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Since air pollution is a major public health concern, collecting and analyzing air quality indicators data is very important for monitoring pollution. Data on these indicators are generally collected through air quality monitoring stations located in specific areas. In this study, 12 monitoring sites belonging to the Beijing Municipal Environmental Monitoring Center air pollution monitoring network are clustered based on their similarity in terms of hourly or monthly concentrations of some air pollutants. The hourly data was collected from these stations between March 2013 and February 2017. The clustering procedure was performed through average linkage and partitioning around medoids algorithms. The preliminary results obtained from the hierarchical algorithm show the presence of two clusters that are well distinguished with meaningful interpretation while the two obtained from the partitional algorithm are not well distinguished. [ABSTRACT FROM AUTHOR]

One of the problems in the power system is the interruption of power distribution. Sometimes faults occur in the power system resulting in power outages. The process of quickly transferring the source from the primary source to the backup source is critical. This study aims to design an automatic transfer switch equipped with a monitoring system based on the Internet of Things (IoT). It begins with identifying and designing the equipment needed. Testing is carried out in 3 conditions to ensure the equipment is working properly. The first condition is the PLN as the primary source turns on and distributes the power to the customers. The second condition is the primary source shuts down and is transferred to the generator set (Genset). The third condition is the main source turns on again when the Genset is used as a backup source. The results of the testing show that the equipment is working properly. The equipment will switch the connections if the main source is turned off and the Genset will automatically be turned on. If the main source has turned on again, the equipment will automatically turn off the Genset and switch the connection to the main source. The monitoring system has been working properly in displaying the voltage, current, and status of the connected source. When PLN is used as the main source, the source status is the power source from PLN and the PLN indicator light is on. The measured voltage is 227 V and the current is 0.26 A if a fan is connected to the main source. When the load is added by turning on the iron, the voltage drops to 218.1 V, and the current rises to 1.71 A. When the main source turns off, the Genset indicator light turns on and the status is the power source from the Genset. The voltage and current measurement results are almost the same as the previous test results. Users can use the study's findings to help them automatically transfer the power source when the primary source is off and monitor its status using a smartphone. [ABSTRACT FROM AUTHOR]

The exposure assessment identifies the pathways by which humans are exposed to a contaminated environment and estimates the magnitude, frequency and duration of these exposures. This paper deals with exposure assessment of fecal contamination, in which exposure assessment is done with the help of the SaniPath Exposure Assessment Tool. By this tool, identify the dominant pathway, a pathway that has a greater contribution to the exposure. The goal of the study was to find the dominant pathway in the study area, Ward 10 Kadakkad, Pathanamthitta, Kerala, India. Lack of sewer lines and sewage treatment facilities and open disposal of fecal waste in the area caused flooding up of sewage and lots of other difficulties as well as threats to the residents. Identifying the dominant transmission pathway or pathways and blocking or breaking this transmission pathway by different interventions like water, sanitation and hygiene programs improve health and also helps to prioritize sanitation investments based on the exposures that have the greatest public health impact. [ABSTRACT FROM AUTHOR]

The Baitarani River, Odisha, has a strong economic and traditional attachment to the local people. The surrounding community makes use of the river water for the multipurpose of irrigation, domestic water supply, recreation and fish harvesting. The study was conducted to assess the Water Quality Index (WQI) by taking nineteen selected significant parameters from thirteen locations for a period of 10 years i.e., (2008-2018). All selected physicochemical parameters were found under prescribed limits as stated by World Health Organization guidelines except turbidity and DO. The pH values depict slightly alkaline in nature. Further, it is apparent from WQI, that water belongs to excellent to poor category during PRM and MON with WQI values ranging from 17.7 to 59.72 and 17.8 to 58.53 while in case of POM, it falls under excellent to very poor category with values of WQI ranged between 19.25 and 77.69. Maximum WQI values were recorded during POM followed by PRM and MON. The overall WQI values showed good water status indicating suitability for different human uses. The present study points out that turbidity and DO play a central role in affecting the WQI of the river, however, in case of nutrient elements, no such significant roles were observed in affecting the water quality of the river. The visualization of the WQI distributions using GIS software suggests point and non-point source pollution to areas of deteriorating water quality. Sampling station site-8 needs special attention. Ca++ is the most dominant cation with HCO3− as the dominantanion. The abundant of the major is as follows: Ca2+>Na+>Mg2+>K+>Fe2+ which is equal to HCO3− > Cl- > SO42- > NO3- > PO43-. As per piper diagram, all the water samples fall under Ca++-Na+-Mg++-HCO3−-Cl-. Chemical indices like SAR, %Na, RSC, PI, KI and PS were reported and indicate that the surface water in the study area is suitable for irrigation. Correlation between SAR and EC revealed that all sites fall under C2-S1 (medium salinity low sodium) type. Through applying GIS techniques, the spatial distribution of surface water quality analysis reveals that most of the samples comply with drinking and irrigation water quality standards with few exceptions and water needs to be prior treatment before consumption. It can be concluded that depending upon physicochemical parameters, the river requires mitigation measures to control pollutant inflow. [ABSTRACT FROM AUTHOR]

