Applying natural tracer technologies in the environmental monitoring of unconventional gas extraction

从最近的媒体报道中可以清楚地看出，公众对英国非常规天然气资源（页岩气和煤层气）的开采非常关注。这些担忧中有许多与浅层含水层的饮用水供应可能受到甲烷污染有关。制定一项全面的战略来监测英国的任何非常规天然气开采，这对于向公众保证开采是在负责任和安全的方式下进行的，将是至关重要的。这一规定必须建立在强有力的科学原则的基础上，这些原则需要在广泛的非常规天然气开采之前建立起来。这个联合项目旨在利用地下水和天然气中的天然化学成分，为未来有关地下水被甲烷污染的指控提供法律上可辩护的证据。这将通过获取已开采煤层气和页岩气甲烷、浅层甲烷源和未污染地下水的化学分析来实现。现有的基线地下水样本化学分析提供了有关甲烷浓度和含有甲烷的水源的信息。然而，它们并不能提供明确确定甲烷来源所需的独特指纹。我们将收集页岩气、煤层气和采出水的样本，并对采出气体中的碳和氢稳定同位素、放射性碳（14C）和稀有气体（He Ne Ar Kr Xe）进行测量。这将使煤层气和页岩气与其他气源区分开来，并为评估地下水污染提供清晰的“指纹”。我们还将收集基线地下水样本，测量甲烷浓度，溶解无机碳（DIC）中的C稳定同位素，H和O稳定同位素，以提供简单的低成本筛选。如果发现这些地下水中的甲烷气体含量超过每升2毫克，我们将分离甲烷气体并测量H和C的稳定同位素特征。这将使我们能够确定地下水和甲烷（可能是浅层细菌或深层热源）的不同来源。如果在煤层气或页岩气开采期间或之后对地下水进行采样和分析表明甲烷浓度增加，则应对地下水进行氢、碳、放射性碳和惰性气体成分的分析。这将使甲烷的来源得到明确的解决——甲烷是浅层细菌产生的，还是来自以前被困在浅层的深层热源，或者增加的甲烷是来自煤层气或页岩气开采的深层热源甲烷的明确添加？拟议中的实验室将由该财团建立，另外还有额外的惰性气体和放射性碳分析设施，这些设施将由苏格兰政府和爱丁堡大学提供匹配资金，将为地下水环境保护提供高质量的保证。该设施在欧洲将是独一无二的，我们将继续在欧洲其他非常规天然气开采地点应用该技术。在英国广泛开展页岩气和煤层气勘探和生产活动之前，现在就需要采取行动。目前有一次机会收集和分析未受污染的基线样本。我们将公布这一研究计划，以表明英国对页岩气和煤层气监管的重视。这将向公众保证，我们已经从美国和澳大利亚遭遇的非常规天然气的负面经验中吸取了教训。

It is clear from recent media coverage that there is significant public concern surrounding the exploitation of unconventional gas resources (shale gas and coal bed methane) in the UK. Many of these concerns relate to potential methane contamination of drinking water supplies in shallow aquifers. Developing a comprehensive strategy for monitoring any unconventional gas extraction in the UK will be paramount in reassuring the public that the extraction is being undertaken in a responsible and safe manner. This regulation must be based on strong scientific principles which need to be established prior to widespread unconventional gas extraction taking place.This consortium project aims to use natural chemical components in groundwater and gases, to provide legally-defensible evidence in case of future allegations of methane contamination of groundwaters. This will be by obtaining chemical analyses of produced CBM and Shale Gas methane, shallow methane sources, and uncontaminated groundwater. Existing chemical analyses of baseline groundwater samples provide information on methane concentrations and the source of the water that the methane is contained in. However, they do not provide the unique fingerprint required to unequivocally determine the origin of methane.We will collect samples of shale gas, CBM and produced waters and undertake measurements of the C and H stable isotopes, radiocarbon (14C) and noble gases (He Ne Ar Kr Xe) in the produced gases. These will allow the CBM and Shale Gas to be distinguished from other gas sources and provide a clear "fingerprint" for assessing groundwater contamination. We will also collect samples of baseline groundwaters and measure methane concentrations, C stable isotopes in the Dissolved Inorganic Carbon (DIC), H and O stable isotopes to provide a simple low-cost screening. Should the methane gas content of these groundwaters be found to be above 2 milligrams per litre we will separate the methane gas and measure the H and C stable isotope signature. This will allow us to determine the separate origins of both the groundwater and of the methane (which may be shallow bacterial or deep thermal source).If sampling and analysis of groundwater during or after CBM or Shale Gas production shows that methane concentrations have increased, then analysis of the H, C, radiocarbon and noble gas components should be made on the groundwaters. This will allow the source of methane to be categorically resolved - is that methane of shallow bacterial origin, or from deep thermal sources which have previously been trapped at shallow depth, or is the increased methane an unambiguous addition of deep thermogenic methane from CBM or Shale Gas exploitation? The proposed laboratory which will be setup by this consortium, along with the extra facilities for noble gas and radiocarbon analysis which will be provided with the match funding secured from the Scottish Government and the University of Edinburgh, will provide a greatly improved approach to high-quality assurance of environmental protection of groundwater. This facility will be unique in Europe and we will pursue application of the techniques at other European sites of unconventional gas extraction.Action needs to be taken now, before widespread Shale Gas and CBM exploration and production activities commence in the UK. There is currently a one-off opportunity to collect and analyse uncontaminated baseline samples. We will publicise this research programme publicised to show the care with which Shale Gas and CBM regulation is being undertaken in the UK. This will provide public reassurance that lessons have been learnt from the negative unconventional gas experiences encountered in the USA and Australia.