Dust Fall Research Articles

Lead Exposure in Young Children over a 5-Year Period using Alternative Exposure Measures with the US EPA IEUBK Model

Background/Aim: In predicting blood lead (PbB) levels in children, the IEUBK model recommends use of site specific data for soil, house dust, ambient air, water, and diet. We evaluated the model by substituting dust fall accumulation and hand wipe data instead of house dust collected by vacuum cleaner, and exterior dust sweepings instead of soil. Most uses have been on industrial sites such as mining and smelting. Methods: Simulations were undertaken on a comprehensive data set, including measured PbB, for 108 children monitored over a 5-year period in Sydney. In contrast to all other IEUBK model studies to our knowledge, data were stratified over the age ranges from 1 to 5 years as well as using data aggregated over the time of the study for each individual. Results were compared with those obtained by mixed model analyses and structural equation modelling. Results: The geometric mean contributions to total Pb intake for a child aged 1-2 years was 0.1% for air, 42% for diet, 5.3% for water and 42% for soil and dust. The median predicted versus measured PbB values were not significantly different over age of collection for soil with petri dish dust (PDD), soil with hand wipes, or sweepings with PDD although the geometric means showed large ranges over the different ages. The predicted PbB values are strongly influenced by soil Pb. Use of site specific soil values with default dust estimates results in higher predicted PbB with the contribution of soil+dust to total Pb exposure for default estimations being 8 to 42% higher than for site specific soil and dust. Conclusions: Our results indicate that it is possible to use alternative measures of soil and dust exposure to provide reliable predictions of PbB in urban environments although very high Pb values for sweepings give an overestimation of PbB.

The Elemental Composition of Atmospheric Particles and Dust Fall Rate in Erbil Governorate

Sand and Dust Storms are usually developed in arid and semi-arid regions. Dust and sand storms are a persistent problem in Iraq and other areas in the Middle East. Dust fall is one of the important air pollutants in the ambient air of Erbil governorate. This study was aimed to investigate the falling dust rate and their chemical element composition by percentage (%) using (CIT-3000SMP X-ray Fluorescence) from January to December 2013. We compared the dust rate fall and elemental composition of atmospheric particles in three different areas within Erbil governorate. The dust fall rate and the chemical element composition of dust particles were determined at four sampling locations in Erbil governorate, which were included (Erbil, koya, Makhmur and Pirmam). Our results showed that the maximum dust fall rate was recorded in Erbil (97.6 gm/m 2 .year), whereas minimum concentration was found in Koya (59.24 gm/m 2 .year). The higher of mean percentage by weight of some elements such as (Fe, Sb, Se, Nb, Tc, Te, Ag, Ta, Mo, Po, In, Cd, V, At and Zr) were higher in Erbil city compared to other areas of study.

Survival of LA-MRSA in Dust from Swine Farms.

Dust is suspected to be an important factor in transmission of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) between pigs and pig farmers and their families. The aim of this study was to determine the rate of decay for Staphylococcus aureus and LA-MRSA in dust from swine farms. Electrostatic dust fall collectors (EDCs) were used for passive sampling of settling airborne dust in 11 stable sections from six swine farms. Extraction, plating, identification, and enumeration of cultivable S. aureus and LA-MRSA from the EDCs were performed after storage for 0–30 days postsampling. The survival of S. aureus was measured in 196 dust samples from all farms, and data were used to estimate the decay constant λ according to a model for exponential decay: N(t) = N0 × e−λt. The number of S. aureus colonies was up to 600-fold higher than the number of LA-MRSA colonies on MRSA selective agar. The data showed a good fit to the model (λ = 0.13, r2 = 0.86) even with a large difference in initial concentrations of S. aureus between stables. The loads of S. aureus and LA-MRSA in the dust were significantly reduced by storage time, and the half-life was 5 days for both S. aureus and LA-MRSA. In dust samples with high initial concentrations, LA-MRSA and S. aureus could still be cultivated 30 days after sampling. On all farms MRSA isolates belonged to the clonal complex (CC) 398, and at one farm some isolates also belonged to CC30. A screening for other Staphylococcus species in the farm dust revealed 13 different species numerically dominated by Staphylococcus equorum. Based on the exponential decay model, S. equorum had a half-life of 4 days. In conclusion, the presence of MRSA in airborne dust from five of six farms indicates that dust might be an important vehicle for transmission of LA-MRSA. LA-MRSA and S. aureus was found to survive well in farm dust with half-lives of 5 days, and dependent on the initial concentration they could be found in farm dust for weeks. The 99.9% die-off rate was 66 days for LA-MRSA. Thus, farm dust can pose an exposure risk for humans in the farm environment, but also when transported to other environments. On the other hand, the risk will decrease by time. These results provide important knowledge to diminish spread from farm environments to other environments on, e.g., tools or clothing, and in relation to cleaning of emptied LA-MRSA-positive stables.

