Caroline Coulter, of Little Rock, AR, came to Chesapeake Biological Laboratory in August 2012 with a B.Sc. degree from UNC Chapel Hill, where she majored in chemistry. Caroline was awarded a 2-year CBL Graduate Education Committee Fellowship and entered the Marine Estuarine Environmental Sciences (MEES) program with a specialization in Environmental Chemistry.
During her interview, Caroline indicated that she wanted to work on "a project with immediate environmental relevance involving lots of fieldwork", not something that her advisor, Dr. Johan Schijf, typically engages in. However, former governor Martin O'Malley's Marcellus Shale Safe Drilling Initiative provided a singular opportunity to collect baseline data on stream water quality in the westernmost part of Maryland before permits that allow gas extraction by hydraulic fracturing (or 'fracking') will be issued there.
In conjunction with efforts by the Maryland Department of Natural Resources, Caroline collected water samples every 6–8 weeks from 14 stream sites, divided over 5 major catchment areas, in mountainous Garrett County for a period of more than one year. Collection continued in the harsh winter of 2014 when temperatures of –1°F made samples freeze in the syringes before they could be filtered and even 4-WD vehicles could not access some of the sites. Although fracking has not commenced in Maryland, several streams originate in nearby Pennsylvania and West Virginia, where fracking activities are widespread and rapidly expanding. In June and July of 2014, an additional 7 sites were sampled in Calvert County to serve as a control area.
The goal of Caroline's research was to identify tracer compounds that can be routinely monitored downstream of well pads to signal potential damage to riverine ecosystems from accidental releases of gas or 'produced water'. In order to be an effective tracer, the compounds must be highly enriched in the released material but rare in nature, with low spatial and temporal variability, and also unambiguously attributable to fracking operations. Whereas other CBL scientists are investigating organic compounds that are known additives of fracking fluid, Caroline focused on a suite of major ions, methane, and the trace metals strontium (Sr) and barium (Ba). In order to study all these solutes she made optimal use of the broad analytical capabilities at CBL, learning advanced techniques including inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission spectrometry, ion chromatography, gas chromatography, and cavity ring-down laser absorption spectroscopy.
Caroline has concluded that major ions, such as sodium, magnesium, and chloride, may be measurably elevated in streams during accidental release of produced water. However, they can also derive from other sources, like road salt and acid mine drainage, and therefore do not constitute good tracers of fracking. An exception may be bromide, whose mere presence could signal a fracking release as its natural background levels are below detection. Methane levels in the streams are low, but extremely variable in space and time. Highly elevated concentrations in summer suggest that it is being naturally produced by living organisms. Carbon isotope ratios of methane can be raised by microbial oxidation and therefore may not be a good indicator of the presence of shale gas. On the other hand, Sr and Ba may be good fracking tracers. In particular, the low solubility of Ba sulfate would enable much less Ba than Sr to stay in solution after a release, causing a tell-tale decrease of the Ba/Sr ratio. In view of the high variability of methane, Sr, and Ba backgrounds, Caroline recommends that they should be monitored persistently before, during, and after fracking operations, as close as possible to the well pad, and with at least monthly frequency. Such recommendations are of great value as Best Management Practices are developed for the responsible extraction of shale gas in Maryland.
On Monday, July 20, 2015 Caroline successfully defended her M.Sc. thesis titled "Monitoring levels of dissolved methane and metals in Maryland streams overlying the Marcellus Shale prior to hydraulic fracturing." Her research was funded by a grant from the Cornell Douglas Foundation and by the Ruth Mathes Scholarship of the Cove Point Natural Heritage Trust. She has not yet announced the next step in her scientific career. With her broad analytical skills and dedication to environmental chemistry, she is sure to accomplish great things.
Congratulations to Caroline Coulter, M.Sc., the Chesapeake Biological Laboratory’s newest graduate!
