Recreational Water Research Articles

Spatio-Temporal Variation in the Exceedance of Enterococci in Lake Burley Griffin: An Analysis of 16 Years' Recreational Water Quality Monitoring Data.

Recreational waterbodies with high levels of faecal indicator bacteria (FIB) pose health risks and are an ongoing challenge for urban-lake managers. Lake Burley Griffin (LBG) in the Australian Capital city of Canberra is a popular site for water-based recreation, but analyses of seasonal and long-term patterns in enterococci that exceed alert levels (>200 CFU per 100 mL, leading to site closures) are lacking. This study analysed enterococci concentrations from seven recreational sites from 2001-2021 to examine spatial and temporal patterns in exceedances during the swimming season (October-April), when exposure is highest. The enterococci concentrations varied significantly across sites and in the summer months. The frequency of the exceedances was higher in the 2009-2015 period than in the 2001-2005 and 2015-2021 periods. The odds of alert-level concentrations were greater in November, December, and February compared to October. The odds of exceedance were higher at the Weston Park East site (swimming beach) and lower at the Ferry Terminal and Weston Park West site compared to the East Basin site. This preliminary examination highlights the need for site-specific assessments of environmental and management-related factors that may impact the public health risks of using the lake, such as inflows, turbidity, and climatic conditions. The insights from this study confirm the need for targeted monitoring efforts during high-risk months and at specific sites. The study also advocates for implementing measures to minimise faecal pollution at its sources.

Leaching characteristics of metals from recycled concrete aggregates (RCA) and reclaimed asphalt pavements (RAP)

Recycled concrete aggregates (RCA) and reclaimed asphalt pavements (RAP) are two construction waste products that are commonly used in the road construction industry. Besides many advantages, pollutants leaching from RCA and RAP are highlighted as the most concerning environmental issue. This study investigated metals leaching characteristics from RCA and RAP due to the variations in key influential factors of pH, dissolved organic carbon (DOC), compaction and liquid to solid ratio (L/S). The leaching tests for RCA and RAP were carried out separately and additionally, the standard leaching test was conducted as the benchmark for leaching investigations. Study outcomes revealed that the combined influences of factors are variable for RCA and RAP, while influences are also variable for individual metals. L/S ratios considerably affect the release of metals from RCA under saturated conditions, facilitating high metal concentrations in the leachate. On the other hand, acidic solutions are more favourable for leaching of metals from RAP. The influence of DOC in solution was minimal on the metal leachability. Interestingly, the increased degree of compaction with a higher density of materials presented the highest negative influence on metal leachability, suggesting that the metal leachability can significantly reduce, in particular when the RCA and RAP are used for the sub-base layers of road structure with a higher degree of compaction. However, the use of these recycled materials under field conditions should be further studied as there is an increasing concern of metal leaching from RCA and RAP with respect to recreational and drinking water thresholds.

Integrated treatment of stormwater using multistage filtration (MSF) for domestic application (reuse)

