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Abstract Access to safe drinking water sources and appropriate sanitation facilities remains a dream in low and middle-income countries including South Africa. This study identified the origin of faecal pollution by using quantitative polymerase chain reaction (qPCR) targeting host-specific Bacteroidales genetic markers to track the distribution of human-specific (BacHum) and animal-specific (cattle—BacCow, chicken—Cytb, pig—Pig-2-Bac, dog—BacCan) markers in water sources used by rural communities of the Vhembe District Municipality (VDM). Results revealed the prevalence of BacHum, BacCow, and BacCan in all surface water sources in Thulamela Local Municipality (TLM) and Collins Chabane Local Municipality (CLM) during wet (100%) and dry seasons (50–75%). Cytb was not detected in untreated spring water in TLM and CLM, and Pig-2-Bac was not detected in untreated hand-dug well water in TLM during both seasons. Household-level analysis detected Cytb (28.8% wet, 17.5% dry), BacHum (34.4% wet, 25% dry for Pig-2-Bac) in stored untreated spring water in CLM, and Cytb (42.9% wet, 28.5% dry) in untreated hand-dug well water in TLM. Despite differences in detection frequencies of host-specific Bacteroidales, the study highlights the public health concern of faecal pollution in rural VDM households.

Access to safe drinking water sources and appropriate sanitation facilities remains a dream in low and middle-income countries including South Africa. This study identified the origin of faecal pollution by using quantitative polymerase chain reaction (qPCR) targeting host-specific Bacteroidales genetic markers to track the distribution of human-specific (BacHum) and animal-specific (cattle—BacCow, chicken—Cytb, pig—Pig-2-Bac, dog—BacCan) markers in water sources used by rural communities of the Vhembe District Municipality (VDM). Results revealed the prevalence of BacHum, BacCow, and BacCan in all surface water sources in Thulamela Local Municipality (TLM) and Collins Chabane Local Municipality (CLM) during wet (100%) and dry seasons (50–75%). Cytb was not detected in untreated spring water in TLM and CLM, and Pig-2-Bac was not detected in untreated hand-dug well water in TLM during both seasons. Household-level analysis detected Cytb (28.8% wet, 17.5% dry), BacHum (34.4% wet, 25% dry for Pig-2-Bac) in stored untreated spring water in CLM, and Cytb (42.9% wet, 28.5% dry) in untreated hand-dug well water in TLM. Despite differences in detection frequencies of host-specific Bacteroidales, the study highlights the public health concern of faecal pollution in rural VDM households. [ABSTRACT FROM AUTHOR]

Access to safe drinking water sources and appropriate sanitation facilities remains a dream in low and middle-income countries including South Africa. This study identified the origin of faecal pollution by using quantitative polymerase chain reaction (qPCR) targeting host-specific Bacteroidales genetic markers to track the distribution of human-specific (BacHum) and animal-specific (cattle—BacCow, chicken—Cytb, pig—Pig-2-Bac, dog—BacCan) markers in water sources used by rural communities of the Vhembe District Municipality (VDM). Results revealed the prevalence of BacHum, BacCow, and BacCan in all surface water sources in Thulamela Local Municipality (TLM) and Collins Chabane Local Municipality (CLM) during wet (100%) and dry seasons (50–75%). Cytb was not detected in untreated spring water in TLM and CLM, and Pig-2-Bac was not detected in untreated hand-dug well water in TLM during both seasons. Household-level analysis detected Cytb (28.8% wet, 17.5% dry), BacHum (34.4% wet, 25% dry for Pig-2-Bac) in stored untreated spring water in CLM, and Cytb (42.9% wet, 28.5% dry) in untreated hand-dug well water in TLM. Despite differences in detection frequencies of host-specific Bacteroidales, the study highlights the public health concern of faecal pollution in rural VDM households. [ABSTRACT FROM AUTHOR]

This study investigates the impact of water faecal contamination on highly threatened European brook lamprey larvae (Lampetra planeri). Water samples and the midgut contents of lampreys collected from a small lowland river upstream (site 1) and downstream from a wastewater treatment plant (WWTP) discharge (site 2) were analysed to check how the faecal microbial load of the habitat is reflected in the intestines of larval lampreys. The counts of viable mesophiles, psychrophiles, Escherichia coli and faecal streptococci as bacterial indicators of microbial (including faecal) water contamination were estimated. Microbial composition and abundance in larval midgut contents depended on the numbers of various microorganisms in the water environment. At site 2, the water was heavily microbiologically contaminated throughout the year by sewage inflow from the WWTP, and the amounts of studied bacteria were also high in the midgut of lampreys inhabiting site 2 regardless of the season. At site 1, water quality was better, and the levels of tested microbial indicators were lower in the intestines of the lampreys living there. The numbers of bacteria dependent on water temperature were growing in warmer seasons both in water and in intestines. Sewage pollution negatively influenced the condition of lampreys in site 2, where they exhibited lower body condition than in site 1. [ABSTRACT FROM AUTHOR]

A safe water supply is a necessity, but it remains one of the backlogs of services rendered in rural areas of developing countries. This leads to vulnerable communities using water from available sources that is unsafe as it is contaminated with faecal matter. Microbial source tracking (MST) methods are gold-standard techniques that detect the exact sources of faecal contamination. This study, therefore, tracked and identified the exact sources of faecal contamination from the catchment to the point of use in rural areas of Vhembe District Municipality. Collected water samples (n = 1048) were concentrated by membrane filtration for the enumeration and detection of E. coli, followed by DNA extraction. The extracted DNA was subjected to a quantitative polymerase chain reaction (qPCR) to track target host-specific Bacteroidales genetic markers from the water source to the point of use. Rivers and dams exhibited maximum E. coli counts of up to 90 CFU/100 mL during the wet season and up to 50 CFU/100 mL during the dry season. Due to the effective treatment of these water sources, no E. coli bacteria were detected in any of the sampled municipal drinking water treatment plants at the point of treatment, while this indicator bacterium was detected at the point of use (households), with a maximum of 4 CFU/100 mL recorded during both the wet and dry seasons. Overall, the most prevalent MST marker exhibited during the wet season was BacCan (dog-associated, 6.87%), followed by BacCow (cow-associated, 5.53%), while Pig-2-Bac (pig-associated, 2.48%) was the least prevalent. The most prevalent marker exhibited during the dry season was BacCan (5.34%), followed by BacCow, with Pig-2-Bac (1.72%) being the least prevalent. A positive correlation (r = 0.31, p = 0.001) was established between the presence of the MST markers and detected E. coli from water sources to the point of use. The knowledge of the faecal contamination attributes in both public and domestic domains will assist in developing prevention and control strategies. [ABSTRACT FROM AUTHOR]

