Water Quality Risk Assessment Research Articles

Stochastic risk assessment of water quality using advection dispersion equation and Bayesian approximation: A case study

ABSTRACTThe influence of various heterogeneous parameters, stochastic uncertain factors, and pollutant particles from the industrial effluents in the water system is investigated using advection dispersion equation (ADE) and the Bayesian approximation. Here, the decay coefficient is decomposed into the exact part and the deviation part. The coefficient is used to find out the errors and deviation in decay during the flow of pollutants. Two Bayesian models are developed to analyze the posterior distributions and to find out the Bayes factor for the stochastic covariance estimation. The Bayesian calibration focused the characteristics of both on mechanistic and statistical approximation. The efficiency and accuracy of the developed models are checked from the results obtained on the basis of the confidence interval. Markov chain Monte Carlo simulation is used to acquire the convergence point of parameters for the posterior estimation. The stochastic covariance or white noise represents the effect of random factors on the river system. The analysis revealed that the rate of decay is dependent upon the duration and distance traveled by the pollutants. The collaboration of ADE and Bayesian approximation encourage the water-quality management and environmental modeling.

Environmental risk assessment of water quality in harbor areas: A new methodology applied to European ports

This work presents a standard and unified procedure for assessment of environmental risks at the contaminant source level in port aquatic systems. Using this method, port managers and local authorities will be able to hierarchically classify environmental hazards and proceed with the most suitable management actions. This procedure combines rigorously selected parameters and indicators to estimate the environmental risk of each contaminant source based on its probability, consequences and vulnerability. The spatio-temporal variability of multiple stressors (agents) and receptors (endpoints) is taken into account to provide accurate estimations for application of precisely defined measures. The developed methodology is tested on a wide range of different scenarios via application in six European ports. The validation process confirms its usefulness, versatility and adaptability as a management tool for port water quality in Europe and worldwide.

River Water Quality Risk Assessment Using Grey Correlation in Baoji Weihe River of China

Based on the grey theory, a grey correlation evaluation model (GCEM) was built for risk assessment of river water quality. Five pollutants are used for risk assessment indicators, while the risk class was determined by the maximum principle. The results indicate that the water quality risk is higher in Baoji Weihe River of China. Potassium permanganate index risk is the maximum and the second is BOD5. The comparison with other methods confirmed that evaluation of GCEM is agreement with the actual condition. Moreover, this method is simple and solid for water risk evaluation and would be used for rive water environmental administration.

Biochemical and PCR Assay for Detection of Pathogenic Bacteria at Shrimp and Shrimp Farms in Bangladesh

The study was conducted to detect faecal coliforms and pathogenic bacteria in shrimp and shrimp farms. Although coliforms are widely distributed in the environment, but only a small percentage are pathogenic to humans. The presence of pathogenic bacteria in shrimp causes several waterborne infections in humans that are worldwide concerning issues. In order to better determination of the health risks that are associated with the exposure to pathogenic bacteria, a multiplex PCR system was used for the rapid detection of pathogenic Aeromonas sp., Clostradium sp., Listeria sp., Salmonella sp., Shigella sp., Vibrio sp. and Staphylococcus sp. in the water, sediment and shrimp. The target genes were chosen for this investigation included: Aer gene for Aeromonas sp., hilA gene for Salmonella sp., virA gene for Vibrio sp., Sec gene for Staphylococcus aureus, neurotoxin gene type A, B, E, F for Clostridium botulinum, internalin gene for Listera sp. andipaH gene for Shigella sp. Seven pairs of specific primers were used to amplify internal fragments of these genes by PCR to generate PCR products that could be analyzed and confirmed with relative ease by gel electrophoresis. The presence of Aeromona and Vibrio sp. were found in the water, sediment as well as in the shrimp that were dominant among other bacteria species. On the other hand, Salmonella and Clostridium group was found in the sediment of one sample but there is no evidence of Listeria, Staphylococcus and Shigella group in the farms. All of the samples contained relatively large number (1100 to ≥2400 cfu/g) of coliform bacteria. The unhygienic condition and polluted water source could be the major reasons for the occurrence of these types of pathogenic bacteria in the shrimp farms in this area. The result revealed that the PCRbased rapid detection system described in this study is a powerful method for routine monitoring and risk assessment of water quality in the shrimp farms and could be an effective tool for disease studies in our shrimp sector.