Stormwater harvesting is a promising solution for global freshwater depletion, particularly in tropical regions with abundant rainfall. However, it is not widely used due to the lack of suitable treatment technologies for domestic applications. Multi-stage filtration (MSF) is an effective integrated treatment technology that provides a cost-effective alternative for stormwater treatment. This study investigated MSF's capacity for treating stormwater at different stages. The MSF designed and built comprised the down-flow roughing filter (DRF) and slow sand filter (SSF). The results achieved by the MSF for the treated effluents were: pH (7.1–8.1), temperature (27.6–29.4°C), electrical conductivity (EC) (100–190 µS/cm) and total dissolved solids (TDS) (70–130 mg/L). Turbidity removal efficiency of the MSF was in the range of 36–99% (5.825–164.05 NTU) and the overall average removal efficiency of the MSF was 74%, 90% and 86% for total coliforms (TC) (360–11 800 CFU/100 mL), faecal coliforms (FC) (0–1 300 CFU/100 mL) and Enterococcus spp. (120– 1 400 CFU/100 mL), respectively. The study identified stormwater reuse potentials based on international guidelines and benchmarks. For the treated effluent, pH, temperature, EC and TDS were all within the permissible limits for toilet, laundry, bathing, recreational and agricultural water reuse, while turbidity suited agricultural (non-food crop) and restricted urban reuse. 46% of the effluent was suitable for recreational purposes as this satisfied the 50 NTU standard. 62.5% of the effluent satisfied the FC standard for toilets and urinals and agricultural reuse (non-food crop) purposes, while 87.5 % of the effluent satisfied urban reuse purposes (restricted access). 66.67% of the effluent satisfied the Enterococcus spp. standard for agricultural reuse (non-food crop). All treated effluents satisfied the TC bathing standard. This study shows that after minimal disinfection, stormwater effluents offer potential reuse in household applications, thereby reducing potable water demand.

Utilizing novel Escherichia coli-specific conserved signature proteins for enhanced monitoring of recreational water quality.

Escherichia coli serves as a proxy indicator of fecal contamination in aquatic ecosystems. However, its identification using traditional culturing methods can take up to 24h. The application of DNA markers, such as conserved signature proteins (CSPs) genes (unique to all species/strains of a specific taxon), can form the foundation for novel polymerase chain reaction (PCR) tests that unambiguously identify and detect targeted bacterial taxa of interest. This paper reports the identification of three new highly-conserved CSPs (genes), namely YahL, YdjO, and YjfZ, which are exclusive to E. coli/Shigella. Using PCR primers based on highly conserved regions within these CSPs, we have developedquantitative PCR (qPCR) assays for the evaluation of E. coli/Shigella species in water ecosystems. Both in-silico and experimental PCR testing confirmed the absence of sequence match when tested against other bacteria, thereby confirming 100% specificity of the tested CSPs for E. coli/Shigella. The qPCR assays for each of the three CSPs provided reliable quantification for all tested enterohaemorrhagic and environmental E. coli strains, a requirement for water testing. For recreational water samples, CSP-based quantification showed a high correlation (r > 7, p < 0.01) with conventional viable E. coli enumeration. This indicates that novel CSP-based qPCR assays for E. coli can serve as robust tools for monitoring water ecosystems and other critical areas, including food monitoring.

Integrating quantitative microbiological risk assessment and disability-adjusted life years to evaluate the effects of urbanization on health risks for river recreationists

Urban rivers provide an excellent opportunity for water recreation. This study probabilistically assessed health risks associated with water recreation in urban rivers in the Bitan Scenic Area, Taiwan, by employing quantitative microbial risk assessment and disability-adjusted life years (DALYs). Moreover, the effects of urbanization on the health risks of river recreation induced by waterborne pathogenic Escherichia coli (E. coli) were investigated. First, data on river E. coli levels were collected in both the Bitan Scenic Area and the upstream river section, and model parameters were obtained through a questionnaire administered to river recreationists. Monte Carlo simulation was then employed to address parameter uncertainty. Finally, DALYs were calculated to quantify the cumulative effects in terms of potential life lost and years lived with disability. The results indicated that the 90 % confidence intervals for the disease burden (DB) were 0.2–74.1 × 10−6, 0.01–94.0 × 10−6, and 0.3–128.9 × 10−6 DALY per person per year (pppy) for canoeing, swimming, and fishing, respectively, in the Bitan Scenic Area. Furthermore, urbanization near the Bitan Scenic Area approximately doubled the DB risks to river recreationists in upstream rural areas. At the 95th percentile, the DB risks exceeded the tolerances recommended by the World Health Organization (1 × 10−6) or U.S. Environmental Protection Agency (1 × 10−4). The findings suggest that the simultaneous implementation of effluent sewer systems and best management practices can reduce health risks to river recreationists by at least half, reducing the DALY levels below 1 × 10−4 or even 1 × 10−5 pppy.

