Page 16 - Shimadzu Journal vol.3 Issue1

Environmental Analysis

it is important to use an ICP-AES that is capable of aspiration of 7. The potential environmental impact of fracking on US
high salt solutions without clogging the nebulizer or excessive water supplies
memory effects that may occur. The Shimadzu ICPE-9000
As the injected water flows through the formation it dissolves
employs a vertical torch arrangement with a high salt nebulizer
existing minerals and carries with it the interstitial water. The
and self-draining spray chamber. The ICPE-9000 software and
fracking solution chemistry differs from the formation water and
potential for both axial and radial orientation of the spray
can dissolve elements, such as uranium, that were trapped in the
chamber make it possible to analyze both trace and very high
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formation . When the fracking water returns back to the surface
concentrations of analyte with very little dilution.
it carries with it some of the interstitial formation water, and any
4. Scale Inhibitor trace inorganic and/or organic compounds that may have
dissolved. As little as 10% to up to 100% of the fracking water
If the concentration of calcium and/or barium is high enough, and returns to the surface as the fracking wastewater . This
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the conditions are right, they can precipitate with carbonate or wastewater is collected into pits and disposed of. It is the
sulfate to form scale. The formation of scale inside the pipe or flow-back water from the fracking process and the large volumes
within the rock fractures decreases gas production. The addition of produced water that pose the largest risk of environmental
of phosphonates or ammonium chloride as ingredients of the contamination . Because of the very high salt content of the
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fracking solution helps to minimize scale. Simple colorimetric tests water, it is difficult to treat by conventional wastewater treatment
combined with visible spectrophotometers, such as the Shimadzu procedures. Because the water contains very high salt
UV-1800 can be used for measurement of scale inhibitors. concentrations, most methods normally used to analyze
wastewater may not be applicable for testing fracking wastewater
5. Acid
without modification . Table 1 is an example of some typical
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Hydrochloric acid and various organic acids, such as citric acid, are fracking solution flow-back water analyses.
used in the fracking solution to dissolve remnants of cement left Other constituents that may be present in flow-back water are
behind from the drilling process or to dissolve the calcite and surfactants, glycols, methanol, and polyacrylates that are major
hematite cement that binds the individual mineral grains of the ingredients added to the stimulation water mixture. These
shale together. Since hydrochloric acid is composed of the compounds are not on the “regular” EPA method lists routinely
hydrogen and chloride ions it is impossible, other than by pH or a used when screening drinking water, groundwater, or wastewater
neutralization titration, to determine the concentration of for environmental compliance. Existing methods, such as EPA
hydrochloric acid in the fracking solution. A Shimadzu organic acid SW846 Method 8015 Non Halogenated organics by Gas
HPLC system with a UV or conductivity detector can be used to Chromatography , may not have sufficient sensitivity or selectivity
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determine concentrations of organic acids. in the complex matrices.
6. Friction Reducer 8. Drinking Water
High molecular weight polyacrylamide blended with petroleum Drinking water supplies such as rivers, lakes, or shallow wells could be
distillates is added to the fracking solution to create laminar flow contaminated by flow-back and production water in the event of spills,
and decrease the total energy (horsepower) required to pump the improperly lined storage ponds, or leaking well casings from disposal by
solution down-hole . The petroleum distillate may contain underground injection. Since the maximum allowable level for TDS in
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aromatics hydrocarbons, such as benzene, toluene, ethylbenzene, drinking water is 500 mg/L and chloride has a high solubility and
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and xylenes (BTEX). USEPA method 624 is a gas chromatography mobility in the environment, drinking water contamination can be
coupled with mass spectrometry method capable of accurate quickly detected by a sudden increase in chloride concentration. With
determination of BTEX along with multiple other volatile organic the exception of potential contaminants for which there are no existing
compounds in very complex matrices. The Shimadzu approved drinking water methods, all approved methods are capable of
GCMS-QP2010SE coupled with an EST Purge and Trap sample analyzing drinking water supplies. See Table 2 for a listing of Maximum
concentrator can be used for the analysis of volatile organics in Contaminant Levels (MCL) for primary drinking water contaminants,
fracking water samples. and Table 3 for a listing of MCLs for secondary contaminants .
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Table 1 Example of Flow Back Water Analysis
Component Concentration (mg/L)
pH 6.6 (S.U)
Alkalinity as CaCO3 140
Total Dissolved Solids (TDS) 67,300
Total Suspended Solids (TSS) 100
Total Organic Carbon (TOC) 63
Biochemical Oxygen Demand (BOD) 3
Oil & Grease < 5
Sodium as Na 18,000
Calcium as Ca 4,950
Magnesium as Mg 560
Barium as Ba 690
Iron as Fe 40
Chloride as Cl - 41,850
-
Bicarbonate as HCO3 74

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