Monitoring water quality in rivers requires a quick and high-accurate analysis method that requires a high number of representative points. To strengthen the monitoring capacity in the field, it is necessary to apply modern, compact, low-cost, and easy-to-use equipment. WATERit (WI) is a quick, and consistent water quality monitoring technology developed by OPTEX GROUP Co. Ltd in Japan, which has successfully demonstrated its feasibility and applicability for water quality monitoring in rivers. In this study, daily monitoring of 30 sites along the Cau River Basin was conducted to assess water quality of the Cau River Basin by WI for parameters: NH4+, NO2-, NO3-, and PO43-. A WI accuracy study was performed by repeating measurements on 30 sites with 2 machines over a 15-week period, and 10 sites with 3 machines over a 9-week period. Based on river water quality assessment, the range of NO2-, NO3-, NH4+, and PO43- oncentrations is 0.02 - 5.6/ 0.25 - 34.9/ 0.2 - 50/ 0.1 - 10.1 mg/L, exceeding National technical regulations on surface water quality (QCVN 08- 2015/BTNMT-column A2) of the total samples is 75.9%, 62.7%, 95.1%, and 50.8% respectively. The correlation coefficients of repeated measurement of 2 devices at 30 sites for 4 parameters were relatively high with 70 to 96.7% of the data having R2>0.75. Similarly, the relative standard deviation (RSD) of repeated measurements of 3 devices was greater than 89% of the data collected, which met the repeatability requirements according to Appendix F-AOAC for each concentration range. In addition, in our previous research, the correlation coefficients between the WI measurement method and standard method are recorded with an R2 ranging from 0.94-0.98. These results have proved WI's accuracy and adaptability for monitoring of NO2-, NO3-, NH4+, and PO43- parameters in assessing river water quality in Vietnam. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the impacts of the tilapia cage culture located within 100ha of the Aquaculture Industrial Zone (AIZ) on the water quality of Temengor Reservoir. Sampling on the physico-chemical parameters was conducted at 15 sampling points at depths of 0m, Secchi depth, 5m, 10m, and 15m. The values of these parameters were observed to be dependent on the distance from the fish cages; the trend of water quality parameters deteriorated upon approaching the fish cages. The higher concentration of nutrients was attributed to the nutrient leaching from uneaten food pellets, fish excretion, and decomposition of nitrogenous and phosphate compounds. Besides, the chemical substances such as vitamins and antibiotics used to increase aquaculture production might also contribute to loads of nutrients. However, the concentrations of nutrients and chlorophyll-a at Temengor Reservoir were still within the acceptable limit of environmental health. The detrimental effects of the fish cages might be reduced by the dilution factors based on volume, depth, and water level of the reservoir and rainfall, resulting in low concentrations of nutrients on the surface compared to other previous studies conducted in rivers, streams, and shallower lakes. [ABSTRACT FROM AUTHOR]

Kranji River, located in Jatirejo Village, Gunung Pati, Semarang, has the potential for river tubing tourism. The purpose study was to determine the condition of river characteristics, water quality and the status of water quality used in river tubing tourism. The research on the Kranji River in September 2020 using survey method and river characteristics data using Digital Elevation Model data remote sensing method then processed ArcGIS software. The water quality method uses the Pollution Index (PI) stated in the Decree of State Minister Environment number 115 of 2003. The quality standard used is class 2 water quality as stated in PP number 82 of 2001. The results data of width, discharge and slope, respectively, obtained an overall of 8.75 m, 2.11 m3/second and 17.78. This value is close to the ideal value of the required characteristics. The water quality parameters measured temperature, TSS, pH, DO, BOD, COD and Escherichia coli bacteria with sequential results of 29.27°C; 0.12 mg/l; 7.34; 9.36 mg/l; 6.82 mg/l; 22 mg/l and 2.725 in/100ml. The results based on the measurement of IP value of 2.73 indicate the quality status of the river water is lightly polluted. The status of water quality has been and is still suitable as river tubing tourism. [ABSTRACT FROM AUTHOR]

