New study measures methane emissions from natural gas production and offers insights into 2 large sources

A team of researchers from the Cockrell School of Engineering at The University of Texas at Austin and environmental testing firm URS reports that a small subset of natural gas wells are responsible for the majority of methane emissions from two major sources — liquid unloadings and pneumatic controller equipment — at natural gas production sites.

With natural gas production in the United States expected to continue to increase during the next few decades, there is a need for a better understanding of methane emissions during natural gas production. The study team believes this research, published Dec. 9 in Environmental Science & Technology, will help to provide a clearer picture of methane emissions from natural gas production sites.

The UT Austin-led field study closely examined two major sources of methane emissions — liquid unloadings and pneumatic controller equipment — at well pad sites across the United States. Researchers found that 19 percent of the pneumatic devices accounted for 95 percent of the emissions from pneumatic devices, and 20 percent of the wells with unloading emissions that vent to the atmosphere accounted for 65 percent to 83 percent of those emissions.

“To put this in perspective, over the past several decades, 10 percent of the cars on the road have been responsible for the majority of automotive exhaust pollution,” said David Allen, chemical engineering professor at the Cockrell School and principal investigator for the study. “Similarly, a small group of sources within these two categories are responsible for the vast majority of pneumatic and unloading emissions at natural gas production sites.”

Additionally, for pneumatic devices, the study confirmed regional differences in methane emissions first reported by the study team in 2013. The researchers found that methane emissions from pneumatic devices were highest in the Gulf Coast and lowest in the Rocky Mountains.

The study is the second phase of the team’s 2013 study, which included some of the first measurements for methane emissions taken directly at hydraulically fractured well sites. Both phases of the study involved a partnership between the Environmental Defense Fund, participating energy companies, an independent Scientific Advisory Panel and the UT Austin study team.

The unprecedented access to natural gas production facilities and equipment allowed researchers to acquire direct measurements of methane emissions.

Study and Findings on Pneumatic Devices

Pneumatic devices, which use gas pressure to control the opening and closing of valves, emit gas as they operate. These emissions are estimated to be among the larger sources of methane emissions from the natural gas supply chain. The Environmental Protection Agency reports that 477,606 pneumatic (gas actuated) devices are in use at natural gas production sites throughout the U.S.

“Our team’s previous work established that pneumatics are a major contributor to emissions,” Allen said. “Our goal here was to measure a more diverse population of wells to characterize the features of high-emitting pneumatic controllers.”

The research team measured emissions from 377 gas actuated (pneumatic) controllers at natural gas production sites and a small number of oil production sites throughout the U.S.

The researchers sampled all identifiable pneumatic controller devices at each well site, a more comprehensive approach than the random sampling previously conducted. The average methane emissions per pneumatic controller reported in this study are 17 percent higher than the average emissions per pneumatic controller in the 2012 EPA greenhouse gas national emission inventory (released in 2014), but the average from the study is dominated by a small subpopulation of the controllers. Specifically, 19 percent of controllers, with measured emission rates in excess of 6 standard cubic feet per hour (scf/h), accounted for 95 percent of emissions.

The high-emitting pneumatic devices are a combination of devices that are not operating as designed, are used in applications that cause them to release gas frequently or are designed to emit continuously at a high rate.

The researchers also observed regional differences in methane emission levels, with the lowest emissions per device measured in the Rocky Mountains and the highest emissions in the Gulf Coast, similar to the earlier 2013 study. At least some of the regional differences in emission rates can be attributed to the difference in controller type (continuous vent vs. intermittent vent) among regions.

Study and Findings on Liquid Unloadings

After observing variable emissions for liquid unloadings for a limited group of well types in the 2013 study, the research team made more extensive measurements and confirmed that a majority of emissions come from a small fraction of wells that vent frequently. Although it is not surprising to see some correlation between frequency of unloadings and higher annual emissions, the study’s findings indicate that wells with a high frequency of unloadings have annual emissions that are 10 or more times as great as wells that unload less frequently.

The team’s field study, which measured emissions from unloadings from wells at 107 natural gas production wells throughout the U.S., represents the most extensive measurement of emissions associated with liquid unloadings in scientific literature thus far.

A liquid unloading is one method used to clear wells of accumulated liquids to increase production. Because older wells typically produce less gas as they near the end of their life cycle, liquid unloadings happen more often in those wells than in newer wells. The team found a statistical correlation between the age of wells and the frequency of liquid unloadings. The researchers found that the key identifier for high-emitting wells is how many times the well unloads in a given year.

Because liquid unloadings can employ a variety of liquid lifting mechanisms, the study results also reflect differences in liquid unloadings emissions between wells that use two different mechanisms (wells with plunger lifts and wells without plunger lifts). Emissions for unloading events for wells without plunger lifts averaged 21,000 scf (standard cubic feet) to 35,000 scf. For wells with plunger lifts that vent to the atmosphere, emissions averaged 1,000 scf to 10,000 scf of methane per event. Although the emissions per event were higher for wells without plunger lifts, these wells had, on average, fewer events than wells with plunger lifts. Wells without plunger lifts averaged fewer than 10 unloading events per year, and wells with plunger lifts averaged more than 200 events per year.Overall, wells with plunger lifts were estimated to account for 70 percent of emissions from unloadings nationally.

Additionally, researchers found that the Rocky Mountain region, with its large number of wells with a high frequency of unloadings that vent to the atmosphere, accounts for about half of overall emissions from liquid unloadings.

The study team hopes its measurements of liquid unloadings and pneumatic devices will provide a clearer picture of methane emissions from natural gas well sites and about the relationship between well characteristics and emissions.

The study was a cooperative effort involving experts from the Environmental Defense Fund, Anadarko Petroleum Corporation, BG Group PLC, Chevron, ConocoPhillips, Encana Oil & Gas (USA) Inc., Pioneer Natural Resources Company, SWEPI LP (Shell), Statoil, Southwestern Energy and XTO Energy, a subsidiary of ExxonMobil.

The University of Texas at Austin is committed to transparency and disclosure of all potential conflicts of interest of its researchers. Lead researcher David Allen serves as chair of the Environmental Protection Agency’s Science Advisory Board and in this role is a paid Special Governmental Employee. He is also a journal editor for the American Chemical Society and has served as a consultant for multiple companies, including Eastern Research Group, ExxonMobil and the Research Triangle Institute. He has worked on other research projects funded by a variety of governmental, nonprofit and private sector sources including the National Science Foundation, the Environmental Protection Agency, the Texas Commission on Environmental Quality, the American Petroleum Institute and an air monitoring and surveillance project that was ordered by the U.S. District Court for the Southern District of Texas. Adam Pacsi and Daniel Zavala-Araiza, who were graduate students at The University of Texas at the time this work was done, have accepted positions at Chevron Energy Technology Company and the Environmental Defense Fund, respectively.

