Download Chemical and Biological Risk Assessment for Natural Gas Extraction

Chemical and Biological Risk Assessment for Natural Gas Extraction in New York
Ronald E. Bishop, Ph.D., CHO
Chemistry and Biochemistry Department
State University of New York, College at Oneonta
Draft, January 21, 2011
http://63.134.196.109/documents/RiskAssessmentNaturalGasExtraction.pdf
Excerpt pg 15-16
Biological Contamination:
Rock strata beneath the earth’s surface are populated by microscopic organisms, and
the advent of air-lubricated drilling (without biocides) has introduced a risk of
contaminating surface (fresh) water zones with bacteria and other microbes from
deeper (brine) layers, where they often flourish. Of particular concern are sulfatereducing bacteria, especially Desulfovibrio desulfuricans, a facultative anaerobe that
thrives in fresh water where some sulfate (such as is present in pyrite or hematite) is
available (66), (Figure 2) (67).
Figure 2: Biofilm of Desulfovibrio desulfuricans Growing on a Hematite Surface 16
These bacteria are especially prevalent and aggressive in oil and gas producing regions,
where they avidly form living black, sticky films in water wells and other structures
(68). There they produce hydrogen sulfide (H2S), characterized by a “rotten eggs” smell.
Rock strata rich in gas are often also rich in this bacterium, and exposure to hydrogen
sulfide along with methane raises significant health concerns –neurological syndromes
in humans and, in livestock, elevated birth defect rates and diminished herd health. At
high concentrations, hydrogen sulfate is lethal (69).
The now-common use of air-lubrication (without biocides) while drilling
the top one- to three thousand feet of gas wells (70) risks contaminating
fresh water aquifers with sulfate-reducing bacteria from the deeper
strata, but there is no clear evidence that this water well-fouling
mechanism is recognized by New York state regulators.
16 Cattle Drop Dead Near
Mysterious Fluid at Gas Drilling
Site
by Abrahm Lustgarten
ProPublica, April 30, 2009, 4 p.m.
http://www.propublica.org/article/16-cattle-drop-dead-near-mysterious-fluid-at-gas-drilling-site430
ProPublica has been reporting for months [2] about how natural gas drilling is affecting the
environment, but of all the causes for concern we've reported, here's a doozy.
Sixteen cattle dropped dead in a northwestern Louisiana field this week after apparently
drinking from a mysterious fluid adjacent to a natural gas drilling rig, according to
Louisiana's Department of Environmental Quality and a report in the Shreveport Times [3]. At
least one worker told the newspaper that the fluids, which witnesses described as green and
spewing into the air near the drilling derrick, were used for a drilling process called hydraulic
fracturing [2]. But the company, Chesapeake Energy [4], has not identified exactly what
chemicals are in those fluids and is insisting to state regulators that no spill occurred. [snip]
In the field where the cattle died on Tuesday, the DEQ [10] reports finding a white milky
substance on the ground, with cattle tracks leading away to the dead animals. Randle said he is
almost certain the substance is a drill fluid or fracturing fluid.
A Chesapeake Energy spokesman told ProPublica that the company is cooperating with
the state and is waiting for test results to determine how the cows died. Schlumberger did
not immediately return calls for comment. If we hear from the company, we'll let you
know.