Integrated Magnetic Analyses for the Discrimination of Urban and Industrial Dusts

Industrial and urban dusts were characterized by investigating their magnetic properties. Topsoil composed of technogenic magnetic particles (TMP) originating from areas affected by three ironworks, street dust mainly composed of traffic-related pollution, and particulate matter (PM) from urban agglomeration in Warsaw, Poland were investigated. Several magnetic methods, namely magnetic susceptibility, thermomagnetic curves, hysteresis loops, decomposition of isothermal remanent magnetization acquisition curves, and first-order reversal curves, were performed to evaluate the magnetic fraction of dust. Magnetite was the main magnetic phase in all types of samples, with a small amount of high-coercive hematite within ironworks and street dust samples. Significant differences were observed in the domain structure (grain size) of industrial and traffic-related magnetic particles. The grain size of TMP obtained from steel production was in the range of 5–20 µm and was predominated by a mixture of single-domain (SD) and multidomain (MD) grains, with the prevalence of SD grains in the topsoil affected by Třinec ironwork. The traffic-related dust contained finer grains with a size of about 0.1 µm, which is characteristic of the pseudo-single-domain (PSD)/SD threshold. Street dusts were composed of a slightly higher proportion of MD grains, while PM also revealed the typical behavior of superparamagnetic particles.

BIOAVAILABILITY AND HEALTH RISK OF METALS IN URBAN DUSTS

Heavy metals gets into human body mostly through oral ingestion of environmental samples. To quantify the risks associated with oral ingestion of urban dust particularly by children, bioavalability fraction is required, as the total metal content may not give the real risk involved. Lead (Pb), Arsenic (As) and Cadmium (Cd) were analysed for bioavailable fraction in urban dust of this study. The risks of these metals on ingestion of urban dust by children were estimated. The results showed that metals solubilized in the gastrointestinal tract. This could possibly be due to metal distribution in the dust sample and the solubilisation of these metals in the gastrointestinal tract. The carcinogenic and non-carcinogenic risks results expressed that all the values were within the permissible limits of 1×10-6 1×10-4 with the order As > Cd > Pb. This indicates that children who ingested dust could have no possibility of both carcinogenic and non-cancer risks because both the CR, TCR and HQ and HI values were below the tolerable limits. Keywords: Bioavailability; risks; metals; urban dust

EVALUATION OF ENVIRONMENTAL EXPOSURE TO Cr, Cu, Pb, Ni AND Zn PRESENT IN URBAN DUSTS

The paper assesses the environmental exposure of urban dwellers to heavy metals present in urban dusts. The research was focused on lifelong exposure of an adult and a child to chromium, lead, nickel, copper and zinc. The assessment of health hazard included exposure by digestion, inhalation and skin contact. The hazard estimation was carried out using a method recommended by the American Environmental Protection Agency (US EPA). The determined hazard index values characterizing a health risk have shown that the highest hazard results from accidental unintentional intake of toxic substances. Skin penetration by metals is much less hazardous, whereas inhalation is least hazardous. According to the accepted scenario of human exposure, children are most at risk compared to other populations considered. The hazard index values obtained for them were the highest.

Chemical Speciation of Heavy Metals and Trace Element in Urban Street Dusts of Beijing, China

Sequential extraction was used to characteristic the heavy metals (Cd, Cr, Zn, Cu, Ni and Pb) and trace element (As) studied in these urban dusts. The ratio of the average total content (F1+F2+F3+F4+R) to the corresponding background value of Beijing soil decreased in the order of Cd>Pb>Cu>Zn>Ni>Cr>As. For fraction distribution, residual form predominated among for Zn, Ni, Cr and Pb. Oxidizable fraction was the leading fraction for Cd and Cu and was the second dominated fraction for Zn and Ni. The results of Risk assessment code (RAC) showed the medium environmental risk of Cd was found in Dongcheng and East 4thRing districts, while a high environmental risk for Cr was present in Xizhimen and Yongdingmen areas.