOG pads disturbed 4.02 ha. Results from this study showed that COG wells disturbed significantly less land area during construction; however, UOG wells produced almost 28 times more energy per hectare of land disturbed. This energy production imbalance as well as the over 65,000 COG wells reporting production in 2020, indicates that the retirement and restoration of COG infrastructure could be done without significantly impacting total energy production. Continued research that includes ecosystem services and carbon sequestration opportunities in relation to production losses from retiring existing infrastructure should be considered.

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Upstream oil and gas systems are negatively impacted by microbial activities that produce hydrogen sulfide gas, enhance corrosion rates of metals, and cause costly damage to infrastructure through biofouling. Although alternatives to biocides such as sulfate removal membranes and corrosion resistant coatings and materials have been developed, biocides and inhibitors still provide the main defense against microbial activity. However, the environmental and economic challenges of employing biocides necessitate oil and gas industries devise better strategies for their use and application. Since oil and gas environments represent physically controlled environments with highly stressed microbial communities experiencing episodes of intermittent slow growth and dormancy, one such strategy can take advantage of environmental stressors (e.g., salinity, starvation, oxygen) to enhance biocide efficacy. Although it is generally thought environmental stressors recruit determinants of resistance in bacteria, there are instances where stress decreases the energy or metabolic state of a cell increasing its susceptibility to some biocides. This review examines stressors in oil and gas environments and provides examples where stress can both increase and decrease biocidal susceptibility. By describing how these stressors and biocides impact metabolic activity as well as affect regulation of genes involved in energy production and conversion, this knowledge can be used to develop new strategies that take advantage of vulnerabilities in bacteria to improve biocide efficacy and reduce environmental threats and operator costs.

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The demand for natural gas has led to the development of techniques used to access unconventional oil and natural gas (UOG) resources, due to the novelty of UOG, the potential impacts to freshwater ecosystems are not fully understood. We used a dual pronged approach to study the effects of UOG development on microbial biodiversity and function via a laboratory microcosm experiment and a survey study of streams with and without UOG development within their watersheds. The microcosm experiment simulated stream contamination with produced water, a byproduct of UOG operations, using sediment collected from one high water-quality stream and two low water-quality streams. For the survey study, biofilm and sediment samples were collected from streams experiencing varying levels of UOG development. In the microcosm experiment, produced water decreased microbial aerobic and anaerobic CO2 production in the high water-quality stream sediment but had a positive effect on this microbial activity in the lower water-quality stream sediments, suggesting habitat degradation alters the response of microbes to contaminants. Results from the stream survey indicate UOG development alters stream water temperature, chemistry, sediment aerobic and anaerobic CO2 production, and microbial community biodiversity in both sediments and biofilms. Correlations among UOG associated land use, environmental, and microbial variables suggest increases in light availability and sediment delivery to streams, due to deforestation and land disturbance, impact stream microbial communities and their function. Consistent changes in the relative abundance of bacterial taxa suggest microorganisms may be good indicators of the environmental changes associated with UOG development. The observed impacts of UOG development on microbial community composition and carbon cycling could have cascading effects on stream health and broader ecosystem function.

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Since the early 2000s, unconventional natural gas development (UNGD) has rapidly grown throughout Pennsylvania. UNGD extracts natural gas using a relatively new method known as hydraulic fracturing (HF). Here we addressed the association of HF with asthma Hospitalization Admission Rates (HAR) using publicly available data. Using public county-level data from the Pennsylvania Department of Health (PA-DOH) and the Pennsylvania Department of Environmental Protection for the years 2001–2014, we constructed regression models to study the previously observed association between asthma exacerbation and HF. After considering multicollinearity, county-level demographics and area-level covariables were included to account for known asthma risk factors. We found a significant positive association between the asthma HAR and annual well density for all the counties in the state (3% increase in HAR attributable to HF, p<0.001). For a sensitivity analysis, we excluded urban counties (urban counties have higher asthma exacerbations) and focused on rural counties for the years 2005–2014 and found a significant association (3.31% increase in HAR attributable to HF in rural counties, p<0.001). An even stronger association was found between asthma hospitalization admission rates (HAR) and PM2.5 levels (7.52% increase in HAR attributable to PM2.5, p<0.001). As expected, asthma HAR was significantly higher in urban compared to rural counties and showed a significant racial disparity. We conclude that publicly available data at the county-level supports an association between an increase in asthma HAR and UNGD in rural counties in Pennsylvania.

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With growing evidence of widespread health and environmental impacts from oil and gas activity, localities and states are beginning to develop protective measures. Interdisciplinary approaches that integrate across human, wildlife, domesticated animal, and land health are likely to provide more just and comprehensive solutions than would be possible with siloed approaches. However, this is not common practice, and there is little guidance on how to apply such a strategy. In the present article, we summarize the state of knowledge on the impacts of terrestrial unconventional oil and gas development from the fields of ecology and public health. We then discuss synergies and trade-offs regarding impacts and mitigation strategies emerging from these two literatures. Finally, we provide recommendations for research and practice to fill knowledge gaps and better inform integrated decision-making to achieve multiple benefits and minimize impacts on human, wildlife, domesticated animals, and land health from energy development.

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Hydraulic fracturing (HF) of shale and other permeable rock formations to extract gas and oil is a water-intensive process that returns a significant amount of flowback and produced water (FPW). Due to the complex chemical composition of HF fluids and FPW, this process has led to public concern on the impacts of FPW disposal, spillage and spreading to regional freshwater resources, in particular to shallow groundwater aquifers. To address this, a better understanding of the chemical composition of HF fluid and FPW is needed, as well as the environmental fate properties of the chemical constituents, such as their persistence, mobility and toxicity (PMT) properties. Such research would support risk-based management strategies for the protection of regional water quality, including both the phase-out of problematic chemicals and better hydraulic safeguards against FPW contamination. This article presents recent strategies to advance the assessment and analysis of HF and FPW associated organic chemicals.