Reassessing the risk of microbial contamination from roosting cormorants in source water supply reservoirs

A previous water quality risk assessment of source water supply reservoirs in subtropical southeast Queensland (Australia) evaluated little black cormorants (Phalocrocorax sulcirostris) roosting on intake infrastructure as potentially posing an extreme risk of microbial contamination through direct deposition of fecal matter to the aquatic environment. To evaluate this risk rating, we assessed populations of little black cormorants occupying 3 intake structures across 2 reservoirs, enumerated Escherichia coli (E. coli) levels collected from fecal matter, and estimated a daily E. coli load to the reservoir for each population. Concurrently, we supplemented the existing routine monthly water quality monitoring program with targeted water sampling to measure E. coli concentrations in water at the 3 water intake points and at 2 sites without extant cormorant populations. Up to 3.9 × 1014 E. coli organisms were estimated to be produced per day by the largest population surveyed. Cormorants were present at intake sites and absent from reference sites; however, concentrations of E. coli were not significantly higher in water at intake sites compared with reference sites (p = 0.793 vs. p = 0.1069, respectively), and there was no significant relationship (p = 0.9671) between cormorant numbers and water column concentrations of E. coli. The inability to quantify significant differences in microbial concentrations among sites suggests a more intensive sampling regime is required to clarify the relative contribution of contamination sources. Populations of roosting cormorants in our study reservoirs are unlikely to pose an extreme risk to source water quality when compared to other catchment-based inputs that dominate microbial pollution.

A comparative analysis of current microbial water quality risk assessment and management practices in British Columbia and Ontario, Canada

Bacteria, protozoa and viruses are ubiquitous in aquatic environments and may pose threats to water quality for both human and ecosystem health. Microbial risk assessment and management in the water sector is a focus of governmental regulation and scientific inquiry; however, stark gaps remain in their application and interpretation. This paper evaluates how water managers practice microbial risk assessment and management in two Canadian provinces (BC and Ontario). We assess three types of entities engaged in water management along the source-to-tap spectrum (watershed agencies, water utilities, and public health authorities). We analyze and compare the approaches used by these agencies to assess and manage microbial risk (including scope, frequency, and tools). We evaluate key similarities and differences, and situate them with respect to international best practices derived from literatures related to microbial risk assessment and management. We find considerable variability in microbial risk assessment frameworks and management tools in that approaches 1) vary between provinces; 2) vary within provinces and between similar types of agencies; 3) have limited focus on microbial risk assessment for ecosystem health and 4) diverge considerably from the literature on best practices. We find that risk assessments that are formalized, routine and applied system-wide (i.e. from source-to-tap) are limited. We identify key limitations of current testing methodologies and looking forward consider the outcomes of this research within the context of new developments in microbial water quality monitoring such as tests derived from genomics and metagenomics based research.

Risk assessment of water quality using Monte Carlo simulation and artificial neural network method

There is always uncertainty in any water quality risk assessment. A Monte Carlo simulation (MCS) is regarded as a flexible, efficient method for characterizing such uncertainties. However, the required computational effort for MCS-based risk assessment is great, particularly when the number of random variables is large and the complicated water quality models have to be calculated by a computationally expensive numerical method, such as the finite element method (FEM). To address this issue, this paper presents an improved method that incorporates an artificial neural network (ANN) into the MCS to enhance the computational efficiency of conventional risk assessment. The conventional risk assessment uses the FEM to create multiple water quality models, which can be time consuming or cumbersome. In this paper, an ANN model was used as a substitute for the iterative FEM runs, and thus, the number of water quality models that must be calculated can be dramatically reduced. A case study on the chemical oxygen demand (COD) pollution risks in the Lanzhou section of the Yellow River in China was taken as a reference. Compared with the conventional risk assessment method, the ANN-MCS-based method can save much computational effort without a loss of accuracy. The results show that the proposed method in this paper is more applicable to assess water quality risks. Because the characteristics of this ANN-MCS-based technique are quite general, it is hoped that the technique can also be applied to other MCS-based uncertainty analysis in the environmental field.

