Mongabay: The burning of fossil fuels has disrupted the nitrogen cycle by altering that amount of nitrogen in the biosphere, according to scientists from Brown University and the University of Washington. It has long been known that fossil fuel combustion releases nitric oxides into the air–which combine with other elements to form both smog and acid rain–but until now scientists have been unsure as to the extent nitric oxide emissions have affected the natural nitrogen cycle. In a study …