Financial support for this work was provided by the Environmental Defense Fund (EDF), Anadarko Petroleum Corporation, BG Group PLC, Chevron, ConocoPhillips, Encana Oil & Gas (USA) Inc., Pioneer Natural Resources Company, SWEPI LP (Shell), Statoil, Southwestern Energy and XTO Energy, a subsidiary of ExxonMobil.

Major funding for the EDF’s 30-month methane research series, including their portion of the University of Texas study, is provided for by the following individuals and foundations: Fiona and Stan Druckenmiller, the Heising-Simons Foundation, Bill and Susan Oberndorf, Betsy and Sam Reeves, the Robertson Foundation, TomKat Charitable Trust and the Walton Family Foundation.

Abandoned wells can be ‘super-emitters’ of greenhouse gas

One of the wells the researchers tested; this one in the Allegheny National Forest. -  Princeton University
One of the wells the researchers tested; this one in the Allegheny National Forest. – Princeton University

Princeton University researchers have uncovered a previously unknown, and possibly substantial, source of the greenhouse gas methane to the Earth’s atmosphere.

After testing a sample of abandoned oil and natural gas wells in northwestern Pennsylvania, the researchers found that many of the old wells leaked substantial quantities of methane. Because there are so many abandoned wells nationwide (a recent study from Stanford University concluded there were roughly 3 million abandoned wells in the United States) the researchers believe the overall contribution of leaking wells could be significant.

The researchers said their findings identify a need to make measurements across a wide variety of regions in Pennsylvania but also in other states with a long history of oil and gas development such as California and Texas.

“The research indicates that this is a source of methane that should not be ignored,” said Michael Celia, the Theodore Shelton Pitney Professor of Environmental Studies and professor of civil and environmental engineering at Princeton. “We need to determine how significant it is on a wider basis.”

Methane is the unprocessed form of natural gas. Scientists say that after carbon dioxide, methane is the most important contributor to the greenhouse effect, in which gases in the atmosphere trap heat that would otherwise radiate from the Earth. Pound for pound, methane has about 20 times the heat-trapping effect as carbon dioxide. Methane is produced naturally, by processes including decomposition, and by human activity such as landfills and oil and gas production.

While oil and gas companies work to minimize the amount of methane emitted by their operations, almost no attention has been paid to wells that were drilled decades ago. These wells, some of which date back to the 19th century, are typically abandoned and not recorded on official records.

Mary Kang, then a doctoral candidate at Princeton, originally began looking into methane emissions from old wells after researching techniques to store carbon dioxide by injecting it deep underground. While examining ways that carbon dioxide could escape underground storage, Kang wondered about the effect of old wells on methane emissions.

“I was looking for data, but it didn’t exist,” said Kang, now a postdoctoral researcher at Stanford.

In a paper published Dec. 8 in the Proceedings of the National Academy of Sciences, the researchers describe how they chose 19 wells in the adjacent McKean and Potter counties in northwestern Pennsylvania. The wells chosen were all abandoned, and records about the origin of the wells and their conditions did not exist. Only one of the wells was on the state’s list of abandoned wells. Some of the wells, which can look like a pipe emerging from the ground, are located in forests and others in people’s yards. Kang said the lack of documentation made it hard to tell when the wells were originally drilled or whether any attempt had been made to plug them.

“What surprised me was that every well we measured had some methane coming out,” said Celia.

To conduct the research, the team placed enclosures called flux chambers over the tops of the wells. They also placed flux chambers nearby to measure the background emissions from the terrain and make sure the methane was emitted from the wells and not the surrounding area.

Although all the wells registered some level of methane, about 15 percent emitted the gas at a markedly higher level — thousands of times greater than the lower-level wells. Denise Mauzerall, a Princeton professor and a member of the research team, said a critical task is to discover the characteristics of these super-emitting wells.

Mauzerall said the relatively low number of high-emitting wells could offer a workable solution: while trying to plug every abandoned well in the country might be too costly to be realistic, dealing with the smaller number of high emitters could be possible.

“The fact that most of the methane is coming out of a small number of wells should make it easier to address if we can identify the high-emitting wells,” said Mauzerall, who has a joint appointment as a professor of civil and environmental engineering and as a professor of public and international affairs at the Woodrow Wilson School.

The researchers have used their results to extrapolate total methane emissions from abandoned wells in Pennsylvania, although they stress that the results are preliminary because of the relatively small sample. But based on that data, they estimate that emissions from abandoned wells represents as much as 10 percent of methane from human activities in Pennsylvania — about the same amount as caused by current oil and gas production. Also, unlike working wells, which have productive lifetimes of 10 to 15 years, abandoned wells can continue to leak methane for decades.

“This may be a significant source,” Mauzerall said. “There is no single silver bullet but if it turns out that we can cap or capture the methane coming off these really big emitters, that would make a substantial difference.”


Besides Kang, who is the paper’s lead author, Celia and Mauzerall, the paper’s co-authors include: Tullis Onstott, a professor of geosciences at Princeton; Cynthia Kanno, who was a Princeton undergraduate and who is a graduate student at the Colorado School of Mines; Matthew Reid, who was a graduate student at Princeton and is a postdoctoral researcher at EPFL in Luzerne, Switzerland; Xin Zhang, a postdoctoral researcher in the Woodrow Wilson School at Princeton; and Yuheng Chen, an associate research scholar in geosciences at Princeton.

Technology-dependent emissions of gas extraction in the US

The KIT measurement instrument on board of a minivan directly measures atmospheric emissions on site with a high temporal resolution. -  Photo: F. Geiger/KIT
The KIT measurement instrument on board of a minivan directly measures atmospheric emissions on site with a high temporal resolution. – Photo: F. Geiger/KIT

Not all boreholes are the same. Scientists of the Karlsruhe Institute of Technology (KIT) used mobile measurement equipment to analyze gaseous compounds emitted by the extraction of oil and natural gas in the USA. For the first time, organic pollutants emitted during a fracking process were measured at a high temporal resolution. The highest values measured exceeded typical mean values in urban air by a factor of one thousand, as was reported in ACP journal. (DOI 10.5194/acp-14-10977-2014)

Emission of trace gases by oil and gas fields was studied by the KIT researchers in the USA (Utah and Colorado) together with US institutes. Background concentrations and the waste gas plumes of single extraction plants and fracking facilities were analyzed. The air quality measurements of several weeks duration took place under the “Uintah Basin Winter Ozone Study” coordinated by the National Oceanic and Atmospheric Administration (NOAA).

