摘要
明确在常规叶片清洗方法(泡洗或泡洗+刷洗)上增加超声清洗对叶面各径级颗粒物滞纳量定量评估的影响,并在此基础上研究叶面颗粒物的粒径分布和吸滞效率,可进一步提高城市树木大气颗粒物吸滞能力的定量评估精度。该文以城市森林建设常用阔叶树种银杏(Ginkgo biloba)和针叶树种油松(Pinus tabuliformis)为研究对象,于雨后(降水量>15 mm)4天(短滞尘时长)和14天(长滞尘时长)分别采集叶样,并依次对其进行泡洗(WC)、刷洗(BC)、超声清洗(UC)等洗脱程序,然后对每个清洗步骤下叶片洗脱液中颗粒物的质量和粒径分布进行测试,并依此估算叶片各径级颗粒物的吸滞效率。结果表明,以"泡洗+刷洗+超声清洗"清洗流程的测试结果为参照,若只对叶片进行泡洗,则银杏和油松对大气颗粒物(PM1,粒径d≤1μm)、PM2.5(d≤2.5μm)、PM5(d≤5μm)、PM10(d≤10μm)吸滞量会分别被低估约一半(54%、53%、53%和53%)和40%(42%、42%、42%和42%);若只进行"泡洗+刷洗",则银杏和油松对相应径级颗粒物的吸滞量仍会分别被低估约15%(17%、16%、15%和15%)和20%(21%、20%、20%和20%)。油松叶面颗粒物粒径分布呈双峰曲线,而银杏叶面颗粒物粒径则呈单峰分布,且银杏叶面颗粒物平均粒径在短、长滞尘时长下均大于油松。油松叶片对PM1、PM2.5、PM5、PM10和总悬浮颗粒物的吸滞效率分别为8.96、23.92、23.96、23.96和23.96 mg·m–2·d–1,分别比银杏叶片高112%、73%、34%、37%和42%。
Aims On the basis of conventional cleaning method (washing + brushing), this study aims to verify the effect of ultrasonic cleaning on quantitative evaluation of particulate matters with various particle sizes retained on tree leaves, and further to investigate the size distribution and retention efficiency of these particulate matters, which will help to improve the accuracy of quantitative assessment of the retention ability of urban trees to atmospheric particles. Methods Taking Ginkgo biloba and Pinus tabuliformis as examples of broadleaf and conifer species, leaf samples were collected 4 days (short dust retention period) and 14 days (long dust retention period) after the rain (rainfall 〉15 mm), and then particles retained on these leaves were collected by the means of washing (WC), brushing (BC) and ultrasonic cleaning (UC). Further, the quality and size distribution of the particulate matters eluted at each wash step were determined to assess the retention efficiency of tree leaves to particulate matter with various particle sizes. Important findings Taking the result of"washing + brushing + ultrasonic cleaning" process as a reference, with only washing process, the retention amount of PM1 (particulate diameter d ≤ 1 μm), PM2.5 (d ≤ 2.5 μm), PM5 (d ≤ 5 μm) and PM10 (d ≤ 10 μm) on G. biloba and P. tabuliformis leaves would be underestimated by around 50% (54%, 53%, 53% and 53%) and 40% (42%, 42%, 42% and 42%), respectively; under washing and brushing protocols, the dust retention capacity of G. biloba and P. tabuliformis were still undervalued by about 15% (17%, 16%, 15% and 15%) and 20% (21%, 20%, 20% and 20%), respectively. Size distribution of particulate matters retained on P. tabuliformis showed bimodal curves, whereas the particulate matters retained on G. biloba exhibited unimodal size distribution. However, the average particle size of particulate matters on G. biloba leaves were greater than that on P. tabuliformis leaves in both short (G. biloba: 1.68 μm; P. tabuliformis: 1.16 μm) and long (G. biloba: 1.51 μm; P. tabuliformis: 1.19 μm) dust retention periods. The retention efficiency of P. tabuliformis to PM1, PM2.5, PM5, PM10 and total suspended particulate (TSP) were 8.96, 23.92, 23.96, 23.96 and 23.96 mg·m-2·d-1, respectively, higher than that of G. biloba by 112%, 73%, 34%, 37% and 42%, respectively.
出处
《植物生态学报》
CAS
CSCD
北大核心
2016年第8期798-809,共12页
Chinese Journal of Plant Ecology
基金
河南省重点科技攻关项目(16210211-0090)
中国博士后科学基金(2015M570629)
关键词
大气颗粒物
吸滞效率
粒径分布
超声清洗
particulate matter
retention efficiency
diameter distribution
ultrasonic cleaning