
Elevated levels of diesel compounds in groundwater derive from surface activity - shawndumas
http://www.pnas.org/content/early/2015/10/07/1511474112.abstract
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andor
This is not about diesel or gasoline fuel. "Diesel range organics" are
hydrocarbons with 10-28 carbon atoms, "gasoline range organics" have 6-10
carbon atoms.

Data:

 _" To address this research gap, we sampled 64 private residential
groundwater wells, ranging from 9–213 m deep, over a 3-y period (2012–2014) in
northeastern Pennsylvania (n = 62) and in southern New York (n = 2) for
analyses of GC-amenable organic compounds. Fifty-nine samples were analyzed
for volatile organic compounds (VOCs) and gasoline range organic compounds
(GRO; defined as the hydrocarbons eluting between 2-methylpentane and
1,2,4-trimethylbenzene; approximately between nC_6 and nC_10), and 41 were
also analyzed for diesel range organic compounds (DRO; defined as the
hydrocarbons eluting between nC_10 and nC_28)"_

Results:

 _" Trace levels of GRO and DRO compounds were detected in 9 of 59 (0–8.8 ppb
total GRO) and 23 of 41 (0–157.6 ppb total DRO) groundwater samples,
respectively. Although the highest concentrations of GRO and DRO were always
detected within 1 km of active shale gas operations, this difference in
concentration within 1 km (n = 21) and beyond 1 km (n = 20) from shale gas
wells was only significantly higher in the case of DRO"_

Discussion:

 _" In this region, there are multiple potential sources of elevated DRO in
groundwater, including (i) upward migration of naturally occurring, formation-
derived organic compounds over geologic time; (ii) lateral transport of
drilling muds, flowback, or produced fluids from faulty wells; (iii) leaking
oil and gas waste containment ponds; (iv) input of organic contaminants from
surface spills of either raw chemicals or residual fracturing fluids; and (v)
leaking underground storage containers or local traffic. To evaluate these
sources systematically, we used geochemical fingerprinting of inorganic
constituents (i.e., Br/Cl ratios), groundwater residence times (i.e., 4 He
concentration), and dissolved methane concentrations, coupled with our GRO,
DRO, and geospatial analysis."_

1) Upward migration: should result in higher levels of 4He in shallow
groundwater. Highest DRO and GRO concentrations occur in young groundwater and
with low 4He levels.

2) Lateral transport from wells: should result in higher GRO concentration but
relatively low levels of DRO (because GROs spread faster), and higher levels
of methane. Samples with high methane levels show no correlation with GRO or
DRO.

3) Leaking waste containment ponds from fracturing operations: They don't have
any data to correlate pond locations with DRO/GRO measurements. Leaks should
result in higher DRO than GRO levels, because GROs evaporate, and also
elevated chloride and bromide levels. They didn't observe these chloride and
bromide levels in high-DRO-samples.

4) Surface spills of fracturing chemicals: should lead to higher DRO and
somewhat lower GRO concentration (again because GROs evaporate). This is what
they observed _in some of their samples_ : DROs vs. distance to active
fracturing wells has "significant" Spearman rank correlation (P=0.03, rho is
not given). They have a graph showing that their samples either have elevated
GRO or DRO levels, but not both at the same time, so the high-GRO-samples are
not explained.

5) Leaking underground fuel tanks, local traffic: the chemicals found are not
usually stored in underground tanks and are distinct from gasoline or diesel
fuels.

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Hydraulix989
Someone got a handsome remittance for saying the right thing.

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riteshkpr
And the people who have gas + water coming out of their kitchen taps are
crazy. This research paper tells them go ahead and drink that funny smelling
water.

~~~
InclinedPlane
Does it? I didn't see a section on potability of contaminated water.

