Chemical and biological tracers to identify source and transport pathways of septic system contamination to streams in areas with low permeability soils.

Septic systems are widely used in rural areas that lack centralized sewage treatment systems. Incomplete removal of domestic wastewater contaminants in septic systems can lead to leaching of nutrients (P and N), bacteria/viruses, and trace contaminants to surrounding groundwater and surface water. This study focuses on delineating the fate of wastewater contaminants in localities where septic systems are installed in moderate to fine-grained overburden materials to assess potential impacts on groundwater and surface water quality in these settings. Nutrients and a suite of anthropogenic tracers, including host-specific fecal indicator bacteria (bovine- and human-specific Bacteroides), pharmaceutical compounds (caffeine, carbamazepine, gemfibrozil, ibuprofen, naproxen, and sulfamethoxazole), and an artificial sweetener (acesulfame-K), were selected to evaluate differences in transport properties. Surface water samples (n = 103) were collected from streams upstream (US) and downstream (DS) of three rural hamlets up to two times monthly over one year. Results indicate the presence of wastewater indicators in the streams, with DS locations showing significantly elevated concentrations of both chemical and biological anthropogenic tracers. Human-specific Bacteroides, caffeine, and acesulfame-K were consistently observed at elevated concentrations at all DS sites. Nutrients exhibited varied concentrations between US and DS locations at three study sites. The occurrence of human-specific Bacteroides in the surface water samples suggests the presence of preferential flow pathways within the silt/clay overburden. These results demonstrate the advantages of using a combined tracer approach, involving a conservative tracer such as acesulfame-K coupled with the human-specific biological indicator Bacteroides (BacHum), to understand not only impacting sources but also potential transport pathways of septic system contamination to nearby streams. Septic systems may be an underappreciated contaminant source in rural hamlets located in fine-grained overburden materials; although, a distinction of specific nutrient sources (septic systems vs. agriculture) remains challenging.

Early identification of a COVID-19 outbreak detected by wastewater surveillance at a large homeless shelter in Toronto, Ontario.

SETTING: Toronto (Ontario, Canada) is a large urban centre with a significant population of underhoused residents and several dozen shelters for this population with known medical and social vulnerabilities. A sizeable men's homeless shelter piloted a facility-level SARS-CoV-2 wastewater surveillance program. INTERVENTION: Wastewater surveillance was initiated at the shelter in January 2021. One-hour composite wastewater samples were collected twice weekly from a terminal sanitary clean-out pipe. The genetic material of the SARS-CoV-2 virus was extracted from the solid phase of each sample and analyzed using real-time qPCR to estimate the viral level. Wastewater results were reported to facility managers and Toronto Public Health within 4 days. OUTCOMES: There were 169 clients on-site at the time of the investigation. Wastewater surveillance alerted to the presence of COVID-19 activity at the site, prior to clinical detection. This notification acted as an early warning signal, which allowed for timely symptom screening and case finding for shelter managers and the local health unit, in preparation for the declaration of an outbreak. IMPLICATIONS: Wastewater surveillance acted as an advanced notification leading to the timely deployment of enhanced testing prior to clinical presentation in a population with known vulnerabilities. Wastewater surveillance at the facility level is beneficial, particularly in high-risk congregate living settings such as shelters that house transient populations where clinical testing and vaccination can be challenging. Open communication, established individual facility response plans, and a balanced threshold for action are essential to an effective wastewater surveillance program.

