Natural Gas Extraction Activities Research Articles

Natural gas extraction activities and host communities concerns in Sub-Saharan Africa: A reflection on the historical riots in Mtwara, Tanzania

This paper examines host community concerns associated with natural gas extraction in Tanzania. Host communities in the Mtwara region in Tanzania have resisted natural gas extraction activities in their area. Using this region as a case study, the research draws on in-depth interviews, focus group discussions, direct field observation, documentary films, and relevant documents to understand the community concerns raised. Through content analysis, five significant themes were identified. Communities report that historical riots were prompted by empty promises, irrational expectations and alienation of communities from participating in and benefiting from natural gas extraction activities. Also, communication hiccups and poor aftermath responses worsened the already fragile situation. Clear communication between host communities and the government that allows participatory dialogue with stakeholders is fundamental for addressing host community concerns before havoc erupts. Likewise, where regulations were not followed adequately, follow-up should be done to resolve emanating circumstances and to hold responsible people accountable for their actions.

Can sea level rise help us restore coastal wetlands? The hydrologic restoration of the Slop Bowl, Brazoria National Wildlife Refuge, Texas

The Slop Bowl marsh in the Brazoria National Wildlife Refuge provides extraordinarily high quality, heavily used bird habitat. Much of this habitat has experienced hypersaline conditions due to both hydrologic alteration by humans and a rapidly and changing physical environment over the past several decades. Oil and natural gas extraction activities have resulted in excavation and channelization along pipelines and hydrologic obstruction by an access road. In addition, subsidence along growth faults has altered hydrologic pathways and lowered surface elevations in the center of the marsh. Our objective was to understand the underlying processes that contribute to hypersaline conditions and to evaluate possible restoration alternatives to reduce the severity of those conditions. Accordingly, we conducted extensive field and hydrologic modeling efforts, and identified the past, present, and future of this marsh habitat under a baseline scenario. We then compared various restoration action scenarios against this baseline. We found that, beginning in about 15 years, relative sea level rise will improve the hydrologic conditions by enhancing tidal flushing. However, if fill material is continually added to elevate the obstructing road as the sea rises, this hydrologic relief may never be realized. Moreover, we found that if a drought occurs during this critical period, a difference of only a few centimeters in the relative water level and road elevation, or changes in marsh surface elevations driven by fault motion and subsidence, may have catastrophic consequences. The modeling also suggests that several potential interventions can bridge this gap over the next 15 years and beyond. Actions that improve tidal circulation, reduce salinity, and enhance marsh accretion are being developed by the project team to enhance and restore habitat in the near term. The most optimal approaches evaluated thus far include the installation of culverts at critical locations, the excavation of a small channel, the modification of flow pathways, and the beneficial use of sediments and vegetative plantings. We conclude that, under specific circumstances or at unique locations such as the Slop Bowl marsh, sea level rise can be leveraged to improve coastal wetland health.

Marcellus Shale Gas Boom and Forestry Employment: Evidence from West Virginia

Abstract Advancement in drilling technology has increased natural gas extraction activities from the Marcellus shale deposit resulting in a shale gas boom in many regions, including West Virginia. This boom has created a significant labor demand shock to local economies experiencing the boom. A number of studies have shown that a shale gas boom directly increases employment and the income of those working in the industry. However, the boom can also have an adverse impact on other sectors through the resource movement effect and intersector labor mobility, pulling workers away from a related sector like forestry. Thus, an econometric model of employment in the forestry sector was developed to investigate the impact of the Marcellus shale gas boom in West Virginia. There is evidence of a labor movement effect with forestry employment negatively affected by the Marcellus shale boom. Specifically, the overall marginal effect of the shale boom on forestry employment is approximately 435 fewer jobs. However, the extent of the decline is slightly moderated by a higher relative wage between gas and forestry, perhaps suggesting diminishing returns and overall slack in the local labor market.

