We aim at investigating whether the chemical composition of the outer region of the protosolar nebula can be consistent with current estimates of the elemental abundances in the ice giants. To do so, we use a self-consistent evolutionary disc and transport model to investigate the time and radial distributions of H2O, CO, CO2, CH3OH, CH4, N2 and H2S, i.e. the main O-, C-, N and S-bearing volatiles in the outer disc. We show that it is impossible to accrete a mixture composed of gas and solids from the disc with a C/H ratio presenting enrichments comparable to the measurements (approx. 70 times protosolar). We also find that the C/N and C/S ratios measured in Uranus and Neptune are compatible with those acquired by building blocks agglomerated from solids condensed in the 10–20 arb. units region of the protosolar nebula. By contrast, the presence of protosolar C/N and C/S ratios in Uranus and Neptune would imply that their building blocks agglomerated from particles condensed at larger heliocentric distances. Our study outlines the importance of measuring the elemental abundances in the ice giant atmospheres, as they can be used to trace the planetary formation location, the origin of their building blocks and/or the chemical and physical conditions of the protosolar nebula. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.

中文翻译：

---

冰线在天王星和海王星形成中的作用

我们的目标是调查原太阳星云外部区域的化学成分是否与目前对冰巨星元素丰度的估计一致。为此，我们使用自洽演化盘和输运模型来研究 H2O、CO、CO2、CH3OH、CH4、N2 和 H2S（即主要的 O-、C-、N 和 S-）的时间和径向分布在外盘中含有挥发物。我们表明，不可能从圆盘中吸积由气体和固体组成的混合物，其 C/H 比呈现出与测量值相当的富集度（大约是原太阳的 70 倍）。我们还发现，在天王星和海王星中测量的 C/N 和 C/S 比与通过从 10-20 arb 中凝结的固体凝聚而成的积木获得的那些相容。原太阳星云的单位区域。相比之下，天王星和海王星中原太阳 C/N 和 C/S 比的存在意味着它们的组成部分是由在更大的日心距离处凝聚的粒子聚集而成的。我们的研究概述了测量冰巨行星大气中元素丰度的重要性，因为它们可用于追踪行星的形成位置、其构建块的起源和/或原太阳星云的化学和物理条件。本文是讨论会问题“冰巨星系统的未来探索”的一部分。因为它们可用于追踪行星的形成位置、其构建块的起源和/或原太阳星云的化学和物理条件。本文是讨论会问题“冰巨星系统的未来探索”的一部分。因为它们可用于追踪行星的形成位置、其构建块的起源和/或原太阳星云的化学和物理条件。本文是讨论会问题“冰巨星系统的未来探索”的一部分。