The KIT measurements focused on health-damaging aromatic hydrocarbons in air, such as carcinogenic benzene. Maximum concentrations were determined in the waste gas plumes of boreholes. Some extraction plants emitted up to about a hundred times more benzene than others. The highest values of some milligrams of benzene per cubic meter air were measured downstream of an open fracking facility, where returning drilling fluid is stored in open tanks and basins. Much better results were reached by oil and gas extraction plants and plants with closed production processes. In Germany, benzene concentration at the workplace is subject to strict limits: The Federal Emission Control Ordinance gives an annual benzene limit of five micrograms per cubic meter for the protection of human health, which is smaller than the values now measured at the open fracking facility in the US by a factor of about one thousand. The researchers published the results measured in the journal Atmospheric Chemistry and Physics ACP.

“Characteristic emissions of trace gases are encountered everywhere. These are symptomatic of gas and gas extraction. But the values measured for different technologies differ considerably,” Felix Geiger of the Institute of Meteorology and Climate Research (IMK) of KIT explains. He is one of the first authors of the study. By means of closed collection tanks and so-called vapor capture systems, for instance, the gases released during operation can be collected and reduced significantly.

“The gas fields in the sparsely populated areas of North America are a good showcase for estimating the range of impacts of different extraction and fracking technologies,” explains Professor Johannes Orphal, Head of IMK. “In the densely populated Germany, framework conditions are much stricter and much more attention is paid to reducing and monitoring emissions.”

Fracking is increasingly discussed as a technology to extract fossil resources from unconventional deposits. Hydraulic breaking of suitable shale stone layers opens up the fossil fuels stored there and makes them accessible for economically efficient use. For this purpose, boreholes are drilled into these rock formations. Then, they are subjected to high pressure using large amounts of water and auxiliary materials, such as sand, cement, and chemicals. The oil or gas can flow to the surface through the opened microstructures in the rock. Typically, the return flow of the aqueous fracking liquid with the dissolved oil and gas constituents to the surface lasts several days until the production phase proper of purer oil or natural gas. This return flow is collected and then reused until it finally has to be disposed of. Air pollution mainly depends on the treatment of this return flow at the extraction plant. In this respect, currently practiced fracking technologies differ considerably. For the first time now, the resulting local atmospheric emissions were studied at a high temporary resolution. Based on the results, emissions can be assigned directly to the different plant sections of an extraction plant. For measurement, the newly developed, compact, and highly sensitive instrument, a so-called proton transfer reaction mass spectrometer (PTR-MS), of KIT was installed on board of a minivan and driven closer to the different extraction points, the distances being a few tens of meters. In this way, the waste gas plumes of individual extraction sources and fracking processes were studied in detail.

Warneke, C., Geiger, F., Edwards, P. M., Dube, W., Pétron, G., Kofler, J., Zahn, A., Brown, S. S., Graus, M., Gilman, J. B., Lerner, B. M., Peischl, J., Ryerson, T. B., de Gouw, J. A., and Roberts, J. M.: Volatile organic compound emissions from the oil and natural gas industry in the Uintah Basin, Utah: oil and gas well pad emissions compared to ambient air composition, Atmos. Chem. Phys., 14, 10977-10988, doi:10.5194/acp-14-10977-2014, 2014.

New tracers can identify frack fluids in the environment

Scientists have developed new geochemical tracers that can identify hydraulic fracturing flowback fluids that have been spilled or released into the environment.

The tracers, which were created by a team of U.S. and French researchers, have been field-tested at a spill site in West Virginia and downstream from an oil and gas brine wastewater treatment plant in Pennsylvania.

“This gives us new forensic tools to detect if ‘frac fluids’ are escaping into our water supply and what risks, if any, they might pose,” said Duke University geochemist Avner Vengosh, who co-led the research.

“By characterizing the isotopic and geochemical fingerprints of enriched boron and lithium in flowback water from hydraulic fracturing, we can now track the presence of frac fluids in the environment and distinguish them from wastewater coming from other sources, including conventional oil and gas wells,” Vengosh said.

Using the tracers, scientists can determine where fracturing fluids have or haven’t been released to the environment and, ultimately, help identify ways to improve how shale gas wastewater is treated and disposed of.

Vengosh and his colleagues published their peer-reviewed findings October 20 in the journal Environmental Science & Technology. Their study, which was funded in part by the National Science Foundation, is the first to report on the development of the boron and lithium tracers.

Nathaniel R. Warner, Obering Postdoctoral Fellow at Dartmouth College, was lead author of the study. “This new technology can be combined with other methods to identify specific instances of accidental releases to surface waters in areas of unconventional drilling,” he said. “It could benefit industry as well as federal and state agencies charged with monitoring water quality and protecting the environment.”

Hydraulic fracturing fluids, or frac fluids, typically contain mixes of water, proprietary chemicals and sand. Mixtures can vary from site to site. Drillers inject large volumes of the fluids down gas wells at high pressure to crack open shale formations deep underground and allow natural gas trapped within the shale to flow out and be extracted. After the shale has been fractured, the frac fluids flow back up the well to the surface along with the gas and highly saline brines from the shale formation.

Some people fear that toxic frac fluid chemicals in this flowback could contaminate nearby water supplies if flowback were accidentally spilled or insufficiently treated before being disposed of.

“The flowback fluid that returns to the surface becomes a waste that needs to be managed,” Vengosh explained. “Deep-well injection is the preferable disposal method, but injecting large volumes of wastewater into deep wells can cause earthquakes in sensitive areas and is not geologically available in some states. In Pennsylvania, much of the flowback is now recycled and reused, but a significant amount of it is still discharged into local streams or rivers.”

Vengosh said it’s possible to identify the presence of frac fluid in spilled or discharged flowback by tracing synthetic organic compounds that are added to the fluid before it’s injected down a well. But the proprietary nature of these chemicals, combined with their instability in the environment, limits the usefulness of such tracers.

