| Drinking water quality is one of the important factors affecting health.However,regional and urban-rural differences in drinking water quality have long existed both in the world and in China.Optimizing drinking water quality evaluation methods and objectively and scientifically evaluating drinking water quality conditions,characteristics and influencing factors are the prerequisite and basis for drinking water safety.The comprehensive water quality evaluation index has the advantages of qualitative and quantitative analysis of water quality,strong stability,and conducive to the comparison of water quality in different dimensions,and it can filter out key pollutants according to the set rules.Object:1.Constructing the Chongqing Rural Drinking Water Quality Index,analyzing the changing trend and water quality characteristics of Chongqing’s rural drinking water quality index from 2013 to 2019,and grasping the characteristics and temporal and spatial changes of Chongqing’s rural drinking water quality.2.Studying the regional distribution characteristics of drinking water quality in rural areas and its correlation with factors such as water supply type,water period,and social and economic factors,and putting forward the main influencing factors of drinking water quality in rural areas in Chongqing,and providing reference and technical support for the formulation and implementation of rural drinking water safety guarantee strategies.Methods:1.Collect the monitoring data of rural drinking water samples in Chongqing from 2013 to 2019 and the social and economic development indicators of Chongqing.2.Establish a comprehensive evaluation index system for drinking water quality and water quality classification evaluation criteria for rural drinking water in Chongqing using the method of literature research.The water quality indicators included in the evaluation index system are selected according to the water quality characteristics over the years,and different sub-index evaluation methods are adopted according to the hygienic significance and health effects of the classification indicators.3.Use Excel 2016 to establish a database and calculate the water quality index and water quality evaluation classification.Using SPSS 22.0 to perform descriptive analysis of water sample monitoring data and calculated water quality index and water quality good rate,non-parametric test of multiple independent samples and single factor and multiple factor analysis,the test level is 0.05.Use ArcGIS 10.2 software to draw regional maps of rural drinking water quality,use GeoDa 1.16 software to analyze the spatial correlation of the rural drinking water good rate and set up a spatial weight matrix;use R software to build a spatial panel model to analyze the society and economic factors of rural drinking water good rate.Results:1.From 2013 to 2019,a total of 29,077 rural drinking water samples were included for analysis,with an average WQI of 0.54±0.56.Among them,the number of good water samples was 25,798,and the total good water quality rate was 88.72%;within the study period,the WQI showed a downward trend,and the good water quality rate showed an upward trend.2.The unqualified indicators for rural drinking water in Chongqing from 2013 to 2019 are mainly microbiological indicators,sensory indicators and general chemical indicators,of which the total coliform is about 60%,the total number of colonies,turbidity,visible matter,and oxygen consumption are qualified.The rate is low.In 201 3,the qualified rate of ammonia nitrogen was low(77.73%),but then the qualified rate gradually increased.The qualified rate of total coliforms,total number of colonies,and naked-eye substances was higher in dry periods than in wet periods;turbidity and oxygen consumption qualified rates in dry periods were lower than in wet periods,and the differences were statistically significant.3.From 2013 to 2019,Chongqing rural drinking water toxicological index and general chemical index sub-index decreased,pollution index sub-index decreased significantly,microbial index sub-index decreased slightly,and the inter-annual difference of each sub-index was statistically significant.4.From 2013 to 2019,the WQI of Chongqing’s rural drinking water is lower than the wet period,the factory water is lower than the end water,and the large-scale water supply project is lower than the small-scale water supply project.The rate of good water quality was higher in the dry season than in the wet season,the factory water was higher than the terminal water,and the large-scale water supply project was higher than that of the small-scale water supply project.The differences were statistically significant(P<0.05).5.The rate of excellent drinking water quality in rural areas of Chongqing from 2013 to 2019 is positively correlated with space.From 2013 to 2017,the global Moran index dropped from 0.7251 to 0.4943;from 2017 to 2019,the global Moran index rose from 0.4943 to 0.5353.The quality of drinking water in rural areas in Chongqing is characterized by regional clustering.In the northeast,west and south,there is a high concentration of high and high drinking water rates in rural areas,which has gradually expanded from 2013 to 2017,and has decreased significantly after 2017.The range of low and low aggregation areas has shrunk since 2015,and the southeast and west have decreased significantly,but there has been no significant change in the northeast.6.The urbanization rate and the per capita disposable income of rural residents are positively correlated with the rate of good water quality.The urbanization rate increased by 1%,and the rate of good water quality increased by 0.4266%;the per capita disposable income of rural residents increased by 1 yuan,and the rate of good water quality increased by 0.0003%.Per capita GDP and the proportion of primary industry in GDP are negatively correlated with the rate of good water quality.Per capita GDP increased by 1 yuan,and the rate of good drinking water in rural areas decreased by 0.0005%;the proportion of primary industry in GDP increased by 1%,and the rate of good drinking water in rural areas decreased by 4.5121%.Conclusion:1.The comprehensive evaluation index of rural drinking water quality in Chongqing based on Nemerow index method and worst factor discriminant method can better reflect local water quality changes and water quality characteristics.2.From 2013 to 2019,the quality of rural drinking water in Chongqing showed an overall improvement trend,and the main unqualified indicators were microbiological indicators and general chemical indicators.3.From 2013 to 2019,the quality of rural drinking water in Chongqing is better in dry periods than in wet periods,factory water is better than peripheral water,and large-scale water supply projects are better than small-scale water supply projects.4.From 2013 to 2019,the rate of good drinking water quality in rural areas in Chongqing is positively correlated,and the improvement trend of water quality in all regions is consistent.From 2013 to 2017,the spatial accumulation and growth rate of the excellent rate of drinking water in Chongqing’s rural areas declined year by year,suggesting that the improvement of drinking water quality in each region at this stage is less affected by the inherent characteristics of the region,and the main influencing factor may be investment in drinking water safety,etc..From 2017 to 2019,the spatial agglomeration of good water quality rates showed an increasing trend,suggesting that the influence of the inherent characteristics of the region at this stage is increasing.There are still certain unbalanced developments in various regions.For example,the low-and low-aggregation areas in the northeast have not changed significantly during the study period.5.Types of water samples,types of water periods,scale of water supply,and water treatment methods are the main technical factors affecting the rate of good drinking water quality in rural areas of Chongqing.Urbanization rate,per capita disposable income of rural residents,per capita GDP and primary industry accounted for GDP Proportion is the main socio-economic factor influencing the rate of good water quality.The difference in development between urban and rural areas may be one of the factors affecting the quality of drinking water. |
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