MS Thesis Defense: Justin Hart

The M.S. Thesis Defense of Justin Hart (Environmental Sciences and Engineering program) will be presented at the Institute of Marine Sciences (IMS) in Morehead City, NC and live broadcast to the 4th floor conference room #4204 of Murray/Venable Hall at UNC in Chapel Hill. This event will be held on Wednesday, July 12th, 2017 at 9:00 AM.

Title: Quantifying sources of fecal contamination in a coastal system with complex stormwater dynamics

Abstract: Stormwater runoff is a concern in coastal communities because it delivers harmful fecal contaminants to receiving waters used for recreation. Coastal North Carolina (NC) exhibits complex meteorological and hydrological dynamics that facilitate the delivery of these contaminants to downstream receiving waters via stormwater runoff. To characterize trends in fecal contamination, stormwater receiving water and standing water in Beaufort, NC were sampled between August, 2016 and June, 2017 (n=27) using human- (Fecal Bacteroides, BacHum-UCD, and HF183 TaqMan) and gull-specific (Gull2 TaqMan) microbial source tracking (MST) quantitative markers. All three human-specific MST markers were detected in stormwater receiving water as well as in upstream standing water in concentrations that were on average 3–5 log10 lower than in concentrations quantified in primary wastewater influent. The Gull2 TaqMan marker was ephemeral in samples and gull feces were determined not to be an important source of fecal contamination. Rather, the relationships between MST marker concentrations and antecedent rainfall evidenced fresh sewage contamination of stormwater was a substantial source of fecal contaminants. Short-term rainfall was predictive of E. coli, Enterococcus spp., and human-specific MST marker concentrations in receiving water, and strong correlation between 12-hr cumulative antecedent rainfall and Enterococcus spp. (r = 0.570, p < 0.001, n=92) suggests a robust predictive model could be developed to anticipate water quality impairment. These data will be used to inform the ongoing development of stormwater mitigation in Beaufort and serve as a conceptual model for the interaction between complex stormwater dynamics and water quality impairment in coastal NC.