Using a long‐range autonomous underwater vehicle to find and sample harmful algal blooms in Lake Erie

AbstractCyanobacterial harmful algal blooms (CyanoHABs) in the Great Lakes pose risks to residential drinking water use, fisheries, and recreation. Active mitigation of these risks requires rapid detection of CyanoHABs and quantification of the toxins they produce. Here, we present a method of using a long‐range autonomous underwater vehicle (LRAUV) equipped with a 3rd‐generation Environmental Sample Processor (3G‐ESP) to search for and adaptively sample areas of high chlorophyll potentially representative of CyanoHAB biomass. In August 2021, this method was used in western Lake Erie. The experiment highlighted the effectiveness of the LRAUV autonomous search‐and‐sample methodology, and demonstrated how an interdisciplinary team located in different states virtually coordinated LRAUV operations and directed sampling activities via Internet connectivity using shared, web‐based situational awareness tools. The advancements made provide a foundation for future work to increase LRAUV autonomy and adaptiveness for CyanoHAB studies and monitoring in both freshwater and marine settings.

Quantitative microbial risk assessment of gastrointestinal illness due to recreational exposure to E. coli and enterococci on the southern coasts of the Caspian Sea

BackgroundGastrointestinal illness refers to a broad range of diseases that affect the digestive system, including infections caused by bacteria, viruses, and parasites. Quantitative Microbial Risk Assessment (QMRA) is a powerful tool used to evaluate the risks associated with microbial pathogens in various environments. The main objective of this study was to conduct a quantitative assessment of gastrointestinal illnesses that occur as a result of exposure to E. coli and enterococci during recreational activities on the southern coasts of the Caspian Sea. MethodsSamples were collected from the recreational beaches along the border line of the Caspian Sea. The samples were analyzed for the presence and enumeration of E. coli and enterococci using the microplate method and membrane filtration techniques. Then, the annual and daily infection risks were computed using the Monte Carlo simulation approach. ResultsThe results revealed that the risk of daily and annual infections on the coasts of Babolsar was higher than that on the coasts of Sari. Also, in the recreational waters of these beaches, the risk of infection by enterococci was higher than that posed by E. coli. In Babolsar, the average annual infection risk caused by E. coli and enterococci was 0.365 and 1 for children and 0.181 and 0.986 for adults. Also, in Sari, the average annual infection risk caused by E. coli and enterococci was 0.060 and 0.908 for children and 0.027 and 0.815 for adults. In addition, children were more likely than adults to become infected. ConclusionIn light of the study's findings, due to the entry of untreated urban wastewater into the southern part of the Caspian Sea (northern Iran) and the high risk of infectious diseases for children, more control and health measures are necessary for children's swimming.

Site-specific risk-based threshold (RBT) concentrations for sewage-associated markers in estuarine swimming waters

This study establishes site-specific risk-based threshold (RBT) concentrations for sewage-associated markers, including Bacteroides HF183 (HF183), Lachnospiraceae Lachno3 (Lachno3), cross-assembly phage (CrAssphage), and pepper mild mottle virus (PMMoV), utilizing quantitative microbial risk assessment (QMRA) for recreational estuarine waters (EW). The QMRA model calculates a RBT concentration corresponding to a selected target illness risk for ingestion of EW contaminated with untreated sewage. RBT concentrations were estimated considering site-specific decay rates and concentrations of markers and reference pathogen (human norovirus; HNoV), aiding in the identification of high-risk days during the swimming season. Results indicated varying RBT concentrations for fresh (Day 0) and aged (Days 1 to 10) sewage contamination scenarios over 10 days. HF183 exhibited the highest RBT concentration (26,600 gene copis (GC)/100 mL) initially but decreased rapidly with aging (2570 to 3120 GC/100 mL on Day 10) depending on the decay rates, while Lachno3 and CrAssphage remained relatively stable. PMMoV, despite lower initial RBT (3920 GC/100 mL), exhibited increased RBT (4700 to 6440 GC/100 mL) with aging due to its slower decay rate compared to HNoV. Sensitivity analysis revealed HNoV concentrations as the most influential parameter. Comparison of marker concentrations in estuarine locations with RBT concentrations showed instances of marker exceedance, suggesting days of potential higher risks. The observed discrepancies between bacterial and viral marker concentrations in EW highlight the need for optimized sample concentration method and simultaneous measurement of multiple markers for enhanced risk predictions. Future research will explore the utility of multiple markers in risk management. Overall, this study contributes to better understanding human health risks in recreational waters, aiding regulators, and water quality managers in effective decision-making for risk prioritization and mitigation strategies.

