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
Through field sampling of atmospheric dustfall in regions of Zhuzhou City, China for a period of one year, the deposition fluxes of atmospheric dustfall and five heavy metals contained inside, including Cr, As, Cd, Hg...Through field sampling of atmospheric dustfall in regions of Zhuzhou City, China for a period of one year, the deposition fluxes of atmospheric dustfall and five heavy metals contained inside, including Cr, As, Cd, Hg and Pb, were analyzed. Meanwhile the enrichment factor and index methods were used to analyze the pollution characteristics of heavy metals of atmospheric dustfall in Zhuzhou. The annual deposition flux of atmospheric dustfall in Zhuzhou was 50.79 g/（m^2.year）, while the annual deposition fluxes of Cr, As, Cd, Hg and Pb were 9.80, 59.69, 140.09, 0.87 and 1074.91 mg/（m^2.year）, respectively. The pollution level of atmospheric dustfall in Zhuzhou was relatively lower compared with most other cities in China, but the deposition fluxes of As, Cd, Hg and Pb in atmospheric dustfall in Zhuzhou were much higher than that in most cities and regions around the world. Cd is the typical heavy metal element in atmospheric dustfall in Zhuzhou, and both the enrichment factor and pollution index of Cd were the highest. Cd, Hg, Pb and As in atmospheric dustfall were mainly from human activities. According to the single-factor index, Nemerow index and pollution load index analyses, the atmospheric dustfall in Zhuzhou could easily cause severe heavy metal pollution to urban soil, and the most polluting element was Cd, followed by Pb, As and Hg. Only the pollution level of Cr lay in the safety region and mainly originated from natural sources.展开更多
Urban particulate pollutants not only affect urban air quality but also directly threaten public health. Lanzhou has been one of the most seriously polluted cities in the world due to its special geophysical location ...Urban particulate pollutants not only affect urban air quality but also directly threaten public health. Lanzhou has been one of the most seriously polluted cities in the world due to its special geophysical location and weather conditions, which makes it an ideal place for urban particulate pollution study. In this study a set of environmental magnetic parameters (χlf, χfd%, χARM, SIRM, HIRM, SOFT and back field IRM) were measured and analyzed for the dustfall samples collected monthly during 1997.4―2000.5 and 2004.11―2005.10 at Lanzhou University campus (KLD and CCS) and at a clear site of Gaolanxian (GLX). Results demonstrate that the main magnetic minerals in the dustfall are magnetite, with some maghaemite and haematite. Cross plots of Mrs/Ms vs. Bcr/Bc and χfd% vs. χARM/SIRM indicate that the main magnetic grain sizes are pseudo-single-domain (PSD). The high concentration of magnetic min-erals in the dustfall indicates that Lanzhou is seriously polluted. The main pollution sources are an-thropogenic activities and nature dust, with the former posing a great threat during the whole year, which is different from the general view that the natural dust is the main contributor in summer. With great efforts of the government and local authority in the past decades, the air quality in Lanzhou has been improved in winter, but it is not so obvious in summer. This study also reveals that as a simple, rapid and accurate technology, environmental magnetism could be a valuable tool for urban pollution study.展开更多
Atmospheric iron has crucial effects on biogeochemical cycles,atmospheric processing,global climate,and human health.In this study,atmospheric dustfall samples were collected from six functional areas in Xi'an,Chi...Atmospheric iron has crucial effects on biogeochemical cycles,atmospheric processing,global climate,and human health.In this study,atmospheric dustfall samples were collected from six functional areas in Xi'an,China,from 2020 to 2021.The spatiotemporal distributions and deposition fluxes of total and water-soluble(ws)Fe as well as the speciation and potential sources of ws-Fe were characterized.Industrial areas had the highest concentrations of total Fe and ws-Fe,which were mainly due to copious emissions of heavy metals during manufacturing.The total Fe concentrations peaked in spring,primarily due to the substantial input of crustal dust,which also led to the lowest Fe solubility in this season.By contrast,the highest levels of ws-Fe occurred during winter due to an increase in biomass combustion.Among the water-soluble forms,ws-Fe(II)was dominant and accounted for 74.8%of the total amount of ws-Fe.Crustal dust was the main contributor to total Fe,whereas biomass burning primarily contributed to peak ws-Fe concentrations.The average total and ws-Fe deposition fluxes in Xi'an were the highest in spring and lowest in autumn,which were related to the distributions of the dustfall deposition fluxes and their Fe contents during these periods.Our study provided a broader and comprehensive understanding of atmospheric iron deposition in Chinese urban area,which is of positive significance for understanding atmospheric chemistry and global climate change.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supported by the Natural Science Foundation of China (Nos. 41205093, 41305124)the National Department Public Benefit Research Foundation (No. 201109005)+2 种基金the Fundamental Research Funds for Central Public Welfare Scientific Research Institutes of China (No. 2016YSKY-025)funded by Opening Project of Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (No. FDLAP18005)National Key Research & Development Program of China (No. 2016YFE0112200)
