Aquifer recharge by stormwater infiltration basins: Hydrological and vadose zone characteristics control the impacts of basins on groundwater chemistry and microbiology

• Published in: The Science of the total environment Vol. 865; p. 161115
• Main Authors: Lebon, Yohan, François, Clémentine, Navel, Simon, Vallier, Félix, Guillard, Ludovic, Pinasseau, Lucie, Oxarango, Laurent, Volatier, Laurence, Mermillod-Blondin, Florian
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.03.2023; Elsevier
• Subjects: Aquifer recharge; Biofilm biomass and activity; Biomass; Clay; Dissolved Organic Matter; Environmental Sciences; Groundwater - chemistry; Groundwater table elevation; Infiltration basin; Rain; Stormwater runoff; Water transit time from surface to groundwater; Infiltration basin; Aquifer recharge; Biofilm biomass and activity; Groundwater table elevation; Water transit time from surface to groundwater; Stormwater runoff; Infiltration basin Aquifer recharge Water transit time from surface to groundwater Groundwater table elevation Biofilm biomass and activity Stormwater runoff
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.161115

Stormwater infiltration systems (SIS) are designed to collect and infiltrate urban stormwater runoff into the ground for flood risk mitigation and artificial aquifer recharge. Many studies have demonstrated that infiltration practices can impact groundwater chemistry and microbiology. However, quantitative assessments of the hydrogeological factors responsible of these changes remain scarce. Thus, the present study aimed to quantitatively test whether changes of groundwater chemistry and microbiology induced by SIS were linked to two factors associated with vadose zone properties (vadose zone thickness, water transit time from surface to groundwater) and one factor associated with groundwater recharge rate (assessed by groundwater table elevation during rain events). To evaluate changes in chemistry (NO3−, PO43− and dissolved organic carbon concentrations), groundwater samples were collected in wells located in SIS-impacted and non-SIS-impacted zones during experimental periods of 10 days. During the same periods, clay beads were incubated in the same wells to measure changes of groundwater microbial biofilms (microbial biomass, dehydrogenase and hydrolytic activities) induced by SIS. Results showed that changes in PO43− supplied to groundwater during stormwater infiltration was negatively correlated with vadose zone thickness. A short water transit time from surface to groundwater increased dissolved organic carbon concentrations in the aquifer which, in turn, increased biofilm biomasses in groundwater. The groundwater recharge rate during rain events (assessed by groundwater table elevation) diluted NO3− concentrations in the aquifer but also influenced the changes of biofilm activities induced by SIS. Groundwater recharge rate during rain events probably increased the fluxes of water and dissolved organic carbon in groundwater, stimulating the activity of microbial biofilms. Overall, the present study is the first to quantify conjointly several factors and processes (water transfer, dilution, solute fluxes) that could explain the impact of stormwater infiltration on chemistry and/or microbiology in groundwater. [Display omitted] •Stormwater infiltration modified groundwater chemistry and microbiology.•The highest enrichments in dissolved organic carbon occurred for the fastest water transfers through the vadose zone.•The highest stimulations of microbial biomass were also measured for the fastest transfers through the vadose zone.•The stimulation of biofilm activities increased with groundwater table fluctuations.•Long stormwater transfer and reduced groundwater recharge rate would be considered for implementing infiltration systems.