The Study On Spatio-temporal Changes Of Air Negative Ion Concentrations And The Relevance With Environmental Factors In Shanghai

Air negative ion have the utilities of disinfection, dusting and purifying, whichcan represent the cleanliness of air.The paper took Shanghai for example, conductingcontinuous monitoring of the air negative ion concentration of each season in traiffcroad, farmland, residential and educational areas, ecological land (urban green space,woodland, wetland, lake, forest parks) rfom2012to2014. There is a total of28monitoring points, including four kinds of typical functional areas. On this basis，synchronized monitoring of air negative ion, environmental factors, meteorologicalfactors has been done in section measuring points, selecting the summer whose airquality is better. Studied the temporal-spatial pattern of air negative ion in thedifferent typical functional areas and the correlation between air negative ion andmeteorological factors,environmental pollution factors. Meanwhile, the daily patternand seasonal pattern of air negative ion concentration were analyzed by the airnegative ion online dynamic continuous monitoring in Chongming andPudong.24Shanghai ecological verification sample areas had been selected accordingto national ecological requirement. In each sample area, we have had simultaneousmonitoring of positive ions, negative ion，vegetation cover and leaf area index tostudy the relevance of air negative ion and the ecological sample area’s propertiesfrom July to September2012.The main conclusions are as follows:(1).The analysis of the day’s negative air ion changes based on the24hoursanion concentration in sunny day of Chongming Environmental Protection Bureauand Pearl Lake Park.It is showed that the air negative ion concentration changedobviously during a day. The concentration of air negative ion in wee hours was higher than in the day. Anion trough mostly in the daytime, it is relatively high at night20:00to4:00am the next day. The total trend of air negative ion concentration is higher insummer and autumn，lower in winter and spring, the evidence is rfom the changingsituation, measured in Chongming and Pudong.(2). The differences of air negative ion concentration in different typicalfunctional areas of Shanghai is signiifcant.In summer: ecological land〉residentialand educational areas> traffic road>farmland.(3). The concentration of negative ion in the ecological sample area withinthe outer-ring road of shanghai are lower than these areas outside the outer-ring road,and these areas far from the sea were lower than the oceanrfont, while ShanghaiBotanical Garden’s is the lowest and Haiwan Forest Park’s is the highest; There are8sample areas whose CI is greater than1and the air cleanliness is A，such as,GongqingForest Park, Shiji Park，Sheshan Forest Park and Jinshan Island nature reserve; Thereisn’t signiflcan correlation among negative ions, vegetation cover and LAI in allecological sample areas, however, when the gap of vegetation coverage is greater than0.10or LAI greater than1in three quadrats of one sample area,they are positively correlated; Negative ions have a non-significant negativelycorrelation with temperature and have a significant positive correlation with relativehumidity.(4). The vegetation coverage was the largest contribution factor in the3principal component factors. By evaluating the principal component scores offavorable impact factors of24ecological lands, the health benefit of Haiwan forestpark is the highest, and Shanghai Botanical Garden is the lowest.(5). Make an analysis rfom the perspective of the relationship between airions and meteorological factors. When the temperature changes slightly, Negativeions have a non-significant negatively correlation with temperature. Negative ionshave a significant positive correlation with relative humidity. The concentration ofnegative ions is affected by rainfall. The concentration of negative ions on rainy daysis higher than sunny days; In different functional areas,there is a negative correlation between solar radiation and air negative ion concentration.(6). When the concentrations of environmental pollutants including S02,N02,PM10，PM2.5，CO，NO，NOx are at a lower range, there are no significant correlation withnegative ions. When the pollutants concentrations are greater than the critical value,negative ions decrease with increasing of the pollution factors concentrations. Theoverall is a significant negative correlation. There is significantly positivelycorrelation between air negative ion and O3.