Conifer Needles as Passive Air Samplers for Biomonitoring Emissions from Swine Farms
SAMANTHA LECLERC, Paul George, Florent Rossi, Nathalie Turgeon, Marc Veillette, Caroline Duchaine, Université Laval
Abstract Number: 163
Working Group: Bioaerosols in Agriculture: Sources, Risks and Mitigation
Abstract
Background:
Swine barns continuously emit substantial quantities of bioaerosols into the environment, which can subsequently travel long distances. Active air samplers are still the gold standard for quantifying these emissions; yet they often fail to capture long-term emission patterns and peak emissions. Swine barns are frequently surrounded by conifers hedges known to bioaccumulate bacteria from local sources. This project therefore explores the potential of conifer needles as passive air samplers for quantifying bacterial and viral emissions from swine barns.
Procedure:
Two swine barns were selected, each surrounded by two conifer hedges positioned at distances of 10m and 50m, and 30m and 60m, respectively. Approximately 240m3 of air was actively collected near the hedges and directly at the exhausts, along with 15g of conifer needles from each distance. For comparison, air and needles were collected from two control sites located six kilometers away from any farm or industrial activities. DNA was extracted from samples and the presence of key bioaerosol markers from the barns (total bacteria (16S rRNA gene), pig DNA, Enterococcus, archaea and an Aerococcus viridans phage) was tested by qPCR.
Findings:
The air at the barns exhausts harbors considerable concentrations of the monitored biomarkers that decrease rapidly with distance, reaching comparable values to those of the control sites at the second hedge. Conifer needles partly mirrored the active air sampling: all markers decreased with distance but remained higher when compared to control sites even at the second hedge, potentially highlighting long-term bioaccumulation. Total bacteria remained constant, likely reflecting the needles’ inherent microbiota.
Implications:
Conifer needles effectively bioaccumulate specific markers of swine emissions, demonstrating their potential as an alternative to traditional active samplers for long term biomonitoring of bioaerosol emissions from agricultural facilities. Further research is underway to estimate the consistency of conifer phyllosphere under different types of pollution exposures.