The Danube River is, at 2857 km, the second longest river in Europe and the most international river in the world with 19 countries in its catchment. Along the entire river, faecal pollution levels are mainly influenced by point-source emissions from treated and untreated sewage of municipal origin under base-flow conditions. In the past 2 decades, large investments in wastewater collection and treatment infrastructure were made in the European Union (EU) Member States located in the Danube River Basin (DRB). Overall, the share of population equivalents with appropriately biologically treated wastewater (without disinfection) has increased from 69% to more than 85%. The proportion of tertiary treatment has risen from 46 to 73%. In contrast, no comparable improvements of wastewater infrastructure took place in non-EU Member States in the middle and lower DRB, where a substantial amount of untreated wastewater is still directly discharged into the Danube River. Faecal pollution levels along the whole Danube River and the confluence sites of the most important tributaries were monitored during four Danube River expeditions, the Joint Danube Surveys (JDS). During all four surveys, the longitudinal patterns of faecal pollution were highly consistent, with generally lower levels in the upper section and elevated levels and major hotspots in the middle and lower sections of the Danube River. From 2001 to 2019, a significant decrease in faecal pollution levels could be observed in all three sections with average reduction rates between 72 and 86%. Despite this general improvement in microbiological water quality, no such decreases were observed for the highly polluted stretch in Central Serbia. Further improvements in microbiological water quality can be expected for the next decades on the basis of further investments in wastewater infrastructure in the EU Member States, in the middle and lower DRB. In the upper DRB, and due to the high compliance level as regards collection and treatment, improvements can further be achieved by upgrading sewage treatment plants with quaternary treatment steps as well as by preventing combined sewer overflows. The accession of the Western Balkan countries to the EU would also significantly boost investments in wastewater infrastructure and water quality improvements in the middle section of the Danube. Continuing whole-river expeditions such as the Joint Danube Surveys is highly recommended to monitor the developments in water quality in the future. [ABSTRACT FROM AUTHOR]

Background: The pollution of water bodies is a serious concern in most rural areas in low- and middle-income countries due to anthropogenic activities which pose the greatest risk of human hepatitis viruses to public health. The aim of the study was to determine the probability of hepatitis A virus (HAV) infection associated with human consumption of water from River Owena, Nigeria. Methods: Water samples were collected from points with intense anthropogenic activities during dry and wet periods. Loads of enteric bacteria and HAV were determined using culture-based method and molecular technique. Risks of HAV infection was estimated using dose-response model, and probabilities of clinical illness and mortality were also determined. Results: Results revealed that the levels E. coli and faecal coliforms were greater during the wet period than the dry period (p< 0.05). Concentration of HAV was greater during the dry period than the wet period (p< 0.05). Risks of HAV infection were higher during the dry period than the wet period, and were all above the US EPA acceptable risk limit. Risk of clinical illness and mortality due to HAV were higher during the dry period than the wet period. Conclusions: Ingestion of water from the river may result into liver inflammation, morbidity or death. Development of active water management plans to reduce pollutant fluxes and address contamination threats must be established.

Background: The pollution of water bodies is a serious concern in most rural areas in low- and middle-income countries due to anthropogenic activities which pose the greatest risk of human hepatitis viruses to public health. The aim of the study was to determine the probability of hepatitis A virus (HAV) infection associated with human consumption of water from River Owena, Nigeria. Methods: Water samples were collected from points with intense anthropogenic activities during dry and wet periods. Loads of enteric bacteria and HAV were determined using culture-based method and molecular technique. Risks of HAV infection was estimated using dose-response model, and probabilities of clinical illness and mortality were also determined. Results: Results revealed that the levels E. coli and faecal coliforms were greater during the wet period than the dry period (p< 0.05). Concentration of HAV was greater during the dry period than the wet period (p< 0.05). Risks of HAV infection were higher during the dry period than the wet period, and were all above the US EPA acceptable risk limit. Risk of clinical illness and mortality due to HAV were higher during the dry period than the wet period. Conclusions: Ingestion of water from the river may result into liver inflammation, morbidity or death. Development of active water management plans to reduce pollutant fluxes and address contamination threats must be established. [ABSTRACT FROM AUTHOR]

Rivers are impacted by microbial faecal pollution from various sources. We report on a short-term faecal pollution event at the pre-alpine Austrian river Traisen caused by the large cultural event FM4 Frequency music festival, with around 200,000 visitors over 4 days. We observed a massive increase of the faecal indicator bacteria (FIB) intestinal enterococci during the event, while Escherichia coli concentrations were only slightly elevated. This increase poses a significant potential health threat to visitors and people recreating downstream of the festival area. A plausible explanation for the uncoupling of the two FIBs may have been a differential persistence caused by a combination of factors including water temperature, solar radiation, and the excessive presence of personal care products (PCPs) in the river water. However, a potential impact of PCPs on FIB assay performance cannot be ruled out. Our observations are relevant for other intensively used bathing sites; detailed investigations on persistence and assay performance of the FIB in response to different ingredients of PCPs are highly recommended. We conclude that for future festivals at this river or other festivals taking place under similar settings, a more effective management is necessary to reduce deterioration in water quality and minimise health risks. HIGHLIGHTS Strong impact of a cultural event on microbial faecal river pollution.; Uncoupling of E. coli and enterococci concentrations during the pollution event.; Plausible explanation for uncoupling is the differential persistence of faecal indicators.; Personal care products may significantly contribute to differential persistence of faecal indicators.;