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Due to the growing hydraulic fracturing (HF) practices in China, the environmental risks of pollutants in flowback and produced waters (FPW) and sludge in impoundments for FPW reserves have drawn increasing attention. In this context, we first characterized the comparative geochemical characteristics of the FPW and the sludge in impoundments that collected FPW from 75 shale gas wells, and then the risks associated with the pollutants were assessed. The results demonstrated that four organic compounds detected in the FPW, naphthalene, acenaphthene, dibutyl phthalate, and bis(2-ethylhexyl)phthalate, were potential threats to surface waters. The concentrations of trace metals (copper, cadmium, manganese, chromium, nickel, zinc, arsenic, and lead) in the FPW and sludge were low; however, those of iron, barium, and strontium were high. The accumulation of chromium, nickel, zinc, and lead in the sludge became more evident as the depth increased. The environmental risks from heavy metals in the one-year precipitated sludge were comparable to those reported in the environment. However, the radium equivalent activities were 10–41 times higher than the recommended value for human health safety, indicating potential radiation risks. Although hydrophobic organic compounds, such as high-molecular-weight polycyclic aromatic hydrocarbons (PAHs), phthalate esters (PAEs), benzene, ethylbenzene, toluene, and xylene (BTEX), tended to accumulate in the sludge, their environmental risks were within tolerable ranges after proper treatment. Multiple antibiotic resistance genes (ARGs), such as those for macrolide, lincosamide, streptogramin (MLS), tetracycline, and multidrug resistances, were detected in the shale gas wastewaters and sludge. Therefore, the environmental risks of these emerging pollutants upon being discharged or leaked into surface waters require further attention.

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Water scarcity has emerged as one of the most important global challenges of the twenty-first century. With rising demand for energy, and water being a critical input in energy production, the availability of water resources has put energy sustainable production under growing strain. While unconventional natural gas (especially shale gas) is seen as an important bridge for promoting the transition of energy system from high to low carbon, water availability is a significant constraint on the development of energy resources owing to the massive quantity of water used by the hydraulic fracturing. Against this background, our study aims to optimize the allocation of regionally scarce water resources for fostering integrated economic, social, and environmental growth in shale gas development plays. In light of the uncertainty inherent in the water supply management system for shale gas development, this work employed the Interval Two-stage Stochastic Programming (ITSP) to establish an optimal allocation model for water resources between wells jointly dispatched by surface water, underground water and reused water. The model predicted water scarcity, optimal water allocation, and the total benefit of the shale gas development water supply system under various scenarios. Furthermore, when compared to the Two-stage Stochastic Programming (TSP) model results, it was found that the ITSP model's interval value may present decision makers with more ideas and options than the TSP model. In addition, since the ITSP model is oblivious to the system risk issue, it incorporated robust optimization into the original ITSP model to build the Interval Two-stage Robust Stochastic Programming (ITRSP) model. Our findings were expressed as intervals that more accurately represent the actual optimal allocation of water resources, which also provided a broader decision-making space for decision makers in managing shale gas development water supply management schemes.

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To potentially mitigate further climate change, the US needs to move away from fossil fuels and towards carbon-free sources of energy. The issue of climate change is highly polarized, which has led to beliefs about climate change becoming entangled with political beliefs. Yet, public support for decreasing the use of fossil fuels and increasing renewable sources is high. In this paper, we use an original survey of about 1300 respondents to examine the potential for the entanglement of political beliefs, climate change beliefs, and energy preferences. We find that the majority of respondents support a decreased use of fossil fuels, a slight increase of nuclear energy, and a large increase of renewable sources; however, conservative Republicans prefer smaller decreases of fossil fuels and smaller increases in renewables. Additionally, we find that as respondents increasingly accept the scientific consensus on climate change, they support larger decreases in fossil fuels and larger increases in renewable energy. Finally, using mediation analysis we find that climate beliefs mediate the relationship between political beliefs and energy preferences for conservative Republicans and liberal Democrats, but not those with more moderate political beliefs. These findings point to the potential for energy preferences to become entangled in climate change as a result of elite discourse.

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Here, we report the draft genome sequence of three glutaraldehyde-resistant isolates from produced water from hydraulic fracturing operations. The three strains were identified as Marinobacter sp. strain G11, Halomonas sp. strain G15, and Bacillus sp. ...

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Brazil has the 10th largest shale gas reservoir, and the Paraná sedimentary basin has a potential area for shale gas production in the western portion of the São Paulo state. Despite that, the knowledge about the impacts of fracking on the local water resources is still limited. This study presents a novel reproducible method to compute the risk of water scarcity in areas with restricted or no shale gas development. Using geospatial numerical simulations under five scenarios from 500 to 2500 wells, we find that the fracking-related risk of water scarcity in the São Paulo state is low. For the 2013–2019 period, the long-term average seasonal water availability is between 0.05 and 1 Gm³ per water resources management unit, whereas fracking water demand would hardly overcome 6 Mm³ y−1. For instance, with 2500 wells, the fracking demand in Pontal do Paranapanema, the most prospective region for shale gas, would not overcome 3% of the yearly local water demand. The riskier areas are in Aguapeí and Baixo do Tietê water resources management units, during winter and autumn, and the most water-stressed area is São José dos Dourados. In regions and periods of low water availability, fracking operators can use adaptative strategies for shale gas production. In the context of imminent droughts, this research debates national energy security and casts doubt on the water efficiency and sustainability of the state's energy generation. At last, this research provides early insights to support shale gas and water policy, and future studies to further investigate relevant aspects to the Brazilian Water-Energy nexus.

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We investigate the interplay between energy prices and drilling activities in the United States and how this relationship has evolved due to the shale revolution. We hypothesize (1) there exists significant information spillover between drilling activities and energy prices; (2) the amount of information transmitted between drilling activities and energy prices has increased since the shale boom; (3) natural gas market is increasingly important information transmitter since the rise of unconventional oil and gas production. Using connectedness indexes constructed based on vector autoregressive models and data from 1997 to 2019, we find support for all three hypotheses. In particular, the linkage between drilling activities, measured by active rotary rigs in operation, and oil and gas prices in the US has strengthened since 2012. Oil and gas drilling activities have become more responsive to price variations during the shale revolution. However, the information transmitted from oil prices to rig count declined when oil prices fluctuated in a relatively stable range toward the end of the sample period. In contrast, the information transmitted from gas prices to gas rig counts has increased during the same time frame.

