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为研究风景游憩林中PM2.5浓度的变化规律及其对气象因子的响应,并分析不同林分对PM2.5浓度的调控作用,在2013年夏、秋、冬季于北京市奥林匹克森林公园内对北京4种典型结构风景游憩林(华山松-银杏混交林、毛白杨-白蜡混交林、毛白杨纯林、多树种复层混交林)中的PM2.5浓度及相关气象因子进行实时测定(共28个观测日).结果表明:在不同空气污染级别下林分内PM2.5浓度的日变化无统一规律,但在同一污染级别下4种林分的PM2.5浓度日变化规律基本一致.当风力为0~2级时,在各污染级别下4片林分内PM2.5浓度的日均值[观测时段内(9:00—15:00)PM2.5浓度平均值]无显著差异.林内PM2.5浓度与空气相对湿度呈显著正相关(P<0.01),与气温呈显著负相关(P<0.05),与风速不相关.相对于林分外空地,林分内PM2.5浓度变化比例在-21.4%~33.2%,其与空气相对湿度呈显著负相关(P<0.05),与风速和气温不相关.林分对PM2.5浓度的调控作用包含增加和降低两种效应,本研究中,这种调控作用发生转变的空气相对湿度临界值为67%.
In order to study the variation regularity of PM2.5 in scenic recreational forest and its response to meteorological factors, and to analyze the regulation effect of different stands on the concentration of PM2.5, in the summer, autumn and winter 2013 in the Olympic Forest Park in Beijing The PM2.5 concentrations and related meteorological factors in four typical scenic recreational forests (Pinus armandii-Ginkgo biloba mixed forest, Populus tomentosa-ash mixed forest, pure Populus tomentosa and pure forest, multi-species mixed forest) in Beijing were measured in real time A total of 28 observation days.) The results showed that there was no uniform law of diurnal variation of PM2.5 concentration in different air pollution levels, but the daily variation of PM2.5 concentration in the four forest types was basically the same under the same pollution level When the wind power was from 0 to 2, the daily mean of PM2.5 concentrations within the four stands at each pollution level [average of PM2.5 concentrations during the observation period (9: 00-15: 00)] was not significantly different There was a significant positive correlation between PM2.5 concentration and air relative humidity (P <0.01), negative correlation with air temperature (P <0.05), and no correlation with wind speed.Compared with the stand outer space, PM2.5 The concentration change ranged from -21.4% to 33.2%, which was significantly negatively correlated with air relative humidity (P <0.05), but not with wind speed and air temperature Off. Stand PM2.5 regulation of the concentration increases and decreases comprises two effects, the present study. This regulation takes place relative humidity of the air transition critical value of 67%.