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1.
BMC Public Health ; 24(1): 1959, 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-39039474

RESUMEN

BACKGROUND: Concerns about mental and cognitive health are common among university students. Engaging in regular physical exercise has been shown to enhance both mental health and cognitive performance, yet most students are not participating in the level of exercise required to obtain these benefits. The Behaviour Change Wheel (BCW) provides a framework for developing behavioural interventions that are informed by theory, evidence, and stakeholder perspectives. The current study aimed to apply the BCW to develop the PEAK Mood, Mind, and Marks program (i.e., PEAK), a behaviour change intervention designed to increase university students' exercise engagement for the benefit of their mental and cognitive health. METHODS: PEAK was developed across three stages of the BCW: (1) understand the target behaviour, (2) identify intervention options, and (3) identify intervention content and delivery mode. Development was informed by triangulated data from a systematic literature review, co-design consultations with key stakeholders, and knowledge of relevant experts. Consultations with stakeholders involved focus groups with 25 university students and individual interviews with 10 university leaders and staff to identify barriers and facilitators to students' exercise engagement and the adoption and implementation of PEAK by universities. Template analysis was used to code transcripts to the capability, opportunity, and motivation (COM-B) model of behaviour. The BCW was applied to identify the most appropriate intervention types and behaviour change techniques (BCTs). RESULTS: Thirty-one barriers and facilitators were identified and mapped to seven intervention types (Education; Modelling; Persuasion; Environmental Restructuring; Incentivisation; Training; and Enablement) and 26 BCTs, which were delivered across digital channels and in-person. The final intervention consisted of multiple components targeting students' capability (e.g., increasing knowledge about the mental and cognitive health benefits of exercise), opportunity (e.g., providing a flexible range of accessible exercise options and social support), and motivation (e.g., increasing the perceived importance of exercise) to exercise. CONCLUSIONS: University students and staff describe a need and appetite for more empowering, scalable solutions to support students' mental and cognitive health. Exercise-based approaches that are informed by behaviour change frameworks, evidence, and stakeholder perspectives, such as PEAK, have the potential to address this need. Current findings will inform a pilot of PEAK to evaluate its efficacy and implementation.


Asunto(s)
Ejercicio Físico , Investigación Cualitativa , Estudiantes , Humanos , Ejercicio Físico/psicología , Estudiantes/psicología , Universidades , Femenino , Masculino , Adulto Joven , Grupos Focales , Salud Mental , Cognición , Adulto , Promoción de la Salud/métodos , Desarrollo de Programa , Adolescente
2.
Front Psychiatry ; 15: 1379396, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38915845

RESUMEN

Introduction: Regular exercise has the potential to enhance university students' mental and cognitive health. The PEAK Mood, Mind and Marks program (i.e., PEAK) is a neuroscience-informed intervention developed using the Behaviour Change Wheel to support students to exercise three or more times per week to benefit their mental and cognitive health. This pilot study assessed the impact of PEAK on exercise, mental and cognitive health, and implementation outcomes. Methods: PEAK was delivered to 115 undergraduate university students throughout a 12-week university semester. The primary outcome was weekly exercise frequency. Secondary outcomes were: time spent engaged in moderate-vigorous exercise, sedentary behaviour and perceived mental health and cognitive health. All were measured via online self-report questionnaires. Qualitative interviews with 15 students investigated influences on engagement, the acceptability and appropriateness of PEAK, and its mechanisms of behaviour change. Paired t-tests, Wilcoxon Signed-Rank tests and template analysis were used to analyse quantitative and qualitative data, respectively. Results: On average, 48.4% of students engaged in the recommended frequency of three or more exercise sessions per week. This proportion decreased towards the end of PEAK. Sedentary behaviour significantly decreased from baseline to end-point, and moderate-vigorous exercise significantly increased among students' who were non-exercisers. Mental wellbeing, stress, loneliness, and sense of belonging to the university significantly improved. There were no significant changes in psychological distress. Concentration, memory, and productivity significantly improved. Sixty-eight percent of students remained engaged in one or more components of PEAK at end-point. Qualitative data indicated students found PEAK to be acceptable and appropriate, and that it improved aspects of their capability, opportunity, and motivation to exercise. Conclusions: Students are receptive to an exercise-based program to support their mental and cognitive health. Students exercise frequency decreased; however, these figures are likely a conservative estimate of students exercise engagement. Students valued the neuroscience-informed approach to motivational and educational content and that the program's goals aligned with their academic goals. Students identified numerous areas PEAK's content and implementation can be optimised, including use of a single digital delivery platform, more opportunities to connect with peers and to expand the content's cultural inclusivity.