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For tectonic earthquakes, slip rate spans a continuum from creep to supershear earthquakes, where slow slip events (SSEs) are important in releasing stress without radiating damaging seismic energy. Industrial-scale subsurface fluid injection has caused induced earthquakes, but the role of SSEs in fault activation is currently unclear. Ground-deformation observations, measured by satellite radar, show that SSEs up to magnitude 5.0 occurred during hydraulic fracturing (HF) operations in northwestern Canada, corroborated by reported deformation of the steel well casing. Although the magnitude 5.0 SSE exceeded the magnitude of the largest induced earthquake in this region (magnitude 4.55), it was undetected by seismograph networks. The observed SSEs occurred within a buried thrust belt and their magnitude and duration are consistent with scaling behavior of SSEs in unbounded natural systems, e.g. slab interfaces in subduction zones.

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Unconventional oil and gas (UOG) production requires a vast quantity of freshwater while generating substantial volumes of wastewater. Although numerous studies have focused on technology development, other aspects beyond treatment technology, including regulations, economics, system logistics, and public perception, play equally or more important roles collectively in the selection and deployment of UOG wastewater management practices. In this article, we begin with a critical analysis of the motivations that drive UOG wastewater management towards treatment and reuse. Then we examine four main barriers against such a paradigm shift, pertaining to treatment technology, regulatory compliance, economic feasibility, and social acceptance. Despite the need of further improving technology efficiency for UOG wastewater treatment, the lack of established regulatory framework, the uncertainties of economic viability, as well as public resistance, hinder practical implementation of treatment technologies. We highlight the importance of knowledge and collaborative efforts from engineers, regulators, policy makers, economists, and social scientists to address those barriers, and emphasize that future research efforts should be directed at domains well beyond treatment technology. A systems approach and broader collaboration across multiple disciplines is needed to translate technology innovation into solutions that truly improve water sustainability in the context of rising UOG production.

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Canadian freshwater ecosystems are vulnerable to oil spills from pipelines, which contain mostly diluted bitumen. This study aimed to compare the toxicity of a dilbit and a conventional oil on developing rainbow trout. A total of five exposure scenarios were performed, from 10 to 43 days, using water-accommodated fraction (WAF) with an initial loading of 1:9 oil to water ratio (w/v) in a range of dilutions from 0.32 to 32% WAF, respectively, with TPAH and VOC concentrations from 2.41 to 17.5 μg/L and 7.94–660.99 μg/L, and with or without a recovery period. Following the five exposures, several endpoints were examined, including survivorship, morphometrics, gene expression, and enzymatic activity. Significant mortality rates were measured for the highest WAF concentration of the dilbit in all five exposures (60–100% mortality at 32% WAF). In comparison, the highest WAF concentration of the conventional oil induced significant mortality in three out of the five exposure (from 35 to 100% mortality at 32% WAF). Hatching delays were noted in embryos exposed to both oils. Developmental delays were observed in dilbit-exposed embryos and are suspected to be an indicator of reduced survivorship after hatching. The induced expression of cyp1a remained a reliable biomarker of exposure and of fish malformations, though it did not always predict mortality. Using CYP1A activity in combination with cyp1a may bring more insights in studies of oil risk assessment. This study demonstrates that dilbits are more toxic to early life stages compared to conventional oils and highlights the need to consider the most sensitive stage of development when performing risk assessment studies on oils.

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Over the last decade, there has been a rapid growth in the use of hydraulic fracturing (fracking) to recover unconventional oil and gas in the Permian Basin of southeastern New Mexico (NM) and western Texas. Fracking generates enormous quantities of wastes that contain technologically enhanced naturally occurring radioactive materials (TENORM), which poses risks to human health and the environment because of the relatively high doses of radioactivity. However, very little is known about the chemical composition and radioactivity levels of Permian Basin fracking wastes. Here, we report chemical as well as radiochemical compositions of hydraulic fracking wastes from the Permian Basin. Radium, the major TENORM of interest in unconventional drilling wastes, varied from 19.1 ± 1.2 to 35.9 ± 3.2 Bq/L for 226Ra, 10.3 ± 0.5 to 21.5 ± 1.2 Bq/L for 228Ra, and 2.0 ± 0.05 to 3.7 ± 0.07 Bq/L for 224Ra. In addition to elevated concentrations of radium, these wastewaters also contain elevated concentrations of dissolved salts and divalent cations such as Na+ (31,856–43,000 mg/L), Ca2+ (668–4123 mg/L), Mg2+ (202–2430 mg/L), K+ (148–780 mg/L), Sr2+ (101–260 mg/L), Cl− (5160–66,700 mg/L), SO42− (291–1980 mg/L), Br− (315–596 mg/L), SiO2 (20–32 mg/L), and high total dissolved solid (TDS) of 5000–173,000 mg/L compared to background waters. These elevated levels are of radiological significance and represent a major source of Ra in the environment. The recent discovery of large deposits of recoverable oil and gas in the Permian Basin will lead to more fracking, TENORM generation, and radium releases to the environment. This paper evaluates the potential radiation risks associated with TENORM wastes generated by the oil and gas recovery industry in the Permian Basin.

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Little is known about whether exposure to unconventional oil and gas development is associated with higher mortality risks in the elderly and whether related air pollutants are exposure pathways. We studied a cohort of 15,198,496 Medicare beneficiaries (136,215,059 person-years) in all major US unconventional exploration regions from 2001 to 2015. We gathered data from records of more than 2.5 million oil and gas wells. For each beneficiary’s ZIP code of residence and year in the cohort, we calculated a proximity-based and a downwind-based pollutant exposure. We analysed the data using two methods: a Cox proportional hazards model and a difference-in-differences design. We found evidence of a statistically significant higher mortality risk associated with living in proximity to and downwind of unconventional oil and gas wells. Our results suggest that primary air pollutants sourced from unconventional oil and gas exploration can be a major exposure pathway with adverse health effects in the elderly.

