| Background:Enteric viruses are an important group of water-borne pathogens,which spread disease mainly through polluting water sources.These viruses are transmitted by the fecal-oral route with the characteristics of rapid transmission and high incidence of susceptibility crowd,resulting in a wide range of waterborne diseases,such as gastroenteritis,poliomyelitis,hand-foot and mouth disease.Infectious diarrhea is the main cause of morbidity and mortality among children in developing countries and a major cause of malnutrition among children.Viral diarrhea is the most common cause of infectious diarrhea in children,accounting for approximately 70% of children with infectious diarrhea.According to the World Health Organization(WHO),diarrheal disease accounts for the second leading cause of death in children under 5 years globally,with 525,000 deaths each year.Therefore,the epidemic of infectious diseases caused by enteric viruses infection has had a serious impact on human health.Exposure to virus-contaminated water is considered to be one of the major causes of outbreaks of enteric viruses infection.Meanwhile,most of the urban sewage and hospital sewage are directly discharged into the water after being treated by the sewage treatment system,the pollution of viruses in water can be an indicator,to some extent,of disease outbreak in people.Therefore,accurate and rapid detection of enteric viruses pollution in water is of great significance for the prevention and control of future infectious diseases.However,there are no ideal methods or indicators that are typically correlated with or specific enough to predict the presence of enteric viruses and the detection of virus in water is time-consuming and laborious,viral pollution in water has been overlooked for a long time.There is an urgent need for new techniques that can accurately predict enteric viruses pollution in water.Thus,we proposed the scientific hypothesis of "Constructing a mathematical model based on routine water quality indices to predict enteric viruses pollution in water".On the basis of the confirmation of enteric viruses pollution regularity in water and the associated factors,we constructed three prediction models based on the physicochemical and bacterial indices to realize the rapid prediction of enteric viruses pollution in water.Purpose and significance:This study aims to realize the rapid and effective prediction of enteric viruses pollution in urban river through the establishment of mathematical models to predict the concentration of enteric viruses in Haihe and Jinhe river,which provids a powerful tool for the rapid prediction of enteric viruses pollution in water and early warning of water-borne disease occurs in people.Beyond that,an efficient method for the concentration of viruses in large volume coastal water was also established in our study and a one-year detection of enteric viruses in Qingdao’s first bathing beach was completed.The distribution rules of enteric viruses in coastal water were preliminarily discussed in our study,which laid a solid foundation for the prediction of enteric viruses pollution in coastal water.In short,this study will bring about new ideas and new ways for the detection of enteric viruses in water and the prevention and control of related diseases.It also provides a theoretical basis for the effective prevention of disease occurrence and the control of disease development,which will ultimately promotes the development of public health.Contents and methods(1)Study on the pollution rules of enteric viruses in urban rivers: Taking Haihe and Jinhe River flowing through the center of tianjin city as research objects,the enteric viruses,water quality physicochemical and bacterial indices as monitoring objects,a four-year study has been conducted from March 2012 to February 2016.By analyzing the temporal variation of enteric viruses,we can master the pollution rules of enteric viruses in urban rivers.(2)Study on the pollution prediction techniques of enteric viruses in urban rivers: The influence of physicochemical and bacterial indices on the concentration of enteric viruses in urban rivers was comprehensively analyzed in this study as well as the correlation between them.Based on the time series variation of enteric viruses concentration,three mathematical models for predicting enteric viruses pollution in urban rivers were established taking physicochemical and bacterial indices as variables,which were also used to predict and verify the pollution of enteric viruses in other urban rivers.(3)The establishment of an efficient method for the concentration of viruses in large volume coastal water: Based on the intelligent system with electropositive granule media independently developed by our laboratory for concentrating viruses from large volumes of water,the influence of coastal water quality on the virus recovery of the system was discussed and the parameters needed for virus cincentration in coastal waters were determined.The established system was also compared with other virus concentration methods to verify its effectiveness.