We provide a global assessment, with detailed multi-scale data, of the ecological and toxicological effects generated by inorganic nitrogen
pollution in aquatic ecosystems. Our synthesis of the published scientific literature shows three major environmental problems: (1) it can increase
the concentration of hydrogen ions in freshwater ecosystems without much acid-neutralizing capacity, resulting in acidification of those systems;
(2) it can stimulate or enhance the development, maintenance and proliferation of primary producers, resulting in eutrophication of aquatic
ecosystems; (3) it can reach toxic levels that impair the ability of aquatic animals to survive, grow and reproduce. Inorganic nitrogen pollution of
ground and surface waters can also induce adverse effects on human health and economy.