3.
Environ Sci Technol ; 58(21): 9147-9157, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38743431

RESUMEN

Recent studies have shown that methane emissions are underestimated by inventories in many US urban areas. This has important implications for climate change mitigation policy at the city, state, and national levels. Uncertainty in both the spatial distribution and sectoral allocation of urban emissions can limit the ability of policy makers to develop appropriately focused emission reduction strategies. Top-down emission estimates based on atmospheric greenhouse gas measurements can help to improve inventories and inform policy decisions. This study presents a new high-resolution (0.02 × 0.02°) methane emission inventory for New York City and its surrounding area, constructed using the latest activity data, emission factors, and spatial proxies. The new high-resolution inventory estimates of methane emissions for the New York-Newark urban area are 1.3 times larger than those for the gridded Environmental Protection Agency inventory. We used aircraft mole fraction measurements from nine research flights to optimize the high-resolution inventory emissions within a Bayesian inversion. These sectorally optimized emissions show that the high-resolution inventory still significantly underestimates methane emissions within the New York-Newark urban area, primarily because it underestimates emissions from thermogenic sources (by a factor of 2.3). This suggests that there remains a gap in our process-based understanding of urban methane emissions.


Asunto(s)
Metano , Ciudad de Nueva York , Metano/análisis , Monitoreo del Ambiente , Contaminantes Atmosféricos/análisis , Teorema de Bayes
4.
BMC Public Health ; 24(1): 171, 2024 01 13.
Artículo en Inglés | MEDLINE | ID: mdl-38218774

RESUMEN

OBJECTIVE: While lifestyle medicine can be highly effective for treating a range of mental illnesses these approaches are grossly underutilised and have not been systematically implemented into health care systems. Understanding the acceptability of lifestyle medicine is a critical first step to remediate this. This study evaluated the acceptability of lifestyle medicine relative to pharmacotherapy and psychotherapy, and explore perspectives of people with and without lived experience of mental illness. METHODS: Six hundred and forty-nine adult Australian residents (62.6% female; 53.6% with a lifetime diagnosis of mental illness) completed an online survey based on the Theoretical Framework of Acceptability assessing the acceptability of lifestyle medicine, pharmacotherapy and psychotherapy for treating mental illness. RESULTS: Most participants felt positive about lifestyle medicine (76.9%) and felt that such approaches aligned with their personal values (74.9%). They understood how lifestyle medicine worked (86.4%) and believed it would be effective (69.6%). Lived experience of mental illness was associated with greater perceived burden and lower self-efficacy to engage in lifestyle medicine activities (both p < 0.001). While there was a clear preference for psychotherapy and lifestyle medicine over pharmacotherapy, pharmacotherapy was perceived as least effortful (p < .001) and participants were least confident in their ability to engage in lifestyle medicine (p < 0.05). CONCLUSION: The findings indicate strong acceptability of lifestyle medicine for mental illness, a preference for non-pharmacological treatment approaches, and an understanding of the challenges associated with making long-term healthy lifestyle modifications amongst people who have lived experience of mental illness.


