title: Multi-bioindicators to assess soil microbial activity in the context of an artificial groundwater recharge with treated wastewater: a large-scale pilot experiment.
abstract: In the context of artificial groundwater recharge, a reactive soil column at pilot-scale (4.5 m depth and 3 m in diameter) fed by treated wastewater was designed to evaluate soil filtration ability. Here, as a part of this project, the impact of treated wastewater filtration on soil bacterial communities and the soil's biological ability for wastewater treatment as well as the relevance of the use of multi-bioindicators were studied as a function of depth and time. Biomass; bacterial 16S rRNA gene diversity fingerprints; potential nitrifying, denitrifying, and sulfate-reducing activities; and functional gene (amo, nir, nar, and dsr) detection were analyzed to highlight the real and potential microbial activity and diversity within the soil column. These bioindicators show that topsoil (0 to 20 cm depth) was the more active and the more impacted by treated wastewater filtration. Nitrification was the main activity in the pilot. No sulfate-reducing activity or dsr genes were detected during the first 6 months of wastewater application. Denitrification was also absent, but genes of denitrifying bacteria were detected, suggesting that the denitrifying process may occur rapidly if adequate chemical conditions are favored within the soil column. Results also underline that a dry period (20 days without any wastewater supply) significantly impacted soil bacterial diversity, leading to a decrease of enzyme activities and biomass. Finally, our work shows that treated wastewater filtration leads to a modification of the bacterial genetic and functional structures in topsoil.
authors.affiliation: BRGM (Bureau de Recherches Géologiques et Minières), BP 36009, 45060 Orléans, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Michel
authors.forename: Catherine
authors.initials: C
authors.lastname: Joulian
authors.forename: Patrick
authors.initials: P
authors.lastname: Ollivier
authors.forename: Audrey
authors.initials: A
authors.lastname: Nyteij
authors.forename: Rémi
authors.initials: R
authors.lastname: Cote
authors.forename: Nicolas
authors.initials: N
authors.lastname: Surdyk
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hellal
authors.forename: Joel
authors.initials: J
authors.lastname: Casanova
authors.forename: Katia
authors.initials: K
authors.lastname: Besnard
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rampnoux
authors.forename: Francis
authors.initials: F
authors.lastname: Garrido
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D058440:Denitrification; D005374:Filtration; D060587:Groundwater / Q000737:chemistry* / Q000382:microbiology; D010865:Pilot Projects; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D062065:Wastewater / Q000737:chemistry* / Q000382:microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D001426:Bacterial Proteins; D012987:Soil; D062065:Wastewater