Person, Place, or Thing: Individual, Community, and Risk Information Seeking

This study focuses on the relationship between the community and the environment to explore (1) how community attachment affects residents’ risk perceptions and risk-coping strategies and (2) how risk knowledge is influenced by community-level psychological factors and, in turn, affects the decision to seek risk information. To find answers, 438 Texans were randomly surveyed on the topic of seismic activity induced by nearby natural gas extraction activities. The findings suggest that risk knowledge and risk information seeking intent are related to lower community attachment. Insights and implications related to the study have been provided for communication practitioners.

Quantifying atmospheric reactive nitrogen concentrations, dry deposition, and isotope dynamics surrounding a Marcellus Shale well pad

Unconventional natural gas (UNG) extraction activities have become important contributors to regional NOx emissions inventories. Currently, there is a knowledge gap in the amount of total N deposition surrounding well pads undergoing UNG extraction despite the fact that some areas with extensive natural gas extraction activity are already in exceedance of nitrogen critical loads. In this study, we measured the magnitude of total dry N deposition from NO2, HNO3, and NH3 attributable to the development of two UNG wells at a Marcellus Shale well pad study site. This study documents concentrations, deposition fluxes, and isotope values of NO2, HNO3, O3, and NH3 up- and down-wind along a 750-m well pad passive sampling transect across a 16-acre well pad containing two unconventional wells during all phases of development and extraction comprising fifteen distinct sampling periods. An access road transect was also utilized to explore reactive N dynamics in a near-road environment on the well pad where NO2 concentration and isotope dynamics were highly correlated with daily traffic count (r2 = 0.78–0.88, p < 0.01). An onsite chemiluminescent NO2 source apportionment model was compared against δ15N–NO2 and δ18O–NO2 source apportionment models (r2 = 0.57 and 0.82 respectively), demonstrating the possible utility of δ18O–NO2 as a source apportionment tool in near-source environments. In addition, the δ15N–NO2 source apportionment method compared well against a background-subtraction method (slope = 0.82, r2 = 0.88, p < 0.001) during non-wintertime conditions and was used to find N loadings directly attributable to well pad activities. In total, the total N deposition across the transect, attributable to well pad activities, utilizing industry's best management practices, ranged from 0.16 to 0.55 kg N ha−1 yr−1. This magnitude of well pad attributable N deposition is high enough to result in exceedances of nitrogen critical loads in areas with high well count densities and high baseline N deposition.

Public Participation in Air Sampling and Water Quality Test Kit Development to Enable Citizen Science

Public Participation in Air Sampling and Water Quality Test Kit Development to Enable Citizen Science Erin N. Haynes, DrPH MS, Timothy J. Hilbert, MS, Rusty Roberts, John Quirolgico, MS, Rachael Shepler, Gerry Beckner, Jennifer Veevers, PhD, Jeff Burkle, and Roman Jandarov, PhD What Is the Purpose of This Study/Review? • To establish an academic–community partnership to address Guernsey County residents' concern regarding environmental quality near proposed and operating natural gas extraction waste sites. • To develop a citizen science tool for water quality assessment by engagement of the local middle and high schools. What Is the Problem? • Natural gas extraction creates liquid, solid, and gaseous waste and the management of these wastes is a public health concern. • Natural gas extraction waste facilities are often located in underserved areas, an environmental justice issue for these communities. • The dramatic increase in natural gas extraction activity has caused concern among community members of Guernsey County and neighboring counties. What Are the Findings? • Together we selected 10 air sampling locations in proximity to current or proposed natural gas extraction sites, obtained cooperation from landowners, and conducted air quality monitoring over a 6-week period. • Volatile organic compounds were detected at all 10 air sampling locations. • Nineteen unique volatile organic compounds were detected; one was above the recommended exposure level. • Water quality test kits were developed and piloted in middle school and high school classrooms. Who Should Care Most? • Residents, public health officials, and emergency responders in rural communities with nearby natural gas extraction activity. • Educators and residents with an interest in participating in environmental health research via citizen science. [End Page 123] Recommendations for Action • Baseline measurements should be taken at any potential natural gas extraction sites and routine monitoring be conducted thereafter to characterize long-term exposures. • Water and soil sampling should be performed. • Data such as truck traffic and gallons of waste injected should be documented. • Engaging residents in research is a useful tool for increasing awareness and connecting communities to research. [End Page 124] Erin N. Haynes Department of Epidemiology, College of Public Health, University of Kentucky Timothy J. Hilbert Department of Environmental Health, College of Medicine, University of Cincinnati Rusty Roberts Cincinnati Children's Hospital Medical Center John Quirolgico Department of Environmental Health, College of Medicine, University of Cincinnati Rachael Shepler Guernsey County resident Gerry Beckner Guernsey County Department of Emergency Management Jennifer Veevers Department of Environmental Health, College of Medicine, University of Cincinnati Jeff Burkle Guernsey County resident Roman Jandarov Department of Environmental Health, College of Medicine, University of Cincinnati Correspondence to: Erin N. Haynes, DrPH MS, Department of Epidemiology, College of Public Health, University of Kentucky, 111 Washington Ave., CPH 212G, Lexington, KY 40536-0003. Phone: (859) 562-2119. Fax: (859) 257-8811. E-mail: Erin.Haynes@uky.edu Copyright © 2019 Johns Hopkins University Press