Real-time water quality forecasting in rivers using satellite data and dynamic models: an online system for operational management, control and citizen science

Increasingly scarce water resources and growing global populations have exacerbated the problems of water quality in river systems and freshwaters in general. New monitoring methodologies and tools to democratize access to water quality information are needed if we are to reach ambitious societal objectives such as the UN Sustainable Development Goals and the European Green Deal. Here we present a cloud-based system for producing publicly accessible real time water quality forecasts coupled to novel biosensor technology. Short term forecasts of water quality impairments, e.g., as cyanobacteria blooms, sediment plumes and toxic pollution incidents are increasingly relevant both to citizens and stakeholders. Here, we present a new cloud based system that utilizes satellite data to produce real time forecasts of flow and water quality using a chain of dynamic catchment-scale models at multiple locations in a river network. We demonstrate this new system using two case studies: the River Thames and the Essex Colne River (United Kingdom). These rivers are key water supply sources for London and South-East England, respectively and are of high interest to recreational water users. We show how the new system can predict and forecast water quality, estimate toxicity and connect to citizen science observations using an App (www.aquascope.com) for information synthesis and delivery.

Wastewater Effluent from Outfalls in Kuwait Bay: A Threat to Recreational Water Quality

The implications of wastewater discharge into marine ecosystems are gravely concerning due to their ability to trigger a chain reaction of contaminants that pose severe risks to both humans and aquatic life. Kuwait Bay is no exception, with numerous wastewater outfalls posing a threat to the marine environment on its southern coasts. This study sought to extensively evaluate the recreational water quality adjacent to wastewater outfalls at five specified sites and compare the results according to the KEPA's (Kuwait's Environmental Public Authority) guidelines. Field measurements and laboratory analyses were conducted to gauge various parameters associated with water quality, such as nutrients, heavy metals, fecal bacterial indicators (FBI), and pharmaceutical compounds. The results of field measurements indicated that two locations had insufficient DO levels with values &lt; 4 mg/l below KEPA standards and brackish to saline water concerning Electrical conductivity (EC) measurements. However, the heavy metal results demonstrated mercury (Hg) pollution at all locations, whereas the nutrient data revealed significant PO4-P concentrations. Furthermore, EPA requirements were considerably exceeded for bacterial indicator counts (fecal coliforms, E. coli, and fecal streptococci), suggesting serious biological pollution at these locations and elevated concentrations of paracetamol and ranitidine have been detected in pharmaceutical compound analysis, particularly in location OC5. The study's findings emphasized the significance of periodic surveillance to ensure the ongoing improvement of water quality and public health in Kuwait's coastal zones and highlighted the dire need to address the extensive contamination by implementing measures to mitigate the dump of unprocessed wastewater into the sea.

