Determination and risk assessment of heavy metals in air dust fall particles

Background: Urban and industrial development has increased the concentration of heavy metals in various environments, and also, increased their amount in dust fall particles. The aim of this study was to determine and assess the risk of heavy metals in air dust fall particles. Methods: Sampling of air dust fall particles was performed using the British model Dust Fall Jar devices. Heavy metals concentrations in the samples were determined using an atomic absorption spectrometer device. Then, the risk assessment of heavy metals in air dust fall was calculated by three indicators including enrichment factor (EF), geo-accumulation index (Igeo), and integrated pollution index (IPI). Data were analyzed using descriptive statistics and Excel 2016 software. Results: Zn was the most abundant heavy metal. The results of EF index showed that the highest degree of enrichment of dust fall particles with heavy metals is related to Ag and the lowest one is related to Cr. Also, the changes of Mean of both Igeo and IP indicators were as Ag > Pb > Zn > Cd > Cu > Co > Cr. Conclusion: According to the results, it can be concluded that Cr metal is originated from the earth and other metals are of man-made origin and are mainly due to the emissions of vehicles and industries. Also, on average, the samples had very low pollution in relation to all metals. Although the amount of pollution caused by heavy metals has not exceeded the allowable limits, but considering industrial development programs in the region, continuous measures to control air pollution caused by industries, are absolutely necessary.

Heavy metal pollution characteristics and health risk assessment of dust fall related to industrial activities in desert steppes

China’s desert steppe is the transition zone between the grasslands in central China and the arid desert. Ecological security in this region has long been a subject of debate, both in the local and academic communities. Heavy metals and other pollutants are readily released during industrial production, combustion, and transportation, aggravating the vulnerability of the desert steppes. To understand the impact of industrial activiteis on the heavy metal content of dust fall in the desert steppe, a total of 37 dust fall samples were collected over 90 days. An inductively-coupled plasma mass spectrometer (NexION 350X) was used to measure the concentration of heavy metals Cu, Cd, Cr, Pb, Mn, Co, and Zn in the dust. Using comprehensive pollution index and multivariate statistical analysis methods, we explored the characteristics and sources of heavy metal pollution. We also quantitatively assessed the carcinogenic risks of heavy metals resulting from dust reduction with the help of health risk assessment models. The heavy metals’ comprehensive pollution index values in the study area’s dust fall were ranked as follows: Zn > Cd > Pb > Mn > Cu > Co > Cr. Among these, Zn, Cd, and Pb were significant pollution factors in the study area, and were affected by industrial production and transportation. The high pollution index was concentrated in the north of the research industrial park and on both sides of a highway. The seven heavy metals’ total non-carcinogenic risk index (HI) values were ranked as follows: Mn > Co > Pb > Zn > Cr > Cu > Cd (only the HI of Mn was greater than one). Excluding Mn, the non-carcinogenic and carcinogenic risk index values of the other six heavy metals were within acceptable ranges. Previous studies have also shown that industrial transportation and production have had a significant impact on the heavy metal content of dust fall in the desert steppe.

Lead Concentration in Dust Fall in Zahedan, Sistan and Baluchistan Province, Iran

Dust is one of the atmospheric pollutants that has adverse environmental effects and consequences. Dust fall contains particles of 100 microns and smaller which fall from the atmosphere onto the earth surface. The aim of this study is to determine the concentration of lead in dust fall samples in order to study the pollution level of this element in Zahedan, Sistan and Baluchistan Province, Iran. Therefore, sampling was carried out using 30 marble dust collectors (MDCO) for 3 months in the spring of 2015 to investigate the quantitative variation and spatial analysis of lead content in dust fall. These dust collectors were placed at 30 stations on the buildings' roofs with a height of approximately 1.5 meters across the city. According to the results, the mean lead concentration in the spring was 90.16 mg/kg. In addition, the zoning map of lead content shows that the lowest level of lead was measured at Imam Khomeini station, while Mostafa Khomeini station had the highest amount of lead.