MALDI-TOF MS for the Identification of Cultivable Organic-Degrading Bacteria in Contaminated Groundwater near Unconventional Natural Gas Extraction Sites.

Groundwater quality and quantity is of extreme importance as it is a source of drinking water in the United States. One major concern has emerged due to the possible contamination of groundwater from unconventional oil and natural gas extraction activities. Recent studies have been performed to understand if these activities are causing groundwater contamination, particularly with respect to exogenous hydrocarbons and volatile organic compounds. The impact of contaminants on microbial ecology is an area to be explored as alternatives for water treatment are necessary. In this work, we identified cultivable organic-degrading bacteria in groundwater in close proximity to unconventional natural gas extraction. Pseudomonas stutzeri and Acinetobacter haemolyticus were identified using matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF MS), which proved to be a simple, fast, and reliable method. Additionally, the potential use of the identified bacteria in water and/or wastewater bioremediation was studied by determining the ability of these microorganisms to degrade toluene and chloroform. In fact, these bacteria can be potentially applied for in situ bioremediation of contaminated water and wastewater treatment, as they were able to degrade both compounds.

On the physics‐based processes behind production‐induced seismicity in natural gas fields

AbstractInduced seismicity due to natural gas production is observed at different sites worldwide. Common understanding states that the pressure drop caused by gas production leads to compaction, which affects the stress field in the reservoir and the surrounding rock formations and hence reactivates preexisting faults and induces earthquakes. In this study, we show that the multiphase fluid flow involved in natural gas extraction activities should be included. We use a fully coupled fluid flow and geomechanics simulator, which accounts for stress‐dependent permeability and linear poroelasticity, to better determine the conditions leading to fault reactivation. In our model setup, gas is produced from a porous reservoir, divided into two compartments that are offset by a normal fault. Results show that fluid flow plays a major role in pore pressure and stress evolution within the fault. Fault strength is significantly reduced due to fluid flow into the fault zone from the neighboring reservoir compartment and other formations. We also analyze scenarios for minimizing seismicity after a period of production, such as (i) well shut‐in and (ii) gas reinjection. In the case of well shut‐in, a highly stressed fault zone can still be reactivated several decades after production has ceased, although on average the shut‐in results in a reduction in seismicity. In the case of gas reinjection, fault reactivation can be avoided if gas is injected directly into the compartment under depletion. However, gas reinjection into a neighboring compartment does not stop the fault from being reactivated.

Air monitoring of volatile organic compounds at relevant receptors during hydraulic fracturing operations in Washington County, Pennsylvania.

