Chemistry of Precipitation Indicates Substantial Changes in our Ambient Air

This paper presents changes in the chemical composition of the atmosphere based on the analysis of the long-term time trends of major ions in atmospheric precipitation. The concentrations of sulphate (SO42–), nitrate (NO3–) and ammonium (NH4+) ions and their changeable relative shares in precipitation over the recent three-decade period is set in the broader context of changes in total sulphur dioxide, nitrogen oxides and ammonia emissions from sources and their subsequent uneven decline in ambient air. Changing ratios of NO3–/SO42–, NH4+/SO42– a NH4+/NO3– not only indicate significant changes in atmospheric chemistry, but may also significantly affect ecosystem behaviour.