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Physical and Microbiological Analyses of a Shallow Wastewater Treatment Outfall Effluent Plume in a Lagrangian Frame P. Holden 1, C. Ohlmann 1, L. Washburn.

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Presentation on theme: "Physical and Microbiological Analyses of a Shallow Wastewater Treatment Outfall Effluent Plume in a Lagrangian Frame P. Holden 1, C. Ohlmann 1, L. Washburn."— Presentation transcript:

1 Physical and Microbiological Analyses of a Shallow Wastewater Treatment Outfall Effluent Plume in a Lagrangian Frame P. Holden 1, C. Ohlmann 1, L. Washburn 1, L. Van De Werfhorst 1, B. Sercu 1, C. Wu 2, and G. Anderson 2 1.Institute for Computational Earth System Science, University of California, Santa Barbara, CA 2.Center for Environmental Biology, Lawrence Berkeley National Laboratory, Berkeley, CA Abstract A wastewater treatment plant effluent plume that discharges roughly 500 meters off the Santa Barbara (CA) coast in a water depth near 10 meters rises quickly to the surface even during the most stably- stratified summer conditions. The advection and diffusion of the surface plume are observed with GPS-tracked surface drifters weekly for an entire year. Physical oceanographic profiles and water samples for microbiological and chemical analyses are then sampled following the plume as marked by the surface drifters. Microbiological analyses include culturable fecal indicator bacteria, indicator DNA, and community profiling and analysis using TRFLP and PhlyoChip, respectively. Ammonium, nitrate and phosphorus concentrations are analyzed. Background control stations located 500 and 1000 meters offshore of the diffuser are similarly sampled. Effluent samples are collected prior to discharge. This sampling design is a novel approach that allows for comprehensive quantitative assessment of plume constituents and their fates. The plume signature is evident in salinity during the majority of sampling days, and nutrient data on many days. Salinity and nutrient data above the diffuser are in line with the expected near-field dilution. Increases in salinity and decreases in nutrient following drifter motion, consistent with dillution, are also evident. Community analyses provide high resolution insight into applicable microbiological tracers of the plume. A) SeaWiFSB) AQUA C) MERIS D) MERGED FATE AND TRANSPORT PROJECT GOAL Examine fate, transport and microbial composition of a wastewater treatment plant effluent plume discharged through a short and shallow outfall. RATIONALE Results are applicable to understanding the role of California’s many short shallow outfalls on beach water quality. EXPERIMENTAL DESIGN Collect water samples for microbiological and chemical analyses following plume motion. Figure 2. Study site roughly 1 km off the Santa Barbara, CA coast. Figure 1. Release surface drifters above the effluent diffuser. Perform CTD profiles and collect water samples following drifter motion. CONCLUSIONS Novel experimental design for observing dilution and transport of a large variety of plume tracers. Microbial communities within effluent are highly variable in time Effluent fertilizes the near-shore environment with elevated concentrations of Nitrate+Nitrite and Phosphate. Treated effluent reaches the surf zone along ~3 km span of shoreline directly inshore of the diffuser with a dilution > 250. No apparent relationship exists between bacterial concentrations in the effluent and sampled in ankle-deep water at the shoreline. The highly diverse set of OTUs distinguishable through PhyloChip analysis provide an improved mechanism for identifying effluent. Lachnospiraceae OTUs are consistently found in effluent and in ocean water at the diffuser, but not beyond. Figure 3. Example of decreasing total coliform concentration following fluid motion from the source, presumably due to ocean mixing. Figure 5. - Non-metric Multi-Dimensional Scaling (MDS) plot of all samples grouped by site from the 26 selected sampling events for DNA-based analysis (stress = 0.08). Site numbers are 1 (Offshore1000), 3 (Diffuser), 4 (Lagrangian), 5 Shoreline, and 6 (Effluent). BACTERIAL COMMUNITY COMPOSITION IN EFFLUENT & OCEAN Table 1. Summary statistics overall and by site for enterococci via IDEXX (top), E. coli via IDEXX (middle), and DNA yield (bottom). IDEXX values are expressed as most probable number (MPN). DNA values are expressed as ng/L. SD = standard deviation, SE = standard error, Min = minimum value, Max = maximum value. FECAL INDICATOR BACTERIA AND BIOMASS IN EFFLUENT & OCEAN Effluent samples are themselves variable in time and distinct from ocean samples. Enterococci values much higher at shoreline than in effluent and other ocean sites. E. coli values much higher at shoreline than in effluent and other ocean sites. DNA yield higher in nearshore than in effluent or offshore. PHYLOCHIP OTU DISTRIBUTIONS Table 2. Number of stable OTUs shared between sampling locations. Total number of stable OTUs are indicated between parentheses for each location. Total number of stable OTUs shared between two locations are shown in bold; number of stable OTUs belonging to each family are added between parentheses. Lachnospiraceae is the only OTU family that appears to consistently and uniquely characterize the effluent. Figure 8. Number of signature OTUs detected at some combination of sites (4 panels on left) during each sampling week. Pf cutoff values range from 0.7 to 1. Right panel shows 1Counts of signature OTUs and families/classes containing signature OTUs, present in at least x sampling events at the diffuser. Few OTUs consistently characterize plume waters Figure 9. Distribution of Lachnospiraceae OTUs that are absent in the Offshore (control) sample across all sampling events and locations (pf > 0.9). Figure 6. Plume modeling shows plume waters always reach sea surface within 70 seconds (left) of discharge and within 125 feet of the diffuser (right) Figure 7. Surface (1 meter depth) drifters tag plume waters (left) and can be tracked to give the distribution of along-shore location where tagged waters reach the surf zone. Roughly 50% of drifters reached the surf zone. Drifters sampled for up to ~6 hours. PLUME DILLUTION FOLLOWING ITS MOTION Figure 4. Example of how fresh effluent waters mix with ocean waters giving increased salinity following plume motion. Left panel shows T-S profiles at the locations shown with diamonds in the right panel following drifter motion. This project searches for similar changes in microbiological tracers. Background ocean salinity is ppt. Salinity(diffuser,1 m) = ppt ppt ppt ppt Paper # IT15E-06 1: Offshore 6: Effluent 3: Diffuser 4a: Lagrangian 1 4b: Lagrangian 2 4c: Lagrangian 3 5: Shoreline Acknowledgements Funding for this project has come from the California State Water Resources Control Board through the California Clean Beaches Initiative. This work would not have been possible without the support and cooperation of Heal the Ocean and the Montecito Sanitary District. blue lines are drifter tracks


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