摘要
选择上海中心城区典型样点开展地表灰尘重金属累积过程的实证研究.结果表明,交通区地表灰尘负荷平均值为12.4g/m,范围为5.04--23.2 g/m;文教区道路灰尘负荷为6.1 g/m,范围为3.8--10.0 g/m.持续时间长、强度较大的降雨对颗粒物负荷有明显的削减作用,而小雨则会使其总量有所增加,土地利用类型和道路交通行为是影响地表灰尘大气环境＂源-汇＂效应的重要因素.在干期累积过程中,随着无雨天数的增加,地表灰尘负荷随之升高,同时颗粒物粒径逐渐增大.在交通流量较高的地区,灰尘重金属浓度呈现降低趋势,表现出对大气悬浮颗粒物的＂源＂效应,而交通流量相对较低的区域灰尘重金属浓度则有所升高,显示出其对大气悬浮物的＂汇＂效应.干期累积过程中,污染物负荷变化取决于灰尘负荷和污染物浓度两者的共同作用,呈现出S型增长趋势,降雨过后10 d内,污染负荷增长缓慢,10--15 d迅速增加,15 d后,污染负荷增长速率减小,颗粒物与大气悬浮物交换保持平衡状态.
This paper investigated heavy metal accumulative process of road dust on paved urban surfaces of Shanghai City in April, 2006. The data indicate that the surface dust load mean value for tragic area is 12.4 g/m and the range is 5.04-23.2 g/m; the mean value for the university area is 6.1 g/m with the range of 3.8-10.0 g/m. The research indicated that long duration and high intensity rainfall has the obvious reduction function to the dust particles load, but the light rain can enable it to increase. Land use and road traffic conditions are the important factors controlling ＂source-sink＂ effect of surface dust particulate emission. Dust load buildup occurs and the particles become coarser over the dry days. In high-traffic flow area, the dust displays ＂source effect＂ on atmospheric particulate with heavy metal concentration decreasing, while in low-traffic area, the dust displays ＂sink effect＂ on atmospheric particulate with heavy metal concentration increasing. The results also show that over the dry days, with S-type growth tendency, pollutant load depends on the couple-variation of dust load and pollutant concentrations. After the rainfall, the rate of accumulation of heavy metal load remain slow within 10 days, and during the following period of 5 days, pollution load increase rapidly. Then after 15 days, the load accumulation rate of heavy metal decrease due to the equilibrium of dust deposition and emission.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2008年第12期3483-3488,共6页
Environmental Science
基金
国家自然科学基金重点项目(40730526)
国家自然科学基金项目(60670253)
关键词
城市地表灰尘
重金属
累积过程
上海
urban surface dust
heavy metal
mass accumulation
Shanghai City