Groundwater is perceived as being less vulnerable to microbiological contamination than surface water, given the natural filtering ability of the subsurface. But several recent studies have reported fecal contamination in shallow groundwater of many regions of Bangladesh and several other countries. Leaching from latrine pits and soakage wells is considered the primary source of fecal contamination of shallow groundwater in Bangladesh. Bangladesh is already suffering from widespread arsenic contamination of groundwater; fecal contamination together with arsenic contamination of groundwater is alarming because shallow/hand tube wells constitute the backbone of rural water supply in Bangladesh. However, there is no comprehensive study on the distribution of fecal contamination of groundwater in the country. This study focuses on assessing fecal contamination in the groundwater of Bangladesh based on an in-depth analysis of available data. Data on concentrations of fecal coliform (FC)/E. Coli and arsenic were collected from the multiple indicator cluster surveys (MICS) conducted by BBS and UNICEF and other secondary sources. The collected data on fecal contamination and arsenic were sorted, categorized into different risk categories, and analyzed in a GIS framework. Maps were then produced in the GIS framework where regions at higher risk from the individual and combined presence of FC and arsenic were identified. Based on the analysis of available FC and arsenic concentration data (for the years 2013 and 2019) in the groundwater of Bangladesh, it appears that the presence of FC is widespread in groundwater. In the districts of Rajshahi, Rangpur, and Barishal divisions, higher percentages of wells have lower levels of FC contamination. For example, high percentage of wells in Patuakhali (96%), Bhola (95%), and Barishal (92%) districts were in the "no risk" category in 2019. On the other hand, a significant fraction of wells have higher FC concentrations in the districts of Sylhet, Comilla, and Chattogram divisions. For example, Rangamati (22%) and Noakhali (21%) districts had a high percentage of wells belonging to the "Very High Risk" category in 2019. It was also found that several districts from Sylhet and Comilla regions are at higher risks from the combined presence of FC and arsenic. In contrast, most districts in the Rangpur, Rajshahi, and Barishal regions are at lower risk from the combined presence of FC and arsenic. Fecal contamination of groundwater at the source and the household level was also analyzed in this study. FC concentrations at the household level are significantly higher than FC concentrations at the source water. The mean FC at the household level was much higher than the mean FC at the source water. Expect for Rangamati, the mean FC concentrations at the household level are higher than that at the source by a factor varying from 1.25 (Gazipur) to 66.3 (Bhola). This finding signifies the role of handling and hygiene practices in keeping water safe. This research highlights the risks associated with fecal contamination in groundwater in the different regions of the country and the urgent need to address this issue. [ABSTRACT FROM AUTHOR]

There are a lot of Iraqi cities in Iraq that used a tree supply water distribution system, it is also an old supply water network, which produces poor water quality in this network. This paper has studied water quality in two system loops and a tree net in two of Iraqi's cities requires Water GEMS. This document's goal is to review the effect of the major types of supply water distribution system on its pollution and characteristic in Iraq. The results of the analysis of two water systems show the efficiency of the loop distribution system of supply water networks compared to the tree distribution system ones in preventing water pressure drop, preserving water type, and preventing pollution. Where the dead ends in the tree network cause the deposition of pollutants, which increases the possibility of an increase in organic pollutants, unlike the loop distribution system ones, which makes the water in constant movement, which prevents the occurrence of pollution and gives water pressure stability. These results are confirmed by laboratory tests for water in both cases loop and tree distribution systems of supply water networks, in addition to QWI which showed that the loop system can maintain the quality of water and reduce the causes of pollution through the absence of this system from dead ends and the continuous movement of water. Although the water quality in the two networks was very poor because the network is old and the treatment system is ineffective. [ABSTRACT FROM AUTHOR]

