A comparison of nitrate level in spinach grown both under different densities in aquaponic system and under natural growth conditions - Ştefan Mihai, Petrea; Victor, Cristea; Lorena, Dediu; Maria, Contoman; Paul, Lupoae; Săndiţa, Plăcintă (Ion); Marian Tiberiu, Coadă; Mugurel, Enache (The Annals of the University Dunarea de Jos of Galati. Fascicle VI - Food Technology, 2013)