Asunto(s)
Trastornos Mentales , Adulto , Humanos , Femenino , Masculino , Australia , Trastornos Mentales/terapia , Trastornos Mentales/diagnóstico , Estilo de Vida , Estilo de Vida Saludable , Psicoterapia
5.
Environ Sci Technol ; 57(48): 19565-19574, 2023 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-37941355

RESUMEN

Urban methane emissions estimated using atmospheric observations have been found to exceed estimates derived by using traditional inventory methods in several northeastern US cities. In this work, we leveraged a nearly five-year record of observations from a dense tower network coupled with a newly developed high-resolution emissions map to quantify methane emission rates in Washington, DC, and Baltimore, Maryland. Annual emissions averaged over 2018-2021 were 80.1 [95% CI: 61.2, 98.9] Gg in the Washington, DC urban area and 47.4 [95% CI: 35.9, 58.5] Gg in the Baltimore urban area, with a decreasing trend of approximately 4-5% per year in both cities. We also find wintertime emissions 44% higher than summertime emissions, correlating with natural gas consumption. We further attribute a large fraction of total methane emissions to the natural gas sector using a least-squares regression on our spatially resolved estimates, supporting previous findings that natural gas systems emit the plurality of methane in both cities. This study contributes to the relatively sparse existing knowledge base of urban methane emissions sources and variability, adding to our understanding of how these emissions change in time and providing evidence to support efforts to mitigate natural gas emissions.


Asunto(s)
Contaminantes Atmosféricos , Metano , Ciudades , Metano/análisis , Gas Natural/análisis , Contaminantes Atmosféricos/análisis , Baltimore
6.
Sci Total Environ ; 858(Pt 1): 159702, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36309263

RESUMEN

Hydraulic fracturing (fracking) is a short phase in unconventional oil and natural gas (O&G) development. Before fracking there is a lengthy period of preparation, which can represent a significant proportion of the well lifecycle. Extensive infrastructure is delivered onto site, leading to increased volumes of heavy traffic, energy generation and construction work on site. Termed the "pre-operational" period, this is rarely investigated as air quality evaluations typically focus on the extraction phase. In this work we quantify the change in air pollution during pre-operational activities at a shale gas exploration site near Kirby Misperton, North Yorkshire, England. Baseline air quality measurements were made two years prior to any shale gas activity and were used as a training dataset for random forest (RF) machine learning models. The models allowed for a comparison between observed air quality during the pre-operational phase and a counterfactual business as usual (BAU) prediction. During the pre-operational phase a significant deviation from the BAU scenario was observed. This was characterised by significant enhancements in NOx and a concurrent reduction in O3, caused by extensive additional vehicle movements and the presence of combustion sources such as generators on the well pad. During the pre-operational period NOx increased by 274 % and O3 decreased by 29 % when compared to BAU model values. There was also an increase in primary emissions of NO2 during the pre-operational phase which may have implications for the attainment of ambient air quality standards in the local surroundings. Unconventional O&G development remains under discussion as a potential option for improving the security of supply of domestic energy, tensioned however against significant environmental impacts. Here we demonstrate that the preparative work needed to begin fracking elevates air pollution in its own right, a further potential disbenefit that should be considered.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Fracking Hidráulico , Gas Natural/análisis , Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente , Contaminación del Aire/análisis
7.
Philos Trans A Math Phys Eng Sci ; 380(2215): 20210192, 2022 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-34865529