By contrast, the new boron and lithium tracers remain stable in the environment. “The difference is that we are using tracers based on elements that occur naturally in shale formations,” Vengosh said.

When drillers inject frac fluids into a shale formation, they not only release hydrocarbon but also boron and lithium that are attached to clay minerals within the formation, he explained. As the fluids react and mix at depth, they become enriched in boron and lithium. As they are brought back to the surface, they have distinctive isotopic fingerprints that are different from other types of wastewater, including wastewater from a conventional gas or oil well, as well as from naturally occurring background water.

“This type of forensic research allows us to clearly delineate between the possible sources of wastewater contamination,” Vengosh said.

A unique approach to monitoring groundwater supplies near Ohio fracking sites

This image shows a drilling rig in Carroll County, Ohio. -  Amy Townsend-Small
This image shows a drilling rig in Carroll County, Ohio. – Amy Townsend-Small

A University of Cincinnati research project is taking a groundbreaking approach to monitoring groundwater resources near fracking sites in Ohio. Claire Botner, a UC graduate student in geology, will outline the project at The Geological Society of America’s Annual Meeting & Exposition. The meeting takes place Oct. 19-22, in Vancouver.

Botner’s research is part of UC Groundwater Research of Ohio (GRO), a collaborative research project out of UC to examine the effects of fracking (hydraulic fracturing) on groundwater in the Utica Shale region of eastern Ohio. First launched in Carroll County in 2012, the GRO team of researchers is examining methane levels and origins of methane in private wells and springs before, during and after the onset of fracking. The team travels to the region to take water samples four times a year.

Amy Townsend-Small, the lead researcher for GRO and a UC assistant professor of geology, says the UC study is unique in comparison with studies on water wells in other shale-rich areas of the U.S. where fracking is taking place – such as the Marcellus Shale region of Pennsylvania.

Townsend-Small says water samples finding natural gas-derived methane in wells near Pennsylvania fracking sites were taken only after fracking had occurred, so methane levels in those wells were not documented prior to or during fracking in Pennsylvania.

Hydraulic fracturing, or fracking, involves using millions of gallons of water mixed with sand and chemicals to break up organic-rich shale to release natural gas resources.

Proponents say the practice promises a future in lower energy prices, an increase in domestic jobs and less dependence on foreign oil from unstable overseas governments.

Opponents raise concerns about increasing methane gas levels (a powerful greenhouse gas) and other contamination involving the spillover of fracking wastewater in the groundwater of shale-rich regions.

“The only way people with private groundwater will know whether or not their water is affected by fracking is through regular monitoring,” says Townsend-Small.

The Ohio samples are being analyzed by UC researchers for concentrations of methane as well as other hydrocarbons and salt, which is pulled up in the fracking water mixture from the shales. The shales are ancient ocean sediments.

Botner’s study involves testing on 22 private wells in Carroll County between November 2012 and last May. The first fracking permits were issued in the region in 2011. So far, results indicate that any methane readings in groundwater wells came from organic matter. In less than a handful of cases, the natural methane levels were relatively high, above 10 milligrams per liter. However, most of the wells carried low levels of methane.

The UC sampling has now been expanded into Columbiana, Harrison, Stark and Belmont counties in Ohio. Researchers then review data on private drinking water wells with the homeowners. “We’re working on interacting with these communities and educating them about fracking as well as gathering scientific data, which is lacking on a very sensitive issue,” says Botner. “It can also be reassuring to receive data on their water supplies from an objective, university resource.”

The team also is seeking additional funding to begin monitoring groundwater wells near wastewater injection wells, where fracking brine is deposited after the wells are drilled.

###

Funding for Botner’s research to be presented at the GSA meeting is supported by a grant from the Missouri-based Deer Creek Foundation.

Botner is among UC graduate students and faculty who are presenting more than two dozen research papers, PowerPoint presentations or poster exhibitions at the GSA meeting. The meeting draws geoscientists from around the world representing more than 40 different disciplines.

UC’s nationally ranked Department of Geology conducts field research around the world in areas spanning paleontology, Quaternary geology, geomorphology, sedimentology, stratigraphy, tectonics, environmental geology and biogeochemistry.

The Geological Society of America, founded in 1888, is a scientific society with more than 26,500 members from academia, government and industry in more than 100 countries. Through its meetings, publications and programs, GSA enhances the professional growth of its members and promotes the geosciences in the service of humankind.

Space-based methane maps find largest US signal in Southwest

An unexpectedly high amount of the climate-changing gas methane, the main component of natural gas, is escaping from the Four Corners region in the U.S. Southwest, according to a new study by the University of Michigan and NASA.

The researchers mapped satellite data to uncover the nation’s largest methane signal seen from space. They measured levels of the gas emitted from all sources, and found more than half a teragram per year coming from the area where Arizona, New Mexico, Colorado and Utah meet. That’s about as much methane as the entire coal, oil, and gas industries of the United Kingdom give off each year.

Four Corners sits on North America’s most productive coalbed methane basin. Coalbed methane is a variety of the gas that’s stuck to the surface of coal. It is dangerous to miners (not to mention canaries), but in recent decades, it’s been tapped as a resource.

“There’s so much coalbed methane in the Four Corners area, it doesn’t need to be that crazy of a leak rate to produce the emissions that we see. A lot of the infrastructure is likely contributing,” said Eric Kort, assistant professor of atmospheric, oceanic and space sciences at the U-M College of Engineering.

Kort, first author of a paper on the findings published in Geophysical Research Letters, says the controversial natural gas extraction technique of hydraulic fracturing is not the main culprit.

“We see this large signal and it’s persistent since 2003,” Kort said. “That’s a pre- fracking timeframe in this region. While fracking has become a focal point in conversations about methane emissions, it certainly appears from this and other studies that in the U.S., fossil fuel extraction activities across the board likely emit higher than inventory estimates.”

While the signal represents the highest concentration of methane seen from space, the researchers caution that Four Corners isn’t necessarily the highest emitting region.

“One has to be somewhat careful in equating abundances with emissions,” said study contributor Christian Frankenberg at Jet Propulsion Laboratory. “The Four Corners methane source is in a relatively isolated area with little other methane emissions, hence causing a well distinguishable hot-spot in methane abundances. Local or more diffuse emissions in other areas, such as the eastern U.S., may be convoluted with other nearby sources

Natural gas is often touted as more sustainable than coal and oil because it releases fewer pollutants when it burns. But when it leaks into the air before it gets to the pilot light, methane has 30 times the short-term heat-trapping effects of carbon dioxide. Policymakers, energy companies and environmentalists alike are aiming to reduce methane emissions as a way to curb climate change. But pinpointing plumes—a first step to stopping them—has been a difficult task with today’s tools.