A 3-month air monitoring study was conducted in Washington County, Pennsylvania, at the request of local community members regarding the potential risks resulting from air emissions of pollutants related to hydraulic fracturing operations. Continuous air monitoring for total volatile organic compounds was performed at two sampling sites, including a school and a residence, located within 900m of a hydraulic fracturing well pad that had been drilled prior to the study. Intermittent 24-hour air samples for 62 individual volatile organic compounds were also collected. The ambient air at both sites was monitored during four distinct periods of unconventional natural gas extraction activity: an inactive period prior to fracturing operations, during fracturing operations, during flaring operations, and during another inactive period after operations. The results of the continuous monitoring during fracturing and flaring sampling periods for total volatile organic compounds were similar to the results obtained during inactive periods. Total volatile organic compound 24-hour average concentrations ranged between 0.16 and 80ppb during all sampling periods. Several individual volatile compounds were detected in the 24-hour samples, but they were consistent with background atmospheric levels measured previously at nearby sampling sites and in other areas in Washington County. Furthermore, a basic yet conservative screening level evaluation demonstrated that the detected volatile organic compounds were well below health-protective levels. The primary finding of this study was that the operation of a hydraulic fracturing well pad in Washington County did not substantially affect local air concentrations of total and individual volatile organic compounds.

The impact of three recent coal-fired power plant closings on Pittsburgh air quality: A natural experiment

ABSTRACTRelative to the rest of the United States, the region of southwestern Pennsylvania, including metropolitan Pittsburgh, experiences high ambient concentrations of fine particulate matter (PM2.5), which is known to be associated with adverse respiratory and cardiovascular health impacts. This study evaluates whether the closing of three coal-fired power plants within the southwestern Pennsylvania region resulted in a significant decrease in PM2.5 concentration. Both PM2.5 data obtained from EPA ground stations in the study region and aerosol optical depth (AOD) data retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites were used to investigate regional air quality from January 2011 through December 2014. The impact of the plant closings on PM2.5 concentration and AOD was evaluated using a series of generalized additive models. The model results show that monthly fuel consumption of the Elrama plant, which closed in October of 2012, and monthly fuel consumption of both the Mitchell and Hatfield’s Ferry plants, which closed in October of 2013, were significant predictors of both PM2.5 concentration and AOD at EPA ground stations in the study region, after controlling for multiple meteorological factors and long-term, region-wide air quality improvements. The model’s power to predict PM2.5 concentration increased from an adjusted R2 of 0.61 to 0.68 after excluding data from ground stations with higher uncertainty due to recent increases in unconventional natural gas extraction activities. After preliminary analyses of mean PM2.5 concentration and AOD showed a downward trend following each power plant shutdown, results from a series of generalized additive models confirmed that the activity of the three plants that closed, measured by monthly fuel consumption, was highly significant in predicting both AOD and PM2.5 at 12 EPA ground stations; further research on PM2.5 emissions from unconventional natural gas extraction is needed.Implications: With many coal-fired power plants scheduled to close across the United States in the coming years, there is interest in the potential impact on regional PM2.5 concentrations. In southwestern Pennsylvania, recent coal-fired power plant closings were coupled with a boom in unconventional natural gas extraction. Natural gas is currently seen as an economically viable bridge fuel between coal and renewable energy. This study provides policymakers with more information on the potential ambient concentration changes associated with coal-fired power plant closings as the nation’s energy reliance shifts toward natural gas.

Reported health conditions in animals residing near natural gas wells in southwestern Pennsylvania

Natural gas extraction activities, including the use of horizontal drilling and hydraulic fracturing, may pose potential health risks to both human and animal populations in close proximity to sites of extraction activity. Because animals may have increased exposure to contaminated water and air as well as increased susceptibility to contaminant exposures compared to nearby humans, animal disease events in communities living near natural gas extraction may provide “sentinel” information useful for human health risk assessment. Community health evaluations as well as health impact assessments (HIAs) of natural gas exploration should therefore consider the inclusion of animal health metrics in their assessment process. We report on a community environmental health survey conducted in an area of active natural gas drilling, which included the collection of health data on 2452 companion and backyard animals residing in 157 randomly-selected households of Washington County, Pennsylvania (USA). There were a total of 127 reported health conditions, most commonly among dogs. When reports from all animals were considered, there were no significant associations between reported health condition and household proximity to natural gas wells. When dogs were analyzed separately, we found an elevated risk of ‘any’ reported health condition in households less than 1km from the nearest gas well (OR = 3.2, 95% CI 1.07–9.7), with dermal conditions being the most common of canine disorders. While these results should be considered hypothesis generating and preliminary, they suggest value in ongoing assessments of pet dogs as well as other animals to better elucidate the health impacts of natural gas extraction on nearby communities.

