Chemical Stress - Atmospheric imbalances

At least two components of the environment, oxygen and carbon dioxide that plants require are predominantly in the gaseous form. As you have learnt, atmospheric nitrogen can be used by nitrogen-fixing bacteria, some prokaryotic algae and plant-bacterial symbiont. The biological cycling of these gases keeps their overall availability buffered within a reasonably stable range. Yet, intensive industrial activities that involve emission of one of these gases or high levels of the oxides of carbon, nitrogen and sulphur has visible effects on the performance of most plant species.