RéSUMé: LIEU: Toronto (Ontario, Canada) est un grand centre urbain qui compte une importante population de résidents mal logés et plusieurs douzaines de refuges pour cette population aux vulnérabilités médicales et sociales connues. Un assez gros refuge pour hommes sans-abri a mis à l'essai dans ses installations un programme de surveillance des eaux usées pour le SRAS-CoV-2. INTERVENTION: La surveillance des eaux usées du refuge a commencé en janvier 2021. Des échantillons composites d'une heure ont été prélevés deux fois par semaine à partir d'un regard de nettoyage à l'extrémité du drain sanitaire. Le matériel génétique du virus du SRAS-CoV-2 a été extrait du support solide de chaque échantillon et analysé par PCR quantitative en temps réel pour estimer le niveau du virus. Les résultats des eaux usées ont été déclarés aux gestionnaires du refuge et à Santé publique Toronto dans un délai de quatre jours. RéSULTATS: Il y avait 169 usagers sur place au moment de l'enquête. La surveillance des eaux usées a averti de la présence d'une activité de la COVID-19 sur les lieux avant sa détection clinique. Cet avertissement a servi de signal d'alerte précoce, ce qui a permis aux gestionnaires du refuge et au bureau de santé local de procéder au dépistage rapide des symptômes et à la recherche des cas en préparation pour la déclaration d'une éclosion. CONSéQUENCES: La surveillance des eaux usées a servi de notification préalable et entraîné le déploiement opportun d'un dépistage complémentaire avant la manifestation clinique dans une population qui présente des vulnérabilités connues. La surveillance des eaux usées d'une installation est avantageuse, surtout dans des milieux d'hébergement collectif à risque élevé comme les refuges qui hébergent des populations de passage, où le dépistage clinique et la vaccination peuvent être difficiles. Une communication ouverte, des plans d'intervention établis pour chaque installation et un seuil d'intervention équilibré sont essentiels à l'efficacité d'un programme de surveillance des eaux usées.

Microbial water quality at contrasting recreational areas in a mixed-use watershed in eastern Canada.

Recreational water use is an important source of human enteric illness. Enhanced (episodic) surveillance of natural recreational waters as a supplement to beach monitoring can enrich our understanding of human health risks. From 2011 to 2013, water sampling was undertaken at recreational sites on a watershed in eastern Canada. This study compared the prevalence and associations of human enteric pathogens and fecal indicator organisms. Beach water samples had lower pathogen presence than those along the main river, due to different pollution sources and the hydrological disposition. Pathogen profiles identified from the beach sites suggested a more narrow range of sources, including birds, indicating that wild bird management could help reduce public health risks at these sites. The presence and concentration of indicator organisms did not differ significantly between beaches and the river. However, higher concentrations of generic Escherichia coli were observed when Salmonella and Cryptosporidium were present at beach sites, when Salmonella was present at the river recreational site, and when verotoxigenic E. coli were present among all sites sampled. In this watershed, generic E. coli concentrations were good indicators of potential contamination, pathogen load, and elevated human health risk, supporting their use for routine monitoring where enhanced pathogen testing is not possible.

Antimicrobial resistance of Salmonella and generic Escherichia coli isolated from surface water samples used for recreation and a source of drinking water in southwestern Ontario, Canada.

Antimicrobial resistance (AMR) in the aquatic environment represents an important means of introduction and dissemination of resistance genes, and presence of resistant pathogens in surface waters may pose a public health concern to recreational and drinking water users. The purpose of this study was to explore antimicrobial resistance patterns in water samples collected from the Grand River watershed (southwestern Ontario, Canada) to describe the composition, trends and potential risks of AMR in the aquatic environment. As part of FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), stream water samples were collected bi-weekly from sampling sites within the Grand River watershed in the Waterloo, Ontario sentinel site and tested for the presence and antimicrobial susceptibility of Salmonella spp. (2005-2013) and generic Escherichia coli (2012-2013). Of all samples tested, 16% of Salmonella and 22% of E. coli isolates were resistant to at least one antimicrobial, including three Salmonella isolates and two E. coli isolates that were resistant to Category I antimicrobials, which are classified as very high importance for the treatment of serious bacterial infections in humans. The greatest proportion of resistant E. coli isolates were observed from the river site upstream of the drinking water intake, while the greatest proportion of resistant Salmonella isolates were from sites upstream in the watershed, and at one recreational water site. Salmonella resistance trends remained fairly stable between 2007 and 2013, with the exception of streptomycin and tetracycline which increased in 2010 and 2013. Continued surveillance of antimicrobial resistance patterns and exploration of risk factor data will allow for a better understanding of resistance transmission in the aquatic environment.

Aquatic Bacterial Communities Associated With Land Use and Environmental Factors in Agricultural Landscapes Using a Metabarcoding Approach.

