Inorganic nitrogen pollution in aquatic ecosystems: environmental problems, water quality criteria, and implications of climate change

Abstract

Inorganic nitrogen pollution in aquatic ecosystems: environmental problems, water quality criteria, and implications of climate change.

The major environmental problems related to inorganic nitrogen pollution in aquatic ecosystems are: (1) acidification of lakes and rivers with low or reduced alkalinity; (2) eutrophication of fresh and marine waters (with the additional problem of toxic algae); and (3) direct toxicity of nitrogenous compounds to aquatic animals. Additionally, inorganic nitrogen pollution could induce adverse effects on human health. On the basis of different water quality criteria, we consider that maximum levels of dissolved inorganic nitrogen within the range 0.5-1.0 mg DIN/l (or even better of total nitrogen within the range 0.5-1.0 mg TN/l) may be suitable to prevent the processes of acidification and eutrophication in aquatic ecosystems (at least by nitrogen) and, at the same time, to protect aquatic animals (and also humans) against the toxic effects of inorganic nitrogenous compounds NH3+, NH4+, HNO2+, NO2-, NO3-. This range of concentrations would not be applicable to those aquatic ecosystems with naturally high nitrogen levels. We conclude that the commented problems can becomeacute in those world’s regions (for example, in southern Spain) where reductions in water resources and rises in environmental temperatures are expected to occur as a consequence of the current climate change.