Recreational Water Quality Status of Charty Beach, Jaffna, Sri Lanka

Recreational water quality assessment is an important step to overcoming safety issues for the users and the conservation of the habitat. The present study was conducted for five months from December 2020 to April 2021 to identify the ongoing issues related to the recreational water quality in Charty Beach, Jaffna, Sri Lanka. The water temperature (29.24 ℃), pH (8.18), turbidity (8 NTU), and DO (6.71 mg L-1) were all under the marine recreational standards' threshold limits. The total coliform (4.85 MPN 100 mL-1) and E. coli count (2.64 MPN 100 mL-1) were both confirmed to be within the international recreational water quality standards. However, measured nitrate (2.66 mg L-1) and phosphate (0.15 mg L-1) levels in the water were found to exceed the threshold limits for marine recreational waters, indicating that the beach has been contaminated with nitrate and phosphate-containing sewage overflow. The higher microbiological indicator values and nitrate content were obtained during the study period in December, which is the year’s rainy season. Surface runoff containing feces, and agricultural waste due to rain may be the cause of the highest values. Based on the overall results of the beach water, it can be deemed that Charty Beach is suitable for bathing and recreational activities.

Environmental factors associated with Escherichia coli concentration at freshwater beaches on Lake Winnipeg, Manitoba, Canada

At many public beaches, routine monitoring of beach water quality using fecal indicator bacteria is conducted to evaluate the risk of recreational water illness. Results from water sample analysis can take over 24-hr, which may no longer accurately reflect current water quality conditions. This study aimed to assess which combination of environmental factors best predicts fecal contamination (E. coli) levels at two of the most popular beaches on Lake Winnipeg, Manitoba (Gimli and Grand Beach), by linking water quality data and publicly available environmental data from 2007 to 2021. We developed separate mixed effects models for each beach for two outcomes, linear (continuous log-transformed E. coli concentration) and categorical (200 CFU/100 ml threshold), to explore differences in the predictors of E. coli concentrations and exceedances of the provincial health risk threshold, respectively. We used a Directed Acyclic Graph to choose which predictor variables to include in the models. For both beaches, we identified clustering of the E. coli outcomes by year, suggesting year-specific variation. We also determined that extreme weather days, with higher levels of rainfall in the preceding 48-hr, previous day average air temperature, and previous day E. coli concentration could result in a higher probability of E. coli threshold exceedances or higher concentrations in the water bodies. In Grand Beach, we identified that days with lower average UV levels in the previous 24-hr and antecedent dry days could result in a higher probability of E. coli threshold exceedances or higher concentrations. The findings can inform possible trends in other freshwater settings and be used to help develop real-time recreational water quality predictive models to allow more accurate beach management decisions and warrant enhancement of beach monitoring programs for extreme weather events as part of the climate change preparedness efforts.

Comparison of methods proposed for monitoring cefotaxime-resistant Escherichia coli in the water environment.

Escherichia coli is a promising subject for globally coordinated surveillance of antimicrobial resistance (AMR) in water environments due to its clinical relevance and widespread use as an indicator of fecal contamination. Cefotaxime-resistant E. coli was recently evaluated favorably for this purpose by the World Health Organization TriCycle Protocol, which specifies tryptone bile x-glucuronide (TBX) medium and incubation at 35°C. We assessed comparability with the U.S. Environmental Protection Agency-approved method for E. coli quantification, which uses membrane-thermotolerant E. coli (mTEC) agar and incubation at 44.5°C, in terms of recovery of E. coli and cefotaxime-resistant E. coli from wastewater influent and surface waters. Total E. coli concentrations in wastewater influent were 106-108 CFU/100 mL, while cefotaxime-resistant E. coli were ~100-fold lower. Total E. coli in surface waters were ~102 CFU/100 mL, and cefotaxime-resistant isolates were near the limit of detection (0.4 CFU/100 mL). Total and putative cefotaxime-resistant E. coli concentrations did not differ significantly between media or by incubation method; however, colonies isolated on mTEC were more frequently confirmed to species (97.1%) compared to those from TBX (92.5%). Incubation in a water bath at 44.5°C significantly decreased non-specific background growth and improved confirmation frequency on both media (97.4%) compared to incubation at 35°C (92.3%). This study helps to advance globally coordinated AMR in water environments and suggests that the TriCycle Protocol is adaptable to other standard methods that may be required in different locales, while also offering a means to improve specificity by decreasing the frequency of false-positive identification of cefotaxime-resistant E. coli by modifying incubation conditions.IMPORTANCEAs antibiotic-resistant bacteria in water environments are increasingly recognized as contributors to the global antibiotic resistance crisis, the need for a monitoring subject that captures antibiotic resistance trends on a global scale increases. The World Health Organization TriCycle Protocol proposes the use of cefotaxime-resistant Escherichia coli isolated on tryptone bile x-glucuronide agar. The U.S. Environmental Protection Agency (USEPA) criteria for safe recreational waters also use E. coli as an indicator but specify the use of mTEC agar at a higher incubation temperature (44.5°C vs 35°C). We assessed the comparability of these methods for isolating total and cefotaxime-resistant E. coli, finding overall good agreement and performance, but significantly higher specificity toward E. coli selection with the use of the USEPA incubation protocol and mTEC agar. This study is the first to directly compare these methods and provides evidence that the methods may be used interchangeably for global surveillance of antibiotic resistance in the environment.