The research team demonstrated a new approach to finding leaks. They used a satellite instrument—the European Space Agency’s SCIAMACHY—to get regional methane measurements over the entire United States. They ran the data through a mathematical model to account for mountains and valleys, which can trap methane. That’s how they identified the anomaly at Four Corners. Then they zoomed in on that region and ran another mathematical model to control for wind, to make sure that didn’t negate the original signal. It didn’t.

“We didn’t know this was a region we should look at. We found it from space,” Kort said. “We’ve demonstrated that satellite measurements can help identify, locate and quantify anomalous methane emissions in regions that are unexpected.”

Methane gets into the atmosphere from both natural and human-made sources. Wetlands and landfills release it, as do certain bacteria. Agriculture is a big contributor. So are gas and oil drilling and distribution. Inventories such as those the EPA compiles make estimates based on measurements from a sampling of these sources. In previous work, air measurements from planes and a sparse network of monitoring towers have revealed that the inventory-based numbers are coming in low—roughly 50 percent low. But towers and planes can’t see everywhere to figure out exactly where all the methane is coming from. With limited observations there can be blind spots, the researchers say.

This study used satellite data from 2003 to 2009. In later years, they were able to validate the satellite measurements with a year of ground-based data.

SCIAMACHY is no longer operating, so there aren’t equivalent satellites to provide this information for other parts of the world. For the Four Corners region, Kort will be taking readings from an airplane next year, to get even closer to identifying the leaks.

###

The study is titled “Four Corners: the largest US methane anomaly viewed from space.” The research was funded by NASA and Los Alamos National Lab.

Eric Kort: http://aoss.engin.umich.edu/people/eakort

Abstract: http://onlinelibrary.wiley.com/doi/10.1002/2014GL061503/abstract

Researcher receives $1.2 million to create real-time seismic imaging system

This is Dr. WenZhan Song. -  Georgia State University
This is Dr. WenZhan Song. – Georgia State University

Dr. WenZhan Song, a professor in the Department of Computer Science at Georgia State University, has received a four-year, $1.2 million grant from the National Science Foundation to create a real-time seismic imaging system using ambient noise.

This imaging system for shallow earth structures could be used to study and monitor the sustainability of the subsurface, or area below the surface, and potential hazards of geological structures. Song and his collaborators, Yao Xie of the Georgia Institute of Technology and Fan-Chi Lin of the University of Utah, will use ambient noise to image the subsurface of geysers in Yellowstone National Park.

“This project is basically imaging what’s underground in a situation where there’s no active source, like an earthquake. We’re using background noise,” Song said. “At Yellowstone, for instance, people visit there and cars drive by. All that could generate signals that are penetrating through the ground. We essentially use that type of information to tap into a very weak signal to infer the image of underground. This is very frontier technology today.”

The system will be made up of a large network of wireless sensors that can perform in-network computing of 3-D images of the shallow earth structure that are based solely on ambient noise.

Real-time ambient noise seismic imaging technology could also inform homeowners if the subsurface below their home, which can change over time, is stable or will sink beneath them.

This technology can also be used in circumstances that don’t need to rely on ambient noise but have an active source that produces signals that can be detected by wireless sensors. It could be used for real-time monitoring and developing early warning systems for natural hazards, such as volcanoes, by determining how close magma is to the surface. It could also benefit oil exploration, which uses methods such as hydrofracturing, in which high-pressure water breaks rocks and allows natural gas to flow more freely from underground.

“As they do that, it’s critical to monitor that in real time so you can know what’s going on under the ground and not cause damage,” Song said. “It’s a very promising technology, and we’re helping this industry reduce costs significantly because previously they only knew what was going on under the subsurface many days and even months later. We could reduce this to seconds.”

Until now, data from oil exploration instruments had to be manually retrieved and uploaded into a centralized database, and it could take days or months to process and analyze the data.

The research team plans to have a field demonstration of the system in Yellowstone and image the subsurface of some of the park’s geysers. The results will be shared with Yellowstone management, rangers and staff. Yellowstone, a popular tourist attraction, is a big volcano that has been dormant for a long time, but scientists are concerned it could one day pose potential hazards.

In the past several years, Song has been developing a Real-time In-situ Seismic Imaging (RISI) system using active sources, under the support of another $1.8 million NSF grant. His lab has built a RISI system prototype that is ready for deployment. The RISI system can be implemented as a general field instrumentation platform for various geophysical imaging applications and incorporate new geophysical data processing and imaging algorithms.

The RISI system can be applied to a wide range of geophysical exploration topics, such as hydrothermal circulation, oil exploration, mining safety and mining resource monitoring, to monitor the uncertainty inherent to the exploration and production process, reduce operation costs and mitigate the environmental risks. The business and social impact is broad and significant. Song is seeking business investors and partners to commercialize this technology.

###

For more information about the project, visit http://sensorweb.cs.gsu.edu/?q=ANSI.

2015 DOE JGI’s science portfolio delves deeper into the Earth’s data mine

The U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science user facility, has announced that 32 new projects have been selected for the 2015 Community Science Program (CSP). From sampling Antarctic lakes to Caribbean waters, and from plant root micro-ecosystems, to the subsurface underneath the water table in forested watersheds, the CSP 2015 projects portfolio highlights diverse environments where DOE mission-relevant science can be extracted.

“These projects catalyze JGI’s strategic shift in emphasis from solving an organism’s genome sequence to enabling an understanding of what this information enables organisms to do,” said Jim Bristow, DOE JGI Science Deputy who oversees the CSP. “To accomplish this, the projects selected combine DNA sequencing with large-scale experimental and computational capabilities, and in some cases include JGI’s new capability to write DNA in addition to reading it. These projects will expand research communities, and help to meet the DOE JGI imperative to translate sequence to function and ultimately into solutions for major energy and environmental problems.”