(4)Study on the distribution rules of enteric viruses in coastal water: Taking Qingdao’s first bathing beach as the research object,the enteric viruses,water quality physicochemical and bacterial indices as the monitoring objects,a one-year study has been conducted from January 2018 to December 2018.By analyzing the temporal variation and spatial distribution of enteric viruses,and the relationship between enteric viruses and water quality physicochemical or bacterial indices,we can preliminarily master the pollution rules of enteric viruses in coastal water.Results:(1)Rotaviruses(HRVs),Astroviruses(AstVs),Noroviruses(HuNoVs)and Adenoviruses(HAdVs)in Haihe and Jinhe River were 100% detected in winter and reached the peak of virus concentration,while Enteroviruses(EnVs)were 100% detected in summer,and the virus concentration reached the highest in August.There is a positive correlation between EnVs concentration and total coliforms(TC)in Haihe and Jinhe River.TC may be an ideal indicator for the presence of EnVs in surface water.In addition,there are different degrees of correlation between enteric viruses concentration and physicochemical or bacterial indices in Haihe and Jinhe River.(2)The Multivariable Linear Regression(MLR),Artificial Neural Network(ANN)and Nonlinear Auto-Regressive with external input(NARX)models can all realize the prediction of the concentrations of enteric viruses in Haihe and Jinhe River.The NARX model has the highest prediction accuracy in predicting the concentrations of viruses in the rivers with the R values fitted to the all data set of Haihe and Jinhe River greater than 0.9.The NARX model can also accurately predict the concentrations of enteric viruses in water 6 months in advance.Compared with the MLR and ANN models for the simultaneous prediction of viruses concentrations,the NARX model has obvious advantages.Followed by the ANN model,the R values fitted to the all data set of Haihe and Jinhe River are all greater than 0.8.The MLR model can accurately predict 23.6% to 86.0% of the concentrations of enteric viruses in Haihe and Jinhe River.The MLR,ANN and NARX models are more suitable for predicting the concentration of viruses in Haihe and Jinhe River and are not fully applicable to the prediction of enteric viruses concentrations in other urban rivers.(3)The Electropositive Granule Media(EGM)filtration system developed in this study could recover more than 88% of the enteric viruses from large volumes(10L~100L)of coastal water.This method is not affected by water temperature,pH value,chemical oxygen consumption,ammonia nitrogen content and virus content,and is suitable for the concentration of Coxsackieviruses(CVs),AstVs,HuNoVs and HAdVs in coastal water.It does not require any clarification steps before filtration,and the viruses adsorbed on the solid matrix can also be effectively enriched.(4)HAdVs and AstVs were detected in varying degrees in different areas of Qingdao’s first bathing beach.HuNoVs and EnVs were detected in the sewage of the sewage outlet,indicating that enteric viruses pollution is prevalent in the bathing beaches.Among them,HAdVs and AstVs in the swimming area reached the lowest concentration in winter,while the virus concentration peaked in the summer and autumn with higher concentrations than that in the middle area and the polluted area,indicating that the tourists on holiday brought a certain degree of fecal pollution to the bathing beaches.The concentrations of HAdVs,AstVs and HuNoVs in sewage reached the highest in winter,and the concentrations of HAdVs and AstVs in the sewage is higher than those in the coastal water of the entrance,indicating that coastal water had a strong dilution effect on enteric viruses discharged with sewage.Conclusions:(1)HAdVs,HRVs,HuNoVs and AstVs in Haihe and Jinhe River all showed obvious seasonal regularity.There are different degrees of correlation between enteric viruses concentrations and physicochemical or bacterial indices in Haihe and Jinhe River.TC may be an ideal indicator for the presence of EnVs in surface water.(2)The MLR,ANN and NARX models established in this study can all realize the prediction of the concentrations of enteric viruses in Haihe and Jinhe River.The NARX model has the highest prediction accuracy and can accurately predict the concentrations of enteric viruses 6 months in advance.The MLR,ANN and NARX models are more suitable for predicting the concentrations of viruses in Haihe and Jinhe River.(3)An efficient method has been successfully established in this study for viruses concentration in large volume(10L~100L)of coastal water with a virus recovery rate higher than 88%.(4)Enteric viruses pollution is prevalent in the Qingdao’s first bathing beach and tourists on holiday bring a certain degree of fecal pollution to the bathing beach.Coastal water has a strong dilution effect on enteric viruses discharged with sewage. |
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