Lead concentration in dust fall in Zahedan, Sistan and Baluchistan Province, Iran

Dust is one of the atmospheric pollutants that have adverse environmental effects and consequences. Dust fall contains particles of 100 microns or even smaller ones, which fall from the atmosphere onto the earth surface. The aim of this study is to determine the concentration of lead in dust fall samples in order to study the pollution level of this element in Zahedan, Sistan and Baluchistan Province, Iran. Therefore, sampling was carried out using 30 marble dust collectors (MDCO) for 3 months in the spring of 2015 to investigate the quantitative variation and spatial analysis of lead content in dust fall. These dust collectors were placed at 30 stations on the building roofs with a height of approximately 1.5 meters across the city. According to the results, the mean lead concentration in the spring was 90.16 mg/kg. In addition, the zoning map of lead content shows that the lowest level of lead was measured at Imam Khomeini station while the highest amount of lead appeared in Mostafa Khomeini station.

Characteristics of Atmospheric Dustfall and Soil Magnetic Susceptibility and Environmental Significance in Xining City

Magnetic susceptibility is an important means to quickly and economically monitor the enrichment of surrounding environmental elements. As a regional central city on the Qinghai-Tibet Plateau, the relationship between atmospheric dust magnetic susceptibility and heavy metal content in Xining area is relatively lacking. In this paper, the magnetic susceptibility and geochemical element content of the collected dust samples, loess samples, surface soil samples and soil profile samples obtained through long-term observations are analyzed. The results show that the magnetic susceptibility of the dust-fall samples is the highest, the soil samples are the second, and the loess samples are the lowest; the magnetic susceptibility of the dust-fall samples in Xining City has a significant correlation with the elements Cd, Cr, Ni, Cu, Pb, Zn and Hg, and the magnetic susceptibility can be used as an indicator of heavy metal in the soil; the elements Cr, Ni, Cu, Zn and As in the soil profile are enriched at 20 cm or 30 cm, which is related to the leaching of surface elements.

Preparation of Lignite Dust Suppressant by Compound Surfactants and Effect of Inorganic Salt on Dust Suppressant

In order to improve the safety, operability, and cleanability of the dust suppressant, this paper uses the surfactant monomers selected in the previous experiment as the main material formula and adds the inorganic salt as the synergist to prepare the dust suppressant for the PMX. The wetting property of the solution was characterized by the surface tension and contact angle of the pressed coal pieces. The sedimentation experiment was used to screen the compounding system of the surfactant. Finally, the dust suppressant was used to reduce the dust of the PMX in the coal dust simulation system. The results show that (1) the surfactant compounding system can effectively improve the wetting property and the sedimentation time of coal dust. The fast penetration T (0.06%), SDBS (0.15%), and APG (0.20%) are the preferred main ingredients. (2) Adding inorganic salts on the basis of compounding, according to the effect of inorganic salts on the effect of dust suppressant, it is concluded that NaCl (1.00%) is the best synergist. (3) In order to save costs, reduce the amount of surfactant. According to the simulated dust reduction experiment, formula N: anionic surfactant SDBS (0.06%), anionic surfactant fast-permeability T (0.06%), and inorganic salt NaCl (1.00%) are the best for PMX dust fall.

Spray Structure and Characteristics of a Pressure-Swirl Dust Suppression Nozzle Using a Phase Doppler Particle Analyze

In order to understand the characteristics of the spray field of a dust suppression nozzle and provide a reference for dust nozzle selection according to dust characteristics, a three-dimensional phase Doppler particle analyzer (PDPA) spray measurement system is used to analyze the droplet size and velocity characteristics in a spray field, particularly the joint particle size–velocity distribution. According to the results, after the ejection of the jet from the nozzle, the droplets initially maintained some velocity; however, the distribution of particles with different sizes was not uniform. As the spray distance increased, the droplet velocity decreased significantly, and the particle size distribution changed very little. As the distance increased further, the large droplets separated into smaller droplets, and their velocity decreased rapidly. The distributions of the particle size and velocity of the droplets then became stable. Based on the particle size-velocity distribution characteristics, the spray structure of pressure-swirl nozzles can be divided into five regions, i.e., the mixing, expansion, stabilization, decay, and rarefied regions. The expansion, stabilization, and decay regions are the effective dust fall areas. In addition, the droplet size in the stabilization region is the most uniform, indicating that this region is the best dust fall region. The conclusions can provide abundant calibration data for spray dust fall nozzles.