RESUMEN

Arctic wetlands and surrounding ecosystems are both a significant source of methane (CH4) and a sink of carbon dioxide (CO2) during summer months. However, precise quantification of this regional CH4 source and CO2 sink remains poorly characterized. A research flight using the UK Facility for Airborne Atmospheric Measurement was conducted in July 2019 over an area (approx. 78 000 km2) of mixed peatland and forest in northern Sweden and Finland. Area-averaged fluxes of CH4 and carbon dioxide were calculated using an aircraft mass balance approach. Net CH4 fluxes normalized to wetland area ranged between 5.93 ± 1.87 mg m-2 h-1 and 4.44 ± 0.64 mg m-2 h-1 (largest to smallest) over the region with a meridional gradient across three discrete areas enclosed by the flight survey. From largest to smallest, net CO2 sinks ranged between -513 ± 74 mg m-2 h-1 and -284 ± 89 mg m-2 h-1 and result from net uptake of CO2 by vegetation and soils in the biosphere. A clear gradient of decreasing bulk and area-averaged CH4 flux was identified from north to south across the study region, correlated with decreasing peat bog land area from north to south identified from CORINE land cover classifications. While N2O mole fraction was measured, no discernible gradient was measured over the flight track, but a minimum flux threshold using this mass balance method was calculated. Bulk (total area) CH4 fluxes determined via mass balance were compared with area-weighted upscaled chamber fluxes from the same study area and were found to agree well within measurement uncertainty. The mass balance CH4 fluxes were found to be significantly higher than the CH4 fluxes reported by many land-surface process models compiled as part of the Global Carbon Project. There was high variability in both flux distribution and magnitude between the individual models. This further supports previous studies that suggest that land-surface models are currently ill-equipped to accurately capture carbon fluxes inthe region. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 2)'.


Asunto(s)
Metano , Humedales , Dióxido de Carbono , Ecosistema , Estaciones del Año
8.
Philos Trans A Math Phys Eng Sci ; 380(2215): 20200449, 2022 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-34865534

RESUMEN

The atmospheric methane (CH4) burden is rising sharply, but the causes are still not well understood. One factor of uncertainty is the importance of tropical CH4 emissions into the global mix. Isotopic signatures of major sources remain poorly constrained, despite their usefulness in constraining the global methane budget. Here, a collection of new δ13CCH4 signatures is presented for a range of tropical wetlands and rice fields determined from air samples collected during campaigns from 2016 to 2020. Long-term monitoring of δ13CCH4 in ambient air has been conducted at the Chacaltaya observatory, Bolivia and Southern Botswana. Both long-term records are dominated by biogenic CH4 sources, with isotopic signatures expected from wetland sources. From the longer-term Bolivian record, a seasonal isotopic shift is observed corresponding to wetland extent suggesting that there is input of relatively isotopically light CH4 to the atmosphere during periods of reduced wetland extent. This new data expands the geographical extent and range of measurements of tropical wetland and rice δ13CCH4 sources and hints at significant seasonal variation in tropical wetland δ13CCH4 signatures which may be important to capture in future global and regional models. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 2)'.


Asunto(s)
Oryza , Humedales , Atmósfera , Metano , Estaciones del Año
9.
Philos Trans A Math Phys Eng Sci ; 380(2215): 20210112, 2022 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-34865533

RESUMEN

We report methane isotopologue data from aircraft and ground measurements in Africa and South America. Aircraft campaigns sampled strong methane fluxes over tropical papyrus wetlands in the Nile, Congo and Zambezi basins, herbaceous wetlands in Bolivian southern Amazonia, and over fires in African woodland, cropland and savannah grassland. Measured methane δ13CCH4 isotopic signatures were in the range -55 to -49‰ for emissions from equatorial Nile wetlands and agricultural areas, but widely -60 ± 1‰ from Upper Congo and Zambezi wetlands. Very similar δ13CCH4 signatures were measured over the Amazonian wetlands of NE Bolivia (around -59‰) and the overall δ13CCH4 signature from outer tropical wetlands in the southern Upper Congo and Upper Amazon drainage plotted together was -59 ± 2‰. These results were more negative than expected. For African cattle, δ13CCH4 values were around -60 to -50‰. Isotopic ratios in methane emitted by tropical fires depended on the C3 : C4 ratio of the biomass fuel. In smoke from tropical C3 dry forest fires in Senegal, δ13CCH4 values were around -28‰. By contrast, African C4 tropical grass fire δ13CCH4 values were -16 to -12‰. Methane from urban landfills in Zambia and Zimbabwe, which have frequent waste fires, had δ13CCH4 around -37 to -36‰. These new isotopic values help improve isotopic constraints on global methane budget models because atmospheric δ13CCH4 values predicted by global atmospheric models are highly sensitive to the δ13CCH4 isotopic signatures applied to tropical wetland emissions. Field and aircraft campaigns also observed widespread regional smoke pollution over Africa, in both the wet and dry seasons, and large urban pollution plumes. The work highlights the need to understand tropical greenhouse gas emissions in order to meet the goals of the UNFCCC Paris Agreement, and to help reduce air pollution over wide regions of Africa. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 2)'.


