Assessing Passive Sampling for the Monitoring of E. coli and Cryptosporidium spp. in Environmental Waters.

Passive sampling has shown promise as an alternative approach for monitoring of pathogens in aquatic matrices. We conducted two controlled experiments to compare the efficacy of membrane passive sampling to composite sampling in both wastewater and surface water for the detection of Escherichia coli and Cryptosporidium. We also investigated the relative uptake of E. coli and Cryptosporidium onto membrane passive samplers over time. Both sampling methods returned positive detections of E. coli at all deployment times (4, 8, 24, 48, 72, and 96 h) in both water matrices. Passive sampling for Cryptosporidium showed similar detection rates as composite samples in surface water (31% passive; 41% composite) and wastewater (76% passive; 86% composite). We found significant linear uptake of E. coli onto passive samplers up to 96 h in surface water (R ² = 0.932; p = 0.002). In wastewater, maximum passive sampler uptake of E. coli was reached after 24 h. For Cryptosporidium, linear uptake was observed up to 96 h for both surface water (R ² = 0.805; p = 0.015) and wastewater (R ² = 0.877; p = 0.006). Our results support that membrane passive samplers may be used for the detection of Cryptosporidium and E. coli in surface waters for up to 96 h.