This study examines toxic metal concentration and bacteriological characteristics of effluents in some parts of southwestern Nigeria. Fourteen wastewaters were analyzed for their trace metal content using Inductive coupled plasma optical emission spectrometry (ICP-OES) while 72-samples were examined for the presence of bacterial load using Standard Microbiological methods (THC-Total viable count and TCC-Total coliform count). Isolates identities were confirmed with relevant biochemical tests. Elevated concentrations of Cu-0.299µg/l, Pb-0.10µg/l, Zn-4.62µg/l, Cr-0.20µg/l, As-0.3µg/l, Ni-0.192µg/l, Cd-0.02µg/l, Se-0.02µg/l, Co-0.099µg/l, V-1.71µg/l, U-0.50µg/l, Sr-1.81µg/l and Ba-0.82µg/l were observed in the cassava market/industry wastewater: signifying this as the most contaminated water in the area. Fe-24.8mg/l in the school wastewater may be geogenically sourced; indicating high degree of weathering with the presence of ferromagnesian minerals while Cu and As in cassava waste-water might be compositional based through bioavailability uptake/sources. Bacteriological analysis revealed Enterobacter spp. and Escherichia coli across all sampled sites; these were consistently present in the wastewaters and are primarily considered as indicators of faecal pollution capable of affecting human health via contamination of surrounding drinking water sources. These species have been associated with several clinical conditions such as pus formation, pneumonia, rheumatic fever and infections in immune compromised inhabitants while others cause severe illness such as respiratory and urinary tract infections in humans. Concentration of toxic metals in the cassava market/industry wastewater should be controlled or monitored and the wastewater made less toxic by constant treatment with adequate remediation facilities to remove the toxic constituents before discharging them to surface water bodies. [ABSTRACT FROM AUTHOR]

Rivers are impacted by microbial faecal pollution from various sources. We report on a short-term faecal pollution event at the pre-alpine Austrian river Traisen caused by the large cultural event FM4 Frequency music festival, with around 200,000 visitors over 4 days. We observed a massive increase of the faecal indicator bacteria (FIB) intestinal enterococci during the event, while Escherichia coli concentrations were only slightly elevated. This increase poses a significant potential health threat to visitors and people recreating downstream of the festival area. A plausible explanation for the uncoupling of the two FIBs may have been a differential persistence caused by a combination of factors including water temperature, solar radiation, and the excessive presence of personal care products (PCPs) in the river water. However, a potential impact of PCPs on FIB assay performance cannot be ruled out. Our observations are relevant for other intensively used bathing sites; detailed investigations on persistence and assay performance of the FIB in response to different ingredients of PCPs are highly recommended. We conclude that for future festivals at this river or other festivals taking place under similar settings, a more effective management is necessary to reduce deterioration in water quality and minimise health risks. [ABSTRACT FROM AUTHOR]

Access to clean and safe drinking water still remains a major challenge in the developing world, causing public health risks in terms of waterborne infections, especially in rural areas of sub-Saharan Africa. This study aimed to track and detect enteric pathogens (Salmonella enterica subsp. enterica serovar Typhimurium str. LT2, Shigella flexneri, and Campylobacter jejuni subsp. jejuni) in rural water sources. It also sought to establish a correlation between these pathogens and the sources of faecal pollution. Multiplex qPCR and specific primers and probes were used for detection and tracking. The study successfully correlated the occurrence of target pathogens with sources of human and animal faecal contamination using host-specific genetic markers (BacHum and HF183 for humans, BacCow for cows, Pig-2-Bac for pigs, Cytb for chickens, and BacCan for dogs). The study revealed that enteric pathogens were found in 47.69% and 32.80% of samples during the wet and dry seasons, respectively. These pathogens were associated with human or animal faecal contamination. Correlations between pathogens and contamination sources were significant (p ≤ 0.05), with varying strengths during the wet and dry seasons. The findings emphasize the importance of identifying faecal contamination sources to protect rural communities from waterborne infections. [ABSTRACT FROM AUTHOR]

The present study aimed to assess the health risks of chemical contaminants of residents in the coastal areas of Cambodia through their drinking water pathways. Water was sampled from tube wells (n = 22), dug wells (n = 31), ponds (n = 11), canals (n = 12) and lakes (n = 4) across the Cambodian coastal areas, and measured for the contaminants of health concern (As, Cu, Cr, Cd, F−, NO2-, NO3-, Pb, Escherichia coli and total coliform) and aesthetic quality following the United States Environmental Protection Agency (USEPA) and standard methods. Analytical results reveal that 9.1% of tube wells and 9.7% of dug wells contained As > 0.01 mg/L. Appropriately, 22.7% of tube wells and 32.3% of dug wells contained Fe > 0.3 mg/L while 100% of tube wells and 80.6% of dug wells contained Mn > 0.1 mg/L. Health risk assessment found that the hazard quotient (HQ) > 1 for children and women. Additionally, the lifetime cancer risk (LCR) was found >1 × 10−4 for As in Cambodian coastal areas. Therefore, a monitoring programme and appropriate treatment to remove contaminants like arsenic, cadmium and fluoride would be required to ensure a safe drinking water supply to Cambodian coastal residents. HIGHLIGHTS Both total coliform and E. coli were found in the tube well, dug well, ponds, canals and lakes while the Cambodian Drinking Water Quality Standard for total coliform and E. coli is not detectable per 100 mL.; Health risk assessment revealed that for children and women residing in the coastal areas of Cambodia had HQ > 1.; Men, women and children residing in the coastal areas of Cambodia are exposed to carcinogenic risk of As through drinking water pathways.;

Water quality affected by polluted surface runoff from agricultural settings, storm-water as well as sewage from urban locations, and mining in the North West Province are reasons for concern. Similar situations may exist in areas elsewhere that have similar water issues and impacts. This study aimed to evaluate the water quality of the Loopspruit River by analysing the physico-chemical and microbiological parameters of the water. Bacterial diversity was the highest in less polluted areas of the Loopspruit River. Dominating at all the sites tested were Proteobacteria, followed by Bacteroidetes, Cyanobacteria, Actinobacteria and Verrucomicrobia. Predicted metagenome analysis revealed a correlation between the physico-chemical parameters and observed taxonomic units (OTU). Temperature had a negative correlation with Patescibacteria, Nanoarchaeaeota and Firmicutes (p < 0.05). The negative correlation was strongest with Patescibacteria. Sulphate had a strong correlation with Fusobacteria (p < 0.05). There was also evidence of faecal and agricultural pollution. Analysing and visually representing the water quality of the Loopspruit River demonstrated the value of combining physico-chemical, microbiology and geospatial data for an overview of understanding the potential environmental health risks. Such data could potentially be used for management strategies. HIGHLIGHTS Nutrient and faecal pollution from various sources impact water quality.; Diversity indices and an abundance of bacteria that are impacted by physico-chemical parameters.; Agricultural and sewage pollution impact levels of nitrates (fertilizer).; Network analysis highlights the impacts of nutrients on bacterial diversity.; Call for integrated water quality management to protect a peri-urban river system.;

