جستجوی مقالات مرتبط با کلیدواژه "dust fall" در نشریات گروه "پزشکی"

Lakes and surface waters are sensitive areas that have potential to pollute with different pollutant sources. Pollutants can enter the sea through inlets, drainages and atmospheric deposits. Atmospheric deposits are one of the most critical factors in increasing the pollutants in a lake. Dust storms, through the movement of plankton on the coast, increase some of the nutrients which ultimately cause the eutrophication and create red waves on the coast. Particle measurement method is described by Dust fall jar, a standard method for collecting and measuring depositional particles in the air, according to ASTM D1739-98, 2004 standards. In this method, containers with standard size and shape are used. These containers are already installed in the laboratory and finally opened and deployed on suitable sites; so particles can be deposited in it for 30 days and then the particles were weighed. Acid digestion was used to measure heavy metals, and the heavy metals were determined using the ICP device. Information about the area of the lake and the volume of water behind the dam were collected from the Iran Water Resources Management. Excel 2016 was used to perform calculations and plotting graphs. The results showed that the average dust fall particles around the Seimare dam were 10.85 g/m2.Month. On average, monthly 306 tons particles enter the dam through the air which increased the concentration of water particles by 0.32 mg /L. These particles increased the Fe and Al concentration in water to140 μg /L, 47.32 μg /L respectively. Fe had the highest content among the metals and formed a bulk of particles. Then, Al, Ti, Mn, Sn, Mg, K, Cr, Ni, Ba, Ca, Zr, Pb, Sr, V, Cu, Co, Li, Zn, Y, Mo, Tl, La, Be and Cd with the lowest amount, respectively. The results showed that most of the metals had high enrichment factor (EF). This represents the anthropogenic origin of these metals

The phenomenon of dust is a serious environmental problem in dry and semi dry regions. It has a destructive effect for the residents of such regions. Over two-thirds of Iran is in areas of dry and semi-dry climate conditions.
In this research, dust fall measurements were taken in 41 stations across Yazd city using a marble dust collector (MDCO) located in different parts of the city. Next, the chemical characteristics of dust were determined using the XRF method. Finally, levels of dust fall across the 4 seasons of the year and status of the constituent elements of dust were determined through ArcGIS software and the Kriging technique. The Raster calculator function was used to make determinations of the effects of dust fall at each of the stations over the course of the year. Remote sensing system, along with maps taken from Landsat and the band combination technique were processed using ENVI software to extract vegetation density and building density maps of the studied region.
Results showed that spring had the highest level of dust fall with a value of 200 g/cm2. In total, in 109 km2 of the studied region had average dust fall of 110 g/m2 that contributed to 12 057 tons of dust over Yazd city in 2015. The constituent elements of the dust fall according to decreasing amounts were as follows: Si>Ca>Al>C>Mg>Fe>K>Na>S>Ti>Cl>P>Mn>Sr>Zn.
These results indicate accuracy of the Kriging technique for application in dust zoning. The factors of vegetation and green space were determined as effective on adsorbing dust. Increased building density and height of buildings also contributed to development of dust fall.