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Unconventional oil and gas (UOG) extraction can augment energy supplies in countries with viable gas resources, but it risks damaging water resources. Water supply problems for fracking can also limit UOG extraction, especially in water-stressed regions. Regulations are one of the main tools used to minimize UOG extraction impacts on water resources. Many states in the US and Canada have extensive regulations to protect water resources during UOG extraction but they are often ineffective, either because they were poorly drafted or because they are not properly enforced. South Africa is a water-scarce, groundwater-dependent country that is considering UOG extraction in the future. South African groundwater experts were surveyed on what regulations are needed to protect groundwater resources and how to enforce them. This study recommends specific UOG extraction regulations to protect groundwater resources, which are not only relevant to South Africa, but also to other countries that extract UOG resources.

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This paper presents a mathematical programming approach for the strategic planning of managing wastewater generated by hydraulic fracturing operations in shale gas production. The proposed approach aims to achieve optimal selection of treatment, storage, and reuse activities. The approach also accounts for the variability of wastewater characteristics including the short-term flowback and transition water as well as the longer-term produced water. Because of the different compositions of the pollutants in the various types of wastewater, stream segregation is considered as an option. Furthermore, the model accounts for seasonal variabilities in freshwater availability. Economic and environmental objectives are considered. The economic objective function aims to determine the minimum total cost, which is composed of freshwater, treatment, storage, and transport costs. Credit is given for reused water. The environmental objective focuses on the reduction of freshwater requirements needed for the fracturing step. The proposed model determines trade-offs between cost and water consumption. A case study is presented, and the results show that it is possible to reduce up to 32.43% of freshwater consumed and to reuse up to 12.26% of the total wastewater from wells for fracturing needs.

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Climate change, the imbalance between China's domestic energy supply and demand, and the success of the shale gas revolution in the United States have been the main motivators for China to actively issue shale gas development policies and explore its own path on this industry. This paper estimates three indicators of economic development: regional GDP, employment level, and the housing price index by using data from China's largest shale gas region, the Fuling District in Chongqing (a municipality in China). The analysis uses a Synthetic Control Method (SCM) model based on data from Fuling itself and other 34 counties of the Chongqing municipality over the period from 2005 to 2018. The results demonstrate that shale gas development has a significant positive effect on both regional GDP and employment level, with average impact growth rates respectively of 9.8% and 12.0%. By contrast, we find an insignificant effect of shale gas development on housing prices. These results support the case for further development of shale gas in China. Note that in some areas our results differ from existing literature, providing a reference for further research in this area.

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Produced water (PW) is a hypersaline waste stream generated from the shale oil and gas industry, consisting of numerous anthropogenic and geogenic compounds. Despite prior geochemical characterization, the comprehensive toxicity assessment is lacking for evaluating treatment technologies and the beneficial use of PW. In this study, a suite of in vitro toxicity assays using various aquatic organisms (luminescent bacterium Vibrio fischeri, fish gill cell line RTgill-W1, and microalgae Scenedesmus obliquus) were developed to investigate the toxicological characterizations of PW from the Permian Basin. The exposure to PW, PW inorganic fraction (PW-IF), and PW salt control (PW-SC) at 30– 50% dilutions caused significant toxicological effects in all model species, revealing the high salinity was the foremost toxicological driver in PW. In addition, the toxicity level of PW was usually higher than that of PW-IF, suggesting that organic contaminants might also play a critical role in PW toxicity. When comparing the observed toxicity with associated chemical characterizations in different PW samples, strong correlations were found between them since higher concentrations of contaminants could generally result in higher toxicity towards exposed organisms. Furthermore, the toxicity results from the pretreated PW indicated that those in vitro toxicity assays had different sensitives to the chemical components present in PW. As expected, the combination of multiple pretreatments could lead to a more significant decrease in toxicity compared to the single pretreatment since the mixture of contaminants in PW might exhibit synergistic toxicity. Overall, the current work is expected to enhance our understanding of the potential toxicological impacts of PW to aquatic ecosystems and the relationships between the chemical profiles and observed toxicity in PW, which might be conducive to the establishment of monitoring, remediation, treatment, and reuse protocols for PW.

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Health studies report associations between metrics of residential proximity to unconventional oil and gas (UOG) development and adverse health endpoints. We investigated whether exposure through household groundwater is captured by existing metrics and a newly developed metric incorporating groundwater flow paths. We compared metrics with detection frequencies/concentrations of 64 organic and inorganic UOG-related chemicals/groups in residential groundwater from 255 homes (Pennsylvania n = 94 and Ohio n = 161). Twenty-seven chemicals were detected in ≥20% of water samples at concentrations generally below U.S. Environmental Protection Agency standards. In Pennsylvania, two organic chemicals/groups had reduced odds of detection with increasing distance to the nearest well: 1,2-dichloroethene and benzene (Odds Ratio [OR]: 0.46, 95% confidence interval [CI]: 0.23–0.93) and m- and p-xylene (OR: 0.28, 95% CI: 0.10–0.80); results were consistent across metrics. In Ohio, the odds of detecting toluene increased with increasing distance to the nearest well (OR: 1.48, 95% CI: 1.12–1.95), also consistent across metrics. Correlations between inorganic chemicals and metrics were limited (all |ρ| ≤ 0.28). Limited associations between metrics and chemicals may indicate that UOG-related water contamination occurs rarely/episodically, more complex metrics may be needed to capture drinking water exposure, and/or spatial metrics in health studies may better reflect exposure to other stressors.

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Regulatory agencies routinely assess the presence of stray gas release from unconventional gas wells by sampling for methane in nearby groundwater after the well is drilled or if citizens complain about methane in their water. We studied whether methane concentrations in groundwater naturally vary through time in a shale gas basin where unconventional development and hydraulic fracturing has not yet occurred, to test the assumption that pre-drilling observations of well water quality can be reliable measures for assessing impacts of later gas drilling. We collected groundwater samples from 11 domestic wells in New York monthly for 13 months for methane and ion concentrations in a highly gas productive part of the Appalachian basin where fracking has been banned. Changing methane concentrations correlated with changes in chloride and bromide, indicating changing mixtures of shallow freshwater and deeper formation brine extracted by the wells through time. The hydrogeologic setting of a water well can cause variability in methane concentrations that may mimic stray gas but cannot be attributable to gas drilling. For this reason, before and after testing has limited utility to distinguish impacts of gas drilling from other causes of changing methane concentrations unless that testing includes sampling a comprehensive set of ions multiple times prior to drilling.