Asunto(s)
Contaminación del Aire , Humedales , Agricultura , Animales , Bovinos , Metano/análisis , Estaciones del Año
10.
J Air Waste Manag Assoc ; 70(12): 1324-1339, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32915694

RESUMEN

We report measurements of methane (CH4) mixing ratios and emission fluxes derived from sampling at a monitoring station at an exploratory shale gas extraction facility in Lancashire, England. Elevated ambient CH4 mixing ratios were recorded in January 2019 during a period of cold-venting associated with a nitrogen lift process at the facility. These processes are used to clear the well to stimulate flow of natural gas from the target shale. Estimates of CH4 flux during the emission event were made using three independent modeling approaches: Gaussian plume dispersion (following both a simple Gaussian plume inversion and the US EPA OTM 33-A method), and a Lagrangian stochastic transport model (WindTrax). The three methods yielded an estimated peak CH4 flux during January 2019 of approximately 70 g s-1. The total mass of CH4 emitted during the six-day venting period was calculated to be 2.9, 4.2 ± 1.4(1σ) and 7.1 ± 2.1(1σ) tonnes CH4 using the simple Gaussian plume model, WindTrax, and OTM-33A methods, respectively. Whilst the flux approaches all agreed within 1σ uncertainty, an estimate of 4.2 (± 1.4) tonnes CH4 represents the most confident assessment due to the explicit modeling of advection and meteorological stability permitted using the WindTrax model. This mass is consistent with fluxes calculated by the Environment Agency (in the range 2.7 to 6.8 tonnes CH4), using emission data provided by the shale site operator to the regulator. This study provides the first CH4 emission estimate for a nitrogen lift process and the first-reported flux monitoring of a UK shale gas site, and contributes to the evaluation of the environmental impacts of shale gas operations worldwide. This study also provides forward guidance on future monitoring applications and flux calculation in transient emission events. Implications: This manuscript discusses atmospheric measurements near to the UK's first hydraulic fracturing facility, which has very high UK public, media, and policy interest. The focus of this manuscript is on a single week of data in which a large venting event at the shale gas site saw emissions of ~4 tonnes of methane to atmosphere, in breach of environmental permits. These results are likely to beresults are likely to be reported by the media and may influence future policy decisions concerning the UK hydraulic fracturing industry.


Asunto(s)
Contaminantes Atmosféricos/análisis , Industria Procesadora y de Extracción , Metano/análisis , Gas Natural , Inglaterra , Monitoreo del Ambiente , Modelos Teóricos
11.
Sci Total Environ ; 708: 134600, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-31767337

