Stream measurements locate thermogenic methane fluxes in groundwater discharge in an area of shale-gas development.
Environ Sci Technol
; 49(7): 4057-65, 2015 Apr 07.
Article
em En
| MEDLINE
| ID: mdl-25786038
ABSTRACT
The environmental impacts of shale-gas development on water resources, including methane migration to shallow groundwater, have been difficult to assess. Monitoring around gas wells is generally limited to domestic water-supply wells, which often are not situated along predominant groundwater flow paths. A new concept is tested here combining stream hydrocarbon and noble-gas measurements with reach mass-balance modeling to estimate thermogenic methane concentrations and fluxes in groundwater discharging to streams and to constrain methane sources. In the Marcellus Formation shale-gas play of northern Pennsylvania (U.S.A.), we sampled methane in 15 streams as a reconnaissance tool to locate methane-laden groundwater discharge concentrations up to 69 µg L(-1) were observed, with four streams ≥ 5 µg L(-1). Geochemical analyses of water from one stream with high methane (Sugar Run, Lycoming County) were consistent with Middle Devonian gases. After sampling was completed, we learned of a state regulator investigation of stray-gas migration from a nearby Marcellus Formation gas well. Modeling indicates a groundwater thermogenic methane flux of about 0.5 kg d(-1) discharging into Sugar Run, possibly from this fugitive gas source. Since flow paths often coalesce into gaining streams, stream methane monitoring provides the first watershed-scale method to assess groundwater contamination from shale-gas development.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Poluentes Químicos da Água
/
Água Subterrânea
/
Monitoramento Ambiental
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Indústria de Petróleo e Gás
/
Metano
País/Região como assunto:
America do norte
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Estados Unidos