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Shale and tight gas developments in the Beetaloo (28,000 km2) and Cooper (139,000 km2) basins of Australia are subject to stringent State and Federal Government controls and assessments. Several scientific investigations are ongoing to improve the scientific basis of the risks from unconventional gas developments to water and the environment. In this study a framework was developed to derive estimates of chemical dilution associated with leakage to groundwater from accidental release of chemicals used for shale and tight gas extraction in Australia. The quantitative assessment accounted for key landscape parameters that determine natural attenuation: soil type, depth to groundwater and groundwater velocity. Both basins were discretised into 1000 × 1000 m2 grids for which the unsaturated zone and groundwater dilution factors were derived. Migration of chemicals through deep unsaturated zones was calculated with the HYDRUS-1D simulator, taking account of best-available hydraulic properties from a digital soil database. A three-dimensional analytical solution of the advection–dispersion equation provided estimates of dilution in groundwater after solutes travelled 500 m from the centre (source location) to the edge of every grid cell. The combined vadose zone-groundwater dilution factors were used to determine under which conditions concentrations of hydraulic fracturing chemicals or flowback water accidentally released into the environment would decrease to levels that are no longer considered harmful to the environment. When the method was applied to 39 hydraulic fracturing chemicals scheduled for stimulation of a shale gas well, ecotoxicological risk quotients (RQ) were calculated to indicate which chemicals were of no environmental concern. This work contributes to increasing the efficiency of quantitative impact assessments and provides a framework to develop dedicated monitoring and management practices to support regulation and management of the gas industry in Australia.

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Hydraulic fracturing (HF) remains a current global energy policy issue, and understanding risks to drinking water resources from HF chemicals is an important aspect of this topic. The quantity and quality of disclosed HF chemical information are significant barriers for stakeholders attempting to perform systemic environmental and public health research. A repeatable approach for processing HF chemical disclosure data is provided using United States FracFocus data as a case study. We fill research gaps by examining HF chemical trends between 2014 and 2020 and comparing HF chemicals with a list of reference chemicals known or suspected to be in contact (unrelated to HF) with drinking water, food, or cosmetics. In total, 1,244 unique HF chemicals were identified. Compared with EPA's 2016 HF chemical disclosure research, 480 new chemicals are identified, and 318 previously reported chemicals were not observed. The annual unique chemical counts have dropped from 878 to 594 (32.3%) over the research period, while data quality and transparency have increased. Approximately 69.7% of the identified HF ingredients were found in a list of reference chemicals known or suspected to be in contact (unrelated to HF) with drinking water, food, or cosmetics. Chemical differences between production types (gas and oil) and states are also reviewed. Our research reveals that the sociotechnical system surrounding HF is dynamic and moving toward fewer and, in general, safer chemicals, for those that are disclosed. This study highlights opportunities for new and updated systemic research regarding HF chemical hazard dynamics and associated risk to drinking water resources.

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Hydraulic fracturing drilling technology can cause a high risk of surface spill accidents and thus water contamination. Climate change together with the high water demand and rapid increase in industrial and agricultural activities are valued reasons why we should all care about the availability of water resources and protect them from contamination. Hence, the purpose of this study is to estimate the risk associated with a site contaminated with benzene from oil spillage and its potential impact on groundwater. This study focused on investigating the impact of soil variability and water table depth on groundwater contamination. Temperature-dependent parameters, such as soil water content and the diffusion of pollutants, were considered as key input factors for the HYDRUS 1D numerical model to simulate benzene migration through three types of soil (loamy, sandy clay loam, and silt loam) and evaluate its concentration in the water aquifer. The results indicated that an anticipated increase in earth’s average surface temperature by 4 °C due to climate change could lead to a rise in the level of groundwater pollution in the study area by 0.017 mg/L in loamy soil, 0.00046 mg/L in sandy clay loam soil, and 0.00023 mg/L in silt loam soil. It was found that climate change can reduce the amount of benzene absorbed from 10 to 0.07% in loamy soil, 14 to 0.07% in sandy clay loam soil, and 60 to 53% in silt loam soil. The results showed that the soil properties and solute characteristics that depend on the temperature have a major and important role in determining the level of groundwater pollutants.

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We analyze the temporal evolution of the induced seismicity related to hydraulic fracturing activities in the Duvernay Formation, near Fox Creek, Alberta, Canada. For this analysis, we estimate annual Gutenberg-Richter parameters, - and - values, and then calculate the annual likelihood of earthquakes greater than magnitude from 2014 to 2020. The seismic hazard near Fox Creek has consistently decreased since 2015, from a 95% probability of an earthquake greater than magnitude in 2015 to 4% in 2019 and less than 1% probability in 2020. The induced seismicity in Fox Creek is characterized by two actively seismic regions with distinctive features: (a) an Eastern region (∼220 events ) with lower b-values and higher hazard; (b) a Western region (∼210 events ) with higher b-values and lower seismic hazard. In contrast, extensive regions where hydraulic fracturing is performed, particularly East of the seismic cluster, remain non-seismogenic. The overall decreasing seismic hazard, which contrasts with increasing operator activity, can be associated with (a) the intensification of hydraulic fracturing operations toward areas less susceptible to induced seismicity and (b) the reduction of seismic activity in the Eastern region, which exhibits the highest seismic hazard. We also find evidence of a minimum annual injection volume required to trigger induced seismicity in both the Western and Eastern regions. The minimum injection threshold increases over the years, implying increasingly successful mitigation strategies, likely due to regulatory implementations in the area, which has led the operators to exercise precaution in regions with significant seismic hazard and adapt treatment strategies to avoid triggering moderate magnitude size events during hydraulic fracturing stimulations.