文摘Through field sampling of atmospheric dustfall in regions of Zhuzhou City, China for a period of one year, the deposition fluxes of atmospheric dustfall and five heavy metals contained inside, including Cr, As, Cd, Hg and Pb, were analyzed. Meanwhile the enrichment factor and index methods were used to analyze the pollution characteristics of heavy metals of atmospheric dustfall in Zhuzhou. The annual deposition flux of atmospheric dustfall in Zhuzhou was 50.79 g/（m^2.year）, while the annual deposition fluxes of Cr, As, Cd, Hg and Pb were 9.80, 59.69, 140.09, 0.87 and 1074.91 mg/（m^2.year）, respectively. The pollution level of atmospheric dustfall in Zhuzhou was relatively lower compared with most other cities in China, but the deposition fluxes of As, Cd, Hg and Pb in atmospheric dustfall in Zhuzhou were much higher than that in most cities and regions around the world. Cd is the typical heavy metal element in atmospheric dustfall in Zhuzhou, and both the enrichment factor and pollution index of Cd were the highest. Cd, Hg, Pb and As in atmospheric dustfall were mainly from human activities. According to the single-factor index, Nemerow index and pollution load index analyses, the atmospheric dustfall in Zhuzhou could easily cause severe heavy metal pollution to urban soil, and the most polluting element was Cd, followed by Pb, As and Hg. Only the pollution level of Cr lay in the safety region and mainly originated from natural sources.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40571147, 40401064, 90502008 and 40421101)the International Collaboration Project of Chinese Ministry of Science and Technology (Grant No. 2002CB714004)
文摘Urban particulate pollutants not only affect urban air quality but also directly threaten public health. Lanzhou has been one of the most seriously polluted cities in the world due to its special geophysical location and weather conditions, which makes it an ideal place for urban particulate pollution study. In this study a set of environmental magnetic parameters (χlf, χfd%, χARM, SIRM, HIRM, SOFT and back field IRM) were measured and analyzed for the dustfall samples collected monthly during 1997.4―2000.5 and 2004.11―2005.10 at Lanzhou University campus (KLD and CCS) and at a clear site of Gaolanxian (GLX). Results demonstrate that the main magnetic minerals in the dustfall are magnetite, with some maghaemite and haematite. Cross plots of Mrs/Ms vs. Bcr/Bc and χfd% vs. χARM/SIRM indicate that the main magnetic grain sizes are pseudo-single-domain (PSD). The high concentration of magnetic min-erals in the dustfall indicates that Lanzhou is seriously polluted. The main pollution sources are an-thropogenic activities and nature dust, with the former posing a great threat during the whole year, which is different from the general view that the natural dust is the main contributor in summer. With great efforts of the government and local authority in the past decades, the air quality in Lanzhou has been improved in winter, but it is not so obvious in summer. This study also reveals that as a simple, rapid and accurate technology, environmental magnetism could be a valuable tool for urban pollution study.
基金the National Key R&D of China(grant No.2022YFF0802502)the State Key Laboratory of Loess and Quaternary National Key R&D of China Geology,Institute of Earth Environment,CAS(grant No.SKLLQG2014).
文摘Atmospheric iron has crucial effects on biogeochemical cycles,atmospheric processing,global climate,and human health.In this study,atmospheric dustfall samples were collected from six functional areas in Xi'an,China,from 2020 to 2021.The spatiotemporal distributions and deposition fluxes of total and water-soluble(ws)Fe as well as the speciation and potential sources of ws-Fe were characterized.Industrial areas had the highest concentrations of total Fe and ws-Fe,which were mainly due to copious emissions of heavy metals during manufacturing.The total Fe concentrations peaked in spring,primarily due to the substantial input of crustal dust,which also led to the lowest Fe solubility in this season.By contrast,the highest levels of ws-Fe occurred during winter due to an increase in biomass combustion.Among the water-soluble forms,ws-Fe(II)was dominant and accounted for 74.8%of the total amount of ws-Fe.Crustal dust was the main contributor to total Fe,whereas biomass burning primarily contributed to peak ws-Fe concentrations.The average total and ws-Fe deposition fluxes in Xi'an were the highest in spring and lowest in autumn,which were related to the distributions of the dustfall deposition fluxes and their Fe contents during these periods.Our study provided a broader and comprehensive understanding of atmospheric iron deposition in Chinese urban area,which is of positive significance for understanding atmospheric chemistry and global climate change.
