French to English Science Environment & Ecology water purification

Am I correct in thinking that the way this is translated depends on the context? It would appear to, from the examples I've found, but I'd appreciate an opinion from someone who knows about chemistry.

Translations I've found are 'nitrate', (nitrate nitrogen) in the following context:
'Le relargage du phosphore à partir des sédiments ainsi que la réduction de l’azote nitrique en azote ammoniacal au fond du lac sont peu marqués en fin d’année ...'

and 'nitrite' (nitrite nitrogen), here:
'... la concentration moyenne annuelle en azote nitrique est de 574 µgN·L-1, ce ...'

Is one of these incorrect, are both correct, or should both be translated differently?