Fecal Bacteria Contamination of Floodwaters and a Coastal Waterway From Tidally-Driven Stormwater Network Inundation.

Inundation of coastal stormwater networks by tides is widespread due to sea-level rise (SLR). The water quality risks posed by tidal water rising up through stormwater infrastructure (pipes and catch basins), out onto roadways, and back out to receiving water bodies is poorly understood but may be substantial given that stormwater networks are a known source of fecal contamination. In this study, we (a) documented temporal variation in concentrations of Enterococcus spp. (ENT), the fecal indicator bacteria standard for marine waters, in a coastal waterway over a 2-month period and more intensively during two perigean spring tide periods, (b) measured ENT concentrations in roadway floodwaters during tidal floods, and (c) explained variation in ENT concentrations as a function of tidal inundation, antecedent rainfall, and stormwater infrastructure using a pipe network inundation model and robust linear mixed effect models. We find that ENT concentrations in the receiving waterway vary as a function of tidal stage and antecedent rainfall, but alsosite-specificcharacteristics of the stormwater network that drains to the waterway. Tidal variables significantly explain measured ENT variance in the waterway, however, runoff drove higher ENT concentrations in the receiving waterway. Samples of floodwaters on roadways during both perigean spring tide events were limited, but all samples exceeded the threshold for safe public use of recreational waters. These results indicate that inundation of stormwater networks by tides could pose public health hazards in receiving water bodies and on roadways, which will likely be exacerbated in the future due to continued SLR.

Algae in Recreational Waters: An Overview within a One Health Perspective

Recreational water activities are widely recognized to have a positive impact on our physical and mental well-being. However, recreational water sources and their management are also a risk factor for human health due to different agents, including the overgrowth of cyanobacteria and algae. The presence of cyanobacteria and algae in recreational waters represents a One Health threat because of their potential release and the overuse of biocides. These organisms have the potential to metabolize organic matter and produce thermophilic and thermotolerant toxins. Moreover, different species of algae are involved in biofilm formation processes, thus impacting water quality and safety and also posing risks to the environment and animal and human health. Different species of algae participate in biofilm formation and have an impact on managing water and equipment maintenance. By searching literature databases, e.g., PubMed, we reviewed the state of the art, providing basic definitions, taxonomy, and epidemiological or medical issues related to the recreational uses of water. Methods of treatments and monitoring were summarized, considering both traditional and innovative strategies. Public health and surveillance approaches focus on the detection of toxins, the formation of biofilms, and the understanding of the benthonic and planktonic components as part of the larger microbial biodiversity. The review process allowed us to acknowledge that this is the first comprehensive overview of algae in recreational waters carried out within a wider One Health outlook.

