The spatial trends of dustfall of different sizes over northern China during April and May 2001,and March 2002,and their influencing factors,were analyzed.We divided the dustfall into seven grades based on particle si...The spatial trends of dustfall of different sizes over northern China during April and May 2001,and March 2002,and their influencing factors,were analyzed.We divided the dustfall into seven grades based on particle size.Total dustfall and dustfall for each grade were highest in desert regions then in regions undergoing desertification,and the total dustfall,dustfall 【100 μm and dustfall 】250 μm were higher in western agricultural regions closer to desert areas than in eastern agricultural regions.The spatial trends in dustfall 【300 μm in diameter were most strongly correlated with dust events,and the content of coarse particles increased with increasing severity of dust events.Because the spatial trend for dust events appears to be controlled by geomorphic conditions,vegetation coverage,soil moisture,and the distance from dust source,dustfall 【300 μm in diameter appears to have the same controlling factors as dust events,but the control decreases with increasing particle size.Wind,the driving force for dust emissions,also influenced the spatial trends in dustfall 【200 μm in diameter,and especially for dustfall 50 to 100 μm in diameter.Although dustfall 【300 μm in diameter and precipitation were not strongly spatially correlated,there is some evidence that high precipitation decreased deposition by restraining blowing sand.The coarser the dustfall,the weaker the correlation with wind speed;however,transport of larger particles still occurs,and further research will be required to test the possibility that this dust is entrained mainly by the small-scale dust devils that are commonly observed in the study area.展开更多
Dustfall is a major threat to agricultural and industrial infrastructures, as well as to other aspects of livelihood. Dustfall associated to a severe dust storm that hit the Al-Ahsa Oasis of Saudi Arabia during 12-13 ...Dustfall is a major threat to agricultural and industrial infrastructures, as well as to other aspects of livelihood. Dustfall associated to a severe dust storm that hit the Al-Ahsa Oasis of Saudi Arabia during 12-13 March 2014 is discussed in this paper. The storm caused widespread and heavy dust deposition. A dramatic decrease in the visibility coincided with the storm, and the average dust concentrations recorded during a peak 10-hour period were 6772, 5862.4 and 451.1 μg/m3 for total suspended particles (TSP), particulate matter smaller than or equal to 10 μm (PM10) and those smaller than or equal to 2.5 μm (PM2.5), respectively. The lowest visibility was 200 m, and the wind speed increased to 17.5 m/s from the north. The average daily dust deposited in the study area during the event was 12.84 (SD = 1.2) g/(m2?d). The dust samples comprised insoluble dust (48.5%) and soluble dust (51.5%). Based on the Munsell color system, the final color description of the falling dust was 10 YR/6/3. A microphotograph of the dustfall (settleable particulate matter) captured by a stereo dissection microscope shows that the dust particles had various colors and sizes, and they contained fibers and vegetative debris).展开更多
Urban greening trees intercept the migration of atmospheric particulate matters near the ground, and it is difficult for the particulate matters trapped by foliage to re-elevate, thus reducing the hafm to humans....Urban greening trees intercept the migration of atmospheric particulate matters near the ground, and it is difficult for the particulate matters trapped by foliage to re-elevate, thus reducing the hafm to humans. The dust-capturing ability and foliar dust size charactetistics of different greening trees are different In addition, the dust capturing of trees is distutbed by many factors such as sel natural and human factors. The foliar dust and natural dustfaJl in 11 common, tree species in Aksu, Northwest China were collected to analyze tihe particle size distribution diacacteristics,and obtain the concentrations of PM^ and PM10. The results showed that Pktanus acenfolia, Populus alba var. pyramidaJis and Uhnus densa. had high foliar dust attachment density and strong particle-capturing capacity,while Elaeagnus angustifoliaL., Pyrns sinldangensis, Sophora japonica L. had low foliar dust attachment density. The foliar PMZ5 and PM10 contents were highest in E. ongustifolia （0.68%） and Vitis vinefcra （3.59%）, tespectively. The volume fraction of fine partides was small in natural dustM and was kige in foliar dust The median of foliar dust particle size followed tiie descending ordei： industrial area 〉 transportation hub area 〉 residential area 〉 clean area; and the median of natural dustfall particle size followed the descending order： dear area 〉 transportation hub area 〉 industrial area 〉 residential area. There was a big difference between the two.展开更多