The CSP 2015 projects were selected by an external review panel from 76 full proposals received that resulted from 85 letters of intent submitted. The total allocation for the CSP 2015 portfolio is expected to exceed 60 trillion bases (terabases or Tb)-or the equivalent of 20,000 human genomes of plant, fungal and microbial genome sequences. The full list of projects may be found at http://jgi.doe.gov/our-projects/csp-plans/fy-2015-csp-plans/. The DOE JGI Community Science Program also accepts proposals for smaller-scale microbial, resequencing and DNA synthesis projects and reviews them twice a year. The CSP advances projects that harness DOE JGI’s capability in massive-scale DNA sequencing, analysis and synthesis in support of the DOE missions in alternative energy, global carbon cycling, and biogeochemistry.

Among the CSP 2015 projects selected is one from Regina Lamendella of Juniata College, who will investigate how microbial communities in Marcellus shale, the country’s largest shale gas field, respond to hydraulic fracturing and natural gas extraction. For example, as fracking uses chemicals, researchers are interested in how the microbial communities can break down environmental contaminants, and how they respond to the release of methane during oil extraction operations.

Some 1,500 miles south from those gas extraction sites, Monica Medina-Munoz of Penn State University will study the effect of thermal stress on the Caribbean coral Orbicella faveolata and the metabolic contribution of its coral host Symbiodinium. The calcium carbonate in coral reefs acts as carbon sinks, but reef health depends on microbial communities. If the photosynthetic symbionts are removed from the coral host, for example, the corals can die and calcification rates decrease. Understanding how to maintain stability in the coral-microbiome community can provide information on the coral’s contribution to the global ocean carbon cycle.

Longtime DOE JGI collaborator Jill Banfield of the University of California (UC), Berkeley is profiling the diversity of microbial communities found in the subsurface from the Rifle aquifer adjacent to the Colorado River. The subsurface is a massive, yet poorly understood, repository of organic carbon as well as greenhouse gases. Another research question, based on having the microbial populations close to both the water table and the river, is how they impact carbon, nitrogen and sulfur cycles. Her project is part of the first coordinated attempt to quantify the metabolic potential of an entire subsurface ecosystem under the aegis of the Lawrence Berkeley National Laboratory’s Subsurface Biogeochemistry Scientific Focus Area.

Banfield also successfully competed for a second CSP project to characterize the tree-root microbial interactions that occur below the soil mantle in the unsaturated zone or vadose zone, which extends into unweathered bedrock. The project’s goal is to understand how microbial communities this deep underground influence tree-based carbon fixation in forested watersheds by the Eel River in northwestern California.

Several fungal projects were selected for the 2015 CSP portfolio, including one led by Kabir Peay of Stanford University. He and his colleagues will study how fungal communities in animal feces decompose organic matter. His project has a stated end goal of developing a model system that emulates the ecosystem at Point Reyes National Seashore, where Tule elk are the largest native herbivores.

Another selected fungal project comes from Timothy James of University of Michigan, who will explore the so-called “dark matter fungi” – those not represented in culture collections. By sequencing several dozen species of unculturable zoosporic fungi from freshwater, soils and animal feces, he and his colleagues hope to develop a kingdom-wide fungal phylogenetic framework.

Christian Wurzbacher of Germany’s the Leibniz Institute of Freshwater Ecology and Inland Fisheries, IGB, will characterize fungi from the deep sea to peatlands to freshwater streams to understand the potentially novel adaptations that are necessary to thrive in their aquatic environments. The genomic information would provide information on their metabolic capabilities for breaking down cellulose, lignin and other plant cell wall components, and animal polymers such as keratin and chitin.

Many of the selected projects focus on DOE JGI Flagship Plant Genomes, with most centered on the poplar (Populus trichocarpa.) For example, longtime DOE JGI collaborator Steve DiFazio of West Virginia University is interested in poplar but will study its reproductive development with the help of a close relative, the willow (Salix purpurea). With its shorter generation time, the plant is a good model system and comparator for understanding sex determination, which can help bioenergy crop breeders by, for example, either accelerating or preventing flowering.

Another project comes from Posy Busby of the University of Washington, who will study the interactions between the poplar tree and its fungal, non-pathogenic symbionts or endophytes. As disease-causing pathogens interact with endophytes in leaves, he noted in his proposal, understanding the roles and functions of endophytes could prove useful to meeting future fuel and food requirements.

Along the lines of poplar endophytes, Carolin Frank at UC Merced will investigate the nitrogen-fixing endophytes in poplar, willow, and pine, with the aim of improving growth in grasses and agricultural crops under nutrient-poor conditions.

Rotem Sorek from the Weizmann Institute of Science in Israel takes a different approach starting from the hypothesis that poplar trees have an adaptive immunity system rooted in genome-encoded immune memory. Through deep sequencing of tissues from single poplar trees (some over a century old, others younger) his team hopes to gain insights into the tree genome’s short-term evolution and how its gene expression profiles change over time, as well as to predict how trees might respond under various climate change scenarios.

Tackling a different DOE JGI Flagship Plant Genome, Debbie Laudencia-Chingcuangco of the USDA-ARS will develop a genome-wide collection of several thousand mutants of the model grass Brachypodium distachyon to help domesticate the grasses that are being considered as candidate bioenergy feedstocks. This work is being done in collaboration with researchers at the Great Lakes Bioenergy Research Center, as the team there considers Brachypodium “critical to achieving its mission of developing productive energy crops that can be easily processed into fuels.”

Continuing the theme of candidate bioenergy grasses, Kankshita Swaminathan from the University of Illinois will study gene expression in polyploidy grasses Miscanthus and sugarcane, comparing them against the closely related diploid grass sorghum to understand how these plants recycle nutrients.

Baohong Zhang of East Carolina University also focused on a bioenergy grass, and his project will look at the microRNAs in switchgrass. These regulatory molecules are each just a couple dozen nucleotides in length and can downregulate (decrease the quantity of) a cellular component. With a library of these small transcripts, he and his team hope to identify the gene expression variation associated with desirable biofuel traits in switchgrass such as increased biomass and responses to drought and salinity stressors.

Nitin Baliga of the Institute of Systems Biology will use DOE JGI genome sequences to build a working model of the networks that regulate lipid accumulation in Chlamydomonas reinhardtii, still another DOE JGI Plant Flagship Genome and a model for characterizing biofuel production by algae.

Other accepted projects include:

The study of the genomes of 32 fungi of the Agaricales order, including 16 fungi to be sequenced for the first time, will be carried out by Jose Maria Barrasa of Spain’s University of Alcala. While many of the basidiomycete fungi involved in wood degradation that have been sequenced are from the Polyporales, he noted in his proposal, many of the fungi involved in breaking down leaf litter and buried wood are from the order Agaricales.

