A simple technique for continuous measurement of time‐variable gas transfer in surface waters
A simple technique for continuous measurement of time‐variable gas transfer in surface waters
复制标题
连续测量地表水中随时间变化的气体传输的简单技术
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
E. Busenberg
中科院分区：
文献类型：
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作者：
C. Tobias;J. Böhlke;J. Harvey;E. Busenberg
河流、湖泊和河流中溶解气体的质量平衡模型是估算各种生物地球化学过程的全生态系统速率的基础。水和大气之间的气体交换速率是这些模型的重要组成部分，也是容易出错的部分。在这里，我们提出了一种简单而有效的SF6气体示踪方法的改进，该方法可以同时使用，同时收集其他溶解气体样品，用于在蒸气中进行溶解气体质量平衡研究。它包括以低流速将SF6饱和的水直接连续计量到溪流中。与脉冲注入水溶液或向气流中鼓泡大量SF6相比，这种方法具有优势。通过将SF6作为饱和溶液加入，我们将其他溶解气体测量受到喷雾和/或气泡喷射影响的可能性降至最低。因为SF6是连续添加的，所以我们有一个与其他非保守环境中溶解气体的采样同步变化的气体传输速度(GTV)的记录。在一段时间内，在二级流(美国印第安纳州糖溪)观察到GTV有30%的变化。GTV的变化可以部分归因于温度和风速的变化，这些变化发生在每小时到每小时的时间尺度上。
Mass balance models of dissolved gases in streams, lakes, and rivers serve as the basis for estimating whole‐ecosystem rates for various biogeochemical processes. Rates of gas exchange between water and the atmosphere are important and error‐prone components of these models. Here we present a simple and efficient modification of the SF6 gas tracer approach that can be used concurrently while collecting other dissolved gas samples for dissolved gas mass balance studies in streams. It consists of continuously metering SF6‐saturated water directly into the stream at a low rate of flow. This approach has advantages over pulse injection of aqueous solutions or bubbling large amounts of SF6 into the stream. By adding the SF6 as a saturated solution, we minimize the possibility that other dissolved gas measurements are affected by sparging and/or bubble injecta. Because the SF6 is added continuously we have a record of changing gas transfer velocity (GTV) that is contemporaneous with the sampling of other nonconservative ambient dissolved gases. Over a single diel period, a 30% variation in GTV was observed in a second‐order stream (Sugar Creek, Indiana, USA). The changing GTV could be attributed in part to changes in temperature and windspeed that occurred on hourly to diel timescales.