title: Effects of pH on nitrogen transformations in media-based aquaponics.
abstract: To investigate the effects of pH on performance and nitrogen transformations in aquaponics, media-based aquaponics operated at pH 6.0, 7.5 and 9.0 were systematically examined and compared in this study. Results showed that nitrogen utilization efficiency (NUE) reached its maximum of 50.9% at pH 6.0, followed by 47.3% at pH 7.5 and 44.7% at pH 9.0. Concentrations of nitrogen compounds (i.e., TAN, NO2(-)-N and NO3(-)-N) in three pH systems were all under tolerable levels. pH had significant effect on N2O emission and N2O conversion ratio decreased from 2.0% to 0.6% when pH increased from 6.0 to 9.0, mainly because acid environment would inhibit denitrifiers and lead to higher N2O emission. 75.2-78.5% of N2O emission from aquaponics was attributed to denitrification. In general, aquaponics was suggested to maintain pH at 6.0 for high NUE, and further investigations on N2O mitigation strategy are needed.
authors.affiliation: School of Environmental Science and Engineering, Shandong University, Jinan, China.
authors.forename: Yina
authors.initials: Y
authors.lastname: Zou
authors.affiliation: School of Environmental Science and Engineering, Shandong University, Jinan, China. Electronic address: huzhen885@sdu.edu.cn.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Hu
authors.affiliation: School of Environmental Science and Engineering, Shandong University, Jinan, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Environmental Research Institute, Shandong University, Jinan, China.
authors.forename: Huijun
authors.initials: H
authors.lastname: Xie
authors.affiliation: Laboratoire de Physique et de Chimie de l'Environnement et de l'Espace, Université d'Orléans, Orléans, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Guimbaud
authors.affiliation: School of Environmental Science and Engineering, Shandong University, Jinan, China.
authors.forename: Yingke
authors.initials: Y
authors.lastname: Fang
mesh_terms: D017756:Aquaculture / Q000379:methods*; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D018628:Gene Dosage; D006863:Hydrogen-Ion Concentration; D018527:Hydroponics / Q000379:methods*; D009584:Nitrogen / Q000032:analysis*; D009609:Nitrous Oxide / Q000032:analysis; D014867:Water
chemical_list: D014867:Water; D009609:Nitrous Oxide; D009584:Nitrogen
keywords: Aquaponics; Microbial abundance; N(2)O emission; Nitrogen transformations; pH