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Development of the Permian Basin in recent years has disrupted the global trade of oil and gas. As of January 2020, it was producing more than five million barrels of oil and 20 billion cubic feet of gas per day, with the greatest growth coming from the Delaware Basin sub-play. In this investigation, we report the results of a novel process-based life cycle assessment (LCA) of the greenhouse gas (GHG) emissions associated with oil and gas products from the Delaware Basin, employing extensive operational data including direct measurements of methane emissions. We find that if 1% of the gross gas produced is flared, then the upstream carbon intensity of crude oil is 19.5 kg CO2eq per barrel of crude oil - substantially lower than “global average” intensities reported in the literature. Moreover, the carbon intensities of gasoline, diesel and jet fuel refined from Delaware Basin crudes are approximately 10% less than the U.S. EPA and Department of Energy baselines when a 1% flaring rate is achieved. The life cycle GHG reductions are also a consequence of the physical and chemical properties of Delaware Basin crudes relative to the average crude blend for the U.S., resulting in reduced refinery GHG emissions. We also find that life cycle GHG emissions associated with natural gas from the Delaware Basin are similar to those reported for U.S. shale gas.

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The high management cost of wastewater generated during oil and gas production using hydraulic fracturing technology necessitates economically viable alternative technologies for remediation and reuse. In this study, an Oklahoma native microalgae strain, Komvophoron sp., was grown in four different flowback and produced water samples generated during hydraulic fracturing. Biomass production profile and pollutant removal efficiency of the strain were evaluated. The experimental data demonstrated that this strain was able to grow in all wastewater samples examined when suitable light intensity and CO2 flow rate were provided. Biomass productivity of the strain varied from 5.5 to 12 g m−3 day−1 depending on the wastewater sample used in the cultivation experiments. Very high nitrogen and phosphorus removal from the growth medium, up to 99 and 63%, respectively, could be achieved by growing and harvesting algal biomass in the wastewater samples. A mathematical model developed based on pH, light intensity and CO2 enriched air flow rate as system variables well described the experimental biomass productivity and pollutant removal efficiency data. The proposed mathematical model was successfully used to identify sets of operating conditions which would maximize biomass productivity and macronutrient removal efficiencies. Hence, the model developed in this study is a useful tool to assess technical viability and design of an efficient algal wastewater remediation process to reduce the impact of hydraulic fracturing on environment while producing biomass that can be converted to industrial bio-products including biofuels.

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Oil and gas extraction produces air pollutants that are associated with increased risks of hypertension. To date, no study has examined residential proximity to oil and gas extraction and hypertensive conditions during pregnancy. This study quantifies associations between residential proximity to oil and gas development on gestational hypertension and eclampsia.We utilized a population-based retrospective birth cohort in Texas (1996–2009), where mothers reside <10 km from an active or future drilling site (n = 2 845 144.) Using full-address data, we linked each maternal residence at delivery to assign exposure and evaluate this exposure with respect to gestational hypertension and eclampsia. In a difference-in-differences framework, we model the interaction between maternal health before (unexposed) or after (exposed) the start of drilling activity (exposed) and residential proximity near (0–1, >1–2 or >2–3 km) or far (≥3–10 km) from an active or future drilling site.Among pregnant women residing 0–1 km from an active oil or gas extraction site, we estimate 5% increased odds of gestational hypertension [95% confidence interval (CI): 1.00, 1.10] and 26% increased odds of eclampsia (95% CI: 1.05, 1.51) in adjusted models. This association dissipates in the 1- to 3-km buffer zones. In restricted models, we find elevated odds ratios among maternal ages ≤35 years at delivery, maternal non-Hispanic White race, ≥30 lbs gained during pregnancy, nulliparous mothers and maternal educational attainment beyond high school.Living within 1 km of an oil or gas extraction site during pregnancy is associated with increased odds of hypertensive conditions during pregnancy.

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Advances in water treatment technologies paired with potential restrictions on oil and gas (O the sole major breakthrough has been in the development of salt-tolerant fracturing chemicals that allow for reuse of produced water for fracking operations. Guided research should assist in the development of fit-for-purpose solutions to maximize the reuse of treated produced water. This is exemplified by the case studies presented here that detail currently operating treatment facilities for reclamation and reuse of produced water.

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The effects of salinity shock on the anaerobic treatment of fracturing wastewater regarding chemical oxygen demand (COD) removal performance, sludge characteristics and microbial community were investigated. Results showed COD removal efficiency decreased from 76.0% to 69.1%, 65.6%, 33.7% and 21.9% with the increase of salinity from 2.5 g/L to 10, 15, 25 and 45 g/L, respectively. The cumulative biogas production decreased by 13.8%–81.1% when salinity increased to 15–85 g/L. The increase of salinity led to the decline in particle size of granular sludge, and the activity of granular sludge, including SMA, coenzyme F420 and dehydrogenase, was inhibited significantly. Flow cytometry indicated the percentage of damaged cells in granular sludge gradually increased with the increase of salinity. Sequence analysis illustrated that microbial community structure in anaerobic digestion reactor was influenced by the salinity, high salinity reduced the diversity of archaea and decreased the abundance of methanogens, especially Methanosaeta.

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Quantifying impacts of unconventional oil and gas production on water resources and aquatic habitats is critical for developing management approaches for mitigation. The study objective was to evaluate impacts of oil and gas production on groundwater and surface water and assess approaches to reduce these impacts using the Permian Basin as a case study. Water demand for hydraulic fracturing (HF) was compared to water supplies. We also examined contamination from surface spills. Results show that water demand for HF peaked in 2019, representing ~28% of water use in non-mining sectors. Most HF water was sourced from aquifers with ~1100 wells drilled in the Ogallala aquifer in 2019. The State monitoring network did not show regional groundwater depletion but was not sufficiently dense to address local impacts. Groundwater depletion is more critical in the western Delaware Basin within the Permian Basin because groundwater is connected to large flowing springs (e.g. San Solomon Springs) and to the Pecos River which has total dissolved solids ranging from ~3000 to 14,000 mg/L. Most produced water (70–80%) is disposed in shallow geologic units that could result in overpressuring and potential groundwater contamination from leakage through ~70,000 abandoned oil wells, including orphaned wells. While there is little evidence of leakage from abandoned wells, the state monitoring system was not designed to assess leakage from these wells. Oil spill counts totaled ~11,000 in the Permian (2009–2018). Approaches to mitigating adverse impacts on water management include reuse of PW for HF; however, there is an excess of PW in the Delaware Basin. Treatment and reuse in other sectors outside of oil and gas are also possibilities. Data gaps include reporting of water sources for HF, PW quality data required for assessing treatment and reuse, subsurface disposal capacity for accommodating PW, and spills from PW in Texas.

