Reconstructions of paleoatmospheric H₂ using polar firn air and ice cores would lead to a better understanding of the H₂ biogeochemical cycle and how it is influenced by climate change and human activity. In this study, the permeability, diffusivity, and solubility of H₂ are determined experimentally in ice Ih at temperatures relevant to polar ice sheets (199–253 K). The experimental data are used in conjunction with simplified diffusion models to assess the implications for: (a) Diffusion of H₂ from pressurized closed bubbles to open pores in polar firn, (b) diffusive smoothing of H₂ gradients in the ice sheet, and (c) post-coring diffusive losses of H₂ from ice core samples. The results indicate that diffusive equilibrium between open and closed pores is likely achieved in the firn lock-in zone. Diffusive smoothing of atmospheric variations is significant and should be accounted for in atmospheric reconstructions on millennial time scales. Diffusive losses from a bubbly ice sample are sufficiently slow that samples may be meaningfully analyzed for H₂ after storage on the order of a year. These results suggest that the mobility of H₂ in ice should not preclude the reconstruction of paleoatmospheric H₂ from firn air and ice cores.

中文翻译：

---

H2在冰中的扩散性和溶解度Ih：对极地冰中H2行为的影响

利用极地火力的空气和冰芯重建古大气H ₂可以更好地了解H ₂生物地球化学循环以及它如何受到气候变化和人类活动的影响。在这项研究中，H ₂的渗透性，扩散性和溶解度是在与极性冰盖相关的温度（199–253 K）下在冰Ih中通过实验确定的。实验数据与简化的扩散模型结合使用，以评估以下方面的含义：（a）H ₂从加压的闭合气泡扩散到极性燃烧的开孔；（b）冰盖中H ₂梯度的扩散平滑；以及（c）H ₂的取芯后扩散损失从冰芯样品中提取。结果表明，在烧结锁定区很可能实现了开孔和闭孔之间的扩散平衡。弥漫性的大气变化平滑作用很重要，应在千年尺度上进行大气重建。气泡状冰样品的扩散损失足够缓慢，以至于在储存大约一年后可以对样品的H ₂进行有意义的分析。这些结果表明，H ₂在冰中的迁移率不应排除从大气和冰芯中重建古大气H ₂的可能性。