Now at the University of Connecticut, Jonathan Klassen conducted postdoctoral studies at GLBRC researcher Cameron Currie’s lab at University of Wisconsin-Madison. His project will study interactions in ant-microbial community fungus gardens in three states to learn more about how the associated bacterial metagenomes contribute to carbon and nitrogen cycling.

Hinsby Cadillo-Quiroz, at Arizona State University, will conduct a study of the microbial communities in the Amazon peatlands to understand their roles in both emitting greenhouse gases and in storing and cycling carbon. The peatlands are hotspots of soil organic carbon accumulation, and in the tropical regions, they are estimated to hold between 11 percent and 14 percent, or nearly 90 gigatons, of the global carbon stored in soils.

Barbara Campbell, Clemson University will study carbon cycling mechanisms of active bacteria and associated viruses in the freshwater to marine transition zone of the Delaware Bay. Understanding the microbes’ metabolism would help researchers understand they capabilities with regard to dealing with contaminants, and their roles in the nitrogen, sulfur and carbon cycles.

Jim Fredrickson of Pacific Northwest National Laboratory will characterize functional profiles of microbial mats in California, Washington and Yellowstone National Park to understand various functions such as how they produce hydrogen and methane, and break down cellulose.

Joyce Loper of USDA-ARS will carry out a comparative analysis of all Pseudomonas bacteria getting from DOE JGI the sequences of just over 100 type strains to infer a evolutionary history of the this genus — a phylogeny — to characterize the genomic diversity, and determine the distribution of genes linked to key observable traits in this non-uniform group of bacteria.

Holly Simon of Oregon Health & Science University is studying microbial populations in the Columbia River estuary, in part to learn how they enhance greenhouse gas CO2 methane and nitrous oxide production.

Michael Thon from Spain’s University of Salamanca will explore sequences of strains of the Colletotrichum species complex, which include fungal pathogens that infect many crops. One of the questions he and his team will ask is how these fungal strains have adapted to break down the range of plant cell wall compositions.

Kathleen Treseder of UC Irvine will study genes involved in sensitivity to higher temperatures in fungi from a warming experiment in an Alaskan boreal forest. The team’s plan is to fold the genomic information gained into a trait-based ecosystem model called DEMENT to predict carbon dioxide emissions under global warming.

Mary Wildermuth of UC Berkeley will study nearly a dozen genomes of powdery mildew fungi, including three that infect designated bioenergy crops. The project will identify the mechanisms by which the fungi successfully infect plants, information that could lead to the development of crops with improved resistance to fungal infection and limiting fungicide use to allow more sustainable agricultural practices.

Several researchers who have previously collaborated with the DOE JGI have new projects:

Ludmila Chistoserdova from the University of Washington had a pioneering collaboration with the DOE JGI to study microbial communities in Lake Washington. In her new project, she and her team will look at the microbes in the Lake Washington sediment to understand their role in metabolizing the potent greenhouse gas methane.

Rick Cavicchioli of Australia’s University of New South Wales will track how microbial communities change throughout a complete annual cycle in three millennia-old Antarctic lakes and a near-shore marine site. By establishing what the microbes do in different seasons, he noted in his proposal, he and his colleagues hope to learn which microbial processes change and about the factors that control the evolution and speciation of marine-derived communities in cold environments.

With samples collected from surface waters down to the deep ocean, Steve Hallam from Canada’s University of British Columbia will explore metabolic pathways and compounds involved in marine carbon cycling processes to understand how carbon is regulated in the oceans.

The project of Hans-Peter Klenk, of DSMZ in Germany, will generate sequences of 1,000 strains of Actinobacteria, which represent the third most populated bacterial phylum and look for genes that encode cellulose-degrading enzymes or enzymes involved in synthesizing novel, natural products.

Han Wosten of the Netherlands’ Utrecht University will carry out a functional genomics approach to wood degradation by looking at Agaricomycetes, in particular the model white rot fungus Schizophyllum commune and the more potent wood-degrading white rots Phanaerochaete chrysosporium and Pleurotus ostreatus that the DOE JGI has previously sequenced.

Wen-Tso Liu of the University of Illinois and his colleagues want to understand the microbial ecology in anaerobic digesters, key components of the wastewater treatment process. They will study microbial communities in anaerobic digesters from the United States, East Asia and Europe to understand the composition and function of the microbes as they are harnessed for this low-cost municipal wastewater strategy efficiently removes waster and produces methane as a sustainable energy source.

Another project that involves wastewater, albeit indirectly, comes from Erica Young of the University of Wisconsin. She has been studying algae grown in wastewater to track how they use nitrogen and phosphorus, and how cellulose and lipids are produced. Her CSP project will characterize the relationship between the algae and the bacteria that help stabilize these algal communities, particularly the diversity of the bacterial community and the pathways and interactions involved in nutrient uptake and carbon sequestration.

Previous CSP projects and other DOE JGI collaborations are highlighted in some of the DOE JGI Annual User Meeting talks that can be seen here: http://usermeeting.jgi.doe.gov/past-speakers/. The 10th Annual Genomics of Energy and Environment Meeting will be held March 24-26, 2015 in Walnut Creek, Calif. A preliminary speakers list is posted here (http://usermeeting.jgi.doe.gov/) and registration will be opened in the first week of November.

Fracking’s environmental impacts scrutinized

Greenhouse gas emissions from the production and use of shale gas would be comparable to conventional natural gas, but the controversial energy source actually faired better than renewables on some environmental impacts, according to new research.

The UK holds enough shale gas to supply its entire gas demand for 470 years, promising to solve the country’s energy crisis and end its reliance on fossil-fuel imports from unstable markets. But for many, including climate scientists and environmental groups, shale gas exploitation is viewed as environmentally dangerous and would result in the UK reneging on its greenhouse gas reduction obligations under the Climate Change Act.

University of Manchester scientists have now conducted one of the most thorough examinations of the likely environmental impacts of shale gas exploitation in the UK in a bid to inform the debate. Their research has just been published in the leading academic journal Applied Energy and study lead author, Professor Adisa Azapagic, will outline the findings at the Labour Party Conference in Manchester, England, today (Monday, 22 September).

“While exploration is currently ongoing in the UK, commercial extraction of shale gas has not yet begun, yet its potential has stirred controversy over its environmental impacts, its safety and the difficulty of justifying its use to a nation conscious of climate change,” said Professor Azapagic.