Proximity to natural gas wells and reported health status: results of a household survey in Washington County, Pennsylvania.

Background: Little is known about the environmental and public health impact of unconventional natural gas extraction activities, including hydraulic fracturing, that occur near residential areas.Objectives: Our aim was to assess the relationship between household proximity to natural gas wells and reported health symptoms.Methods: We conducted a hypothesis-generating health symptom survey of 492 persons in 180 randomly selected households with ground-fed wells in an area of active natural gas drilling. Gas well proximity for each household was compared with the prevalence and frequency of reported dermal, respiratory, gastrointestinal, cardiovascular, and neurological symptoms.Results: The number of reported health symptoms per person was higher among residents living < 1 km (mean ± SD, 3.27 ± 3.72) compared with > 2 km from the nearest gas well (mean ± SD, 1.60 ± 2.14; p = 0.0002). In a model that adjusted for age, sex, household education, smoking, awareness of environmental risk, work type, and animals in house, reported skin conditions were more common in households < 1 km compared with > 2 km from the nearest gas well (odds ratio = 4.1; 95% CI: 1.4, 12.3; p = 0.01). Upper respiratory symptoms were also more frequently reported in persons living in households < 1 km from gas wells (39%) compared with households 1–2 km or > 2 km from the nearest well (31 and 18%, respectively) (p = 0.004). No equivalent correlation was found between well proximity and other reported groups of respiratory, neurological, cardiovascular, or gastrointestinal conditions.Conclusion: Although these results should be viewed as hypothesis generating, and the population studied was limited to households with a ground-fed water supply, proximity of natural gas wells may be associated with the prevalence of health symptoms including dermal and respiratory conditions in residents living near natural gas extraction activities. Further study of these associations, including the role of specific air and water exposures, is warranted.Citation: Rabinowitz PM, Slizovskiy IB, Lamers V, Trufan SJ, Holford TR, Dziura JD, Peduzzi PN, Kane MJ, Reif JS, Weiss TR, Stowe MH. 2015. Proximity to natural gas wells and reported health status: results of a household survey in Washington County, Pennsylvania. Environ Health Perspect 123:21–26; http://dx.doi.org/10.1289/ehp.1307732

Ecology of the redfin darter and a potential emerging threat to its habitat

The basic biologies and ecologies of most freshwater fishes throughout the world are poorly understood. But such knowledge may be critical for conservation decisions. The redfin darter (Etheostoma whipplei), a poorly understood fish species, is an excellent model for highlighting this situation. Much of the limited range of this species is experiencing nontraditional natural gas extraction activities including hydraulic fracturing, which may be a significant source of silt input for streams. We investigated aspects of the ecology and metrics of reproductive success of redfin darters in central Arkansas. We examined habitat occupation through quantitative surveys of fish assemblages and habitat variables, and reproductive life history through field and laboratory surveys in Cypress Creek, Arkansas. We also examined the proportion of young fishes in populations relative to intensity of natural gas extraction activity. Ordination analysis found habitat gradients relating primarily to stream size. Redfin darters had the highest relative abundance in samples in small, high gradient streams. Redfin darters reproduce in the spring, peaking with the rainy season, using larger substrate than their close relatives. Reproductive success appears to be negatively related to natural gas extraction intensity. Redfin darters reproduce at both a time and in a habitat which may be especially susceptible to siltation from natural gas extraction activities, which may be reflected in fewer young fishes in populations. Our research highlights the importance of life history data in understanding responses to novel disturbances in freshwater fishes.

