dissolved greenhouse gases in water tracks

Water samples were collected in triplicate from flowing, surface water of six water tracks draining the Kuparuk River basin, Alaska. Samples were collected without headspace and kept at collection temperature and under water during transport to the laboratory. 40 mL water was equilibrated with 20 mL ultra-high purity helium. Resulting gas samples were analyzed on a gas chromatograph equipped with a flame ionization detector (CH4) with methanizer (CO2), and an electron-capture detector (N2O). Certified standards were used for calibration of the instrument. Dissolved concentrations were calculated using temperature-specific Henry's coefficients and % saturation was estimated relative to global average atmospheric concentrations monitored by NOAA at Mauna Loa during the season of sample collection during each year.

本研究从阿拉斯加库帕鲁克河（Kuparuk River）流域内6条径流河道的流动地表水中，采集了三份平行水样。水样采集时未预留顶空空间，运输至实验室的过程中，全程维持采集时的温度，并始终浸没于水中。取40 mL水样与20 mL超高纯氦气进行气液平衡。所得气体样品采用气相色谱仪分析，该仪器配备火焰离子化检测器（用于检测CH4）与搭载甲烷化装置的火焰离子化检测器（用于检测CO2），同时配有电子捕获检测器（用于检测N2O）。采用标准认证气体完成仪器校准。溶解态气体浓度通过温度特异性亨利定律系数计算得到；气体饱和百分比则以每年样品采集季期间，美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）在冒纳罗亚（Mauna Loa）监测站记录的全球平均大气浓度为基准进行估算。