“There are many unknowns in the debate surrounding shale gas, so we have attempted to address some of these unknowns by estimating its life cycle environmental impacts from ‘cradle to grave’. We looked at 11 different impacts from the extraction of shale gas using hydraulic fracturing – known as ‘fracking’- as well as from its processing and use to generate electricity.”

The researchers compared shale gas to other fossil-fuel alternatives, such as conventional natural gas and coal, as well as low-carbon options, including nuclear, offshore wind and solar power (solar photovoltaics).

The results of the research suggest that the average emissions of greenhouse gases from shale gas over its entire life cycle are about 460 grams of carbon dioxide-equivalent per kilowatt-hour of electricity generated. This, the authors say, is comparable to the emissions from conventional natural gas. For most of the other life-cycle environmental impacts considered by the team, shale gas was also comparable to conventional natural gas.

But the study also found that shale gas was better than offshore wind and solar for four out of 11 impacts: depletion of natural resources, toxicity to humans, as well as the impact on freshwater and marine organisms. Additionally, shale gas was better than solar (but not wind) for ozone layer depletion and eutrophication (the effect of nutrients such as phosphates, on natural ecosystems).

On the other hand, shale gas was worse than coal for three impacts: ozone layer depletion, summer smog and terrestrial eco-toxicity.

Professor Azapagic said: “Some of the impacts of solar power are actually relatively high, so it is not a complete surprise that shale gas is better in a few cases. This is mainly because manufacturing solar panels is very energy and resource-intensive, while their electrical output is quite low in a country like the UK, as we don’t have as much sunshine. However, our research shows that the environmental impacts of shale gas can vary widely, depending on the assumptions for various parameters, including the composition and volume of the fracking fluid used, disposal routes for the drilling waste and the amount of shale gas that can be recovered from a well.

“Assuming the worst case conditions, several of the environmental impacts from shale gas could be worse than from any other options considered in the research, including coal. But, under the best-case conditions, shale gas may be preferable to imported liquefied natural gas.”

The authors say their results highlight the need for tight regulation of shale gas exploration – weak regulation, they claim, may result in shale gas having higher impacts than coal power, resulting in a failure to meet climate change and sustainability imperatives and undermining the deployment of low-carbon technologies.

Professor Azapagic added: “Whether shale gas is an environmentally sound option depends on the perceived importance of different environmental impacts and the regulatory structure under which shale gas operates.

“From the government policy perspective – focusing mainly on economic growth and energy security – it appears likely that shale gas represents a good option for the UK energy sector, assuming that it can be extracted at reasonable cost.

“However, a wider view must also consider other aspects of widespread use of shale gas, including the impact on climate change, as well as many other environmental considerations addressed in our study. Ultimately, the environmental impacts from shale gas will depend on which options it is displacing and how tight the regulation is.”

Study co-author Dr Laurence Stamford, from Manchester’s School of Chemical Engineering and Analytical Science, said: “Appropriate regulation should introduce stringent controls on the emissions from shale gas extraction and disposal of drilling waste. It should also discourage extraction from sites where there is little shale gas in order to avoid the high emissions associated with a low-output well.

He continued: “If shale gas is extracted under tight regulations and is reasonably cheap, there is no obvious reason, as yet, why it should not make some contribution to our energy mix. However, regulation should also ensure that investment in sustainable technologies is not reduced at the expense of shale gas.”

Contaminated water in 2 states linked to faulty shale gas wells

Faulty well integrity, not hydraulic fracturing deep underground, is the primary cause of drinking water contamination from shale gas extraction in parts of Pennsylvania and Texas, according to a new study by researchers from five universities.

The scientists from Duke, Ohio State, Stanford, Dartmouth and the University of Rochester
published their peer-reviewed study Sept. 15 in the Proceedings of the National Academy of Sciences. Using noble gas and hydrocarbon tracers, they analyzed the gas content of more than 130 drinking water wells in the two states.

“We found eight clusters of wells — seven in Pennsylvania and one in Texas — with contamination, including increased levels of natural gas from the Marcellus shale in Pennsylvania and from shallower, intermediate layers in both states,” said Thomas H. Darrah, assistant professor of earth science at Ohio State, who led the study while he was a research scientist at Duke.

“Our data clearly show that the contamination in these clusters stems from well-integrity problems such as poor casing and cementing,” Darrah said.

“These results appear to rule out the possibility that methane has migrated up into drinking water aquifers because of horizontal drilling or hydraulic fracturing, as some people feared,” said Avner Vengosh, professor of geochemistry and water quality at Duke.

In four of the affected clusters, the team’s noble gas analysis shows that methane from drill sites escaped into drinking water wells from shallower depths through faulty or insufficient rings of cement surrounding a gas well’s shaft. In three clusters, the tests suggest the methane leaked through faulty well casings. In one cluster, it was linked to an underground well failure.

“People’s water has been harmed by drilling,” said Robert B. Jackson, professor of environmental and earth sciences at Stanford and Duke. “In Texas, we even saw two homes go from clean to contaminated after our sampling began.”

“The good news is that most of the issues we have identified can potentially be avoided by future improvements in well integrity,” Darrah stressed.

Using both noble gas and hydrocarbon tracers — a novel combination that enabled the researchers to identify and distinguish between the signatures of naturally occurring methane and stray gas contamination from shale gas drill sites — the team analyzed gas content in 113 drinking-water wells and one natural methane seep overlying the Marcellus shale in Pennsylvania, and in 20 wells overlying the Barnett shale in Texas. Sampling was conducted in 2012 and 2013. Sampling sites included wells where contamination had been debated previously; wells known to have naturally high level of methane and salts, which tend to co-occur in areas overlying shale gas deposits; and wells located both within and beyond a one-kilometer distance from drill sites.

Noble gases such as helium, neon or argon are useful for tracing fugitive methane because although they mix with natural gas and can be transported with it, they are inert and are not altered by microbial activity or oxidation. By measuring changes in ratios in these tag-along noble gases, researchers can determine the source of fugitive methane and the mechanism by which it was transported into drinking water aquifers — whether it migrated there as a free gas or was dissolved in water.

“This is the first study to provide a comprehensive analysis of noble gases and their isotopes in groundwater near shale gas wells,” said Darrah, who is continuing the analysis in his lab at Ohio State. “Using these tracers, combined with the isotopic and chemical fingerprints of hydrocarbons in the water and its salt content, we can pinpoint the sources and pathways of methane contamination, and determine if it is natural or not.”