Browne Bryant A
College of Natural Resources, University of Wisconsin-Stevens Point, Stevens Point, Wisconsin 54481, USA.
Environ Sci Technol. 2004 Nov 1;38(21):5729-36. doi: 10.1021/es035464m.
The incorporation of multiple dissolved gas measurements in biogeochemical studies remains a difficult and expensive challenge. Incompatibilities in collection, handling, and storage procedures generally force the application of multiple sampling procedures for multiple gases. This paper introduces the concept and application of pumping-induced ebullition (PIE), a unified approach for routine measurement of multiple dissolved gases in natural waters and establishes a new platform for development of in situ real-time dissolved gas monitoring tools. Ebullition (spontaneous formation of bubbles) is induced by pumping a water sample through a narrow-diametertube (a "restrictor") to decrease hydrostatic pressure (PH) below total dissolved gas pressure (PT). Buoyancy is used to trap bubbles within a collection tower where gas accumulates rapidly (1 mL/min) to support multiple chemical analyses. Providing for field collection of an essentially unlimited and unified volume of gas sample, PIE afforded accurate and precise measurements of major (N2, 02, Ar), trace (CO2, N20, CH4) and ultratrace (CFC11, CFC12, CFC113, SF6) dissolved gases in Wisconsin groundwater, revealing interrelationships between denitrification, apparent recharge age-dates, and historical land use. Compared to conventional approaches, PIE eliminates multiple gas-specific sampling methods, reduces data computations, simplifies laboratory instrumentation, and avoids aqueous production and consumption of biogenic gases during sample storage. A lake depth profile for CO2 demonstrates PIE's flexibility as an in situ real-time platform for dissolved gas measurements. The apparent departures of some gases (SF6, H2, N2O, CO2) from solubility equilibrium behavior warrant further confirmation and theoretical investigation.
在生物地球化学研究中纳入多种溶解气体测量仍然是一项困难且昂贵的挑战。采集、处理和储存程序中的不兼容性通常迫使针对多种气体采用多种采样程序。本文介绍了泵激沸腾（PIE）的概念和应用，这是一种用于常规测量天然水中多种溶解气体的统一方法，并建立了一个用于开发原位实时溶解气体监测工具的新平台。通过将水样泵入一根窄直径管（“节流器”）以将静水压力（PH）降低至低于总溶解气体压力（PT），从而引发沸腾（气泡的自发形成）。利用浮力将气泡捕获在一个收集塔内，气体在其中迅速积聚（1毫升/分钟）以支持多种化学分析。PIE能够现场采集基本无限量且统一的气体样本，从而对威斯康星州地下水中的主要（N2、O2、Ar）、痕量（CO2、N2O、CH4）和超痕量（CFC11、CFC12、CFC113、SF6）溶解气体进行准确而精确的测量，揭示了反硝化作用、表观补给年龄日期和历史土地利用之间的相互关系。与传统方法相比，PIE消除了多种针对特定气体的采样方法，减少了数据计算，简化了实验室仪器设备，并避免了样品储存期间生物源气体的水相产生和消耗。一个关于CO2的湖泊深度剖面展示了PIE作为溶解气体测量原位实时平台的灵活性。一些气体（SF6、H2、N2O、CO2）偏离溶解度平衡行为的明显情况值得进一步确认和理论研究。