This study applied a 16S rRNA gene metabarcoding approach to characterize bacterial community compositional and functional attributes for surface water samples collected within, primarily, agriculturally dominated watersheds in Ontario and Québec, Canada. Compositional heterogeneity was best explained by stream order, season, and watercourse discharge. Generally, community diversity was higher at agriculturally dominated lower order streams, compared to larger stream order systems such as small to large rivers. However, during times of lower relative water flow and cumulative 2-day rainfall, modestly higher relative diversity was found in the larger watercourses. Bacterial community assemblages were more sensitive to environmental/land use changes in the smaller watercourses, relative to small-to-large river systems, where the proximity of the sampled water column to bacteria reservoirs in the sediments and adjacent terrestrial environment was greater. Stream discharge was the environmental variable most significantly correlated (all positive) with bacterial functional groups, such as C/N cycling and plant pathogens. Comparison of the community structural similarity via network analyses helped to discriminate sources of bacteria in freshwater derived from, for example, wastewater treatment plant effluent and intensity and type of agricultural land uses (e.g., intensive swine production vs. dairy dominated cash/livestock cropping systems). When using metabarcoding approaches, bacterial community composition and coexisting pattern rather than individual taxonomic lineages, were better indicators of environmental/land use conditions (e.g., upstream land use) and bacterial sources in watershed settings. Overall, monitoring changes and differences in aquatic microbial communities at regional and local watershed scales has promise for enhancing environmental footprinting and for better understanding nutrient cycling and ecological function of aquatic systems impacted by a multitude of stressors and land uses.

Representing a large region with few sites: The Quality Index approach for field studies.

Many environmental studies require the characterization of a large geographical region using a range of representative sites amenable to intensive study. A systematic approach to selecting study areas can help ensure that an adequate range of the variables of interest is captured. We present a novel method of selecting study sites representing a larger region, in which the region is divided into subregions, which are characterized with relevant independent variables, and displayed in mathematical variable space. Potential study sites are also displayed this way, and selected to cover the range in variables present in the region. The coverage of sites is assessed with the Quality Index, which compares the range and standard deviation of variables among the sites to that of the larger region, and prioritizes sites that are well-distributed (i.e. not clumped) in variable space. We illustrate the method with a case study examining relationships between agricultural land use, physiography and stream phosphorus (P) export, in which we selected several variables representing agricultural P inputs and landscape susceptibility to P loss. A geographic area of 110,000km2 was represented with 11 study sites with good coverage of four variables representing agricultural P inputs and transport mechanisms taken from commonly-available geospatial datasets. We use a genetic algorithm to select 11 sites with the highest possible QI and compare these, post-hoc, to our sites. This approach reduces subjectivity in site selection, considers practical constraints and easily allows for site reselection if necessary. This site selection approach can easily be adapted to different landscapes and study goals, as we provide an algorithm and computer code to reproduce our approach elsewhere.

Characterization of sources and loadings of fecal pollutants using microbial source tracking assays in urban and rural areas of the Grand River Watershed, Southwestern Ontario.

Sources of fecal water pollution were assessed in the Grand River and two of its tributaries (Ontario, Canada) using total and host-specific (human and bovine) Bacteroidales genetic markers in conjunction with reference information, such as land use and weather. In-stream levels of the markers and culturable Escherichia coli were also monitored during multiple rain events to gain information on fecal loadings to catchment from diffuse sources. Elevated human-specific marker levels were accurately identified in river water impacted by a municipal wastewater treatment plant (WWTP) effluent and at a downstream site in the Grand River. In contrast, the bovine-specific marker showed high levels of cattle fecal pollution in two tributaries, both of which are characterized as intensely farmed areas. The bovine-specific Bacteroidales marker increased with rainfall in the agricultural tributaries, indicating enhanced loading of cattle-derived fecal pollutants to river from non-point sources following rain events. However, rain-triggered fecal loading was not substantiated in urban settings, indicating continuous inputs of human-originated fecal pollutants from point sources, such as WWTP effluent. This study demonstrated that the Bacteroidales source tracking assays, in combination with land use information and hydrological data, may provide additional insight into the spatial and temporal distribution of source-specific fecal contamination in streams impacted by varying land uses. Using the approach described in this study may help to characterize impacted water sources and to design targeted land use management plans in other watersheds in the future.