Understanding and measuring groundwater gases

了解和测量地下水气体

• 批准号: 194108-2011
• 负责人: Ryan, Cathryn
• 金额: $ 2.04万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=569731
• 关键词: Understanding; measuring; groundwater; gases

Dissolved groundwater gases have been under-utilized as a tool to understand groundwater geochemistry partly because their sampling and analysis can be challenging. Groundwater gases are particularly important in the natural attenuation of groundwater contaminants, since many of the desired end products are gases (e.g. CO2, CH4, and N2). True dissolved gas concentration estimates rely on accurate in situ measurement of total dissolved gas pressure (TDGP). The measurement of TDGP, and its incorporation into 'true' groundwater gas concentration estimation is relatively new, and accurate field measurement approaches are still in development. The goal of this proposal will be to improve accurate groundwater gas pressure measurement, and to use these improved techniques to better understand controls on groundwater gas ebullition and transport. This will permit more robust mass balances of geochemical reactions (including natural attenuation of groundwater contaminants). The research has five related investigations. 1. Development of downhole instrumentation to trap and measure the volume of gas bubbles released from gas-charged groundwater; 2. This 'ebullition trap' will be one of the tools used to investigate the reason that groundwater in open wells degasses to concentrations that are well below solubilities (which increase with depth below the groundwater table). 3. In situ TDGPs will be measured in gas-charged wells to evaluate the common assumption that TDGP increase linearly with depth (and solubility). 4. Seasonal changes in groundwater temperatures at shallow, contaminated and groundwater gas-charged sites will provide an opportunity to measure varying rates of gas production, and incorporate them into estimates of contaminant degradation rates in the context of Monitored Natural Attenuation at contaminated sites. 5. The accrued experience on measuring and understanding groundwater gas concentrations will be brought to bear to solve a hydrogeologic 'mystery' of the source of oxygen poor gas that has been responsible for six deaths and three near-deaths in central Alberta well pits.

溶解的地下水气体作为了解地下水地球化学的工具一直没有得到充分利用，部分原因是它们的采样和分析可能具有挑战性。地下水气体对地下水污染物的自然衰减尤为重要，因为许多所需的最终产品都是气体(如二氧化碳、甲烷和氮气)。真正的溶解气体浓度估计依赖于对溶解气体总压力(TDGP)的准确现场测量。TDGP的测量及其纳入“真正的”地下水气体浓度估计是相对较新的，而精确的野外测量方法仍在开发中。这项提议的目标将是改进准确的地下水气体压力测量，并利用这些改进的技术来更好地了解对地下水气体涌出和运输的控制。这将使地球化学反应(包括地下水污染物的自然衰减)达到更稳健的质量平衡。 这项研究有五个相关的调查。1.开发井下仪器，以捕获和测量从充气地下水中释放出的气泡的体积；2.这一“沸腾圈闭”将是用于调查露天井中地下水的浓度降至远低于溶解度(随着地下水位下的深度增加而增加)的原因的工具之一。3.将在充气井中现场测量TDGPs，以验证TDGp随深度(和溶解度)线性增加的普遍假设。4.浅层、受污染和地下水充气地点的地下水温度的季节性变化将提供一个机会，以衡量不同的气体产生速度，并将其纳入受污染地点监测的自然衰减情况下污染物降解率的估计。5.将利用在测量和了解地下水气体浓度方面积累的经验，解开阿尔伯塔省中部井坑中造成6人死亡和3人险些死亡的贫氧气体来源的水文地质学“谜团”。