Water is a natural resource and plays an important role in human life to be consumed. Water used for consumption should be clean, colorless, tasteless, odorless according the Indonesia Ministry of Health standards. The water quality test measures parameters such as pH, total dissolve solid (TDS), and water temperature based on IoT and Arduino as a microcontroller. The design of Water Quality Device Test is carried out using the value and trust design method. To solve these challenges, we propose a value-oriented reference process for innovative functionalities of a Water Quality Device Test. We have found that the consideration of the human values involved is of great importance for the identification of stakeholders throughout the development process. The results show that the comparison between laboratory test results versus Water Quality Device Test. The quality test comes from 10 depots. Based on the results of the paired sample t-test, it is known that the t-statistic or t-value for pH, TDS and drinking water temperature values shows lower value (<) than the t-table value (1.81246). These means that the pH, TDS, and temperature values of drinking water do not show differences in results when tested in the laboratory and using Water Quality Device Test. [ABSTRACT FROM AUTHOR]

Urbanization and industrialization have contributed to a deterioration of water quality at an unprecedented pace, con- tributing to harrowing diseases. Water Quality Classification is required for the purpose of public health. In this paper, an effective Support Vectot Machine (SVM) model is developed to estimate the Water Quality Class (WQC) based on the parameters like tem- perature, dissolved oxygen, pH value, Turbidity,Nitrates and fecal coliform. The dataset that has been used for WQC estimation consists total of 1991 samples with six columns corresponds to six parameters mentioned earlier. Based on the simulation results it has been observed that the proposed SVM model is able to estim ate the WQC effectively. [ABSTRACT FROM AUTHOR]

Nitrogen pollution contributes to climate change, acid rain and eutrophication. The present study evaluates the degree of nitrogen contamination of air, surface and ground waters in Bulgaria with reference to the 2021 EU Action Plan 'Towards Zero Pollution for Air, Water and Soil' as well as the relevant international and national regulations in the field. The analysis uses data from the Bulgarian Ministry of Environment and Water, Ministry of Agriculture, the European Emission Database for Global Atmospheric Research - EDGAR, and FAO. The main sources of nitrogen pollution are considered with special attention to the mineral fertilizers applied to soils in agriculture. Numerical experiments implemented with the mathematical model WAVE identified rational fertilization rates, achieving permissible nitrogen pollution of the atmosphere and groundwater at good crop yields. The methodology can be applied for recommendation of good agricultural practices in order to preserve the ecological balance and optimize the economic costs of mineral fertilizers, especially in the current situation of their prices sharp increase. [ABSTRACT FROM AUTHOR]

Thamiraparani River, flowing continuously for 128km, passes through many villages, towns and Tirunelveli Corporation. It is a perennial river and monsoon based catchment, where drainage water and night soil pollutants are mixed and the pollutants from Textile and Paper industries are drained to this region. These are the main sources of pollutants of ThamiraparaniRiver. Since long, Thamiraparani Riveris a main source of water supply to many towns which include Tirunelveli Corporation. Rapid urbanization and industrialization are the significant issues in environmental degradation especially in the quality of both surface and ground water quality. The fundamental water quality factors are, natural contamination indicated by Biological Oxygen Demand (BOD) and pathogens confirmed by coliform. The idea of the study is to predict the influences of BOD and Fecal coliform in Total coliform by using Neural Network. Water quality dataof Thamiraparani River for 12 years were collected from Central Pollution Control Board (CPCB), for six different locations such as Papanasam, Cheranmahadevi, Tirunelveli, Murappanadu, Ambasamuthram and Arumuganeri. In those samples, BOD and Fecal coliform biological parameters are used as independent variables and Total coliform is used as dependent variable. The multilayer perceptron neural network is designed to predict the Total coliform with BOD and fecal coliform as input variables. Study revealed that the association between the independent and dependent variables are good and R2value of the model was 0.846. The investigation recommends that fecal coliform and Total coliform versus BOD can be applied as contamination indicator for further research of water quality,Since BOD levels mostly mirror the level of natural contamination related tofecal sources in this waterway. The proposed ANN model uses BOD and fecal coliform to predict the future Total coliform values, which assists in easy predictability of water contaminants. [ABSTRACT FROM AUTHOR]

The study aims to determine the health safety of bottled water in the local Iraqi markets. Water samples were collected randomly for 15 brands (three replicates). Physical, chemical and bacterial tests of water samples were conducted with the application of the water quality model (WQI) to determine the quality of the studied water. The results showed that all the physical and chemical parameters analyzed were within the desired limits of the WHO, Bacteriological analysis showed that the total bacterial count of bottled water was within the limits of who except for the samples of Kani and 133 brands, which rates were 49 and 29 cells/ml and the absence of faecal coliform bacteria and WQI values ranged from 11.9 to 114.4, which were classified as excellent to poor Category. [ABSTRACT FROM AUTHOR]

