249 Emerging Contaminants: Geochemical Insights and Impacts on Human and Environmental Health

This session addresses advanced detection techniques, ecological impact assessments, and innovative remediation strategies for emerging contaminants focusing on safeguarding geohealth and ensuring sustainable protection of ecosystems and human health.

Wednesday, 22 October 2025
8:00 AM - 12:00 PM
HBGCC, 302A

Microbial Community Dynamics in Biochar and Sand Reactors for Phytoremediation of Perchlorate and Nitrate

Paper number: 249-6
Program: Technical Sessions
Time: 9:30 AM – 9:45 AM

Authors

Abstract

Perchlorate contamination in groundwater poses a persistent remediation challenge due to its chemical stability and co-occurrence with nitrate, a competitive electron acceptor that hinders microbial reduction. Therefore, resulting in increased plant uptake and phytoaccumulation of perchlorate in leaf tissue. This study characterizes baseline microbial communities in bioreactors configured with sand only, biochar only, and a 1:1 biochar-sand mix, both planted (Salix spp.) and unplanted, designed for perchlorate and nitrate phytoremediation.

16S rRNA gene amplicon sequencing was performed, and diversity analyses were conducted in QIIME2 to understand microbial communities in different bioreactors. Taxonomic profiling showed dominance of Proteobacteria, Acidobacteria, and Actinobacteria in all reactors, and planted systems exhibited enrichment in rhizosphere-associated taxa such as Burkholderiaceae and Comamonadaceae. Biochar–sand reactors consistently supported the most diverse and stable microbial communities. Sand-only reactors showed moderate diversity with mixed taxa, and biochar-only systems were often dominated by fewer groups. Alpha diversity metrics, including Shannon index, Faith’s phylogenetic diversity, evenness, and observed features, indicated greater microbial richness in planted and biochar-amended systems. However, Kruskal-Wallis tests revealed no statistically significant differences across groups (p > 0.05). In contrast, unweighted UniFrac-based beta diversity analysis combined with PERMANOVA identified a significant shift in microbial community composition between planted and unplanted reactors (p = 0.002, q = 0.002), highlighting tree presence as a major driver of microbial differentiation.

By capturing early microbial dynamics, this baseline assessment informs the design of optimized phytoremediation systems for co-contaminants such as nitrate and perchlorate. These microbial community dynamics will be further analyzed to assess their roles in biostimulation and rhizodegradation of co-occurring nitrate and perchlorate during phytoremediation.

 

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413781

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