| The Weihe River is a tributary of the Yellow River and an important river in Shaanxi Province.With the rapid economic development of Shaanxi Province,the water consumption of industry and agriculture has increased,and the pollutants discharged into the water body have been increasing,which has caused the water quality to deteriorate and lose its originality.The function.In recent years,the state has gradually attached importance to the protection of the ecological environment.The Shaanxi Provincial Government has issued a number of policy documents on the restoration and restoration of the water quality of the Weihe River.In this study,the water quality monitoring of the Shaanxi section of the Weihe River Basin in 2017 and 2018 was carried out to evaluate the water quality status and provide reference for the comprehensive management of the Weihe River.The main findings are as follows:(1)The Baoji section of the Weihe River has a good water quality.The Linjiacun section meets Class II water quality standards for surface water in 2017 and 2018,and the Wolongsi Bridge section meets Class III water quality standards.From the Nanying section to the Shaoguanqiao section,the water body is polluted to varying degrees.In 2017,the Nanying section,the railway bridge section,the Tianjiang Rendu section,and the Genzhen bridge section were seriously polluted,only for Class IV and Class V water quality.As it goes downstream,with the continuous re-inflow of tributaries,the pollution of the main stream is more serious.(2)The COD of the Weihe River tributary section meets the water environment functional standards.In 2017,the main stream of the Weihe River was mainly the section of the Genzhen Bridge and the section of the ammonia-nitrogen section of the Tongguan Bridge.The ammonia-nitrogen concentration in the spring-season period(April)of the Genzhen Bridge section was 1.21 mg/L in spring and the ammonia nitrogen concentration in the wet season(June)was 0.43.Mg/L,the ammonia nitrogen concentration in the high water period(August)was 3.71 mg/L,exceeding the standard 1.85 times,and the ammonia nitrogen concentration in the autumn flat water period(October)was 0.56 mg/L.The Tongguan Bridge in the spring of 2017(April)has an ammonia nitrogen concentration of 2.87 mg/L,which is 1.43 times higher than the standard.In the wet season(June),the ammonia nitrogen concentration is 2.40 mg/L,exceeding the standard by 1.2 times,and the flood season(August).The ammonia nitrogen concentration was 1.33 mg/L,and the ammonia nitrogen concentration in the flat water period(October)was 0.65 mg/L.In 2018,the ammonia nitrogen in the section of the Genzhen Bridge section exceeded the standard,and the remaining sections were able to meet the water environment functional standards.(3)In addition to the section of Linjia Village and the section of Wolongsi Bridge in the Weihe River Basin in 2017,the total phosphorus in the other sections exceeded the standard,and the total phosphorus in some sections exceeded the standard.In 2017,the total phosphorus concentration in the main stream section exceeded the standard,and the excess standard exceeded from 1.3 times to 5.4 times.In 2018,except for the section of Linjia Village and Wolongsi Bridge,the total phosphorus in each section meets the water quality standard of Class IV or V.Compared with 2017,the total phosphorus concentration in 2018 is significantly lower,but it still cannot meet the standard requirements.(4)The results of analysis of dissolved organic matter in water show that the type of dissolved matter in the water quality of Weihe River in October 2018 is mainly a complex type of proteinoid and humus,and the main external organic matter is judged according to the organic matter type in the Linjiacun section,Wolongsi section,Thousands of rivers into the Weihe section.(5)Among the monitored tributaries,the Qianhe River into the Weihe section and the Heihe River into the Weihe section have good water quality and can meet the water quality functional zoning requirements.The Weihe River into the Weihe section and the Beiluo River into the Weihe section are more serious.The most serious section is the Beiluo River into the Weihe section.In 2017,the ammonia nitrogen exceeded the surface water IV standard by 0.59 to 0.91 times.(6)The main component factor analysis method was used to analyze the monitoring results,and the components that mainly affect the water quality of the Weihe River were COD,ammonia nitrogen and total phosphorus.The comprehensive water quality index method was used to evaluate the water quality status of the Weihe River in 2017 and 2018.It was found that the Linjia Village,Wolongsi Bridge,Nanying and Railway Bridge sections met the water environment functional standards in the main stream of the Weihe River in 2017.Since the Tianjiang Rendu section,the water quality of the Weihe River has been polluted to a certain extent.The water quality results are only for Class IV and Class V water,of which the Shaoguan Bridge section is the most polluted.In 2018,the water quality of the main stream section of the Weihe River has been significantly improved compared with 2017,and all sections meet the water environment functional standards.(7)The grey model of the water quality of the Shaoguanqiao section of the Weihe River in Shaanxi Province was modeled in 2017,and the COD,ammonia nitrogen and total phosphorus content of the Shaoguanqiao section in October 2018 were predicted and compared with the measured values.The COD,ammonia nitrogen and total phosphorus contents of the Shaoguanqiao section were predicted in April 2019,and the concentrations were 2.13 mg/L,0.03 mg/L,and 1.09 mg/L,respectively.The comprehensive water quality index was used to evaluate the section of Shaoguan Bridge in April 2019.The evaluation result is I_wq=3.313,which belongs to Class III water.It can be inferred from the prediction results that the water quality of the main stream of the Weihe River will change continuously in 2019 to reduce the pollution and meet the water environment functional standards. |
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