One week a study comes out saying fracking is not a hazard, this week another comes out saying not so fast, it could be an issue.
Just who do you believe? The latest study looked at 100 private water wells in and near the Barnett Shale region and it showed elevated levels of potential contaminants such as arsenic and selenium closest to natural gas extraction sites, according to a team of researchers led by University of Texas Arlington associate professor of chemistry and biochemistry Kevin Schug.
“This study alone can’t conclusively identify the exact causes of elevated levels of contaminants in areas near natural gas drilling, but it does provide a powerful argument for continued research,” said Brian Fontenot, a UT Arlington graduate with a doctorate in quantitative biology and lead author of a paper on the subject.
The results of the North Texas well study published online by the journal Environmental Science & Technology. The peer-reviewed paper focused on the presence of metals such as arsenic, barium, selenium and strontium in water samples. Many of these heavy metals occur naturally at low levels in groundwater, but disturbances from natural gas extraction activities could cause them to occur at elevated levels.
“We expect this to be the first of multiple projects that will ultimately help the scientific community, the natural gas industry, and most importantly, the public, understand the effects of natural gas drilling on water quality,” Fontenot said.
The increased presence of metals could be the result of a variety of factors including, industrial accidents; mechanical vibrations from natural gas drilling activity, or the lowering of water tables through drought or the removal of water used for the hydraulic fracturing, or fracking, process. Any of these scenarios could release dangerous compounds into shallow groundwater.
Researchers gathered samples from private water wells of varying depth within a 13 county area in or near the Barnett Shale in North Texas over four months in the summer and fall of 2011. Ninety-one samples came from what they termed “active extraction areas,” or areas that had one or more gas wells within a five kilometer radius. Another nine samples came from sites either inside the Barnett Shale and more than 14 kilometers from a natural gas drilling site, or from sites outside the Barnett Shale altogether. Researchers called those sites “non-active/reference areas.”
Researchers compared the samples to historical data on water wells in these counties from the Texas Water Development Board groundwater database for 1989-1999, prior to the proliferation of natural gas drilling.
In addition to standard water quality tests, the researchers used gas chromatography – mass spectrometry (GC-MS), headspace gas chromatography (HS-GC) and inductively coupled plasma-mass spectrometry (ICP-MS). Many of the tests took place in the Shimadzu Center for Advanced Analytical Chemistry on the UT Arlington campus.
On average, researchers detected the highest levels of these contaminants within 3 kilometers of natural gas wells, including several samples that had arsenic and selenium above levels considered safe by the Environmental Protection Agency (EPA). For example, 29 wells that were within the study’s active natural gas drilling area exceeded the EPA’s Maximum Contaminant Limit of 10 micrograms per liter for arsenic, a potentially dangerous situation.
The areas lying outside of active drilling areas or outside the Barnett Shale did not show the same elevated levels for most of the metals.
Researchers said they did not find uniformity among the contamination in the active natural gas drilling areas. That means not all gas well sites had higher levels of the metals in well water.
Some of the most notable results were on the following heavy metals:
• Arsenic occurs naturally in the region’s water and was in 99 of the 100 samples. But, the concentrations of arsenic were significantly higher in the active extraction areas compared to non-extraction areas and historical data. The maximum concentration from an extraction area sample was 161 micrograms per liter, or 16 times the EPA safety standard set for drinking water.
• Selenium was in 10 samples near extraction sites, and all of those samples showed selenium levels were higher than the historical average. Two samples exceeded the standard for selenium set by the EPA.
• Strontium was also in almost all the samples, with concentrations significantly higher than historical levels in the areas of active gas extraction. A toxicological profile by the federal government’s Agency for Toxic Substances and Disease Registry recommends no more than 4,000 micrograms of strontium per liter in drinking water. Seventeen samples from the active extraction area and one from the non-active areas exceeded that recommended limit.
The paper recommends further research on levels of methanol and ethanol in water wells. Twenty-nine private water wells in the study contained methanol, with the highest concentrations in the active extraction areas. Twelve samples, four of which were from the non-active extraction sites, contained measurable ethanol. Both ethanol and methanol can occur naturally or as a result of industrial contamination.
Members of the research team are now conducting well water sampling in the Permian Basin region of Texas, establishing a baseline set of data prior to gas well drilling activities there. That baseline will be able to compare samples collected during and after natural gas extraction. The team hopes that these efforts will shed further light on the relationship between natural gas extraction and ground water quality.
Meanwhile, last week the Department of Energy said there is no evidence that chemicals used from fracking, or hydraulic fracturing, during the natural gas drilling process moved up to contaminate drinking water aquifers at a western Pennsylvania drilling site.