Significant contribution of combustion-related emissions to the atmospheric phosphorus budget

Atmospheric phosphorus fertilizes plants and contributes to Earths biogeochemical phosphorus cycle. However, calculations of the global budget of atmospheric phosphorus have been unbalanced, with global deposition exceeding estimated emissions from dust and sea-salt transport, volcanic eruptions, biogenic sources and combustion of fossil fuels, biofuels and biomass, the latter of which thought to contribute about 5% of total emissions. Here we use measurements of the phosphorus content of various fuels and estimates of the partitioning of phosphorus during combustion to calculate phosphorus emissions to the atmosphere from all combustion sources. We estimate combustion-related emissions of 1.8 Tg P yr(-1), which represent over 50% of global atmospheric sources of phosphorus. Using these estimates in atmospheric transport model simulations, we find that the total global emissions of atmospheric phosphorus (3.5 Tg P yr(-1)) translate to a depositional sink of 2.7 Tg P yr(-1) over land and 0.8 Tg P yr(-1) over the oceans. The modelled spatial patterns of phosphorus deposition agree with observations from globally distributed measurement stations, and indicate a near balance of the phosphorus budget. Our finding suggests that the perturbation of the global phosphorus cycle by anthropogenic emissions is larger thanpreviously thought.