Models that can predict the level of faecal pollution in rivers are of great significance in low-and middle-income countries where residents rely on them for anthropogenic activities. Water samples from River Ala were collected from seven representative monitoring points and the load of enteric bacteria were determined. The physicochemical characteristics were determined, linear regression models and risk maps for the representative monitoring points on River Ala were developed. The concentration of Escherichia coli in the water samples from River Ala ranged from 4.87 to 5.41 log10 CFU 100 ml−1 and faecal coliforms 5.23 to 5.42 log10 CFU 100 ml−1. Temperature ranged from 26.75 to 27.50 °C and turbidity 25.10 to 36.86 NTU. E. coli had positive relationships with turbidity (r = 0.62) and rainfall (r = 0.73). Faecal coliforms had positive relationships with turbidity (r = 0.76) and rainfall (r = 0.72). Regression models produced for rainfall as a function of E. coli had R² value of 0.667; and rainfall as a function of faecal coliforms had R² value of 0.683. The developed models demonstrated high predictive values and application to other monitoring points on the course of River Ala and can be adopted in water safety plans and water management practices. HIGHLIGHTS High levels of faecal contamination at the different representative monitoring points.; Physicochemical parameters and rainfall at 12 h before sampling influenced the load of enteric bacteria.; Risk maps showed areas highly prone to faecal pollution.; Human activities affected all regions in the representative monitoring points.;

Increasing urbanisation and industrialisation of the Visakhapatnam region have brought domestic sewage and industrial wastewater discharge into the coastal ocean. This study examines the indicator and pathogenic bacteria's quantitative abundance and antibiotic susceptibility. This study collected surface and subsurface water samples from ten different regions (147 stations; 294 samples), including 12 industrial discharge points, surrounding stations and two harbours from the coast of Pydibheemavaram to Tuni. Physicochemical parameters like salinity, temperature, fluorescence, pH, total suspended matter, nutrients, chlorophyll-a and dissolved oxygen showed a difference between regions. We noticed the presence of indicator (Escherichia coli and Enterococcus faecalis) and pathogenic (Aeromonas hydrophila, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella and Shigella, Vibrio cholera and Vibrio parahaemolyticus) bacteria among the samples. Waters from the near harbour and Visakhapatnam steel plant showed lower bacterial load with no direct input from industries to the coastal water. Samples collected during the industrial discharge period had a higher bacterial load, including E. coli. Enteric bacteria were found in higher numbers at most stations. Some isolates were resistant to multiple antibiotics with higher antibiotic resistance and multiple antibiotic resistance indexes compared with the other coastal water habitats in the Bay of Bengal. The occurrence of these bacteria above the standard limits and with multiple antibiotic resistance in the study region may pose a potential threat to the local inhabitants. It can create an alarming situation in the coastal waters in the study region. [ABSTRACT FROM AUTHOR]

The present study aimed to assess the health risks of chemical contaminants of residents in the coastal areas of Cambodia through their drinking water pathways. Water was sampled from tube wells (n ¼ 22), dug wells (n ¼ 31), ponds (n ¼ 11), canals (n ¼ 12) and lakes (n ¼ 4) across the Cambodian coastal areas, and measured for the contaminants of health concern (As, Cu, Cr, Cd, F-, NO2 -, NO3 -, Pb, Escherichia coli and total coliform) and aesthetic quality following the United States Environmental Protection Agency (USEPA) and standard methods. Analytical results reveal that 9.1% of tube wells and 9.7% of dug wells contained As > 0.01 mg/L. Appropriately, 22.7% of tube wells and 32.3% of dug wells contained Fe > 0.3 mg/L while 100% of tube wells and 80.6% of dug wells contained Mn > 0.1 mg/L. Health risk assessment found that the hazard quotient (HQ) > 1 for children and women. Additionally, the lifetime cancer risk (LCR) was found .1 x 104 for As in Cambodian coastal areas. Therefore, a monitoring programme and appropriate treatment to remove contaminants like arsenic, cadmium and fluoride would be required to ensure a safe drinking water supply to Cambodian coastal residents. [ABSTRACT FROM AUTHOR]

Sewage pollution leads to the contamination of bivalve shellfish by pathogenic microorganisms. Bacterial indicators support the management of risks associated with the consumption of shellfish; however, they often fail to indicate adequately the potential hazard to human health posed by certain human enteric viruses. Bacteriophages have been proposed as alternative indicators that may more effectively predict the presence of enteric viral pathogens. This study explored the relationships between bacterial indicators (Escherichia coli (E. coli), faecal coliforms (FC) and intestinal enterococci (IE)), phages (somatic (SOMPH), F-specific RNA (F + PH) and human-specific Bacteroides GB-124 phages (GB124PH)) and Norovirus (NoV) (GI/GII) in mussels (Mytilus edulis) and their overlying waters. The bioaccumulation of these indicators and Norovirus in shellfish matrices (e.g., flesh, digestive gland) was investigated bimonthly over a 12-month period in an English estuary. The findings revealed a marked seasonality in the distribution of all organisms, with the highest levels occurring during the autumn/winter months. The levels of all phages in shellfish and their overlying waters correlated better with the levels of Norovirus than with those of bacterial indicators. Somatic coliphages were the indicator that exhibited the strongest correlations with NoV (rho = 0.929). This study suggests that relatively low-cost culture-based phage enumeration appears to offer a more accurate indication of the likely presence of Norovirus in mussels than traditional bacterial indicators.