RESUMEN

Baseline mobile surveys of methane sources using vehicle-mounted instruments have been performed in the Fylde and Ryedale regions of Northern England over the 2016-19 period around proposed unconventional (shale) gas extraction sites. The aim was to identify and characterise methane sources ahead of hydraulically fractured shale gas extraction in the area around drilling sites. This allows a potential additional source of emissions to atmosphere to be readily distinguished from adjacent sources, should gas production take place. The surveys have used ethane:methane (C2:C1) ratios to separate combustion, thermogenic gas and biogenic sources. Sample collection of source plumes followed by high precision δ13C analysis of methane, to separate and isotopically characterise sources, adds additional biogenic source distinction between active and closed landfills, and ruminant eructations from manure. The surveys show that both drill sites and adjacent fixed monitoring sites have cow barns and gas network pipeline leaks as sources of methane within a 1 km range. These two sources are readily separated by isotopes (δ13C of -67 to -58‰ for barns, compared to -43 to -39‰ for gas leaks), and ethane:methane ratios (<0.001 for barns, compared to >0.05 for gas leaks). Under a well-mixed daytime atmospheric boundary layer these sources are generally detectable as above baseline elevations up to 100 m downwind for gas leaks and up to 500 m downwind for populated cow barns. It is considered that careful analysis of these proxies for unconventional production gas, if and when available, will allow any fugitive emissions from operations to be distinguished from surrounding sources.

12.
Sensors (Basel) ; 19(21)2019 Oct 29.
Artículo en Inglés | MEDLINE | ID: mdl-31671919

RESUMEN

Point-source methane emission flux quantification is required to help constrain the global methane budget. Facility-scale fluxes can be derived using in situ methane mole fraction sampling, near-to-source, which may be acquired from an unmanned aerial vehicle (UAV) platform. We test a new non-dispersive infrared methane sensor by mounting it onto a small UAV, which flew downwind of a controlled methane release. Nine UAV flight surveys were conducted on a downwind vertical sampling plane, perpendicular to mean wind direction. The sensor was first packaged in an enclosure prior to sampling which contained a pump and a recording computer, with a total mass of 1.0 kg. The packaged sensor was then characterised to derive a gain factor of 0.92 ± 0.07, independent of water mole fraction, and an Allan deviation precision (at 1 Hz) of ±1.16 ppm. This poor instrumental precision and possible short-term drifts made it non-trivial to define a background mole fraction during UAV surveys, which may be important where any measured signal is small compared to sources of instrumental uncertainty and drift. This rendered the sensor incapable of deriving a meaningful flux from UAV sampling for emissions of the order of 1 g s-1. Nevertheless, the sensor may indeed be useful when sampling mole fraction enhancements of the order of at least 10 ppm (an order of magnitude above the 1 Hz Allan deviation), either from stationary ground-based sampling (in baseline studies) or from mobile sampling downwind of sources with greater source flux than those observed in this study. While many methods utilising low-cost sensors to determine methane flux are being developed, this study highlights the importance of adequately characterising and testing all new sensors before they are used in scientific research.

13.
Sci Total Environ ; 684: 1-13, 2019 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-31150871

RESUMEN

We report a 24-month statistical baseline climatology for continuously-measured atmospheric carbon dioxide (CO2) and methane (CH4) mixing ratios linked to surface meteorology as part of a wider environmental baselining project tasked with understanding pre-existing local environmental conditions prior to shale gas exploration in the United Kingdom. The baseline was designed to statistically characterise high-precision measurements of atmospheric composition gathered over two full years (between February 1st 2016 and January 31st 2018) at fixed ground-based measurement stations on, or near to, two UK sites being developed for shale gas exploration involving hydraulic fracturing. The sites, near Blackpool (Lancashire) and Kirby Misperton (North Yorkshire), were the first sites approved in the UK for shale gas exploration since a moratorium was lifted in England. The sites are operated by Cuadrilla Resources Ltd. and Third Energy Ltd., respectively. A statistical climatology of greenhouse gas mixing ratios linked to prevailing local surface meteorology is presented. This study diagnoses and interprets diurnal, day-of-week, and seasonal trends in measured mixing ratios and the contributory role of local, regional and long-range emission sources. The baseline provides a set of contextual statistical quantities against which the incremental impacts of new activities (in this case, future shale gas exploration) can be quantitatively assessed. The dataset may also serve to inform the design of future case studies, as well as direct baseline monitoring design at other potential shale gas and industrial sites. In addition, it provides a quantitative reference for future analyses of the impact, and efficacy, of specific policy interventions or mitigating practices. For example, statistically significant excursions in measured concentrations from this baseline (e.g. >99th percentile) observed during phases of operational extraction may be used to trigger further examination in order to diagnose the source(s) of emission and links to on-site activities at the time, which may be of importance to regulators, site operators and public health stakeholders. A guideline algorithm for identifying these statistically significant excursions, or "baseline deviation events", from the expected baseline conditions is presented and tested. Gaussian plume modelling is used to further these analyses, by simulating approximate upper-limits of CH4 fluxes which could be expected to give observable enhancements at the monitoring stations under defined meteorological conditions.