Losses in fishery ecosystem services of the Dnipro river Delta and the Kakhovske reservoir area caused by military actions in Ukraine

We studied the development of commercial and recreational fishing on the Kakhovske Reservoir (aka Kakhovka) and the Dnipro (aka Dnieper) River lowlands in 2020–2023. The fish assemblage of the Kakhovske Reservoir is under consideration for the period 1956–2021. The dynamics of the fish population transformation, species extinction, and the emergence of new invasive species are given. The losses in Kakhovske Reservoir’s ecosystem services as a result of the Kakhovska Hydroelectric Power Plant’s (HPP) Dam explosion in June 2023 are analyzed. The states and prospects for local recreational and commercial fishing development are assessed. By field research and monitoring observations of the Kakhovske Reservoir and the Dnipro River lowland using the Earth remote sensing data, it was established that 2 months after the accident, the area of the remained reservoir water surface was ∼430 km2 (about 19% of the initial, including the restored Dnipro River bed). The newly formed shallow waterbodies, which do not have a water connection between each other, occupy an area of about 300 km2. These areas continue to dry out, shrink, and become overgrown with vegetation. The draining of the Kakhovske Reservoir caused an ecological disaster for about 40 species and subspecies of fish. The total monetary losses of commercial fishing are about $5.5 million annually. Losses in fishery from the vanishing of spawning grounds are estimated at 20,000 tons of fish resources (∼$40 million). The negative consequences of the loss of the Kakhovske Reservoir aquatic ecosystems will affect the socio-economic development of the entire South of Ukraine for a long time. Among the major ecosystem services lost is the cessation of water supply. Ukraine’s priority issues are the post-war rehabilitation of the country, its degraded lands, territories, and water areas, and ensuring water and food security. One of the urgent problems will be the feasibility of reconstruction of the Kakhovska HPP’s Dam and restoration of the Reservoir, renovation of water supply, fishery, navigation, energy, and recreation. Biodiversity is a basis for the efficient and sustainable ecosystem functions that provide many ecosystem services, and it should be considered for the post-war recovery and development of Ukraine.

Monetization of Ecosystem Services from Nature-Based Solutions for Agricultural Diffuse Pollution Control: Simplified Value Transfer Method at European Scale

When nature-based solutions (NBS) are developed with a primary scope, they also provide simultaneous additional economic, social, and environmental benefits, i.e., Ecosystem Services. A monetary assessment that accounts for these additional benefits is provided by this work, with a focus on Europe. Specifically, this is intended to evaluate nine identified benefits of those wetlands and buffer strips designed to primarily address agricultural diffuse pollution, which must surely be listed among the negative externalities of economic activities that NBS can help resolve. The aim of developing a simplified value transfer methodology for a rapid evaluation of NBS benefits with the adjusted unit Value Transfer method is to create an accessible solution when time, funding, or other constraints prevent the use of highly technical primary monetization approaches. The developed exercise allows us to gather insights from several primary valuation studies and to appropriately transfer the monetary valuation outcomes to new policy sites. In order to reduce the distance from the expected and required concrete achievements of the economic valuations, the study has been integrated with an case study located in the Venice lagoon catchment in Northwestern Italy. The results obtained are to be considered sound, with existing evidence showing that the most valuable benefits of the considered NBS are both water quality and recreation and tourism, to which is added, in the case of wetlands, water supply.

