Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716, USA.
Waste Manag. 2012 Feb;32(2):297-304. doi: 10.1016/j.wasman.2011.09.016. Epub 2011 Oct 12.
Gas tracer tests can be used to determine gas flow patterns within landfills, quantify volatile contaminant residence time, and measure water within refuse. While gas chromatography (GC) has been traditionally used to analyze gas tracers in refuse, photoacoustic spectroscopy (PAS) might allow real-time measurements with reduced personnel costs and greater mobility and ease of use. Laboratory and field experiments were conducted to evaluate the efficacy of PAS for conducting gas tracer tests in landfills. Two tracer gases, difluoromethane (DFM) and sulfur hexafluoride (SF(6)), were measured with a commercial PAS instrument. Relative measurement errors were invariant with tracer concentration but influenced by background gas: errors were 1-3% in landfill gas but 4-5% in air. Two partitioning gas tracer tests were conducted in an aerobic landfill, and limits of detection (LODs) were 3-4 times larger for DFM with PAS versus GC due to temporal changes in background signals. While higher LODs can be compensated by injecting larger tracer mass, changes in background signals increased the uncertainty in measured water saturations by up to 25% over comparable GC methods. PAS has distinct advantages over GC with respect to personnel costs and ease of use, although for field applications GC analyses of select samples are recommended to quantify instrument interferences.
气体示踪剂测试可用于确定垃圾填埋场内的气体流动模式、量化挥发性污染物停留时间，并测量垃圾中的水分。虽然传统上使用气相色谱法 (GC) 来分析垃圾中的气体示踪剂，但光声光谱法 (PAS) 可能允许以更低的人员成本、更高的机动性和易用性进行实时测量。进行了实验室和现场实验，以评估 PAS 用于在垃圾填埋场进行气体示踪剂测试的效果。使用商业 PAS 仪器测量了两种示踪气体，二氟甲烷 (DFM) 和六氟化硫 (SF6)。相对测量误差与示踪剂浓度无关，但受背景气体影响：在垃圾填埋气中误差为 1-3%，而在空气中误差为 4-5%。在好氧垃圾填埋场中进行了两次分配气体示踪剂测试，由于背景信号的时间变化，PAS 对 DFM 的检测限 (LOD) 比 GC 高 3-4 倍。虽然可以通过注入更大的示踪剂质量来补偿更高的 LOD，但背景信号的变化使测量的水分饱和度的不确定性增加了高达 25%，与可比的 GC 方法相比。与 GC 相比，PAS 在人员成本和易用性方面具有明显优势，尽管对于现场应用，建议对选定样品进行 GC 分析以量化仪器干扰。
