Dust events control nitrogen cycling and nitrate/(per)chlorate relationships on Mars

Abstract

Abstract Nitrogen is an important part of any biosphere/organic cycling, but aspects of the nitrogen cycle for Mars are quite unclear. Nitrate and (per)chlorate have been detected in sedimentary rocks and aeolian sediments in Gale crater on Mars as well as in martian meteorites. Their occurrences have implications for global nitrogen/chlorine cycles and the habitability on Mars. However, the origins of nitrate and (per)chlorate, and their possible formation are not well understood. Interaction between the atmosphere and surface of Mars during dust events have cause electrostatic discharge (ESD). By simulating this process in a Mars chamber, nitrate and (per)chlorate can form from halite precursors under martian atmospheric conditions. The obtained nitrate/(per)chlorate ratio (0.28 ± 0.19) is in agreement with Gale crater observations (0.23 ± 0.12), which is much lower than in terrestrial Mars analogues and the products of other pathways proposed for Mars. The electrochemistry during Mars dust events represents a new nitrogen fixation mechanism, which may also act as a crucial part of global nitrogen cycling on present-day Mars even throughout the whole Amazonian period. These nitrate salts in martian dusts potentially provide an accessible source of nitrogen for possible organic molecule formation on Mars.