14.
Sci Total Environ ; 673: 445-454, 2019 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-30991334

RESUMEN

Rural observations of air quality and meteorological parameters (NOx, O3, NMHCs, SO2, PM) were made over a 2.5-year period (2016-2018) before, during and after preparations for hydraulic fracturing (fracking) at a shale gas exploration site near Kirby Misperton, North Yorkshire, England. As one of the first sites to apply for permits to carry out hydraulic fracturing, it has been subject to extensive regulatory and public scrutiny, as well as the focus for a major programme of long-term environmental monitoring. A baseline period of air quality monitoring (starting 2016) established the annual climatology of atmospheric composition against which a 20-week period of intensive activity on the site in preparation for hydraulic fracturing could be compared. During this 'pre-operational phase' of work in late 2017, the most significant effect was an increase in ambient NO (3-fold) and NOx (2-fold), arising from a combination of increased vehicle activity and operation of equipment on site. Although ambient NOx increased, air quality limit values for NO2 were not exceeded, even close to the well-site. Local ozone concentrations during the pre-operational period were slightly lower than the baseline phase due to titration with primary emitted NO. The activity on site did not lead to significant changes in airborne particulate matter or non-methane hydrocarbons. Hydraulic fracturing of the well did not subsequently take place and the on-site equipment was decommissioned and removed. Air quality parameters then returned to the original (baseline) climatological conditions. This work highlights the need to characterise the full annual climatology of air quality parameters against which short-term local activity changes can be compared. Based on this study, changes to ambient NOx appear to be the most significant air quality ahead of hydraulic fracturing. However, in rural locations, concentrations at individual sites are expected to be below ambient air quality limit thresholds.

15.
Waste Manag ; 87: 883-892, 2019 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-29329657

RESUMEN

This paper describes the development of a new sampling and measurement method to infer methane flux using proxy measurements of CO2 concentration and wind data recorded by Unmanned Aerial Systems (UAS). The flux method described and trialed here is appropriate to the spatial scale of landfill sites and analogous greenhouse gas emission hotspots, making it an important new method for low-cost and rapid case study quantification of fluxes from currently uncertain (but highly important) greenhouse gas sources. We present a case study using these UAS-based measurements to derive instantaneous methane fluxes from a test landfill site in the north of England using a mass balance model tailored for UAS sampling and co-emitted CO2 concentration as a methane-emission proxy. Methane flux (and flux uncertainty) during two trials on 27 November 2014 and 5 March 2015, were found to be 0.140 kg s-1 (±61% at 1σ), and 0.050 kg s-1 (±54% at 1σ), respectively. Uncertainty contributing to the flux was dominated by ambient variability in the background (inflow) concentration (>40%) and wind speed (>10%); with instrumental error contributing only ∼1-2%. The approach described represents an important advance concerning the challenging problem of greenhouse gas hotspot flux calculation, and offers transferability to a wide range of analogous environments. This new measurement solution could add to a toolkit of approaches to better validate source-specific greenhouse emissions inventories - an important new requirement of the UNFCCC COP21 (Paris) climate change agreement.


Asunto(s)
Contaminantes Atmosféricos , Gases de Efecto Invernadero , Eliminación de Residuos , Dióxido de Carbono , Inglaterra , Monitoreo del Ambiente , Metano , Paris , Instalaciones de Eliminación de Residuos
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