ABSTRACT Viruses are the most biologically abundant entities and may be ideal indicators of fecal pollutants in water. Anthropogenic activities have triggered drastic ecosystem changes in rivers, leading to substantial shifts in chemical and biological attributes. Here, we evaluate the viability of using the presence of crAssphage as indicators of fecal contamination in South African rivers. Shotgun analysis revealed diverse crAssphage viruses in these rivers, which are impacted by chemical and biological pollution. Overall, the diversity and relative abundances of these viruses was higher in contaminated sites compared to pristine locations. In contrast to fecal coliform counts, crAssphage sequences were detected in pristine rivers, supporting the assertion that the afore mentioned marker may be a more accurate indicator of fecal contamination. Our data demonstrate the presence of diverse putative hosts which includes members of the phyla Bacteroidota, Pseudomonadota, Verrucomicrobiota, and Bacillota. Phylogenetic analysis revealed novel subfamilies, suggesting that rivers potentially harbor distinct and uncharacterized clades of crAssphage. These data provide the first insights regarding the diversity, distribution, and functional roles of crAssphage in rivers. Taken together, the results support the potential application of crAssphage as viable markers for water quality monitoring. IMPORTANCE Rivers support substantial populations and provide important ecosystem services. Despite the application of fecal coliform tests and other markers, we lack rapid and reproducible approaches for determining fecal contamination in rivers. Waterborne viral outbreaks have been reported even after fecal indicator bacteria (FIB) were suggested to be absent or below regulated levels of coliforms. This indicates a need to develop and apply improved indicators of pollutants in aquatic ecosystems. Here, we evaluate the viability of crAssphage as indicators of fecal contamination in two South African rivers. We assess the abundance, distribution, and diversity of these viruses in sites that had been predicted pristine or contaminated by FIB analysis. We show that crAssphage are ideal and sensitive markers for fecal contamination and describe novel clades of crAss-like phages. Known crAss-like subfamilies were unrepresented in our data, suggesting that the diversity of these viruses may reflect geographic locality and dependence.

Access to clean and safe drinking water still remains a major challenge in the developing world, causing public health risks in terms of waterborne infections, especially in rural areas of sub-Saharan Africa. This study aimed to track and detect enteric pathogens (Salmonella enterica subsp. enterica serovar Typhimurium str. LT2, Shigella flexneri, and Campylobacter jejuni subsp. jejuni) in rural water sources. It also sought to establish a correlation between these pathogens and the sources of faecal pollution. Multiplex qPCR and specific primers and probes were used for detection and tracking. The study successfully correlated the occurrence of target pathogens with sources of human and animal faecal contamination using host-specific genetic markers (BacHum and HF183 for humans, BacCow for cows, Pig-2-Bac for pigs, Cytb for chickens, and BacCan for dogs). The study revealed that enteric pathogens were found in 47.69% and 32.80% of samples during the wet and dry seasons, respectively. These pathogens were associated with human or animal faecal contamination. Correlations between pathogens and contamination sources were significant (p ≤ 0.05), with varying strengths during the wet and dry seasons. The findings emphasize the importance of identifying faecal contamination sources to protect rural communities from waterborne infections.

• Faecal pollution data from the past 11 years in the Adriatic sea were analysed. • FIB contamination changed over space and time. • A general reduction of structural zeros over time was found. River discharge and rainfall did not explain faecal pollution • CSOs events were highly correlated with peaks in FIB. Faecal contamination of the coastal sea poses widespread hazard to human and environmental health and is predicted to rise in response to global change and human pressure. For better management and risk reduction it is thus imperative to clarify and predict trends of faecal pollution over spatial and temporal scales, and to assess links with climate and other variables. Here, we investigated the spatio-temporal variation in the Faecal Indicator Bacteria (FIB) Escherichia coli and enterococci, over a time frame spanning 11 years (2011–2021) along a coastal area covering approximately 40 km and 59 bathing sites in the Marche region (Adriatic Sea, Italy), characterized by intense beach tourism, high riverine inputs, resident population, maritime traffic and industrial activities. Our analysis, that considers 5,183 measurements during the bathing season (April to October), shows that FIB abundance varied significantly among years. A general, although not significant, increase over time of both FIB was observed, mainly due to a general reduction of structural zeros (i.e., zeros originated from the actual absence of the response variable) over the examined time period. FIB abundances displayed their maxima and minima in different years according to the municipality, with overall peaks recorded in different months (May-June or September), whereas the lowest values were always observed in October. FIB levels were not significantly related neither to rainfalls nor to river discharge, but the activation of combined sewer overflows (CSOs), typically occurring after intense rainfall events, appeared as a necessary condition for the high faecal contamination levels. Considering climate change scenarios predicting significant increases in extreme weather events, our findings support the usefulness of analysing long-term trends to identify pollution sources, and the prioritization of control strategies to better manage the release of microbial pollutants from combined sewer overflows in coastal waters to reduce human risks. [Display omitted] [ABSTRACT FROM AUTHOR]

The use of faecal coliforms as indicators is the traditional approach of testing water quality. Unfortunately, for a comprehensive water quality analysis, there is an increasing body of evidence that demonstrates coliforms as insufficient indicators for water quality assessment. Therefore, during the last two decades, alternative water testing approaches such as the use of coliphage as well as cholesterol detection have gained popularity. In the present study, we evaluated and compared the reliability of data from three different indicators that included coliforms (Streptococcus), coliphage and cholesterol. Four sites were chosen for sample collection and these included one site from Haart river (HR1) and three sites from Barberspan (BP1, 2 and 3) in the North West Province of South Africa. Samples were collected during winter and summer seasons. Collected samples were subjected to different analyses for detection of coliphage, coliforms and cholesterol. Faecal indicator bacteria were detected at all sites and in some cases were relatively high (HR1: 287 cfu/100 mL faecal coliform and 228.6 cfu/100 mL faecal streptococci; BP1: 1,730 cfu/100 mL Escherichia coli). The HR1 site consistently had the highest levels of bacterial faecal indicators of the four sampling sites. Most notably, faecal streptococci were detected in higher numbers than any other bacterial indicator. A significant finding was the general higher levels of faecal indicator markers at the BP3. Based on the outcome of this study, a combination of these indicators offers a comprehensive and promising approach for monitoring water quality. HIGHLIGHTS This manuscript provides historical data for Barberspan, a Ramsar site.; It shows the strengths of using multiple faecal indicators together at one site.; It shows the advantages of using Streptococci, coliphages and cholesterol as faecal pollution indicators.; It informs the water management strategy of Baberspan.; It informs on the water quality of Barberspan.;

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Colistin is one of the antibiotics of last resort for human health. However, the dissemination of the plasmid-mediated colistin resistance gene mcr-1 is of great concern globally. In the One Health framework, the environment is an important component for managing antimicrobial resistance. However, little information is available concerning the prevalence of mcr-1 in water environments. We aimed to reveal the prevalence of mcr-1 in different water environments in Hanoi, Vietnam. Quantitative PCR was applied to detect mcr-1 in four urban drainages receiving untreated domestic wastewater, three rivers, five lakes and two groundwater samples. Urban drainages contained higher concentrations of mcr-1, suggesting that urban residents carry the gene. The class 1 integron-integrase gene was identified as a good surrogate of antibiotic resistance genes including mcr-1. A significant correlation was found between the levels of mcr-1 and the human-specific cross-assembly phage, which is an indicator of human faecal pollution. These results indicated that the primary source of mcr-1 in urban water environments is human faeces, which is consistent with the fact that most domestic wastewater is untreated in Hanoi. The control of untreated wastewater is critical for alleviating the spread of mcr-1 in water environments in Vietnam. [ABSTRACT FROM AUTHOR]

