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No signs of fracking fluids in Arkansas drinking water

DUKE (US) — Samples from drinking water wells show no evidence of groundwater contamination from shale gas production in Arkansas.

“Our results show no discernible impairment of groundwater quality in areas associated with natural gas drilling and hydraulic fracturing in this region,” says Avner Vengosh, professor of geochemistry and water quality at Duke University’s Nicholas School of the Environment.

Scientists sampled 127 shallow drinking water wells in areas overlying Fayetteville Shale gas production in north-central Arkansas. They analyzed the samples for major and trace elements and hydrocarbons, and used isotopic tracers to identify the sources of possible contaminants.

The researchers compared the chemical composition of the contaminants to those found in water and gas samples from nearby shale gas drilling sites.

Good water quality

“Only a fraction of the groundwater samples we collected contained dissolved methane, mostly in low concentrations, and the isotopic fingerprint of the carbon in the methane in our samples was different from the carbon in deep shale gas in all but two cases,” Vengosh says.

This indicates the methane was produced primarily by biological activity in the region’s shallow aquifers and not from shale gas contamination, he adds.

“These findings demonstrate that shale gas development, at least in this area, has been done without negatively impacting drinking water resources,” says Nathaniel R. Warner, a PhD student at Duke and lead author of the study.

Robert Jackson, a professor of environmental sciences at Duke, adds, “Overall, homeowners typically had good water quality, regardless of whether they were near shale gas development.”

Vengosh, Warner, Jackson, and colleagues published their peer-reviewed findings in the online edition of the journal Applied Geochemistry.

Contradicts previous studies?

Hydraulic fracturing, also called hydrofracking or fracking, involves pumping water, sand and chemicals deep underground into horizontal gas wells at high pressure to crack open hydrocarbon-rich shale and extract natural gas.

Accelerated shale gas drilling and hydrofracking in recent years has fueled concerns about water contamination by methane, fracking fluids and wastewater from the operations.

Previous peer-reviewed studies by Duke scientists found direct evidence of methane contamination in drinking water wells near shale-gas drilling sites in the Marcellus Shale basin of northeastern Pennsylvania, as well as possible connectivity between deep brines and shallow aquifers, but no evidence of contamination from fracking fluids.

“The hydrogeology of Arkansas’s Fayetteville Shale basin is very different from Pennsylvania’s Marcellus Shale,” Vengosh notes.

Far from contradicting the earlier studies, the Arkansas study “suggests that variations in local and regional geology play major roles in determining the possible risk of groundwater impacts from shale gas development. As such, they must be taken into consideration before drilling begins.”

Human factors—such as the drilling techniques used and the integrity of the wellbores—also likely play a role in preventing, or allowing, gas leakage from drilling sites to shallow aquifers, Vengosh notes.

“The take-home message is that regardless of the location, systematic monitoring of geochemical and isotopic tracers is necessary for assessing possible groundwater contamination,” he adds.

“Our findings in Arkansas are important, but we are still only beginning to evaluate and understand the environmental risks of shale gas development. Much more research is needed.”

Scientists from the US Geological Survey (USGS) contributed to the study, which was funded by Duke’s Nicholas School of the Environment and the Duke Center on Global Change. Field sampling activities were funded by Shirley Community Development Corporation; Faulkner County, Arkansas; the University of Arkansas; the Arkansas Water Resource Center; and the USGS Arkansas Water Science Center.

Source: Duke University

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3 Comments

  1. Nathaniel

    Who funded this study? Just wait a few more years.

  2. Floyd Gary Thacker

    Nathaniel – my question exactly: WHO FUNDED THIS STUDY? And who is going to fund the additional studies over time. The headline to this article should have been:

    Much more research is needed to understand environmental risks of shale gas development.

    “The take-home message is that regardless of the location, systematic monitoring of geochemical and isotopic tracers is necessary for assessing possible groundwater contamination,” WHO IS GOING TO DO AND PAY FOR THIS SYSTEMATIC MONITORING???

  3. Dave

    Read the study. They did NOT test the water BEFORE the fracking started. They use lots of complicated language to prevaricate the actual issue: is fracking adding any pollution to the water? The study ignores what may have been or may not have been in the water before 2004; from the abstract:
    “The geochemistry of domestic groundwater wells was
    investigated in aquifers overlying the Fayetteville Shale in north-central Arkansas, where approximately
    4,000 wells have been drilled since 2004 to extract unconventional natural gas. Monitoring was
    performed on 127 drinking water wells and the geochemistry of major ions, trace metals, CH4 gas
    content and its C isotopes (δ 13CCH4), and select isotope tracers (δ11B, 87Sr/86Sr, δ2H, δ18O, δ13C
    DIC) compared to the composition of flowback-water samples directly from Fayetteville Shale gas wells”

    Tell us researchers, what was the condition of the water 1 year, or 1 day BEFORE the drilling started? How long did the “monitoring” last? Are you still monitoring the water? What chemicals, precisely, were/are used in the “fracking” you are monitoring, and did you check for the presence of those chemicals before the fracking started? Just because you have some kind of metric of how the water was supposed to be; or is supposed to be, does not mean you can assume ANYTHING. The study is flawed, and probably funded by the oil industry. This is a sham.

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