Spectroscopic Characterization of Dust-Fall Samples Collected from Greater Cairo, Egypt

Microscopic characteristics and sources of atmospheric dustfall in open-pit mining coal resource-based city in the arid desert area of Northwest China

Atmospheric dustfall is solid air pollutant, has a major impact on the environment and human health. The objective of this study was to investigate the microscopic characteristics and sources of atmospheric dustfall in open-pit mining coal resource-based city in the arid desert area of Northwest China. The characteristics of size and shape factors, variation of shape factors with size distribution, types of individual particles, and sources of atmospheric dustfall, which were collected in the open-pit mining area and surrounding areas, were analyzed by X-ray diffraction (XRD) and scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS) combined with graphical method and shape factors. The results showed that the atmospheric dustfall in all functional areas was dominated by coarse-grained particles. The shape of the atmospheric dustfall deviated from spherical shape, and with decreasing particle size, the difference in shape factors increased in each functional area. The EDS and XRD analyses indicated the presence of 13 types of particles. The sources were mainly local and included soil dust from each functional area; industrial dust, construction dust, biogenic impurities, fossil fuel combustion, wear products of motor vehicle parts, motor vehicle exhaust emissions, and emission and excreta from biological activities in each functional area except the desert area; emissions from a steel plant in the industrial area; coal-associated ore, coal dust, coal gangue emissions, and emissions from the spontaneous combustion of coal gangue in the open-pit mining area; secondary chemical crystallization products in the industrial area and the open-pit mining area; dust generated by vehicles abrading the surface of the off-mine coal road and in the open-pit mining area.

Computational prediction of dust deposition on solar panels

This research is concerned with performing computational fluid dynamics (CFD) simulations to investigate the air flow and dust deposition behavior around a ground-mounted solar PV panel. The discrete phase model (DPM) is adopted to model the gas-solid flow. The influence of the wind speed, the dust particle size, and the dust material on the dust deposition rate was investigated based on the environment of Cairo, Egypt. The wind speeds range between 1 and 11.5 m/s with an average of 3.7 m/s. It is found that increasing the wind speed decreases the dust deposition rate. For wind speeds higher than 2 m/s, it is found that increasing the dust particle diameter or the dust density increases the dust deposition rate. For wind speeds lower than 2 m/s, it is found that there is a critical particle size before which increasing the dust density causes dust deposition rate to increase and after which increasing the dust density decreases the dust deposition. The maximum percentage of deposition rate equals 10.8% and occurs for the dolomite dust material at a wind speed of 2 m/s and particles diameter of 150 μm.

Pollution and ecological risk assessment of nutrients associated with deposited sediments collected from roof and road surfaces

Surface-deposited sediment in urban areas is an essential environmental medium for assessing nutrient contamination. The total nitrogen (TN) and total phosphorus (TP) pollution associated with surface-deposited sediments can be transported into urban water bodies by runoff and can cause eutrophication of those water bodies. By analyzing the samples collected on roof surfaces and road surfaces, this study provides a comparison of the differences in TN and TP pollution loading in sediments on these two different impervious surface materials. Also, an assessment of the ecological risk of nutrients in surface-deposited sediments with respect to grain size fraction was performed. The results indicate that the TN and TP pollution loading in both road-deposited sediments and roof-deposited sediments indicated an asymmetric "W" trend along with grain size fraction, and both road-deposited sediments and roof-deposited sediments had the highest TN and TP pollution contribution when the particle size is between 250 and 500 μm. TN in roof-deposited sediments has high ecological risk when the particle size is less than 250 μm. These findings help to provide guidance for the management of surface-deposited sediment pollution.