The development of new methods to directly measure the radiocarbon age of dissolved and evaded aquatic carbon dioxide has enhanced our ability to understand carbon transport and cycling in the soil–water–atmosphere system. One of the methods involves collecting enough carbon dioxide for radiocarbon dating by allowing carbon dioxide to outgas from the water surface into an enclosed floating chamber, with the gas subsequently trapped onto a zeolite molecular sieve cartridge. There are, however, several different methodological approaches that can be used for the collection of floating chamber samples, and it is currently unknown whether these different approaches influence the isotopic (stable carbon and radiocarbon) composition of the measured sample. Here, we evaluate four different floating chamber approaches and compare the stable and radiocarbon composition of the evaded carbon dioxide. Chamber conditions varied considerably with the different methodologies, with for example, maximum chamber CO₂ concentration ranging from approximately 400–6,300 ppm during sampling. Despite the varying chamber conditions, our results indicate no significant differences in the ¹⁴C age of evasion (range: 1,276–1,364 years before present) with any of the methodological approaches (in chambers where atmospheric carbon dioxide had been excluded). This confirms the methodologies are both robust and widely applicable.

中文翻译：

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对腔室14C方法学评估水生二氧化碳逃逸的评估

直接测量溶解和逃逸的水生二氧化碳的放射性碳年龄的新方法的开发，增强了我们了解土壤-水-大气系统中碳迁移和循环的能力。一种方法涉及通过允许二氧化碳从水表面除气到封闭的浮腔中来收集足够的二氧化碳以进行放射性碳测年，随后将气体捕集到沸石分子筛盒中。但是，有几种不同的方法学方法可用于收集漂浮室样品，目前尚不清楚这些不同方法是否会影响所测量样品的同位素（稳定碳和放射性碳）组成。这里，我们评估了四种不同的漂浮室方法，并比较了逃逸的二氧化碳的稳定成分和放射性碳成分。腔室条件因不同的方法而异，例如最大腔室CO₂采样期间的浓度范围约为400–6,300 ppm。尽管试验箱条件各不相同，但我们的结果表明，采用任何一种方法学方法（在排除了大气二氧化碳的试验箱中），在¹⁴ C的逃避年龄（范围：目前的1,276–1,364年）之间均无显着差异。这证实了该方法既健壮又广泛适用。