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Toxicity of Hydraulic Fracturing Brine and Biocide:
The Impact of NaCl and Tributyl Tetradecyl Phosphonium Chloride on 4th Instar
Chironomus riparius
Zainab H. Alali and Carolyn S. Bentivegna, Seton Hall University, South Orange, NJ 07079 USA
One modern technology that currently concerns many environmental scientists is hydraulic
fracturing. Hydraulic fracturing extracts oil and gas from deep underground and has expanded into
areas where production was once considered impractical. Given the increase in hydraulic fracking,
there is a risk that chemical components of fracturing fluids could enter fresh waterways and
impact aquatic organisms. FracFocus disclosure lists additives used in fracturing fluid of 39,000
individual oil and gas production wells in the U.S.A. Additives include sodium chloride and
tributyl tetradecyl phosphonium chloride (TTPC) as a biocide to minimize bacterial contamination
of hydrocarbons. Waste water produced from hydraulic fracturing can contain total dissolved
solids and Cl exceeding 100,000mg/L. According to HALLIBURTON company, the
concentration of TTPC in fracturing fluid is 300 mg/L. In this study, the acute toxicity of TTPC
and NaCl were tested using 4th instar Chironomus riparius. Results showed that 48 h LC50 of
TTPC and NaCl were 0.48mg/L and 9368mg/L, respectively. As a part of investigating
mechanisms of action of TTPC, ATP was measured from hemolymph samples of larvae raised
in various concentrations and collected at 24h. Results showed that ATP levels increased at
low concentrations then decreased as concentrations and concurrent mortality increased.
This likely demonstrated an initial defensive response followed by a loss in mitochondrial
membrane integrity. Red (cool) laser technology was used to investigate the integrity of
mitochondria. ATP levels increased at low TTPC concentrations when larva were exposed to
the laser. This indicated that mitochondria were still functioning, but as the mortality
increased, excitation of red laser did not stimulate additional ATP production demonstrating
injury to the mitochondria. These studies should provide information about the sensitivity
of aquatic biota to components of hydraulic fracturing as well as toxic mechanisms of action
that can help distinguish effects of TTPC from other environmental stressors.
Zainab Hussain Alali
Seton Hall University
[email protected]
(203) 998-8334