O_2_ laboratory atmosphere simulation experiments

Here, we experimentally investigate the effect of O_2_ on the formation and composition of aerosols to improve our understanding of haze formation on the Neoproterozoic Earth. We obtained in situ size, particle density, and composition measurements of aerosol particles produced from N_2_/CO_2_/CH_4_/O_2_ gas mixtures subjected to FUV radiation (115-400nm) for a range of initial CO_2_/CH_4_/O_2_ mixing ratios (O_2_ ranging from 2ppm to 0.2%).

At the lowest O_2_ concentration (2ppm), the addition increased particle production for all but one gas mixture. At higher oxygen concentrations (20ppm and greater), particles are still produced, but the addition of O_2_ decreases the production rate. Both the particle size and number density decrease with increasing O_2_, indicating that O_2_ affects particle nucleation and growth.