Microbial Screening of Urban Stormwater and Constructed Wetlands Using Passive Sampling and TaqMan Array Cards

This study evaluates the use of passive samplers containing passive materials and qPCR array cards to understand the microbial quality of stormwater and constructed wetlands. Passive samplers were deployed at the inlet and outlet of a stormwater-constructed wetland alongside paired water sample collection, all of which indicated high fecal contamination and human wastewater inputs. Passive materials demonstrated good performance for frequently detected enteric bacteria (e.g., Campylobacter spp.) and surrogate viruses (e.g., CrAssphage), but showed mixed performance for protozoa (e.g., Cryptosporidium spp.). Logistic regression indicated a significant interactive effect between material and location (p < 0.01), but further analysis indicated that location was likely a proxy for turbidity, significantly different between the inlet and outlet (p < 0.01). Some passive materials performed better at the inlet, which had a median turbidity of 20.6 NTU (e.g., cotton-based materials for Campylobacter spp.), while others were better at the outlet, with a median turbidity of 90.15 NTU (e.g., electronegative membrane for Campylobacter spp. and crAssphage, swab for crAssphage, and gauze for Cryptosporidium spp.). Passive sampling is a promising approach for continuously sampling urban stormwater to monitor and manage pathogen risks. Further research should compare composite samples and passive materials to evaluate target attachments during rainfall events.