Selective determination of rhodium and iridium in the urban environment using the catalytic method

The problem of studying the level of technogenic pollution of the environment with platinum group metals is attributed first to the release of platinum metals into the environment together with the exhaust gases of cars using afterburning catalysts containing Pt, Pd, Rh. The pharmaceutical, electronics and jewelry industries the waste of which contains PGMs also contribute to the pollution of the environment. A number of studies have shown the toxic effects of PGM on humans. The goal of the study is to obtain new information about the level of technogenic pollution of the environment with platinum group metals (such as water-washings from roads, bio-collector plants, roadside dust), which necessitates developing of the method for sample preparation and determination of rhodium and iridium. A technique of sample opening and determination of rhodium and iridium in environmental objects, water-washings from roads, bio-collector plants, roadside dust is proposed. To increase the selectivity of rhodium determination, the samples were treated with a mixture of concentrated perchloric acid and sodium periodate when heated to boiling, which provided more than 5-fold increase the rhodium signal. Moreover, the permissible excess of iridium and ruthenium was increased by 5 and 20 times, respectively, due to the conversion of other PGMs into catalytically inactive forms. The indicator reaction of sulfarsazen oxidation by periodate was used in the kinetic determination of rhodium and iridium. The correctness of the results obtained by the developed method was confirmed by the ETAAS method. The determined content of Rh and Ir: in roadside waters (μg/liter) up to 0.015 and 0.005; in collector plants (g/ton) up to 0.030 Rh and 0.022; in street dust (g/ton) up to 0.05 and 0.025, respectively. The standard deviation of the repeatability of the determination results does not exceed 0.07 (Rh) and 0.12 (Ir). The developed method of opening samples and determining rhodium and iridium in environmental objects provided a great bulk of information about the content of rhodium and iridium in water-flushes from Moscow roads, bio-collector plants, roadside dust, which correlate fairly well with the scarce data from other geographic regions available in the literature and our earlier results on rhodium content in dust. The developed technique made it possible to obtain data on the level of technical pollution of the environment with PGMs in places with different traffic density in Moscow.

Sedimentological and Heavy Metals Characteristics of Streets Dust in some Areas East of Baghdad for 2020

Road-side dust samples were collected during August in 2020 from selected areas of, Al-Rusafa, Baghdad, Iraq. A sedimentological and mineralogical analysis of street dust was conducted. Three areas were selected to study street dusts which are Al-Baladitat, Al-Obaidi and Ziona. The laboratory analyses were done in the Department of Geology, College of Science, University of Baghdad. The heavy metal contents were determined in the roadside dust using XRF Method. It was found that the dust is of muddy texture, and is believed to be transmitted with the various storms blowing on Baghdad or by the wheels of Cars. The results of mineralogical investigation revealed that the dust samples composed of quartz, feldspar, calcite, gypsum and sedimentary rocks fragments, as light minerals and the heavy minerals were found as garnet, epidote, chlorites, pyroxene, biotite, zircon, muscovite, hornblende, tourmaline. The heavy metals (Fe, Co, Ni, Cu, Zn and Pb) in these streets dust samples were studied and used as indicator for pollution. two o main indices are applied: contamination factor, and pollution load index. The contamination factor for Co, Zn, Pb, and Ni is classified as class 2, which indicate moderately contamination, while the contamination factor for Fe and Cu is classified as class 1, which indicate low contamination. The pollution load index values in the all of studied sites are classified as class 2 (Deterioration on site quality) indicating local pollution, as well as denote perfection with class 0 of no pollution.

Determination of Heavy Metal Contamination and Pollution Indices of Roadside Dust in Dhaka City, Bangladesh

Urban roadside dust samples from Dhaka City in Bangladesh were collected from a planned residential area (PRA), spontaneous residential area (SRA), commercial area (CA), and urban green area (UGA) in winter and summer to study how season and different urban land-use categories influence the concentrations of heavy metals (Cr, Mn, Co, Ni, Cu, Zn, As, and Pb) and different pollution indices. The dust samples were fractionated into <32 μm particles, extracted by acid digestion followed by estimation of heavy metals, using ICP-MS. Pollution indices were calculated from the metal concentrations, using standard protocols. The concentrations of heavy metals in roadside dust varied significantly (all p < 0.05), due to sampling seasons and the land-use category. Higher concentrations of heavy metals (Cr, Mn, Ni, Cu, Zn, and Pb) were found in the dust sampled during the winter season than in the summer season, except for As and Co. The geo-accumulation index (Igeo) indicated that the commercial area was heavily contaminated with Cu and Zn during the winter season. The contamination factor (CF) was higher for Cu and Zn in the CA, PRA, and SRA of Dhaka City in winter than in the summer season. The enrichment factor (EF) suggested that Mn and Co were the least enriched metals, and significant enrichment was seen for Cu and Zn for all land-use categories, both in summer and winter. A moderate potential ecological risk for Cu was estimated in CA and PRA in the winter season.

