Analysis of individual particles collected at Beijing in northern China revealed that particles abundant in calcium (Ca) always
constituted a large fraction of mineral particles in the urban atmosphere. The particles were characterized by cubic morphologies.
The major mineral element in the particles was Ca and few or no other mineral elements were detected. A large number of the
particles were in the range of diameter <1 μm, where common natural mineral particles were rarely detected. The contribution
of the Ca particles to the volume of total mineral particles greatly exceeded that of other mineral particles during non-dust-storm
periods and was comparable to that during dust-storm periods. Reagent film tests showed that particulate sulfate and nitrate
formation on the Ca particles was similar to that on common mineral particles. These results indicate that a large portion
of Ca in the atmospheric particulate matter in Beijing was from anthropogenic sources rather than from natural sources, and
the anthropogenic Ca particles acted as a significant medium for the formation of sulfate and nitrate. Similar particles were
also detected at Qingdao, a coastal city in northern China. Data of a dust storm event showed that Ca-abundant particles from
East China arrived there and moved out of the continent, similarly to Asian dust storm particles, suggesting possible contributions
of anthropogenic Ca even in Asian dust storm samples in the downstream areas. Therefore, Ca may not be a good indicator of
Asian dust from natural sources. However, the Ca particles, due to their unique shapes and elemental compositions, may provide
an indicator for the atmospheric dispersion of anthropogenic particulate matters in East Asia. 相似文献
PM2.5 samples were collected by a three-stage cascade impactor at two kinds of Chinese restaurants to characterize fine organic particulate matter from Chinese cooking sources. Major individual organic compounds have been quantified by GC/MS, including series of alkanes, n-alkanoic acids, n-alkanals, alkan-2-0nes and PAHs.Alkanes and ketones make up a significant fraction of particle-phase organic compounds, ranging from C11 to C26,and (C9 to C19, respectively. In addition, other organic compound classes have been identified, such as alkanols,esters, furans, lactones, amides, and nitriles. The mass concentrations of fine particles, alkanes, n-alkanoic acids and PAHs in air emitted from the Uigur style cooking are hundreds times higher than ambient PM2.5in Beijing. 相似文献
Ecological indicators have widespread appeal to scientists, environmental managers, and the general public. Remote sensing is unique in its capability to record variety of spatio-temporal information on land surface with complete coverage, especially with regard to larger spatial scales, which has been proven to be an effective data source to create indicators to rapidly identify regional eco-environment. In this paper, a new index, remote sensing based ecological index (RSEI) based on the pressure-state-response (PSR) framework, was applied to assess regional ecological changes in Fuzhou City of Fujian Province, southeastern China, using Landsat ETM+/OLI/TIRS images. Taking the advantages of being totally free of artificial interference in the calculation using principal components analysis (PCA) to assign weights of each variable, the RSEI can assess the regional ecological status more objectively and easily. The effectivity of the new index was validated by four approaches, including point-based, classification-based, correlation-based, and urban-rural-gradient-based comparisons. The case study showed that Fuzhou has witnessed ecological improvement during the study period, with the value of RSEI increasing from 0.663 in 2000 to 0.675 in 2016. Spatial variation analysis showed that the poor level of RSEI distributed mostly in the central urban areas, and the ecological degradation was attributed to the fast expansion of the built-up area, characterized by increasing greatly in the value of the normalized differential built up and soil index (NDBSI) in such areas.