Conservation genetics and breeding system of Penstemon debilis (Plantaginaceae), a rare beardtongue endemic to oil shale talus in western Colorado, USA

AbstractRare species of plants are especially vulnerable to extinction when populations are few, have small numbers of individuals, and are fragmented. Such conditions lead to a reduction in gene flow and genetic diversity, and encourage inbreeding depression. We conducted a study of the reproductive biology and population genetics of Penstemon debilis (Plantaginaceae), a Federally Threatened species endemic to a small region of oil shale extraction in western Colorado, USA. Most of the habitat area is privately owned and undergoing natural gas extraction activities. Penstemon debilis reproduces both vegetatively and as an outcrosser that requires a pollen vector. Moderate levels of inbreeding, but no inbreeding depression, were found within populations of P. debilis. Genetic divergence among the extant populations surveyed was moderate (FST values = 0.069–0.231; Nm = 0.831–3.385) with levels of genetic diversity within populations relatively low compared to congeners with similar modes of pollination and reproductive biology. STRUCTURE analysis revealed three population clusters with some admixture among all extant populations. Genetic diversity within and among P. debilis populations is similar to genetic diversity found for other rare and endemic outcrossing plant species. Our results are consistent with a pattern of recent population fragmentation or low levels of pollen‐mediated gene flow among populations in close proximity to one another. Conservation of P. debilis will require cooperative management strategies between private landowners, government agencies, and concerned NGOs to preserve habitat for this rare species.

Anatomy of wintertime ozone associated with oil and natural gas extraction activity in Wyoming and Utah

Abstract Winter maximum daily 8-hour average (MDA8) ozone concentrations in the Upper Green River Basin, Wyoming (UGRBWY) and the Uintah Basin, Utah (UBUT) have frequently exceeded 100 ppb in January, February and March, in the past few years. Such levels are well above the U.S. air quality standard of 75 ppb. In these two remote basins in the Rockies, local ozone precursor emissions result from intense oil and gas extraction activities that release methane, volatile organic compounds (VOCs), and nitrogen oxides (NOx) to the atmosphere. These emissions become trapped beneath a stable and shallow (∼50–200 m) boundary layer maintained in low wind conditions. Wintertime surface ozone formation conditions are more likely in the UBUT than in the UGRBWY as the topography of the UBUT is an enclosed basin whereas the UGRBWY is open on its southern perimeter thus allowing for more air turnover. With snow-covered ground, high ozone events regularly begin in mid-December and last into early March in the UBUT whereas they usually do not begin in earnest until about a month later in the UGRBWY and may persist until mid-March. Winters without snow cover and the accompanying cold pool meteorological conditions do not experience high ozone events in either basin. For nine years with ozone observations in the UGRBWY (2005–2013) and four in the UBUT (2010–2013), all years with adequate (≥6 inches) and persistent snow cover, experienced days with ozone values ≥75 ppb except in 2012 in the UGRBWY when persistent high wind (&amp;gt;5 m/s) conditions were prevalent. Year to year differences in the occurrences of high ozone episodes appear to be driven primarily by differing meteorological conditions rather than by variations in ozone precursor levels.

Interpretation of volatile organic compound measurements by proton-transfer-reaction mass spectrometry over the deepwater horizon oil spill

A proton-transfer-reaction mass spectrometer (PTR-MS) was used onboard the NOAA WP-3D aircraft for atmospheric measurements over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico in 2010. A mass spectrum obtained by PTR-MS downwind from the accident site revealed the presence of a complex mixture of volatile organic compounds (VOCs). Here, we interpret this mass spectrum by comparing it with mass spectra of crude oil, gasoline and diesel samples measured in the laboratory. Aromatics were less abundant over the spill than from crude oil samples, due to the dissolution of these species in the seawater. The mass spectra obtained from aircraft measurements and crude oil samples both show strong signals at masses with mass-to-charge ratio (m/z) of 14×n±1, including 43, 57, 69, 71, 83, 85, 97 and 111Yamu. PTR-MS coupled with a gas chromatograph was used to identify major mass signals from crude oil samples. Cycloalkanes are important contributors to the signals of mass m/z 14×n±1, especially for masses 69, 83, 97 and 111amu. Aromatics could be interpreted from their specific masses without significant interference for crude oil vapors, but the interferences to benzene from higher aromatics can be significant as crude oil evaporates. The interpretation of DWH mass spectrum is not only helpful in understanding the atmospheric emissions associated with the DWH oil spill, but also for the interpretation of PTR-MS measurements in urban air, near natural oil seeps and oil as well as natural gas extraction activities.