To evaluate the bacteriological contamination of groundwater wells due to onsite sanitation in Jempol coast, a survey was conducted in order to measure the concentration of E. coli, and fecal coliform indicators, as well as the presence of viruses, generally infect the human. Groundwater specimens were collected from twenty-five wells in Jempol coast and were analyzed for the presence of E. coli and fecal coliform. Dominantly, bacteriological analysis results were in accordance with the Indonesian standards based on Permenkes RI no no 416/MENKES/PER/XI/1990 Occasionally, bacteriological contaminations were found in all sites. E. coli were found in all samples, respectively. Twenty-one samples (84%) were positive contaminated by Escherichia coli, and nineteen samples (76%) were positive contaminated by Faecal coliform. The overall data showed that groundwater well is impacted by human viruses. Both bacterial as indicators of pollution that have high predictive capability for the presence of other human viruses in a groundwater well. The distance of onsite sanitation analysed was closely related to the presence of the bacterial indicator and viruses. Appropriate and effective actions must be taken to improve water quality and reduce public health risk. [ABSTRACT FROM AUTHOR]

The work considered a software package that takes into account such physical processes as: transport of pollutants and heat; change in turbulent exchange coefficient; the transition of water from liquid to gaseous state; precipitation of a substance; temperature change due to condensation and evaporation of aerosols; turbulent mixing of multicomponent air; heat transfer between liquid and gaseous states; the presence of distributed sources of matter and temperature; the power of Archimedes; tangential stress at the interfaces; variable density, depending on: concentration of pollutants, temperature, pressure; compressibility of the medium due to: changes in temperature, evaporation and condensation of the liquid, changes in pressure, the presence of sources. It is proposed to expand the applicability of this software package through the use of schemes operating at large Peclet grid numbers and apply an improved software package to calculate the distribution of emissions from mobile microenergy complex. [ABSTRACT FROM AUTHOR]

Waterborne outbreaks of diseases caused by pathogenic strains of E. coli have been described in many parts of the world. For the past five years in a row, water has been the main source of contamination. Aleppo River is highly polluted by the sewage water that transferred directly without processing. So, we conducted estimate total count of bacteria, the census total coliform group, also detected E. coli and especially serotype E. coli O157:H7 in water samples that were taken from eight villages passed by the river. Our results showed significant differences between the collected samples, the total count of bacteria and total coliforms in the first site (Handarat) for water samples were the lowest, but in the last site (Jezraya) were the highest among all samples. Molecular characterization was done for eight strains of E. coli using the primer (COL-1) and eight strains of E. coli O157:H7 using the primers (OPA-03, OPA-13 OPC-12, OPE-20) in RAPD. After gel documentation, we have got eight different bands from isolated strains of E. coli, and forty-five total bands with thirteen polymorphic bands from E. coli O157:H7, also showed that primer OPA-13 was the best primer for detect E. coli O157:H7. This article also showed that RAPD analysis had a high discriminatory capacity for typing E. coli isolates. Because of its simplicity and rapidity. [ABSTRACT FROM AUTHOR]

Recent studies has shown that road traffic pollute the environment not only by generating exhaust gas emissions but also by the suspensions produced from tyre wear. Due to their composition (natural rubber, synthetic rubber and other chemicals), vehicles tyres through the interaction with the driveway pollute the environment. This process can be accelerated in a negative manner by the appearance of some technical malfunctions of the steering system. Thus, by a quick and efficient diagnosis of the steering system even during the vehicle operation can have a positive impact on the environment. The aim of this paper is to analyse the possibility of detecting the occurrence of wear in the spherical joints of the steering system, while the vehicle is running. The main methodological component of this research is a system composed by a DA20-RION 4-channels data recorder, a CAT 78 WR - Version 4.018 data processing software and a 3-axis piezoelectric accelerometer (Brüel & Kjær-type 4321). The resulted data show that in the bar end spherical joint occurs shocks due to wear. These mechanical events that can be perceived as “beats” or “steering wheel shocks” produce a misalignment of the steering system. In addition, the resulted data show that an efficient detection of this problem reduces the accelerated tyre wear and, by default, reduces micro plastics pollution. [ABSTRACT FROM AUTHOR]