Pepper mild mottle virus (PMMoV), a plant pathogenic virus belonging to the family Virgoviridae, has been proposed as a potential viral indicator for human faecal pollution in aquatic environments. The present study investigated the occurrence, amount and diversity of PMMoV in water environments in Italy. A total of 254 water samples, collected between 2017 and 2019 from different types of water, were analysed. In detail, 92 raw sewage, 32 treated sewage, 16 river samples, 9 estuarine waters, 20 bathing waters, 67 groundwater samples and 18 drinking waters were tested. PMMoV was detected in 79% and 75% of untreated and treated sewage samples, respectively, 75% of river samples, 67% and 25% of estuarine and bathing waters and 13% of groundwater samples. No positive was detected in drinking water. The geometric mean of viral concentrations (genome copies/L) was ranked as follows: raw sewage (2.2 × 106) > treated sewage (2.9 × 105) > river waters (6.1 × 102) > estuarine waters (4.8 × 102) > bathing waters (8.5 × 101) > groundwater (5.9 × 101). A statistically significant variation of viral loads could be observed between raw and treated sewage and between these and all the other water matrices. PMMoV occurrence and viral loads did not display seasonal variation in raw sewage nor correlation with faecal indicator bacteria in marine waters and groundwater. This study represents the first report on the occurrence and quantification PMMoV in different water environments in Italy. Further studies are required to evaluate the suitability of PMMoV as a viral indicator for human faecal pollution and for viral pathogens in waters. [ABSTRACT FROM AUTHOR]

Lake Victoria is the primary source of water for millions of people in the Sub-Saharan Africa region. In recent years, population development around the lake has resulted in compromised sanitation standards resulting in increased faecal pollution of the lake. Consequently, this condition has increased the chances of waterborne enteric viruses, such as adenoviruses' circulation in the community. Adenoviruses can affect health in both humans and animals by causing a myriad of diseases including the gastrointestinal infections. The study aimed to detect contamination of the lake water with pathogenic human adenoviruses along Homa Bay town, Homa Bay County, Kenya. To examine the presence of adenoviral genome, we collected a total of 216 (monthly n = 36) water samples from six different locations marked by high levels of anthropogenic activities along the shoreline. Molecular amplification technique using the nested PCR procedure was used to detect the genomes from the water samples. Human adenoviruses were detected in 11 samples (5.09%). Statistical analyses indicated a significant correlation between adenovirus presence and the approximate distance from pit latrines and sewage treatment works at the area. The findings indicate that faecal contamination of the lake waters originated from the point sources. The findings also suggest a possibility of elevated levels of faecal pollution in different surface waters within the lake basin. The findings indicate that some of the enteric viruses circulating in the local community are human adenovirus type 40, and 41. The data may provide a basis for recognizing the need to prioritize environmental monitoring for enteric virus contamination on an on-going basis. [ABSTRACT FROM AUTHOR]

The respirable fraction of resuspended urban road dust contains phosphorous at enhanced concentrations which may imply the potential presence of animal faeces.Specific biomarkers such as faecal sterols and bile acids are commonly used to verify the presence of faecal pollution in various environmental samples. The quantification of faecal materials in matrices is usually based on the analysis of bile acids which are persistent and refractory, and can be found in the digestive systems of all mammals and birds. In this study, by measuring the concentrations of bile acids in resuspended PM1−10 samples collected from paved roads on urban locations for the first time in aerosol science we have attempted to estimate the potential mass contribution of animals' faeces to the respirable fraction of road dust. A special sampling unit was applied for the collection of resuspended and respirable road dust in Veszprém and Budapest, Hungary. The concentrations of bile acids were determined by gas chromatography−mass spectrometry (GC−MS). Elemental phosphorous was found in the resuspended PM1−10 fraction in concentrations of 2 mg g−1 whereas the total concentrations of bile acids such as LCA (lithocholic acid), DCA (deoxycholic acid), CDCA (chenodeoxycholic acids), and HDCA (hyodeoxycholic acid) were in the order of 10 μg g−1. Based on the measured mass concentrations of bile acids, the estimated mass contribution of faeces to resuspended PM1−10 mass was found to be in the range of 0.02–0.54 m/m%. Our results imply that wind- or traffic-driven resuspension of dried animals’ faeces, which has never been considered as a potential source of urban PM1−10, is a detectable contributor to urban PM1−10 with all its potential health and epidemiological implications.

Faecal microorganisms represent a key threat to human health. Potential origins of faecal microbial contamination in a typical urban-representative micro-scale were evaluated. The quantitative polymerase chain reaction (qPCR) method was used in this study. The Bacteroidetes is selected as the indicative microorganism in runoff samples that are collected during four representative stormwater events in north China. The principal component analysis (PCA) method indicated the distribution feature of the environmental factors. The largest contributor is dog, followed by bird and human to the faecal pollution in stormwater runoff. The output of human and dog faecal pollutants in response to the first flush effect of nonpoint source pollution while the transmit time of bird faecal pollutant is relatively longer. In addition, the number of antecedent drying days represents the key factor for dog faecal pollution, while human faecal pollution is impacted by more factors. The results of this study will provide sound evidence for the tracking and management of nonpoint source faecal pollution in urban catchment areas. [ABSTRACT FROM AUTHOR]

