Evaluation Of Water-quality And Water Environmental Capacity Of Guangdang River In Yantai

Water environment has been seriously damaged because of the development of my country’s economy.Higher requirements were put forward for water environment management.The overall evaluation of water environment based on water environment capacity was of great significance.In this paper,water-quality index of the river is measured,and the water environmental capacity is calculated under different hydrological conditions.The main research contents include:（1）The analysis of environmental factors and the use of water quality comprehensive pollution index method for water quality Evaluation;（2）Analyze the sediment nitrogen,phosphorus and heavy metals,and use the geo-accumulation index evaluation method to evaluate the sediment heavy metal pollution;（3）Select chemical oxygen demand and ammonia nitrogen as total control factors,and use one-dimensional water quality model to caculate water environment capacity under different hydrological conditions.The main results and conclusions of this paper are as follows:（1）The temporal and spatial distribution of water environmental factors in the Guandang River were obvious.In terms of time,the seasonal changes of TN and COD concentration were consistent,showing summer>autumn>winter>spring;TP concentration distribution law was summer>spring>autumn>winter;NH₃-N concentration distribution pattern was summer>spring>winter>autumn.There were differences among the pollution factors in space.The concentration of NH₃-N and TP at the upstream source and De yuan shopping area was lower,and the pollution factors at downstream points close to the factory were more serious.（2）From the calculation results of the comprehensive pollution index,the comprehensive pollution index of the five samping points from the source to the estuary were P₁=1.5,P₂=1.75,P₃=1.95,P₄=2.19,P₅=2.17 respectively.Except point 5,the overall trend was increasing,and 1.0<P≤2.0,indicating that the Guangdang River had reached moderate pollution and above.（3）The total number of bacterial colonies in the Guangdang River fluctuated greatly,ranging from 2.2×10³CFU/m L to 3×10⁴CFU/m L.The average total number of colonies in spring,summer,autumn and winter were 7.8×10³CFU/m L,2.4×10⁴CFU/m L,1.5×10⁴CFU/m L,and 7.4×10³CFU/m L,respectively.（4）The concentration of TN in the sediments of the Guangdang River ranged from 534.17 mg/kg to 812.19 mg/kg,with annual average content of 635.89 mg/kg;the TP content ranged from 66.29 mg/kg to 285.98 mg/kg,and the average content was 184.87 mg/kg,sediment nitrogen pollution was more serious than phosphorus pollution.（5）The Cu element in the sediments of the Guangdang River ranged from 44.28mg/kg to 148.23 mg/kg,with an average of 84.67 mg/kg;the Zn element varied from107.25 mg/kg to 372.48 mg/kg,with an average of 247.15 mg/kg;Pb element varies from 54 mg/kg to 102.6 mg/kg,with an average value of 70.02 mg/kg;Ni element varies from 17.75 mg/kg to 47.75 mg/kg,with an average value of 32.28 mg/kg;Cr element varies between 30 mg/kg to 141.5 mg/kg.The content of heavy metals was Zn>Cu>Cr>Pb>Ni.（6）According to the calculation results of water environment capacity,the total COD water environment capacity in the dry season was 9244.59 t/a,and the total NH₃-N water environment capacity was 1375.04 t/a.The water environment capacity was different in different hydrological periods,and the water environment capacity was the largest in the wet period.The flat water period was the second,and the dry period was the smallest.Affected by the length and attenuation coefficient of the river section,the water environment capacity of sections C and D was large,and the water environment capacity of sections A and B was small.