Detecting the effects of coal mining, acid rain, and natural gas extraction in Appalachian basin streams in Pennsylvania (USA) through analysis of barium and sulfate concentrations

Abstract

To understand how extraction of different energy sources impacts water resources requires assessment of how water chemistry has changed in comparison with the background values of pristine streams. With such understanding, we can develop better water quality standards and ecological interpretations. However, determination of pristine background chemistry is difficult in areas with heavy human impact. To learn to do this, we compiled a master dataset of sulfate and barium concentrations ([SO], [Ba]) in Pennsylvania (PA, USA) streams from publically available sources. These elements were chosen because they can represent contamination related to oil/gas and coal, respectively. We applied changepoint analysis (i.e., likelihood ratio test) to identify pristine streams, which we defined as streams with a low variability in concentrations as measured over years. From these pristine streams, we estimated the baseline concentrations for major bedrock types in PA. Overall, we found that 48,471 data values are available for [SO] from 1904 to 2014 and 3243 data for [Ba] from 1963 to 2014. Statewide [SO] baseline was estimated to be 15.8 ± 9.6 mg/L, but values range from 12.4 to 26.7 mg/L for different bedrock types. The statewide [Ba] baseline is 27.7 ± 10.6 µg/L and values range from 25.8 to 38.7 µg/L. Results show that most increases in [SO] from the baseline occurred in areas with intensive coal mining activities, confirming previous studies. Sulfate inputs from acid rain were also documented. Slight increases in [Ba] since 2007 and higher [Ba] in areas with higher densities of gas wells when compared to other areas could document impacts from shale gas development, the prevalence of basin brines, or decreases in acid rain and its coupled effects on [Ba] related to barite solubility. The largest impacts on PA stream [Ba] and [SO] are related to releases from coal mining or burning rather than oil and gas development.

Assessing changes in groundwater chemistry in landscapes with more than 100 years of oil and gas development

“…The distributions of sulfate concentrations in both the NW and NE PA datasets decreased from pre-2000 to post-2010 (Table 2) 7 . Such decreases in both NE and NW PA are consistent with the state-wide trend of decreasing sulfate concentrations in PA streams 36 . This change has been attributed mostly to the effects of the decline of coal production (and associated acid mine drainage) and the Clean Air Act (CAA) and its amendments since the 1970s that contributed to the amelioration of acid rain in the state 7,36,37 .…”

“…Such decreases in both NE and NW PA are consistent with the state-wide trend of decreasing sulfate concentrations in PA streams 36 . This change has been attributed mostly to the effects of the decline of coal production (and associated acid mine drainage) and the Clean Air Act (CAA) and its amendments since the 1970s that contributed to the amelioration of acid rain in the state 7,36,37 . The similarity between observations of trends in sulfate concentrations in streams in PA and in groundwaters in NW and NE PA may be a good indicator that the trends are temporal indicators of change related to state-wide rather than regionally distinct changes.…”

Exploring How to Use Groundwater Chemistry to Identify Migration of Methane near Shale Gas Wells in the Appalachian Basin

“…For example, the depth of ABB is so shallow in SW PA that the prevalence of brine salts (with some natural methane) may simply be ubiquitous, and therefore, the salt signature could be present even in the presence of anomalous methane migration. Furthermore, the prevalence of impacts from coal mining and acid mine drainage where high concentrations of Fe and SO 4 are common − may also mask the evidence related to the geochemical protocol, making detection difficult. It is known, for example, that some new shale gas drilling in the area has intersected acid mine drainage, coal mines, and shallow brines .…”

25-Year Trends in Stage-Specific Incidence Rates for Bladder Cancer in a Large Statewide Registry

“…In the northeast portion of Pennsylvania, the historical high incidence of BC may be attributed to coal-mining exposure. Intensive coal-mining activities, along with natural gas extraction, in regions of the state have been identified as possible sources of surface water contamination [21,22]. However, the direct relationship between these contaminations and the increased incidence of BC is unclear.…”