Isotopic constraints on lightning as a source of fixed nitrogen in Earth's early biosphere

Bioavailable nitrogen is thought to be a requirement for the origin and sustenance of life. Before the onset of biological nitrogen fixation, abiotic pathways to fix atmospheric N2 must have been prominent to provide bioavailable nitrogen to Earth's earliest ecosystems. Lightning has been shown to produce fixed nitrogen as nitrite and nitrate in both modern atmospheres dominated by N2 and O2 and atmospheres dominated by N2 and CO2 analogous to the Archaean Earth. However, a better understanding of the isotopic fingerprints of lightning-generated fixed nitrogen is needed to assess the role of this process on the early Earth. Here, we present results from spark discharge experiments in N2-CO2 and N2-O2 gas mixtures. Our experiments suggest that lightning-driven nitrogen fixation may have been similarly efficient in the Archaean atmosphere, compared to modern times. Measurements of the isotopic ratio {\delta}15N of the discharge-produced nitrite and nitrate in solution show very low values of -6 to -15 permil after equilibration with the gas phase with a calculated endmember composition of -17 permil. These results are much lower than most {\delta}15N values documented from the sedimentary rock record, which supports the development of biological nitrogen fixation earlier than 3.2 Ga. However, some Paleoarchean records (3.7 Ga) may be consistent with lightning-derived nitrogen input, highlighting the potential role of this process for the earliest ecosystems.Comment: Accepted manuscript. Version of record published in Nature Geoscience. 29 pages (main text, methods, supplementary material), 5 figures + 4 supplementary figure

Nitrogen fixation rates and isotopic measurements of aqueous nitrite and nitrate from spark discharge experiments (dataset)

Concentrations of gaseous and aqueous fixed nitrogen products and isotopic measurements of aqueous nitrite and nitrate in spark discharge experiments. Spark experiments were conducted at the University of St Andrews in the St Andrews Isotope Geochemistry Lab (StAIG) between November 2020 and February 2022. Analysis of gaseous products was carried out with a quadrupole mass spectrometer (Hiden Analytical ExQ Quantitative Gas Analyser) in St Andrews. Measurement of concentrations of aqueous nitrite and nitrate and their isotopic composition were carried out for one part of the samples in St Andrews and for the other part at Brown University, Rhode Island, USA. Experiments with a different type of artificial seawater were carried out and analysed for nitrite concentration (colorimetric method) and pH in St Andrews. The data was collected to investigate the efficiency of nitrogen fixation by lightning in different gas compositions, resembling the atmospheres of modern and early Earth. The isotope data was used to determine the role of lightning in the delivery of nutrients to the earliest ecosystems on Earth by comparing our results to measurements of sedimentary rock samples from the Archean. The experimental set up was built by Patrick Barth and Eva E. Stüeken, the experiments were conducted by Patrick Barth, Lukas Rossmanith, and Yuqian Peng, the analysis conducted by Patrick Barth, Lukas Rossmanith, Yuqian Peng, and Wendell Walters with support from Mark Claire, and the data was analysed by Patrick Barth, Eva E. Stüeken, Christiane Helling, and Wendell Walters. This dataset includes all data that is reliable and was used in the accompanying publication

Status of the Horizon 2020 EuPRAXIA Conceptual Design Study

The Horizon 2020 Project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) is producing a conceptual design report for a highly compact and cost-effective European facility with multi-GeV electron beams accelerated using plasmas. EuPRAXIA will be set up as a distributed Open Innovation platform with two construction sites, one with a focus on beam-driven plasma acceleration (PWFA) and another site with a focus on laser-driven plasma acceleration (LWFA). User areas at both sites will provide access to FEL pilot experiments, positron generation and acceleration, compact radiation sources, and test beams for HEP detector development. Support centres in four different countries will complement the pan-European implementation of this infrastructure

ILC Reference Design Report Volume 1 - Executive Summary

The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of about 31 km and is designed for a peak luminosity of 2x10^34 cm^-2s^-1. This report is the Executive Summary (Volume I) of the four volume Reference Design Report. It gives an overview of the physics at the ILC, the accelerator design and value estimate, the detector concepts, and the next steps towards project realization.The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a total footprint of about 31 km and is designed for a peak luminosity of 2x10^34 cm^-2s^-1. This report is the Executive Summary (Volume I) of the four volume Reference Design Report. It gives an overview of the physics at the ILC, the accelerator design and value estimate, the detector concepts, and the next steps towards project realization