Understanding sources and processes using chemistry of fine and coarse particles simultaneously collected from different windward locations in N-NW India

PM2.5and PM2.5-10 particles, simultaneously collected from Bikaner (BKR) and New Delhi (DEL) through Jhunjhunu (JHJ) located along S-SW wind pathduring summer in N-NW India were chemically characterized to understand their sourcesand related processes.Winds preferentially picked and trasnported PM2.5 compared to PM2.5-10 in windward direction. Ratios of mass concentrations and WSII in PM2.5 and PM2.5-10 were three or more at all sites. Thermal power plants, vehicles, and plastic burning were major contributors of SO42-, NO3- and Cl- ionsat DEL. Crustal materials, salt lakes/playas and contaminated aged particles were sources of WSIIs in PM2.5 over BKR and JHJ. In PM2.5, burning of wood and cow dung resulted in high OC/EC ratio (6.9) at BKR whereas EC emissions from vehicles lowered this ratio (3.5) at DEL. EC was dominated by char-EC compared to soot-EC. Major elements showed similar concentrations in both size particles but were depleted compared to Upper Continental Crustal (UCC) due to silica dilution effect. Ba and Sr, and Ba, Cr, Sr and Zn content showed site specific variations in PM2.5 and PM2.5-10, respectively. Trace elements in PM2.5 showed high enrichment compared to UCC at DEL due to re-suspension of roadside dust and vehicle related emissions.

Traffic-related activities driven dust-bound magnetic pollution in urban road-system: Case study of Xiamen island, China

Sources of magnetic phases in urban dust include traffic-related activities, industrial products and detrital minerals. Exposure to magnetic phases in urban dust co-associated with trace metals is associated with respiratory ailments in sensitive organisms. Here, we collected samples of surface roadside dust and topsoil from Xiamen island, Fujian, China and then magnetic properties were determined using rock-magnetic methods. Magnetic particle concentrations in surface roadside dust was found to be significantly high compared with magnetic content in topsoil using magnetic susceptibility (𝜒LF), saturation isothermal remanent magnetization (SIRM) and susceptibility of anhysteretic remanent magnetization (𝜒ARM). Roadside dusts had much lower percent frequency-dependent susceptibility (1.83 ± 0.12%) than topsoil (2.96 ± 0.14%). Given the 𝜒ARM/SIRM vs 𝜒fd% and first-order reversal curves, most of the magnetic particles in roadside dust were large than in topsoil. Variable temperature dependence of magnetization, isothermal remanent magnetization decomposition spectra and first-order reversal curves suggested the enhancement of dust 𝜒LF, SIRM and 𝜒ARM were related to the exogenous pseudo-single-domain magnetite-like materials. This study provides a better understanding of magnetic ageing of dust particles in coastal cities. These results will be useful in optimizing environmental policies aimed at regulating magnetic dust particles pollution in coastal cities.

Tyre Weights an Overlooked Diffuse Source of Lead and Antimony to Road Runoff

Lead (Pb) remains elevated in road runoff and roadside dust, which has been attributed to legacy lead in surface soils from leaded petrol. However, “lead” tyre weights, an alloy of 95% Pb and 5% Sb, may be a relatively unrecognised diffuse source of Pb and Sb as they are still used in many countries. An unknown number of these weights drop off tyre rims and deposit on the road where they are abraded and dispersed, potentially causing adverse environmental effects. The type, number and weight of tyre weights lost from motor vehicles were characterised for a range of roading infrastructures and motor vehicle intensities in a 38 month long study of a 6.9 km length of road in Hamilton City, New Zealand. Overall, 1070 tyre weights with a combined mass of 18.6 kg were collected. About 96.4% of the collected weights were made of “lead”, which is an alloy of 95% Pb and 5% Sb, indicating tyre weights can be a major source of Pb and Sb in urban areas. The tyre weight distribution on roads used in this study depended mainly on traffic density and the prevalence of “start stop” patterns in traffic flow influenced by roundabouts and intersections. “Lead” tyre weights should be phased out and replaced with environmentally benign materials.