Author: Ryan  Newton,   (University of Wisconsin-Milwaukee)

Designation: 

Description:
Urban waterways are often impaired by multiple pollutant types, such as sediment, nutrients, and fecal bacteria/viruses, which may or may not originate from the same sources. Determining the sources of these pollutants in complex mixed-use watersheds is important for efficient mitigation efforts but is challenged by the rapidly changing nature of urban rivers, especially during storm events. In this study, we used high-frequency time-series sampling to evaluate the sources and linkages between sediment and microbial pollution in the Milwaukee River watershed in Milwaukee, Wisconsin, USA. Samples were processed to measure concentrations of standard fecal indicator bacteria, total suspended solids (TSS), microbial source tracking genetic markers, and microbial community composition in 13 separate events across two years. We determined that general fecal bacterial indicators, TSS, and human fecal marker concentrations consistently peak at different points in a storm hydrograph in the river, suggesting that these regulated pollutants originate from distinct upstream sources. River microbial communities exhibited rapid composition shifts (<4 hours) during storm events according to different source water influxes and sediment resuspension. Isotope and microbial source data indicated the majority of TSS loading originated in non-urban river regions while fecal pollution was mainly due to urban discharge. Overall, high-frequency sampling provided the temporal resolution needed to determine pollutant sources and their timing in this urban river, a crucial step in developing actionable mitigation plans for this impaired waterway.

Category: Scientific Program Abstract > Special Sessions > SS59 The power of time series for unraveling aquatic microbial community interactions and functions