Influence du réchauffement climatique sur les cycles biogéochimiques des nutriments dans les eaux de surface : cas du dioxyde de carbone, de l’azote et du phosphore

Résumé

Influence of climate warming on the biogeochemical cycles of nutrients in surface waters: case of carbon dioxide, nitrogen, and phosphorus

The  interest  of  this  study  is  to  raise  awareness  and explain, from the modification of the biogeochemical cycles of carbon dioxide, nitrogen and phosphorus, how warming manages to eutropicate surface waters. Water dismutation is in itself an uncontrolled chemical mechanism within biogeochemical cycles. However, it could favour the incidence of some thermodynamically stable derivatives of these nutrients at the expense of others in warm aquatic and atmospheric conditions. The biogeochemical cycles of carbon dioxide, nitrogen and phosphorus have been modified to highlight the impact of thermal flux. The analysis of the expected carbon cycle shows that the iron-sulfur combination conditionally weakens the biological and carbonate pumps. Moreover, the low solubility of carbon dioxide contributes, in conjunction with the high production of nitrous oxide (N₂O) in the nitrogen cycle, to heating the surface of aquatic areas. In the case of phosphorus, on the one hand, its increasing fraction destruction related to carbonates and calcium and, on the other hand, the probable dynamics of phosphorus hydrides (PH₃ and PH₅) motivated by the increasing reducing power of aquatic environments tend to constitute an ecosystem chemical risk.

Keywords: Biogeochemical cycles; Global warming; Chemical risk.