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The effectiveness of oil and gas produced water (OGPW) applied to unpaved roads to reduce particulate matter (PM10) generation has not been well-characterized. Here we quantify the efficacy of OGPW compared to commercial and alternative byproducts as dust suppressants applied to unpaved roads and estimate efficacy of a dust suppressant extrapolated from both lab experiments and published data for OGPW across U.S. states. Both treated and untreated OGPW, simulated brines, and commercial dust suppressants were characterized by major and trace element composition and then applied to road aggregate in the laboratory. PM10 generation after treatment was quantified, both before and after simulated rain events to assess the need for multiple applications. We found the dust suppression efficacy of all OGPW to be less than commercial products and alternative byproducts such as waste soybean oil. In addition, OGPW lost efficacy following simulated rain events, which would require repeated applications of OGPW to maintain dust suppression. The dust suppression efficacy of OGPW can be estimated based on two chemical measurements, the sodium absorption ratio (SAR) and the total dissolved solids (TDS). OGPW with the lowest SAR and highest TDS performed best as dust suppressants while high SAR and lower TDS led to greater dust generation.

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This paper examines public perceptions of shale gas development in China and the United States. Public perceptions are important, as they are known to influence public policy at national and local levels of government in both multi-party and single-party governance systems. Online surveys were conducted in several states/provinces in each country, the US survey in 2014 (N = 2833); the China survey in 2016 (N = 1571). Similar survey instruments were used in both countries.The survey results show that the reported levels of public support for shale gas development among Chinese respondents in select provinces are significantly higher than that among US respondents in the states included in this study. Perceptions of the advantages and disadvantages of shale gas have both similarities and differences. Shale gas is perceived favorably in both samples because it is seen as a way to reduce dependence on foreign energy suppliers and strengthen the economy. The potential environmental advantages appear to be relatively more important to Chinese respondents than to American respondents. The statement “shale gas development is good for the environment because it substitutes dirty energy such as coal and oil” is seen as “Extremely important” by 54.23% of all Chinese respondents but by only 33.75% of American respondents. When it comes to the potential disadvantages of shale gas development, concerns about impacts on drinking water quality are important in both samples. Earthquakes related to shale gas is the second most important concern to Chinese respondents but a lesser concern to US respondents. We argue that the results are consistent with risk experiences, a variety of socio-cultural theories, and differences in media coverage in the two countries. Future work should examine how public perceptions in the two countries change over time, and how the stances of environmental groups, government, and industry may influence public opinion.

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Conflicting evidence exists as to whether or not unconventional oil and gas (UOG) development has enhanced methane transport into groundwater aquifers over the past 15 years. In this study, recent groundwater samples were collected from 90 domestic wells and 4 springs in Northeastern Pennsylvania located above the Marcellus Shale after more than a decade of UOG development. No statistically significant correlations were observed between the groundwater methane level and various UOG geospatial metrics, including proximity to UOG wells and well violations, as well as the number of UOG wells and violations within particular radii. The δ13C and methane-to-higher chain hydrocarbon signatures suggested that the elevated methane levels were not attributable to UOG development nor could they be explained by using simple biogenic–thermogenic end-member mixing models. Instead, groundwater methane levels were significantly correlated with geochemical water type and topographical location. Comparing a subset of contemporary methane measurements to their co-located pre-drilling records (n = 64 at 49 distinct locations) did not indicate systematic increases in methane concentration but did reveal several cases of elevated concentration (n = 12) across a spectrum of topographies. Multiple lines of evidence suggested that the high-concentration groundwater methane could have originated from shallow thermogenic methane that migrated upward into groundwater aquifers with Appalachian Basin brine.

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Our study goal was to investigate the impact of biocides and nanoparticles (NPs) on the microbial diversity in a hydraulic fracturing impacted stream. Biocides and NPs are known for their antimicrobial properties and controlling microbial growth. Previous work has shown that biocides can alter the microbial community composition of stream water and may select for biocide-resistant bacteria. Additional studies have shown that nanoparticles can also alter microbial community composition. However, previous work has often focused on the response to a single compound. Here we provide a more thorough analysis of the microbial community response to three different biocides and three different nanoparticles. A microcosm-based study was undertaken that exposed stream microbial communities to either biocides or NPs. Our results showed a decrease in bacterial abundance with different types of nanoparticles, but an increase in microbial abundance in biocide-amended treatments. The microbial community composition (MCC) was distinct from the controls in all biocide and NP treatments, which resulted in differentially enriched taxa in the treatments compared to the controls. Our results indicate that NPs slightly altered the MCC compared to the biocide-treated microcosms. After 14 days, the MCC in the nanoparticle-treated conditions was similar to the MCC in the control. Conversely, the MCC in the biocide-treated microcosms was distinct from the controls at day 14 and distinct from all conditions at day 0. This finding may point to the use of NPs as an alternative to biocides in some settings.

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Background:  Prenatal exposure to hydraulic fracturing (HF), a chemically intensive oil and gas extraction method, may be associated with adverse birth outcomes, but no health studies have been conducted in California. Methods:  We conducted a retrospective cohort study of 979,961 births to mothers in eight California counties with HF between 2006 and 2015. Exposed individuals had at least 1 well hydraulically fractured within 1 km of their residence during pregnancy; the reference population had no wells within 1 km, but at least one oil/gas well within 10 km. We examined associations between HF and low birth weight (LBW), preterm birth (PTB), small for gestational age birth (SGA), and term birth weight (tBW) using generalized estimating equations and assessing urban-rural effect modification in stratified models. Results:  Fewer than 1% of mothers (N = 1,192) were exposed to HF during pregnancy. Among rural mothers, HF exposure was associated with increased odds of LBW (odds ratio [OR] = 1.74; 95% confidence interval [CI] = 1.10, 2.75), SGA (OR = 1.68; 95% CI = 1.42, 2.27) and PTB (OR = 1.17; 95% CI = 0.64, 2.12), and lower tBW (mean difference: –73 g; 95% CI = –131, –15). Among urban mothers, HF exposure was positively associated with SGA (OR = 1.23; 95% CI = 0.98, 1.55), inversely associated with LBW (OR = 0.83; 95% CI = 0.63, 1.07) and PTB (OR = 0.65; 95% CI = 0.48, 0.87), and not associated with tBW (mean difference: –2 g; 95% CI = –35, 31). Conclusion:  HF proximity was associated with adverse birth outcomes, particularly among rural Californians.