基金the Natural Science Foundation of China through grant No. 40638038
文摘The spatial trends of dustfall of different sizes over northern China during April and May 2001,and March 2002,and their influencing factors,were analyzed.We divided the dustfall into seven grades based on particle size.Total dustfall and dustfall for each grade were highest in desert regions then in regions undergoing desertification,and the total dustfall,dustfall 【100 μm and dustfall 】250 μm were higher in western agricultural regions closer to desert areas than in eastern agricultural regions.The spatial trends in dustfall 【300 μm in diameter were most strongly correlated with dust events,and the content of coarse particles increased with increasing severity of dust events.Because the spatial trend for dust events appears to be controlled by geomorphic conditions,vegetation coverage,soil moisture,and the distance from dust source,dustfall 【300 μm in diameter appears to have the same controlling factors as dust events,but the control decreases with increasing particle size.Wind,the driving force for dust emissions,also influenced the spatial trends in dustfall 【200 μm in diameter,and especially for dustfall 50 to 100 μm in diameter.Although dustfall 【300 μm in diameter and precipitation were not strongly spatially correlated,there is some evidence that high precipitation decreased deposition by restraining blowing sand.The coarser the dustfall,the weaker the correlation with wind speed;however,transport of larger particles still occurs,and further research will be required to test the possibility that this dust is entrained mainly by the small-scale dust devils that are commonly observed in the study area.
文摘Dustfall is a major threat to agricultural and industrial infrastructures, as well as to other aspects of livelihood. Dustfall associated to a severe dust storm that hit the Al-Ahsa Oasis of Saudi Arabia during 12-13 March 2014 is discussed in this paper. The storm caused widespread and heavy dust deposition. A dramatic decrease in the visibility coincided with the storm, and the average dust concentrations recorded during a peak 10-hour period were 6772, 5862.4 and 451.1 μg/m3 for total suspended particles (TSP), particulate matter smaller than or equal to 10 μm (PM10) and those smaller than or equal to 2.5 μm (PM2.5), respectively. The lowest visibility was 200 m, and the wind speed increased to 17.5 m/s from the north. The average daily dust deposited in the study area during the event was 12.84 (SD = 1.2) g/(m2?d). The dust samples comprised insoluble dust (48.5%) and soluble dust (51.5%). Based on the Munsell color system, the final color description of the falling dust was 10 YR/6/3. A microphotograph of the dustfall (settleable particulate matter) captured by a stereo dissection microscope shows that the dust particles had various colors and sizes, and they contained fibers and vegetative debris).
基金Sponsored by Natural Science Foundation of Xinjiang Uyghur Autonomous Rrgion(2017D01B15)
文摘Urban greening trees intercept the migration of atmospheric particulate matters near the ground, and it is difficult for the particulate matters trapped by foliage to re-elevate, thus reducing the hafm to humans. The dust-capturing ability and foliar dust size charactetistics of different greening trees are different In addition, the dust capturing of trees is distutbed by many factors such as sel natural and human factors. The foliar dust and natural dustfaJl in 11 common, tree species in Aksu, Northwest China were collected to analyze tihe particle size distribution diacacteristics,and obtain the concentrations of PM^ and PM10. The results showed that Pktanus acenfolia, Populus alba var. pyramidaJis and Uhnus densa. had high foliar dust attachment density and strong particle-capturing capacity,while Elaeagnus angustifoliaL., Pyrns sinldangensis, Sophora japonica L. had low foliar dust attachment density. The foliar PMZ5 and PM10 contents were highest in E. ongustifolia （0.68%） and Vitis vinefcra （3.59%）, tespectively. The volume fraction of fine partides was small in natural dustM and was kige in foliar dust The median of foliar dust particle size followed tiie descending ordei： industrial area 〉 transportation hub area 〉 residential area 〉 clean area; and the median of natural dustfall particle size followed the descending order： dear area 〉 transportation hub area 〉 industrial area 〉 residential area. There was a big difference between the two.
