Hydrochemical Characteristics And Source Analysis Of Nitrogen In The Upper Reaches Of Qinhe River

As the first tributary of the Yellow River,the Qin River flows through the two populous provinces of Shanxi and Henan,and its water quality is healthy and whether it effectively controls the source of pollution has a very important impact on residents along the line.However,with the rapid development of modern industry and agriculture,and the greater intensity of human activities,the surface water of the Qin River has been polluted to a certain extent.Among them,the nitrate pollution of river water has been widely concerned because of its universality and particularity,and the upstream is a river basin that is vital to the river.Therefore,this paper conducts an in-depth study on the nitrate pollution in the upper reaches of the Qin River.In this paper,in the upper reaches of the Anze County of the Qin River,in October 2017,March 2018 and June 2018,three field samplings were carried out on the main stream and tributaries of the Qin River,with a total of 38 water samples and16 soil samples..The land types in the upper reaches of the Qin River are mainly farmland and woodland.The main tributaries include Ashiqiao River,Zihong River,Langwei River,Jiaokou River,the tributary of Xuemeng Village,the tributary of Longtou Village and the tributary of Dabeiwan.In this paper,water chemical analysis,statistical analysis and other research methods are combined with the ion concentration in the river water,nitrogen and oxygen and water isotope values(?¹⁵N-NO₃^-??¹⁸O-NO₃^-??¹⁵N-NH₄⁺and?¹⁸O-H₂O).The water chemistry characteristics,nitrate pollution characteristics,pollution sources and migration and transformation processes in the upper reaches of the Qin River were investigated during different sampling periods.The main research results are as follows:?1?Analysis of the physical parameters such as temperature,dissolved oxygen,conductivity,total dissolved solids and pH in the upper reaches of the Qin River during the three sampling periods,as well as the concentrations of chloride,nitrate,ammonia and total nitrogen in river water.It can be concluded that the water quality in the upper reaches of the Qin River is good.From the source to the bottom,the ion concentration in the river water increased.During the different sampling periods,there were differences in the physical and chemical parameters of the river.Among them,the nitrate concentration was higher when sampling in October 2017.?2?During the sampling period in October 2017 and June 2018,the ratio of?¹⁵N-NO₃^-and?¹⁸O-NO₃^-is about 1,indicating that the assimilation process occurred in the upper reaches of the Qin River,during the sampling period in March 2018.No obvious assimilation occurred.According to the occurrence of nitrification,one third of the produced?¹⁸O-NO₃^-is derived from atmospheric dissolved oxygen,two-thirds of the oxygen from the water,and the trend of nitrate ion and ammonia ion concentration in the river water are judged three times.Nitrification occurs during the sampling period.Combined with nitrate nitrogen and oxygen isotope values and nitrate ion concentration,it was judged that denitrification occurred at some points in June 2018.When there is a positive linear correlation between the?¹⁵N-NO₃^-value of the river water and the reciprocal of the NO₃^-concentration,there is a mixing process,and it is judged that during the sampling period in June 2018,some points are mixed.?3?The nitrate nitrogen and oxygen equivalents and the ammonia nitrogen and nitrogen isotope values are different in different pollution sources,and based on the chloride ion concentration and NO₃^-/Cl^-molar ratio,and investigating the nitrate value and nitrate value of different land types in the upper reaches of the Qin River,comprehensively determine the nitrate in the river during different sampling periods.Source of pollution.The results showed that the source of nitrate pollution in October 2017 was mainly ammonia fertilizer urea,soil nitrogen and animal manure;in March 2018,nitrate source was mainly soil N and domestic sewage;in June 2018,the source of nitrate pollution was mainly ammonia fertilizer,soil N animal waste and domestic sewage.