Extensive development of shale gas has generated some concerns about environmental impacts such as the migration of natural gas into water resources. We studied high gas concentrations in waters at a site near Marcellus Shale gas wells to determine the geological explanations and geochemical implications. The local geology may explain why methane has discharged for 7 years into groundwater, a stream, and the atmosphere. Gas may migrate easily near the gas wells in this location where the Marcellus Shale dips significantly, is shallow (∼1 km), and is more fractured. Methane and ethane concentrations in local water wells increased after gas development compared with predrilling concentrations reported in the region. Noble gas and isotopic evidence are consistent with the upward migration of gas from the Marcellus Formation in a free-gas phase. This upflow results in microbially mediated oxidation near the surface. Iron concentrations also increased following the increase of natural gas concentrations in domestic water wells. After several months, both iron and SO₄²⁻ concentrations dropped. These observations are attributed to iron and SO₄²⁻ reduction associated with newly elevated concentrations of methane. These temporal trends, as well as data from other areas with reported leaks, document a way to distinguish newly migrated methane from preexisting sources of gas. This study thus documents both geologically risky areas and geochemical signatures of iron and SO₄²⁻ that could distinguish newly leaked methane from older methane sources in aquifers.

页岩气的大规模开发引起了人们对环境影响的担忧，例如天然气迁移到水资源中。我们研究了马塞勒斯页岩气井附近水域中的高气体浓度，以确定地质解释和地球化学含义。当地的地质或许可以解释为什么甲烷在七年来一直排入地下水、溪流和大气中。马塞勒斯页岩在该位置的气井附近很容易运移，该位置的马塞勒斯页岩倾角较大、较浅（约 1 公里）且裂缝较多。与该地区报告的钻前浓度相比，天然气开发后当地水井中的甲烷和乙烷浓度有所增加。稀有气体和同位素证据与气体从马塞勒斯地层以游离气相向上运移的情况一致。这种上升流导致表面附近微生物介导的氧化。随着生活水井中天然气浓度的增加，铁浓度也随之增加。几个月后，铁和SO ₄ ²⁻浓度均下降。这些观察结果归因于与新升高的甲烷浓度相关的铁和SO ₄ ²⁻还原。这些时间趋势以及来自报告泄漏的其他地区的数据记录了一种区分新迁移的甲烷与先前存在的天然气来源的方法。因此，这项研究记录了地质风险区域以及铁和SO ₄ ²⁻的地球化学特征，可以区分含水层中新泄漏的甲烷和较旧的甲烷来源。