The redox chemistry of anoxic continental margin settings evolved from widespread sulfide-containing (euxinic) conditions to a global ferruginous (iron-containing) state in the early Neoproterozoic era (from ~1 to 0.8 billion years ago). Ocean redox chemistry exerts a strong control on the biogeochemical cycling of phosphorus, a limiting nutrient, and hence on primary production, but the response of the phosphorus cycle to this major ocean redox transition has not been investigated. Here, we use a geochemical speciation technique to investigate the phase partitioning of phosphorus in an open marine, early Neoproterozoic succession from the Huainan Basin, North China. We find that effective removal of bioavailable phosphorus in association with iron minerals in a globally ferruginous ocean resulted in oligotrophic (nutrient limited) conditions, and hence a probable global decrease in primary production, organic carbon burial and, subsequently, oxygen production. Nevertheless, phosphorus availability and organic carbon burial were sufficient to maintain an oxidizing atmosphere. These data imply substantial nutrient-driven variability in atmospheric oxygen levels through the Proterozoic, rather than the stable levels commonly invoked.

缺氧大陆边缘环境的氧化还原化学在新元古代早期（从1到8亿年前）从广泛的含硫化物（含氧）状态演变为全球性含铁（含铁）状态。海洋氧化还原化学对磷（一种有限的养分）的生物地球化学循环具有重要的控制作用，因此对初级生产也有很强的控制作用，但是磷循环对这一主要海洋氧化还原转变的响应尚未得到研究。在这里，我们使用地球化学形态学技术研究了来自华北淮南盆地的一个开放的海洋，新元古代早期演替过程中磷的相分配。我们发现，在全球铁质海洋中，有效去除与铁矿物质相关的可生物利用的磷会导致贫营养（营养受限）状况，因此，全球范围内初级生产，有机碳埋藏以及随后的氧气生产可能会减少。然而，磷的有效性和有机碳的埋葬足以维持氧化气氛。这些数据表明，通过元古代，营养素驱动的大气氧含量存在很大的变化，而不是通常所称的稳定水平。