Hazard identification, qualitative risk assessment and monitoring on the Western Corridor Recycled Water Project

This paper explains how the results of the source water characterisation for the Western Corridor Recycled Water Project in South East Queensland was used to augment the qualitative water quality risk assessment process and design of the monitoring programs. Results were evaluated against health standards published in 2008 by Queensland Health and also against level of reporting. This determined the relative risk of exceeding the health standard for parameters detected in the source. The relative risk was used to inform the qualitative risk assessment as well as the frequency of monitoring in both the source and purified water. Categorising hazards using their ionic charge and hydrophobicity enabled the selection of indicators for both source and purified water compliance monitoring programs.

Low cost microbioassay test for assessing cytopathological and physiological responses of ciliate model Paramecium caudatum to carbofuran pesticide

One of the major changes that have occurred over the past few years is the re-examination of conventional methods and the global demand for innovative low cost bioassay tests for assessing water quality, toxicity evaluation and bioremediation. In the present study acute toxicity, physiological and cytotoxic impact of carbofuran to a commonly occurring fresh water ciliate was measured. Intrinsic cytotoxicity was evident on macro nuclear apparatus that exhibited deformities such as fragmentation, deep incision, vacuolization and degenerative macronucleus. Depletion in the food vacuole formation of Paramecia was evident. Changes in the pulsatory vacuole activity of Paramecium caudatum, highlighted dose dependent response by the test compound. The simplicity of handling this ciliate makes unicellular eukaryote, an alternative organism for the toxicity assessment of pollutants. The tests carried in this study are simple and fast, a bioassay that gives overall information about the physiological and cytotoxic effects of carbofuran to P. caudatum. Such bioassay tests using ciliates are more suitable for risk assessment of water quality, early detection of water pollution and possible role of ciliates as bioindicators and strategic tools in the bioremediation of water bodies.

The complete book of pesticide management: science, regulation, stewardship, and communication

Contributors. Preface. Introduction. The Evolution of Pesticide Regulations: The Shift From Benefits to Risks (F. Whitford, et al.). Human Health Risk Assessment: Evaluating Potential Effects of Pesticides on Humans (F. Whitford, et al.). Epidemiology: Validating Human Risk Assessments (F. Whitford, et al.). Ecological Risk Assessments: Evaluating Pesticide Risks to Nontarget Species (F. Whitford, et al.). Water Quality Risk Assessment: Predicting Complex Interactions Between Pesticides and the Environment (F. Whitford, et al.). Product Development and Registration: Blending Scientific Information into Public Policy Decisions (F. Whitford, et al.). Pesticide Lables: The Convergence of Science, Public Policy, and User Responsibility (F. Whitford, et al.). Liabilities and Lawsuits: Understanding Regulations, Inspections, and the Courts (F. Whitford, et al.). Environmental Site Assessments: Managing the Facility Against Contamination (F. Whitford, et al.). Occupational Use of Pesticides: Handling Products in the Workplace (F. Whitford, et al.). Personal Protective Equipment: Selection, Care, and Use (F. Whitford, et al.). The Employee Bulletin Board: Where Employers Communicate Policies, Procedures, and Practices to Employees (F. Whitford, et al.). Planning for Emergencies: Preventing and Reacting to Emergencies in the Workplace (F. Whitford, et al.). The Insurance Policy: Protecting Yourself Against the Unexpected (F. Whitford, et al.). Educating the Community and the Workforce About Hazardous Chemicals (F. Whitford, et al.). Educating Your Consumer Clientele: A Holistic Approach to Pest Management (F. Whitford, et al.). Risk Communication: Interactions and Dialogues with the Public (F. Whitford, et al.). Today s Discussions, Tomorrow s Issues (F. Whitford, et al.). Conclusion. Index.

