Uranium (U) is of enormous global importance because of its use in energy generation,
albeit with potential environmental legacies. While naturally occurring U is widespread in the …

Nitrogen is an essential nutrient for all life on Earth and it acts as a major control on
biological productivity in the modern ocean. Accurate reconstructions of the evolution of life …

The origin of eukaryotes remains unclear,,–. Current data suggest that eukaryotes may have
emerged from an archaeal lineage known as 'Asgard'archaea,. Despite the eukaryote-like …

We present a framework for interpreting the carbon isotopic composition of sedimentary
rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox …

The atmosphere–ocean system experienced a progressive change from anoxic to more
oxidizing conditions through time. This oxidation is traditionally envisaged to have occurred …

Marine planktonic cyanobacteria contributed to the widespread oxygenation of the oceans
towards the end of the Pre-Cambrian and their evolutionary origin represents a key …

Major changes in atmospheric and ocean chemistry occurred in the Paleoproterozoic era
(2.5 to 1.6 billion years ago). Increasing oxidation dramatically changed Earth's surface, but …

Nitrogen isotope compositions in sedimentary rocks (d 15 N sed) are routinely used for
reconstructing Cenozoic N-biogeochemical cycling and are also being increasingly applied …

It is unclear why atmospheric oxygen remained trapped at low levels for more than 1.5
billion years following the Paleoproterozoic Great Oxidation Event. Here, we use models for …

Carbonates from approximately 2.3–2.1 billion years ago show markedly positive δ13C
values commonly reaching and sometimes exceeding+ 10‰. Traditional interpretation of …