Monitoring induced denitrification during managed aquifer recharge in an infiltration pond

Abstract

Managed aquifer recharge (MAR) is a well-known technique for improving water quality and increasing groundwater resources. Denitrification (i.e. removal of nitrate) can be enhanced during MAR by coupling an artificial recharge pond with a permeable reactive layer (PRL). In this study, we examined the suitability of a multi-isotope approach for assessing the longterm effectiveness of enhancing denitrification in a PRL containing vegetal compost. Batch laboratory experiments confirmed that the PRL, installed in 2011, was continuing to enhance denitrification. At the field scale, changes in redox indicators along a flow path and below the MAR-PRL system was monitored over 21 months during recharge (RP) and non-recharge (NRP) periods. Our results showed that the PRL was still releasing non-purgeable dissolved organic carbon five years after installation. Nitrate concentration and isotope data indicated that denitrification was occurring under and close to the infiltration area where recharge water and native groundwater mix. Furthermore, longer operational periods of the MAR-PRL system increased denitrification. Multi-isotope analysis might be useful in identifying and quantifying denitrification in MAR-PRL systems.

Microbial community changes induced by Managed Aquifer Recharge activities: Linking hydrogeological and biological processes

“…This assumption is consistent with nitrate isotopic 15 data presented in Grau-Martínez et al (2018), and is also in agreement with the study of Rodriguez-Escales et al (2016) in which biomass decay acted as an endogenous carbon source for respiration once the input carbon was reduced, maintaining denitrification rates.…”

Coupling Flow, Heat, and Reactive Transport Modeling to Reproduce In Situ Redox Potential Evolution: Application to an Infiltration Pond

“…Iron and sulfate reduction coexistence was associated to the sulfate reduction due to the re-oxidation of Fe(II) 40 . The activation of more reducing processes was clearly related with the SOM concentration increasing during the warm periods of the year, in line with the observations in infiltration ponds elsewhere 48,49 .…”

Managed Aquifer Recharge as a Tool to Enhance Sustainable Groundwater Management in California

“…127,128 One potential strategy to promote denitrification that is currently being investigated is the addition of reactive carbon sources to infiltration basins. 170,171 In coastal areas, there is concern about the effect of sea-level rise associated with climate change on the continued effectiveness of current MAR projects. Many modeling and laboratory studies have attempted to determine how sea-level rise will affect seawater intrusion, although the results of these studies show significant variability, ranging from no effect on seawater intrusion to migration of seawater several kilometers further inland.…”