Faecal pollution of water by bacteria has a negative effect on water quality and can pose a potential health hazard. Conventional surveillance of microbial water quality relies on the analysis of low-frequency spot samples and is thus likely to miss episodic or periodic pollution. This study aimed to investigate the potential of filter-feeding sponges for time-integrated biomonitoring of microbial water quality. Laboratory trials tested the effects of different ratios of bacterial abundance and the sequence of exposure on bacterial retention by the freshwater sponge Ephydatia fluviatilis (Linnaeus, 1759) to establish its potential to indicate bacterial exposure. Gemmule grown sponges were simultaneously exposed to Escherichia coli and Enterococcus faecalis but at different ratios (Trial 1) or individually exposed to each bacterial species but in different sequential order (Trial 2). The E. coli and E. faecalis retained in each sponge was quantified by culture on selective agars. Data analysis was conducted using the Kruskal-Wallis test and/or the Mann-Whitney U test to compare between the numbers of bacteria retained in each treatment. Additionally, the Wilcoxon matched-paired signed-rank test was used for comparison of the different bacterial abundances retained within each individual sponge. Sponges from all trials retained E. coli and E. faecalis in small numbers relative to the exposure (<0.05 % Trial 1 and <0.07 % Trial 2) but exhibited higher retention of E. coli . Higher abundance of either bacterial species resulted in significantly lower ( P <0.005) retention of the same species within sponges (Trial 1). An initial exposure to E. coli resulted in significantly higher ( P =0.040) retention of both bacterial species than when sponges were exposed to E. faecalis first (Trial 2).Bacterial retention by sponges was neither quantitatively representative of bacterial abundance in the ambient water nor the sequence of exposure. This implies either selective filtration or an attempt by sponges to prevent infection. However, freshwater sponges may still be useful in biomonitoring as qualitative time-integrated samplers of faecal indicator bacteria as they detect different bacteria present in the water even if their quantities cannot be estimated., Competing Interests: The authors declare that there are no conflicts of interests. All work was conducted by the authors. Kindly note that much of this work has been reported previously in my PhD thesis cited below (Cartwright, 2018)., (Copyright © 2024 Crown Copyright.)

ColiSense, an early warning system developed for Escherichia coli detection, is assessed using environmental samples. The system relies on the detection of β-glucuronidase (GUS), a biomarker enzyme for E. coli. In contrast with other rapid GUS-based methods, ColiSense is the only method that uses 6-chloro-4-methyl-umbelliferyl-β-d-glucuronide (6-CMUG) as a fluorogenic substrate. The system measures a direct kinetic response of extracted GUS, and the detection was carried out in the absence of particles or bacteria. It is necessary to evaluate the system with environmental samples to establish the relationship between faecal indicator bacteria E. coli and the response measured by the ColiSense. This paper presents the results of tests carried out with the ColiSense system for 2 trials, one conducted with freshwater samples collected from rivers in the Dublin area and a second conducted with seawater samples from coastal areas collected over the bathing season. A positive linear correlation was found between E. coli (MPN 100 mL−1) and ColiSense response (R2 = 0.85, N = 125, p < 0.01) for the seawater sample. A ColiSense response threshold was identified as 0–1.8 pmol min−1 100 mL−1, equivalent to 0–500 E. coli 100 mL−1. Using this threshold, 96.8% of the samples were correctly classified as being above or below 500 E. coli 100 mL−1 by the ColiSense system. Results presented demonstrate that the ColiSense system can be used as an early warning tool with potential for active management of bathing areas by providing results in 75 min from sample collection. [ABSTRACT FROM AUTHOR]

Recent studies have shown that crAssphage is abundant in human faecal samples worldwide. It has thus been postulated as a potential microbial source tracking (MST) marker to detect human faecal pollution in water. However, an effective implementation of crAssphage in water management strategies will depend on an understanding of its environmental dynamics. In this work, the abundance and temporal distribution of crAssphage was analysed in the effluent of wastewater treatment plants using different sewage treatments, and in two rivers (water and sediments) that differ in pollution impact and flow regime. Additionally, the influence of environmental conditions (temperature and rainfall) on the removal of the marker was studied along a river section, and natural inactivation was assessed by a mesocosms approach. Molecular and culture-based tools were used to compare crAssphage abundance and dynamics with those of bacteria and bacteriophages currently applied as global indicators (E. coli , somatic coliphages, Bacteroides GA17 bacteriophages, and the human-associated MST markers HF183 and HMBif). CrAssphage concentrations in sewage effluent and river samples were similar to those of HF183 and HMBif and higher than other general and/or culture-based indicators (by 2–3 orders of magnitude). Measurement of crAssphage abundance revealed no temporal variability in the effluent, although rainfall events affected the dynamics, possibly through the mobilisation of sediments, where the marker was detected in high concentrations, and an increase in diffuse and point pollution. Another factor affecting crAssphage inactivation was temperature. Its persistence was longer compared with other bacterial markers analysed by qPCR but lower than culturable markers. The results of this study support the use of crAssphage as a human source tracking marker of faecal pollution in water, since it has similar abundances to other molecular human MST markers, yet with a longer persistence in the environment. Nevertheless, its use in combination with infectious bacteriophages is probably advisable. Graphical abstract Image 1 Highlights • CrAssphage is highly abundant in sewage polluted environments. • CrAssphage inactivates faster at high than at low temperature. • CrAssphage persists more than molecular bacterial MST markers but less than culturable phages. • Sediments can become a reservoir of crAssphage. • CrAssphage is a good potential MST marker for water management in the studied context. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the seasonal variation of microbial quality in urban waterbodies along urbanization gradients. Bimonthly samples were collected from 14 recreational lakes and flood mitigation ponds in the Klang Valley, Malaysia, between May and October 2017. Samples were analysed for the presence and abundance of Escherichia coli, Clostridium perfringens, faecal coliforms (FC), faecal streptococci (FS), enterococci and total coliforms as indicator organisms, using standard methods. All studied lakes contained indicator bacteria that exceeded the National Lake Water Quality Standards (NLWQS) to varying degrees. The mean of the FC/FS ratios in all lakes exceeded four, indicating that the faecal contamination might have originated from human sources. Escherichia coli, C. perfringens and faecal coliform concentrations were negatively correlated with temperature (P < 0.01) and positively correlated with turbidity and suspended solids (P < 0.05). Non-parametric test results revealed that only the density of C. perfringens varied significantly according to season and urbanization impacts (P < 0.05). The Secchi depth transparency and dissolved oxygen (DO) levels explain the largest variation in bacterial communities. This study showed that contamination of faecal bacteria in the waterbodies varied spatially and temporally along urbanization gradients. Water quality monitoring and improvements are needed before the waterbodies can be used for direct body-contact recreation and as alternative water sources for drinking purposes. [ABSTRACT FROM AUTHOR]