Toxic Neighborhood

This work is part of a multisited ethnographic study on health and natural gas drilling in North Texas. In this article, I incorporate field notes, in-depth interview transcripts, and creative nonfiction to create a composite character to demonstrate the impact of natural gas drilling on some of the respondents. My goal is to communicate the perspectives of individuals living near natural gas extraction activities who have constructed a representation of the site as a threat to their health.

Toxicity of sediments potentially contaminated by coal mining and natural gas extraction to unionid mussels and commonly tested benthic invertebrates

Sediment toxicity tests were conducted to assess potential effects of contaminants associated with coal mining or natural gas extraction activities in the upper Tennessee River basin and eastern Cumberland River basin in the United States. Test species included two unionid mussels (rainbow mussel, Villosa iris, and wavy-rayed lampmussel, Lampsilis fasciola, 28-d exposures), and the commonly tested amphipod, Hyalella azteca (28-d exposure) and midge, Chironomus dilutus (10-d exposure). Sediments were collected from seven test sites with mussel communities classified as impacted and in proximity to coal mining or gas extraction activities, and from five reference sites with mussel communities classified as not impacted and no or limited coal mining or gas extraction activities. Additional samples were collected from six test sites potentially with high concentrations of polycyclic aromatic hydrocarbons (PAHs) and from a test site contaminated by a coal ash spill. Mean survival, length, or biomass of one or more test species was reduced in 10 of 14 test samples (71%) from impacted areas relative to the response of organisms in the five reference samples. A higher proportion of samples was classified as toxic to mussels (63% for rainbow mussels, 50% for wavy-rayed lampmussels) compared with amphipods (38%) or midge (38%). Concentrations of total recoverable metals and total PAHs in sediments did not exceed effects-based probable effect concentrations (PECs). However, the survival, length, or biomasses of the mussels were reduced significantly with increasing PEC quotients for metals and for total PAHs, or with increasing sum equilibrium-partitioning sediment benchmark toxic units for PAHs. The growth of the rainbow mussel also significantly decreased with increasing concentrations of a major anion (chloride) and major cations (calcium and magnesium) in sediment pore water. Results of the present study indicated that (1) the findings from laboratory tests were generally consistent with the field observations of impacts on mussel populations; (2) total recoverable metals, PAHs, or major ions, or all three in sediments might have contributed to the sediment toxicity; (3) the mussels were more sensitive to the contaminants in sediments than the commonly tested amphipod and midge; and (4) a sediment toxicity benchmark of 1.0 based on PECs may not be protective of mussels.

Benefits of pan‐sharpened Landsat imagery for mapping small waterbodies in the Powder River Basin, Wyoming, USA

AbstractPan‐sharpened Landsat imagery was used to map waterbodies of a wide variety of sizes in the Powder River Basin (PRB) in northcentral Wyoming, USA. Coal bed natural gas extraction activities have been intensive in the PRB over the past decade, with abundant co‐produced water being discharged into retention ponds and small ephemeral channels. Although land management agencies are tasked with monitoring these waterbodies, traditional field survey methods might not be feasible during rapid development. Remote‐sensing applications could be used in such cases. Although Landsat and similar medium‐resolution datasets do not have detailed spatial information at fine resolutions required to map small waterbodies, they do contain rich spectral information. Panchromatic data collected by satellites have an appropriate spatial resolution, but lack detailed spectral information. Thus, image fusion techniques were used to create a pan‐sharpened image, by merging multispectral (30‐m resolution) and panchromatic (15‐m) bands from Landsat 7 imagery. Both the original and the pan‐sharpened images were used to map waterbodies and estimate their area, being compared to photo‐interpretation results. The accuracy of mapping waterbodies with pan‐sharpened imagery was significantly higher than the original Landsat data for waterbodies ranging in size from 901 to 8100 m2. Large reservoirs (&gt;8100 m2) were very accurately mapped, both images producing identical results (96%). Neither image was able to suitably detect very small waterbodies (&lt;900 m2). Detailed analysis within 901–3600 m2 size category revealed that the benefits of pan‐sharpened imagery were most pronounced (25% higher accuracy) for mapping waterbodies ranging in size from 1801 to 2700 m2.