Principal Component Analysis Of Eutrophication And Nutrient Criteria In Xi’an Urban Landscape Waters

Urban landscape water can not only enhance the urban environment, but also improve local micro-climate, make people feel better and have other functions. Therefore, it is indispensable to modern urban infrastructure. However, due to a variety of causes of man-made or natural result in the deterioration of the water quality, even eutrophication, make it loss some or all of its original features. To investigate the main reasons of Xi’an urban landscape waters eutrophication and nutrient criteria, taken Xi’an 13 urban landscape waters as the reach object, water quality was Comprehensively measured. Based on this, Three nutritional status evaluation methods were used to evaluate the trophic state, and applied factor analysis to extract the main components of effecting eutrophication of urban waters. Finally, statistical method was applied to try to develop the candidate values of Xi’an urban landscape waters nutrient criteria. The main results were as follows:(1) In the monitored 13 urban landscape waters, Taiye Pool was nitrogen limitation over 80% of the whole year time, Yanming Lake was about 45% of the whole year time, Qvjiang Pool and Guangyuntan were entirely phosphorus limitation, and the remaining waters were phosphorus limitation over 75% of the whole time. Xi’an 13 urban waters presented phosphorus limitation as a whole.(2) Modified Carlson index(TSIM), comprehensive nutrition status index(TLI) and gray clustering method were used to evaluate the trophic state of Xi’an urban waters. The results arranged according to the severity of eutrophication were TSIM> TLI> gray clustering, so eventually TLI was adopted to evaluate trophic state of Xi’an city waters. Only 6.25 percent of the whole year monitoring data was in the mesotrophic state, the rest was in eutrophic state. Xi’an urban waters was in serious eutrophication.(3) The three factors of affecting eutrophication of Xi’an urban landscape waters(in order): Nitrogen and phosphorus nutrients(included soluble phosphate, total phosphorus and ammonia nitrogen); Sensory properties index(included chromaticity, TSS and turbidity); Physical and chemical properties(included conductivity and alkalinity).(4) Total phosphorus, ammonia-nitrogen, conductivity and chlorophyll a were selected as candidate variables for the nutrient criteria, and the recommended nutrient criteria values of Xi’an urban landscape waters was obtained by the use of statistical methods and regression inference method. So the commanded range values were Conductivity: 237.5μs/cm~302.0μs/cm; TP: 0.0576mg/L~0.0691mg/L; chlorophyll a: 10.01μg/L~12.76μg/L; ammonia: 0.0598mg/L~0.0927mg/L.