Analysis Of Water Environmental Quality Trends And Evaluation In The Decade Of The Liao River Basin

At present,the water environment pollution trend in the Liao River Basin has not been fundamentally curbed,and the pressure on the water environment is increasing.The Liao River lacks an evaluation system for these problems.In order to solve these problems,this study collected the monitoring indicators of the summer flood season during the ten-year time span of the Liao River in 2005,2010,and2015.Changes in the quality of the water environment in the Liao River Basin.The single-factor evaluation method,Weber-Fischer evaluation method,and comprehensive marker index method were used to evaluate the water environment of the Liao River Basin.The advantages and disadvantages of these methods were analyzed,and a scientific and suitable method for the evaluation of the water environment of the Liao River was selected.Research indicates:1.Evaluation and analysis of 25 monitoring sections in the Liao River Basin found that the water quality of the Liao River gradually improved during the ten years from 2005 to 2015,and the proportion of inferior Class V and Class V water decreased year by year,and the water quality compliance rate?Class IV?increased.2.There were three types of pollution in the Liao River Basin in 2005.Aerobic organic pollution(CODcr,BOD₅,COD_Mn)toxic organic pollution?volatile phenol?,and nutrient salt pollution?NH₃-N,TP?.There are still three main types of pollution in 2010:nutrient salt pollution?NH₃-N,TP?,aerobic organic pollution?BOD₅?,and toxic organic pollution?volatile phenol?.The proportion of nutrient salt pollution in the main pollution types increased.The proportion of pollution caused by oxygen organic matter pollution and toxic organic matter decreased.It can be seen from the main exceeding standards in the table that there are two types of pollution in the Liao River Basin in 2015,nutrient salt pollution?NH₃-N?,and aerobic organic pollution?CODcr,BOD₅?,of which nutrient salt pollution accounts for a large proportion.3.The water quality of the main stream of the Liao River is better than that of the Huntai River.The water pollution of the Huntai River is the most serious.This may be due to the high population density of the Hun and Tai Rivers.Large amounts of pesticides,fertilizers,urban sewage and industrial sewage are discharged.A large amount is related.4.Regarding the water quality of the Liao River Basin,the water quality in the upper reaches of the Liao River Basin is significantly better than that in the lower reaches.The sections of Sanhetun,Xing'an,Qitaizi,Yujiafang,and Tangmazhai are more polluted.Downstream pollution mainly comes from industrial wastewater discharged upstream and a large amount of township industrial wastewater received each year downstream.In addition,due to the small water flow in the downstream,the water body does not have any dilution and self-purification ability,resulting in increased water pollution.5.From the three evaluation methods,the results of the single factor evaluation method are too conservative,but can clearly see the pollutants that exceed the standard.The Weber Fischer method and the comprehensive water quality index method can reasonably and comprehensively reflect the water quality situation,but Weber Fischer method cannot directly see whether the water quality meets the standards,and it is too conservative in judging the water quality inferior to the functional area of the water body.Therefore,it is recommended to use the comprehensive identification index method for evaluation.