The problem of oil spills during the marine transportation of oil products is still urgent today. The pollution fate and self-purification of the local ecosystem rates are still insufficiently studied. The article presents data on concentration of chloroform-extractable substances, oil hydrocarbons and the number of anaerobic bacteria in the sea bottom sediments of the Kerch Strait after the vessel’s accident in November 2007 for period of 2007 – 2009. Chloroform-extractable substances concentration in the bottom sediments of the Kerch strait belonged to low pollution level, which was typical for relatively clean water areas. It was detected the dotty distribution of oil hydrocarbons contamination in the sea bottom sediments and the tendency to its reduction through the time. The ubiquitous presence of microorganisms involved in anaerobic oil hydrocarbons degradation was demonstrated. The quantitative content of bacteria in the sea bottom sediments of the Kerch Strait during 2007 – 2009 was characterized as follows: the number of the studied bacteria groups varied widely, and there was a reduction in their numbers in compare with 2007 and 2008. [ABSTRACT FROM AUTHOR]

The microbiological quality of water at public bathing beaches is regularly monitored using fecal indicator bacteria (FIB) as a surrogate for the presence of human sewage and pathogens. The common feature of all these routine screening procedures is that the primary analysis is for indicator organisms rather than the pathogens that might cause concern. Indicator organisms are bacteria such as non-specific coliforms, Escherichia coli and Pseudomonas aeruginosa that are very commonly found in the human or animal gut and which, if detected, may suggest the presence of sewage. Indicator organisms are used because even when a person is infected with more pathogenic bacteria, they will still be excreting many millions times more indicator organisms than pathogens. It is therefore reasonable to surmise that if indicator organism levels are low, then pathogen levels will be very much lower or absent. Judgments as to suitability of water for use are based on very extensive precedents and relate to the probability of any sample population of bacteria being able to be infective at a reasonable statistical level of confidence. Exposure to FIB and associated pathogens may also occur through contact with contaminated beach sand, but no standards limiting levels of microbes in sand or required monitoring program has been established. As a result, the factors affecting FIB and pathogen survival/persistence in sand remain largely unstudied. A possible contamination of the sand by bacterial communities could be a source of transmission of certain pathogenic bacteria. The goal of this study was to look for a presence of certain bacteria that could be a source of illness to swimmers and compare the different levels of contamination between beach sand and sea water in four sites along the Western Oranian coast. First analysis were made during the dry season and rainy season from December 2010 to June 2012 to estimate fecal coliforms, Pseudomonas spp and total germs levels. E.coli and Enterococcus.ssp levels were estimated from September 2012 to June 2015. Highest levels of bacterial flora were detected in dry sand beach in impacted locations for almost all the period of studies. PCR or molecular biology techniques can be used in order to show the presence of pathogenic strains of E. coli like E.coli O157:H7. [ABSTRACT FROM AUTHOR]

Faecal contamination is of surface water resources is a significant public health problem in South Africa. Once microbial contamination has taken place, its source needs to be identified as soon as possible to decrease public health risks to emergency responders and the population at large. The standard indicator Escherichia coli is currently used as the golden standard in microbial water quality monitoring in South Africa. However, it does not allow for identification of the source of microbial contamination. Concentration ratio of the sorbitol-utilising bifidobacteria and the total bifidobacteria, i.e. tracking ratio, can be used to distinguish between animal and human sources of faecal water contamination based on a cut-off value. The cut-off value to be calibrated for site specific conditions and such a calibration is outline in this paper for South Africa. Seven sites with permanent faecal contamination were selected based on overlap between enumerations of faecal coliforms, E. coli, Rhodococcus coprophilus and the positive hydrogen-sulphide test. Concentrations of faecal coliforms and E. coli ranged from 2 to above 16000 cells/100 cm³. At the same time, concentrations of the sorbitol-utilising bifidobacteria ranged from 10-50000 cells/100 cm³, while the total bifidobacteria concentrations ranged from 0-8000 cells/100 cm³. The tracking ratio ranged from 0.10 to 6.25, but it was not able to distinguish between origins between the human and animal sources of faecal contamination. Results of survival studies showed that the total bifidobacteria died off faster than the sorbitol-utilising ones. Thus total bifidobacteria can be used to detect microbial contamination of surface water up to 48 hours, while finite concentration of sorbitol-utilising bifidobacteria indicates that a longer time has passed since the contamination event. [ABSTRACT FROM AUTHOR]