Water Pollution Situation And Establishment Of Evaluation Index System In The Yellow River Estuary

With the rapid economic development, freshwater runoff reduction andeutrophication has become major environmental problems in the Yellow River Estuary.There is an urgent need to establish the evaluation index system for regionalcharacteristics and problems to understand the environmental quality of the YellowRiver Estuary correctly.Relying on the State Oceanic Administration“the North Sea Estuary WatersEnvironmental Quality Comprehensive Evaluation Method Project”, This studyinvestigates the changes of nutrients fluxes from1980to2011in the Yellow RiverEstuary. The evaluation index has been screened with the analysis of waterenvironment characteristics and mathematical statistical method. The evaluation indexsystem of water quality in the Yellow River Estuary has been established. The waterquality of the Yellow River Estuary has been evaluated. Ultimately serve for theestablishment of the North Sea estuary water comprehensive evaluation method.The study has shown that every ten interannual variability of DIN and NO₃-Nfluxes from1980to2011is decreased first and then increasd. While the fluxes ofNH₄-N and NO₂-N is rising. By comparing the flux variation with runoff rate, it isfound that the concentration of various forms of inorganic nitrogen in every ten yearsshows an upward trend. The mean annual flux of DIN in the Yellow River Estuaryfrom2001to2011is6.67×104t/a by the estimation of scale factors between monthlyconcentration and mean annual concentration. The flux of NO₃-N is5.92×104t/a，NH₄-N is0.71×104t/a and NO₂-N is0.095×104t/a. Higher flux of inorganicnitrogen into the sea is one of the main pressures of water quality in the Yellow RiverEstuary.The current water quality status in the Yellow River Estuary is that DIN is stillserious. DO and non-ionic ammonia are all conformed to the national first classseawater quality standard. The spatial distribution and temporal variation of NO₂-N and NH₄-N is severe. DIN, COD and petroleum are higher than the standard in the S≤20zone. The over standard percentage are100%,92%and85%respectively. Theexceeded rate of PO₄-P is33%. pH, NO₂-N and Chl-a were basically conformed tothe standard. The over standard percentage of DIN is66%in S>20waters. Theexceeded rate of PO₄-P, COD and petroleum was reduced to4%,7%and11%.The screening evaluation index are DO, TSS, DIN, PO₄-P, COD, petroleum andnonionic ammonia which is based on the analysis of water environmentcharacteristics and mathematical statistical method in the Yellow River Estuary. pHfluctuation caused by mixed river and seawater is easily conceal the expression signalof pollution and the biological activity. Potentiometric method can not eliminate theimpact of dramatic changes in the ionic strength and it is difficult to accurately reflectthe changes in the acidity of the water. In addition, pH and S have good correlationwith DO, COD, DIN and PO₄-P. NO₃-N is the main component of DIN. NO₂-N hassignificantly correlation with DO, COD and non-ionic ammonia. Biodegradableorganic matter has a more significant impact for aquatic organisms. Theconcentrations of POPs and heavy metal in low in the Yellow River Estuary. Based onthe principle of indicators screening, S, pH, NO₃-N, NO₂-N, TOC, POPs and heavymetals have not been chosen as evaluation index.