InterPore2026

Microbiological and pore-structure characterization of an urban aquifer contaminated by sewage leakages

20 May 2026, 15:35

1h 30m

Poster Presentation (MS02) Environmental Porous Media: Water, Agriculture, and Remediation Poster

Speaker

Dr Daphne Silva Pino (University of Sao Paulo (USP))

Description

Nitrate is the most common inorganic contaminant in aquifers worldwide and is almost ubiquitous in urban unconfined aquifers in the state of São Paulo (Brazil). It poses a significant challenge for a state in which more than 80% of municipalities rely on groundwater. However, the control mechanisms governing nitrogen species in groundwater remain incompletely understood. Recent studies have shown that nitrification and denitrification reactions can occur within distances of a few centimeters due to permeability heterogeneity that creates microcosms (Varnier et al., 2017). Thus, in this work, we sought to identify the hydrobiogeochemical characteristics that control nitrogen reactions at the pore scale. The study is being conducted in the urban area of Bauru, where several hydrogeological studies have been conducted over the last two decades (Hirata 2000; Giafferis and Oliveira 2006; Silva 2009; Procel 2011; IG 2012; Varnier et al. 2010, 2012; DAEE 2015; Hirata et al. 2020). The study area encompasses a region that chronically experiences water insecurity and nitrate contamination from sewage leaks, thereby constituting an exceptional field laboratory. This is an essential and unprecedented opportunity to implement high-resolution methods for aquifer investigation, enabled by synchrotron technology. The characterization of the aquifer matrix was performed using visual field analysis, SPT tests, petrographic thin sections, X-ray diffraction, and X-ray microtomography at a synchrotron light source. These results will be correlated with microbiological (through 16S rRNA gene sequencing) and hydrogeochemical analyses of soil and groundwater. This will enable correlations among the vertical distribution of porous structure across different hydrogeological units, their capacity to form more or less isolated zones (microcosms), the occurrence of nitrogenous species in soil and groundwater, and the presence of nitrifying/denitrifying bacteria. This study is expected to provide information on hydrobiogeochemical nitrogen-cycle processes and to improve procedures for hydrogeological studies at synchrotron facilities.