Analysis Of The Water Quality Of Water Disperse Supply In Rural Area Of Guizhou Province

Guizhou,located in southwestern China,is rich in water resources,with surface water reserves exceeding 120 billion m~3.However,Guizhou water resources are labeled as“water shortage”,“distribution imbalance”,“uneven supply and demand”,and“rural water pollution”because of the typical karst landform.To this end,Guizhou’s"13th Five-Year Plan"and the 2019"Guizhou Water Resources Protection Plan"have made decisions to increase investment in water conservancy projects,and have focused on the weak links of Guizhou’s water conservancy projects,especially focused on rural disperse water supply safety.According to statistics,the rural population of Guizhou using decentralized water supply accounts for about 76%of the rural population in the province.In January 2018(dry season),May(beverage period),and September(flat period),the conventional index analysis and modeling evaluation of the decentralized water supply quality were carried out in Luoguang Village,Wudang District,Guiyang City.On this basis,MiSeq sequencing technology studies the community structure and diversity of drinking water microbes in different water source types and different periods in the water supply system.The effects of microbial community structure and diversity on drinking water quality in rural areas were discussed,and the response relationship between microbial community and environmental factors was clarified.We have the following findings:(1)A total of 33 water samples were collected during the three periods.In the analysis of 17 physical and chemical indicators,fluoride,nitrate nitrogen and iron were all lower than the national standard limit.However,the turbidity in the dry season exceeded the standard significantly,reached 61%;Manganese content exceeded the standard in some water samples.(2)It is found by the traditional HPC counting test that there is serious microbial contamination in the water sample.In terms of the total number of bacterial colonies,the over-standard rate in dry season was 36.36%,the over-standard rate in the wet season reached 84.62%,the over-standard rate in the flat water period was 100%,and the total over-standard rate of bacterial colonies was 72.73%.The results of coliform group test showed that the over-standard rate was 9.10%in dry season,69.23%in high-water period,44.44%in flat water period,and 42.42%in coliform group.(3)Based on physical and chemical indicators and microbial indicators,the water quality was evaluated by grey correlation method.The results showed that the water quality of all water samples was Class I,and the water quality was better.(4)A total of 26 phylums,55 classes,154 orders,270 families and 479 genera were detected in the collected water samples.Proteobacteria and Bacteroidetes were dominant at the phylum level,while the proportion of bacteria in each sample was different at the genus level.Limnohabitans and Flavobacillus were the two dominant genera with high abundance in all samples.(5)Environmental factors have a great influence on species distribution,and which dissolved oxygen and pH are the main environmental factors affecting the distribution of bacterial communities.In general,the correlation analysis between species and environmental factors was affected by sampling time,sampling point and water sample type.(6)In addition to stream water,there is no significant difference in species distribution between different water source types and different sampling points of the same type of water source.However,there are some differences in microbial species composition of water samples in different periods,and the similarity of microbial species composition among the samples in the wet season is high.