Variation Characteristics And Evaluations Of Water Environment In Typical Landscape Waters In Hefei City

To investigate the water environmental quality of the urban landscape water in Hefei,we selected6typical landscape waters around the city and collected water samplesthree times a month from September2012to July2013. Based on the results of thewater physical and chemical indicators, such as TN, NH4-N, NO3-N, NO2-N, TP,PO4-P, COD, Chl-a, pH, EC, WT and so on, we analyzed the spatial and temporalvariation characteristics of the water environment in landscape waters, and evaluatedthe water environmental quality and the degree of eutrophication. Some resonablemeasures and suggestions were put forward to control the eutrophication of thelandscape waters.The main contents and results were as follows:(1) The analysis of the spatial and temporal variation of water environment showedthat in addition to landscape waters of Baohe Park and Xiaoyaojin Park, the nitrogenand phosphorus pollution was relatively serious in the other waters. What’s worse, theconcentrations of nitrogen and phosphorus in some landscape waters were much higherthan the V class standard in the Surface Water Environment Quality Standard(GB3838-2002). According to the TN/TP ratios of the landscape waters, an initialjudgment could be presented that waters in Yuhuatang Park and Heichiba Park werephosphorus-limited while nitrogen-limited in Xiaoyaojin Park.(2) Correlation analysis results showed that very significant positive correlationswere found between TN and NH4-N, and between TP and PO4-P, and the correlationcoefficients were0.864and0.989, respectively. Clustering analysis showed that waterin Heichiba Park and Nanfei River was a relatively seriously polluted cluster while therest of closed water belonged to another cluster. From the results of the principalcomponent analysis, we found that TN、NH4-N、NO2-N and COD were mainlycontrolled by the first principal component while pH and NO3-N were dominated bythe second principal component. What’s more, analysis of variance (ANOVA) showedthat the indicators of flowing water in Nanfei River was significantly different withthose in otherlandscape waters, but the difference between closed landscape waterswas less.(3) Based on the6element connection number of the entropy weight, we evaluatedthe water quality of the landscape waters. The results showed that water quality inBaohe and Xiaoyaojin Park met Ⅳ class standard, Yuhuatang Park was in Ⅴ, andYinhe Park, Heichiba Park and Nanfei River were in worse Ⅴ. (4) According to the standard of the single factor of eutrophication in OECD (Chl-a),Yinhe park belonged to the serious eutrophication level while the other landscapewaters belonged to the eutrophication level. From the results of the trophic state index(EI) and the comprehensive trophic state index (TLI), we concluded that the studylandscape waters were basically in a state of eutrophication, and the order of theeutrophication degree was Yinhe Park> Nanfei River>Heichiba Park>YuhuatangPark> Baohe Park.