| Qilu Lake is one of the nine largest plateau lakes in Yunnan Province,It is an important water resource in Tonghai county,Since the mid-to-late 1980s,Qilu Lake has been heavily polluted because many pollutants have been released into the lake,So It is imminent to carry out the basic investigation and research on the prevention and control of eutrophication of Qilu Lake,To this end,I proposed practical measures for preventing and controlling eutrophication,offering a basis for decision-making to improve,conditions of the water bodies(eutrophication status)in the near and long term.The conclusion was as follows:(1)The annual comprehensive nutritional statu s index in 2018 was 62.8,listed as moderately eutrophication.(2)The correlation between the comprehensive nutritional status index and the monitoring value of the monthly evaluation index was studied,the detection data came from three areas:regional centers,shallow water and near shore of Qilu lake.The results showed that the total nitrogen correlation was the highest among the four positively related evaluation(R~2=0.904),and the correlation of permanganate index was the lowest(R~2=0.369),It indicated that the agricultural area was major pollution source.The total nitrogen value for improving eutrophication status of Qilu Lake is the most important and it is the first index which would be reduced.(3)There are four types of pollution source in the Qi lu lake,1)the runoff of five main rivers,2)the discharge by agricultural slope of the discharge area after rain,3)the agricultural drainage area during drainage,and 4)nature release when raining and dust falling.(4)Based on the similarity and typical characteristics of the pollutant into the lake,the lake basin is divided into four pollution control area modules in accordance with principles of similarity,and typical and conjugate of the basin.They are lake river area,lakeside agricultural drainage area,agricultural slope dispersion area and rainfall and dust areas on the lake,which are divided into the river area into the lake-in-the-lake,the lake-side agricultural drainage area,the agricultural slope scattered flow area,the lake surface rainfall and dust drop area.The module will be divided into regional modular control.(5)The net pollution load discharged into the lake in 2018,in the lake river area,the lakeside agricultural drainage area,the agricultural slope scattered area,the lake surface rain and dust drop area into the lake is:3632.04 tons chemical oxygen demand(chromium method),776.68 tons permanganate,921.96 tons total nitrogen,39.70tons total phosphorus.(6)The eutrophicization control of the four types of basins of Qilu lake includes several steps:1)the prevention and control of the lakeside agricultural drainage area,2)the prevention and control of agricultural slope scattered drainage areas,3)the prevention and control into the lake river area again,and 4)the prevention and control of lake rainfall and dust ingenuity areas.The above steps in the abstract and the conclusion(2)further showed that the pollution source of Qilu lake is mainly agricultural cultivation source pollution.(7)After the implementation of the prevention and control,the results showed a great deal of reduction:200.69 tons total nitrogen,4.97 tons total phosphorus,142.99tons permanganate,674.14 tons chemical oxygen demand(chromium method),total nitrogen concentration by 0.93 mg/L,total phosp horus concentration by 0.06 mg/L,permanganate concentration by 6.2 mg/L,Chemical Oxygen demand(chromate method)concentration by 27 mg/L.Through prediction without considering the impact of endogenous pollution and self-purification ability of Qilu Lak e,the comprehensive nutritional status index will drop from 62.8(before the implementation of the prevention and control)to 58.3,and the eutrophication level of Qilu Lake will change from moderate nutrition to mild nutrition after implementation,and the water quality will be significantly improved。... |
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