We developed a passive sampler for time-integrated collection and radiocarbon (14C) analysis of soil respiration, a major flux in the global C cycle. It consists of a permanent access well that controls the CO2 uptake rate and an exchangeable molecular sieve CO2 trap. We tested how access well dimensions and environmental conditions affect collected CO2, and optimized cleaning procedures to minimize 14CO2 memory. We also deployed two generations of the sampler in Arctic tundra for up to two years, collecting CO2 over periods of 3 days–2 months, while monitoring soil temperature, volumetric water content, and CO2 concentration. The sampler collects CO2 at a rate proportional to the length of a silicone tubing inlet (7–26 µg CO2-C day-1·m Si-1). With constant sampler dimensions in the field, CO2 recovery is best explained by soil temperature. We retrieved 0.1–5.3 mg C from the 1st and 0.6–13 mg C from the 2nd generation samplers, equivalent to uptake rates of 2–215 (n=17) and 10–247 µg CO2-C day-1 (n=20), respectively. The method blank is 8 ± 6 µg C (mean ± sd, n=8), with a radiocarbon content (fraction modern) ranging from 0.5875–0.6013 (n=2). The sampler enables more continuous investigations of soil C emission sources and is suitable for Arctic environments.

中文翻译：

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用于土壤 14C 分析的 CO2 时间积分收集

我们开发了一种用于时间整合收集和放射性碳的被动采样器（14C) 土壤呼吸分析，这是全球 C 循环中的主要通量。它由一个控制 CO 的永久通道组成2吸收率和可交换分子筛 CO2陷阱。我们测试了进入井尺寸和环境条件如何影响收集的二氧化碳2，并优化清洁程序，以尽量减少14一氧化碳2记忆。我们还在北极苔原上部署了两代采样器长达两年，收集二氧化碳2在 3 天至 2 个月期间，同时监测土壤温度、体积含水量和 CO2浓度。采样器收集 CO2速率与硅胶管入口的长度成正比（7–26 µg CO2-C天-1·米硅-1）。现场采样器尺寸恒定，CO2土壤温度最好地解释了恢复。我们从第一代采样器中回收了 0.1-5.3 mg C，从第二代采样器中回收了 0.6-13 mg C，相当于 2-215 (n=17) 和 10–247 µg CO2-C天-1(n=20），分别。方法空白为 8 ± 6 µg C（平均值 ± 标准差，n=8），放射性碳含量（现代分数）范围为0.5875-0.6013（n=2）。该采样器可以对土壤碳排放源进行更持续的调查，适用于北极环境。