Kribi is a seaside town that welcomes thousands of tourists each year. However, the poor sanitation condition of its beaches along the Atlantic coast is not without risk for visitors. In this study, we used the formol-ether concentration technique to identify and quantify larvae or eggs of intestinal helminths in waters of three regularly visited Kribi beaches (Mpalla, Ngoyè, and Mboamanga). Results revealed that all identified larvae and eggs were cestodes ( Hymenolepis nana ) and nematodes ( Strongyloides sp., Ascaris sp., Ancylostoma duodenale and Trichuris trichiura ). All the helminth eggs and larvae showed high abundance at low tide during rainy seasons. Ancylostoma duodenale eggs, totally absent at Mpalla, were densely present at low tide at Ngoyè (301 ± 15 eggs/L). Trichuris trichiura eggs showed the lowest abundance (0 to 62 eggs/L) at all sites. Abiotic variables indicated that waters at the various beaches were basic (pH: 8.75-9.77), generally warmer (32.44°C at Mpalla in the Short Rainy Season), more oxygenated at low tide, and moderately mineralized at high tide. Positive and significant correlations were observed at Ngoyè at low tide between Strongyloides sp. larvae and dissolved oxygen ( P ˂ 0.05); and between Ancylostoma duodenale eggs and temperature ( P ˂ 0.05). The overall results indicated that the beaches studied are subjected to fecal pollution. This pollution is more accentuated during low tides than during high tides. Depending on tidal movements, swimmers risk exposure to helminth eggs and larvae known to be responsible for gastroenteritis.

Aims: Evaluate the T90 and compare the decay of different faecal indicator bacteria (FIB) and molecular microbial source tracking (MST) markers of human and animal sources during summer and winter. Methods and Results: The persistence of Escherichia coli and enterococci and several MST molecular markers targeting host‐specific Bifidobacterium and Bacteroidales species (BifHM, BifCW, BifPL, HF183/BFD, Rum2Bac and Pig2Bac) was assessed at the same time using mesocosms. Dialysis bags filled with diluted wastewater from different sources were kept in an outdoor water tank and monitored regularly to assess the inactivation rates. The T90 values of E. coli by culture methods ranged from 1·52 to 5·69 days in summer and 2·06 to 6·19 days in winter, whereas with qPCR 2·29–4·23 days in summer and 4·17–8·09 days in winter. T90 values for enterocci ranged from 1·15 to 3·10 days in summer and from 3·01 to 5·46 days in winter. Significant differences were observed between faecal sources for both markers. For the MST makers similar T90 values were obtained in summer (1·05–1·91 days), whereas higher variability was observed in winter (2·90–6·12 days). Conclusions: Different decay rates were observed for the FIB from the different sources, especially for E. coli in ruminant samples. A higher variability among T90 values of the different MST markers in winter was observed, whereas similar T90 values were detected in summer highlighting the stronger effect of environmental parameters during this season. Significance and Impact of the Study: The diverse inactivation rates observed in bacteria from different faecal sources have implications when these rates are used to model faecal pollution in water. The use of FIBT90 of different sources is essential to develop reliable predictive models. Since different inactivation of E. coli regarding the source of pollution has been observed, the source of the pollution has to be considered for modelling approaches. [ABSTRACT FROM AUTHOR]

EC Regulation 854/2004 requires the classification of bivalve mollusc harvesting areas according to the faecal pollution status of sites. It has been reported that determination of Escherichia coli in bivalve shellfish is a poor predictor of norovirus (NoV) contamination in individual samples. We explore the correlation of shellfish E. coli data with norovirus presence using data from studies across 88 UK sites (1,184 paired samples). We investigate whether current E. coli legislative standards could be refined to reduce NoV infection risk. A significant relationship between E. coli and NoV was found in the winter months (October to February) using data from sites with at least 10 data pairs (51 sites). We found that the ratio of arithmetic means (log10 E. coli to log10 NoV) at these sites ranged from 0.6 to 1.4. The lower ratios (towards 0.6) might typically indicate situations where the contribution from UV disinfected sewage discharges was more significant. Conversely, higher ratios (towards 1.4) might indicate a prevalence of animal sources of pollution; however, this relationship did not always hold true and so further work is required to fully elucidate the factors of relevance. Reducing the current class B maximum (allowed in 10% of samples) from 46,000 E. coli per 100 g (corresponding NoV value of 75750±103) to 18,000 E. coli per 100 g (corresponding NoV value of 29365±69) reduces maximum levels of NoV by a factor of 2.6 to 1; reducing the upper class B limit to 100% compliance with 4,600 E. coli per 100 g (corresponding NoV value of 7403±39) reduces maximum levels of NoV by a factor of 10.2 to 1. We found using the UK filtered winter dataset that a maximum of 200 NoV corresponded to a maximum of 128±7 E. coli per 100 g. A maximum of 1,000 NoV corresponded to a maximum of 631±14 E. coli per 100 g. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop faecal pollution model structures with artificial neural networks (ANNs) for cost-effective lake water quality management studies. In this study 5 artificial neural networks model structures were applied to predict the Faecal coliform concentrations for 4 different coast areas "Göllüce, İnciraltı, Darka, Orhangazi" and all data of the coasts in Lake İznik- Turkey. The Levenberg-Marquardt and backpropagation algorithm was proposed for feed-forward neural networks training. According to performance functions root mean squared error (RMSE), neural network model structures provided acceptable results. Correlation values (R) were found between 0.590 and 0.999. Increasing the number of hidden layer in the model structures was not raised the model efficiency in each trial. Type and number of input parameters were more effective for some model efficiency. Increasing the number of hidden layer and inputs in the model structures did not raise the model efficiency in each trial. Because depending on the numbers and chemical compositions of the substrates in the lake water microorganism's metabolism and their growth rates could be influenced differently and the larger error values of the modeling results determined in Göllüce and Orhangazi Coasts which influenced by pollution sources. Water quality modeling studies and increasing of monitoring would provide more productive results for protection and management of coastal. [ABSTRACT FROM AUTHOR]

This article describes a methodology for optimising predictive models for concentrations of faecal indicator organisms (FIOs) in coastal areas based on geographic and meteorological characteristics of upstream catchments. Concentrations of FIOs in mussels and water sampled from 50 sites in the south of Brazil from 2012 to 2013 were used to develop models to separately predict the spatial and temporal variations of FIOs. The geographical parameters used in predictive models for the spatial variation of FIOs were human population, urban area, percentage of impervious cover and total catchment area. The R 2 of models representing catchments located within 3.1 km from the monitoring points was up to 150% higher than that for the nearest catchment. The temporal variation of FIOs was modelled considering the combined effect of meteorological parameters and different time windows. The explained variance in models based on rainfall and solar radiation increased up to 155% and 160%, respectively. [ABSTRACT FROM AUTHOR]