Shale gas development has limited effects on stream biology and geochemistry in a gradient-based, multiparameter study in Pennsylvania

Abstract

The number of horizontally drilled shale oil and gas wells in the United States has increased from nearly 28,000 in 2007 to nearly 127,000 in 2017, and research has suggested the potential for the development of shale resources to affect nearby stream ecosystems. However, the ability to generalize current studies is limited by the small geographic scope as well as limited breadth and integration of measured chemical and biological indicators parameters. This study tested the hypothesis that a quantifiable, significant relationship exists between the density of oil and gas (OG) development, increasing stream water concentrations of known geochemical tracers of OG extraction, and the composition of benthic macroinvertebrate and microbial communities. Twenty-five headwater streams that drain lands across a gradient of shale gas development intensity were sampled. Our strategy included comprehensive measurements across multiple seasons of sampling to account for temporal variability of geochemical parameters, including known shale OG geochemical tracers, and microbial and benthic macroinvertebrate communities. No significant relationships were found between the intensity of OG development, shale OG geochemical tracers, or benthic macroinvertebrate or microbial community composition, whereas significant seasonal differences in stream chemistry were observed. These results highlight the importance of considering spatial and temporal variability in stream chemistry and biota and not only the presence of anthropogenic activities in a watershed. This comprehensive, integrated study of geochemical and biological variability of headwater streams in watersheds undergoing OG development provides a robust framework for examining the effects of energy development at a regional scale.

Genomic evidence for a chemical link between redox conditions and microbial community composition

“…The RDP taxon Spartobacteria genera incertae sedis, which is relatively abundant in the Baltic Sea (Herlemann et al, 2016), was mapped to NCBI class Spartobacteria. The RDP taxon Subdivision3 genera incertae sedis, which was identified here in some stream datasets (Mumford et al, 2020) was mapped to NCBI family Verrucomicrobia subdivision 3. The RDP taxon Marinimicrobia genera incertae sedis, which was identified in this study in some deep ocean datasets (Ganesh et al, 2015;Meier et al, 2017), was mapped to NCBI species Candidatus Marinimicrobia bacterium, which is the only representative of the Candidatus Marinimicrobia phylum in the RefSeq database.…”

Arsenic release to the environment from hydrocarbon production, storage, transportation, use and waste management

“…They found significant positive relationships between As concentration in streams and UOG well density but the mechanism of mobilization was not identified. Mumford et al (2020), however, found no statistically significant relationship between the intensity, presence, or absence of shale gas development and any signal in a comprehensive set of chemical constituents, including As, in their study of 25 small PA state forest watersheds over the course of 2 years. In another large-scale study of water quality data from PA watersheds, Olmstead et al (2013) also found that the presence of shale gas wells upstream from a particular watershed did not result in increased Cl concentrations downstream; however, the release of treated wastewater from shale gas wells by permitted wastewater treatment plants did appear to influence stream Cl concentrations.…”

Assessment of groundwater well vulnerability to contamination through physics-informed machine learning

“…Details on the materials released, volumes, and durations of spill events remain sparse, thus precluding the comprehensive assessment of groundwater contamination risks and potential public health implications [35]. Produced waters typically contain high concentrations of B, Ba, Br, Ca, Cl, Li, Na, Ra, and Sr, and hence their co-occurrence at anomalously elevated concentrations in shallow groundwater may be a useful indicator of contamination by UD [36][37][38][39]. Organic chemicals used in hydraulic fracturing fluid additives and derived from hydrocarbonbearing formations are also present in UD wastewaters and have been detected in groundwaters near UD sites [40][41][42][43][44][45].…”