Abstract:
Biocides are applied as chemical additives in hydraulic fracturing fluids to control subsurface microbial activity. When biocides are released into the subsurface, their fate is controlled by sorption to solids and heterogeneous electron transfer (redox) reactions at the mineral–fluid interface. The ability to predict whether produced water may contain unreacted biocides, or biocide–mineral transformation products, is relevant for defining optimal produced water treatment and beneficial use approaches. This article reviews major minerals that may impact biocide sorption and reactivity in the Marcellus Shale, with a specific focus on biocide–mineral interactions. The chemical and physical properties of quartz, illite, chlorite, pyrite, calcite and dolomite are presented and their reactions with organic compounds structurally similar to biocides are identified. Oxygen-containing functional groups are common among organic biocides, where the carbonyl (–C=O) substructure is integrated into many biocides. Cationic surfactant biocides are expected to sorb to every mineral. Clays, because of their negative surface charge and comparatively high surface area, make excellent sorbents of positively charged biocides. Sorption to organic matter is expected to be limited due to the very polar groups found in biocides. Pyrite is most likely to cause transformation of biocides due to its ability to reduce halogenated organic compounds and initiate Fenton-like reactions, which generate non-specific hydroxyl radicals that react with biocides. Carbonate minerals may act as potential chemisorption sites for biocides possessing a carbonyl group adjacent to another electronegative group. However, the rapid dissolution of this mineral limits its persistence at the mineral–fluid interface. These potential sorption versus transformation reactions can be applied to predict biocide fate in unconventional oil and gas reservoirs and, where appropriate, other subsurface reservoirs used for energy resource extraction or storage.

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Low-cost gravity-driven membrane (GDM) filtration has the potential to efficiently manage highly decentralized shale gas wastewater (SGW). In this work, the feasibility of combining low dosage pre-ozonation with the GDM process was evaluated in the treatment of SGW. The results showed that pre-ozonation significantly increased the stable flux (372%) of GDM filtration, while slightly deteriorating the quality of the effluent water in terms of organic content (−14%). These results were mainly attributed to the conversion of macromolecular organics to low-molecular weight fractions by pre-ozonation. Interestingly, pre-ozonation markedly increased the flux (198%) in the first month of operation also for a GDM process added with granular activated carbon (GGDM). Nevertheless, the flux of O3-GGDM systems dropped sharply around the 25th day of operation, which might be due to the rapid accumulation of pollutants in the high flux stage and the formation of a dense fouling layer. Pre-ozonation remarkably influenced the microbial community structure. And O3-GDM systems were characterized by distinct core microorganisms, which might degrade specific organics in SGW. Furthermore, O3-GDM outperformed simple GDM as a pretreatment for RO. These findings can provide valuable references for combining oxidation technologies with the GDM process in treating refractory wastewater.

Abstract:
With the increasing consumption of energy in the world, shale gas, as a clean, efficient, and unconventional energy source, has been paid more and more attention. However, it should not be ignored that the process of shale gas exploitation will cause serious environmental pollution, especially water resource consumption and pollution. At present, the quantitative research on water resource cost of shale gas exploitation is rare. On the basis of summarizing the water resource consumption, pollution source in shale gas exploitation. This paper takes Chongqing Fuling national shale gas demonstration area as the research object, and cost measurement models are established from three aspects: water resource consumption, human body damage, and water quality decline. This paper innovatively calculates the water consumption cost of shale gas exploitation in Fuling, Chongqing. The calculation results show that the water consumption cost of Fuling shale gas in Chongqing is 93,639 Yuan per well. The research results provide theoretical basis and data support for enterprises to develop shale gas and the Chinese government to formulate shale gas development plan.

Abstract:
We already know that the construction of shale gas extraction infrastructure exacerbates soil erosion in vulnerable areas. We are not clear however, about whether the completed well pads and pipelines continue to influence soil erosion after the construction is completed. We applied high-resolution remote sensing images and DEM data from 2014 and 2017 and the Revised Universal Soil Loss Equation (RUSLE) model to calculate how the layout of the well pads and pipelines in a shale gas development area affected soil erosion. We used Geodetector to analyze the factors that affected the soil erosion intensity around the well pads. The results showed that about 0.02% and 0.12% of the total erosion in the shale gas development zone was directly caused by the completed well pads and pipelines in 2014 and 2017, respectively. Most of the erosion was related to the completed pipelines. The completed shale gas well pads affected the soil erosion intensity up to 90 and 60 m from the pads in 2014 and 2017, respectively. The soil erosion around the completed pipelines was mainly from the soil surface over the pipeline and had little effect on the surroundings. The main influences on the soil erosion intensity at different distances from the well pads were land use and slope, and the interactions between them. We suggest that, when developing new shale gas extraction facilities, gas pipelines should be arranged in gently sloping areas, and vegetation should be planted on the bare soil over the pipelines to reduce soil erosion.

Abstract:
With unconventional oil and gas booming in commercial development, its inevitable environmental damage has aroused the public’s vigilance. To support the regulation improvement and early-warning system building, it is of great need to learn the regular patterns in recurrent violations both for practitioners and governments. In this respect, we utilized the “Oil and Gas Compliance Report” from the Pennsylvania Department of Environmental Protection from 2000 to 2019, a total of 5737 violation records, to dig out the historical violation patterns. Through LDA (Latent Dirichlet Allocation) analysis combined with the decision tree model, our research attained the following conclusions: first, we find that the LDA themes of violations as “Erosion and sediment” and “Water pollution” are critical factors for “Failed” enforcement results. Therefore, policymakers and practitioners should pay more attention to those two types of accidents. Second, it is noted that counties are also one of the essential features that matter the enforcement results. Third, we need to consider the role of economic punishment dialectically, while it is not a significant feature for successful enforcement results. That is to say, a monetary penalty may not necessarily improve the effectiveness of the company’s measurements.