The Marine Water Quality Criteria Of N&P And Application In Yueqing Bay

Harbor is an important area for marine economic development and marine biological ecological environment protection.With the reform and opening up,the continuous development of the economy,the harbor area of the marine environment has been more serious pollution.At present,the assessment of the water environment of the harbor is mainly based on the single factor,and the most polluting indicators represent the overall environmental status of the region.This will not objectively reflect the present situation and changes of the water environment in China.According to the existing water quality evaluation methods in China,the water quality of harbor waters in China cannot meet the water quality requirements of any functional area.However,in fact,the marine function of harbor is better and the difference is significant.Therefore,in view of the shortcomings of the existing evaluation methods in the harbor,it is necessary to establish a water quality evaluation method which is more applicable to the harbor waters of our country on the basis of the system research for a more scientific and objectively reflecting the present situation of the water environment in the Yueqing Bay waters.In the establishment of this evaluation method,the environmental benchmark is an important part,but now our country for a variety of environmental factors criteria value of the study is still not perfect,and China’s coastal waters have their own characteristics of different characteristics of foreign indicators criteria values and research methods used to take over the direct use of its evaluation results in China is not applicable.Based on the above-mentioned problems,this paper takes the important harborYueqing Bay in Zhejiang Province as the research area,taking inorganic nitrogen and active phosphate as the research factor to determine the criteria value of inorganic nitrogen and active phosphate in Yueqing Bay as the research topic,coefficient of variation(Cv)and frequency analysis were used to analyze the data of the monitoring data,the monitoring data of Yueqing Bay,the monitoring data at the entrance of Yueqing Bay,and the environmental quality bulletin of coastal waters in China.Yueqing Bay inorganic nitrogen and active phosphate base year and the criteria value,and divided the inorganic nitrogen and active phosphate water quality assessment of the status quo.On the basis of the above research,this thesis has applied the criteria values of the water quality to the evaluation of marine water quality condition in the Yueqing Bay by integrating the specific geographical and environmental conditions,and contrastive analysis the evaluation results with China’s coastal sea water quality status of communique.The main results of this paper are as follows:(1)Based on the coefficient of variation of continuous survey data of E3 section in the East China Sea,the base years of inorganic nitrogen and active phosphate in Yueqing Bay are 1991 and 1992 respectively.(2)With reference to the base year,through the mathematical calculation and frequency analysis of the survey data of Yueqing Bay,the criteria value of seawater quality of active phosphate in Yueqing Bay is 0.03 mg / L,and the reference value of inorganic water is 0.39 Mg / L.(3)According to the marine water monitoring data at the entrance of the Yueqing Bay in the year of 2012,combined with the criteria value of the inorganic nitrogen and active phosphate witch are determined in this paper to statistical analysis.The Yueqing Bay inorganic nitrogen and active phosphate evaluation rating are divided into 3 grades(good,general and poor).And the three evaluation grades for the corresponding density range of inorganic nitrogen respectively are 0.39~0.55mg/L(good),0.55~0.75mg/L(general),greater than 0.75mg/L(poor).The three evaluation grades for the corresponding density range of active phosphate respectively are 0.03~0.045mg/L(good),0.045~0.055mg/L(general),greater than 0.055mg/L(poor).(4)According to the topography,hydrodynamic conditions and distribution of water quality in Yueqing Bay,Yueqing Bay is divided into three evaluation units: Y1,Y2 and Y3.(5)On the basis of investigated data of Yueqing Bay in the year of 2015,in combination with the hierarchical partition evaluation method based on the criteria value to evaluate the marine water quality of Yueqing Bay in two different point of seasonal and annual change.The evaluation results of individual index factors(N,P)in the Yueqing Bay show that the N and P marine water quality in the Yueqing Bay area can meet the ocean function of each area and that there exist the relative environmental and spatial differences of marine environmental water quality.(6)Basing on the criteria evaluation method to evaluate the marine water quality in harbor area of our country has a certain amount of superiority,to be able to more detailed and specific to reflects the spatio-temporal difference of marine water quality in harbor areas from time and space,and its specific changes in time and space.The benchmark value determined by this method can reflect the present situation of Yueqing Bay seawater quality more effectively and can provide reference for the determination of other benchmark factors in Yueqing Bay.The new evaluation grade method is used to evaluate the water environment of Yueqing Bay,Which can reflect the current situation of Yueqing Bay more realistically and can reflect the change of water environment in Yueqing Bay from time and space in order to provide the basis for the development of marine economy and marine environment protection.