Distribution of antibiotic resistant bacteria and genes in sewage and surrounding environment of Tórshavn, Faroe Islands

Several studies have investigated the effects of swimming in sewage-polluted recreational beach water, highlighting the associated health hazards. To mitigate potential pathogen transmission, it is imperative that the polluted water is released away from recreational waters and foreshores, where children tend to play. At present, domestic sewage in the Faroe Islands solely undergoes primary wastewater treatment within primary settling tanks before being discharged into the ocean. Effluents are a major anthropogenic source of antibiotic resistance genes and antibiotic resistant bacteria, which are released into the environment. The aim of this study was to investigate antibiotic resistant Gram-negative bacteria and antibiotic resistance genes in influents and effluents of wastewater subjected solely to primary treatment, along with their release into the environment during both summer and winter. Water samples were collected from influents and effluents as well as with increasing distance away from the wastewater outlet and from nearby tidepools. Samples were cultured on MacConkey agar with four different antibiotics for detection of antibiotic-resistant bacteria and antibiotic resistance genes were quantified by droplet digital PCR. All multi-drug resistant bacteria were identified using the API 20E kit. We observed an overall decrease of the abundance of Gram-negative bacteria from the effluents compared to influents, however, we observed the opposite trend in the antibiotic resistance genes. Antibiotic resistant bacteria and antibiotic resistance genes in addition to multi-drug resistant bacteria were found in the surrounding oceanic and several terrestrial tidepool samples. Of the multi-drug resistant bacteria, we found, e.g., Escherichia coli, P. aeruginosa, and A. hydrophila species, which can be pathogenic, potentially causing an infection if encountering a host. These results indicate a relatively wide pollution range of the effluents from the septic tank and treated sewage released into the environment, posing a potential hazard for both humans and wildlife.

Performance of Chlorella vulgaris in Phycoremediation of Livestock Effluent

Livestock effluent is known to contain significantly higher concentrations of organic matter and challenging-to-degrade organic compounds compared to urban wastewater. This makes the effluent treatment challenging and adversely affects nearby aquatic environments if improperly treated. Phycoremediation uses microalgae in water and wastewater treatment. This research aim was to evaluate pollutant removal efficiencies, including chemical oxygen demand (COD), total suspended solids (TSS), nitrate (NO₃-N), turbidity, and phosphate (P), using microalgae Chlorella vulgaris (C. vulgaris) cultivation systems for livestock effluent treatment. The biomass weight of C. vulgaris in the cultivation systems was also observed. In this study, C. vulgaris was cultivated in closed cultivation systems in 5 L water bottles with different dilutions (100%, 75%, 50%, and 25%). The water effluent was compared to permissible values using the National Water Quality Standard (NWQS) class II for recreational water use. TSS was significantly removed by 61.97%, while COD and P were removed by 39.1% and 36.4%, respectively. The biomass growth was observed through the dry weight of the C.vulgaris. Therefore, the removal of nutrients from cattle farm effluent by phytoremediation using C. vulgaris demonstrates potential for treatment efficacy.

Predicting recreational water quality and public health safety in urban estuaries using Bayesian Networks

To support the reactivation of urban rivers and estuaries for bathing while ensuring public safety, it is critical to have access to real-time information on microbial water quality and associated health risks. Predictive modelling can provide this information, though challenges concerning the optimal size of training data, model transferability, and communication of uncertainty still need attention. Further, urban estuaries undergo distinctive hydrological variations requiring tailored modelling approaches. This study assessed the use of Bayesian Networks (BNs) for the prediction of enterococci exceedances and extrapolation of health risks at planned bathing sites in an urban estuary in Sydney, Australia. The transferability of network structures between sites was assessed. Models were validated using a novel application of the k-fold walk-forward validation procedure and further tested using independent compliance and event-based sampling datasets. Learning curves indicated the model's sensitivity reached a minimum performance threshold of 0.8 once training data included ≥ 400 observations. It was demonstrated that Semi-Naïve BN structures can be transferred while maintaining stable predictive performance. In all sites, salinity and solar exposure had the greatest influence on Posterior Probability Distributions (PPDs), when combined with antecedent rainfall. The BNs provided a novel and transparent framework to quantify and visualise enterococci, stormwater impact, health risks, and associated uncertainty under varying environmental conditions. This study has advanced the application of BNs in predicting recreational water quality and providing decision support in urban estuarine settings, proposed for bathing, where uncertainty is high.