Comprehensive Analysis Of Physical And Chemical Factors And Species And Quantity Of Phytoplankton In Ankang Yinghu Reservoir

Ankang Yinghu Reservoir is located 16km southwest of Ankang City,on the main road of Hanjiang River.It is an artificial lake formed by the dam of Ankang Hydropower Station to intercept the water of the Han River.It has functions of water supply,power generation,flood control,shipping,tourism and fishery.After the operation of the reservoir,the Ankang fishery,which is mainly based on cage culture of Yinghu Reservoir,has developed rapidly.According to the Ankang Statistical Yearbook,the fishery output increased from 6,687 tons to 41,421 tons in the 13 years from 2006 to 2018,with an output value of 0.88 billion yuan to 19.5.100 million yuan,an annual increase of 143 million yuan.In 2014,the operation of the Middle Route of the South-to-North Water Transfer Project,Yinghu Reservoir as an important water source conservation area in the upper reaches of the Han River,the development of fisheries and the protection of the water environment have produced certain contradictions.In order to protect the water quality of the water source conservation area of the South-to-North Water Diversion Project and accumulate the basic data of the Yinghu Reservoir,this experiment monitored the water quality and the species and quantity of plankton from 2015 to 2018,including July 2015-June 2016.It is monitored once every two months from August 2016 to June 2017 and once every quarter in 2018.During the period,due to the removal of the cages in Yinghu,the sampling points in 2018 were adjusted from 6in the previous year to 6.The monitoring results showed that the physical and chemical indicators showed periodic changes,and individual indicators such as sulfate ion,COD?permanganate index?and total phosphorus fluctuated greatly?p<0.05?.The water temperature is the highest in summer,34.29°C,the lowest in winter,10.14°C;the average transparency of water body is2.38 m,the highest in winter is 4.37 m;the pH is 7.39-8.90;the content of Cl^-?Mg²⁺?Ca²⁺?SO₄^2-and the total hardness of water are consistent.Class I water quality standard for surface water;dissolved oxygen in water 10.16 mg/L,close to saturation,COD content 5.60 mg/L,in line with surface water III water standard,total nitrogen content of water body 2.02 mg/L,exceeding the standard of surface water V water The total phosphorus content is 0.36 mg/L,which is in line with the surface water?river?V water standard;in 2018,the petroleum content is 2.22 mg/L,which exceeds the standard of surface water V water.From the results of phytoplankton monitoring,in 2015-2016,a total of 41 species of 37genus of phytoplankton were found in the water body,and 39 species of phytoplankton were found in 2018.The phytoplankton monitoring results in 2015-2016 showed that the phytoplankton density peaked at 1.76 million/L in May,and was significantly lower than the other months?p<0.05?.The results of 2018 showed that the dominant algae species were transgenic algae,chlorella,chlorella and alfalfa-shaped algae,among which the spring algae,summer chlorella,autumn algae,and winter algae were dense.Both belong to the green algae gate,indicating that the water body is rich in nutrients,and the highest density of algae in April is 200,000/L.The phytoplankton diversity index H'value was 1.58 in 2015-2016,the water quality was moderately polluted,the J value was 0.55,and the water body was clean-widowed;while the H'value was 3.19 in 2018,the water quality was cleaner,2018 J The water value is 0.87,and the water body is clean.The phytoplankton diversity index in2018 is higher than that in 2015-2016,and the overall water quality has improved.Conclusion:?1?The physical and chemical factors of water quality in Ankang Yinghu Reservoir basically meet the national water quality class II water standard,the water quality is gradually improving,and individual factors have a tendency to deteriorate,such as total nitrogen and total phosphorus;?2?The species and quantity of phytoplankton and the species and species uniformity index indicate that the water quality of the lake is gradually improving,and the water body is suitable for fish growth.