Rapid detection of six types of bacterial pathogens in marine waters by multiplex PCR

A rapid multiplex PCR (m-PCR) method that allows the simultaneous detection, in a single tube, of six commonly encountered waterborne pathogens is developed. The target genes used were: the aerolysin ( aero) gene of Aeromonas hydrophila, the invasion plasmid antigen H ( ipaH) gene of Shigella flexneri, the attachment invasion locus ( ail) gene of Yersinia enterocolitca, the invasion plasmid antigen B ( ipaB) gene of Salmonella typhimurium, the enterotoxin extracellular secretion protein ( epsM) gene of Vibrio cholerae and a species-specific region of the 16S–23S rDNA ( Vpara) gene of Vibrio parahaemolyticus were used as the gene targets. Multiplex PCR using the six pairs of primers produced specific amplicons of the expected sizes from mixed populations of reference bacterial strains in seawater and from pure cultures. The m-PCR assay was specific and rapid, with a turnaround time of <12 h. The detection limit of the assay for the bacterial targets was estimated at 10 0–10 2 cfu. Multiplex PCR analysis was performed on 19 seawater samples collected around Hong Kong and the results indicated significant levels of four bacterial pathogens at several sites where primary sewage wastes are discharged, and the levels of which showed no correlation with E. coli counts. Overall, both laboratory and field validation results demonstrated that the m-PCR assay developed in this study could provide a cost-effective and informative supplement to conventional microbiological methods for routine monitoring and risk assessment of water quality.

A Sensitive and Versatile Multiplex PCR System for the Rapid Detection of Enterotoxigenic (ETEC), Enterohaemorrhagic (EHEC) and Enteropathogenic (EPEC) Strains of Escherichia coli

Although Escherichia coli is widely distributed in the marine environment, only a small percentage are pathogenic to humans. Nonetheless, the widespread occurrence of waterborne infections of E. coli origin in humans has become one of the major health problems worldwide. To date, several types of enterovirulent E. coli have been recognized as the aetiologic agents of various gastrointestinal infections in humans. The most commonly encountered are those belonging to the enterotoxigenic (ETEC), enteroinvasive (EIEC), enterohaemorrhagic (EHEC) and enteropathogenic (EPEC) subtypes. In order to better determine the health risks that are associated with exposure to some of these specific subtypes, we have developed a very sensitive multiplex PCR system for the rapid detection and typing of ETEC, EHEC and possibly EPEC strains of E. coli in the aquatic environment. The target genes chosen for this investigation included: the PHO-A housekeeping gene (present in all E. coli); the LT1, LT2 and ST1 genes of ETEC; the VT1 and VT2 verotoxin, and EAE virulence genes of EHEC and EPEC, respectively. Six pairs of oligonucleotide primers were designed to simultaneously amplify internal fragments of these genes by multiplex PCR to generate PCR products that could be analysed and confirmed with relative ease by gel electrophoresis and HincII enzyme digestion. The results showed that the six sets of PCR primers were highly specific for their target genes and produced specific amplimers of the expected size from several control strains of E. coli – ATCC 35401 (LT1+/ST1+); SA53 (LT2+/VT2+); and O157 (VT1+/VT2+/EAE+). The detection sensitivity of the multiplex PCR system for the six target genes in an E. coli cell mixture was optimized and enhanced by preincubating serially diluted cells in Luria-Bertani broth for 6 h prior to PCR analysis. The results obtained indicated a detection sensitivity of 10° CFU (of each strain) per 100 μl reaction. Multiplex PCR analysis of seawater samples collected from four sewage-polluted sites in Hong Kong indicated the presence in all four samples of E. coli bacteria that were positive for LT1, ST1, VT1 and EAE virulence genes. Overall, the data indicated that the multiplex PCR system described in this study is a potentially very useful and powerful method for routine monitoring and risk assessment of water quality.