Ocular infections after penetrating keratoplasty

Context Early diagnosis of ocular infections following penetrating keratoplasty (PK) depending on clinical presentation in addition to ancillary laboratory investigations facilitates preservation of useful vision and prevention of further intraocular spread. Aim The aim of this research was to study donor and recipient risk factors in post-PK ocular infections. Patients and methods This is an interventional prospective study. This prospective study was conducted in 34 patients who underwent PK under peribulbar anaesthesia from 2014 to 2016 in a tertiary hospital. Six patients developed signs and symptoms suspicious of postoperative infections. Inclusion and exclusion criteria are mentioned. MS excel was used for statistical analyses. Results The mean age was 53±18.04 years, ranging from 12 to 86 years with 24 (70.59%) male and 10 (29.41) female individuals studied. There were 24 (70.59%) right eyes and 10 left eyes (29.41). The mean age was 63.97±16.8 years among the donors. Six (17.64%) patients developed postoperative infections that included one patient with Pseudomonas aeroginosa keratoconjunctivitis, two patients with fusarium fungal keratitis and growth could not be established in the remaining three cases. Positive microbial identification by culture was possible in three (8.82%) patients. Conclusion Microbial identification was confirmed in three cases, and three cases were negative for growth. The risk factor found among recipients were vegetative injury, dust fall and eye rubbing, as well as taking a very hot bath. Graft clarity restoration significantly improved after topical management with fortified antibiotics and antifungal agents.

Manganese and lead levels in settled dust in elementary schools are correlated with biomarkers of exposure in school-aged children.

Previously, we showed that manganese (Mn) levels in settled dust in elementary schools increased at a rate of 34.1% per km closer to a ferro-manganese alloy plant in the rainy season. In this study, we investigated how this environmental pollution indicator varied in the dry season and if there was an association with Mn biomarker levels in school-aged children. Dust samples were collected with passive samplers (disposable Petri dishes) placed in interior and exterior environments of 14 elementary schools. Occipital hair, toenails and blood samples were collected from 173 students aged 7-12 years from three of these schools, with varying distance from the industrial plant. Mn and lead (Pb) levels were measured by graphite furnace atomic absorption spectrometry. Mn concentration geometric means (GM) in dust fall accumulation in interior environments of schools located at 2, 4, 6 and>6km-radii from the plant were 2212, 584, 625 and 224μg Mn/m2/30 days, respectively. The modelled rate of change of dust Mn levels decreases by 59.8% for each km further from the plant. Pb levels in settled dust varied between 18 and 81μg/m2/30 days with no association with distance from the plant. Blood lead levels median (range) were 1.2μg/dL (0.2-15.6), of which 97.8% were <5μg/dL. Mn in hair and toenails were 0.66μg/g (0.16-8.79) and 0.86μg/g (0.15-13.30), respectively. Mn loading rates were positively associated with log MnH (β=1.42×10-5, p<0.001) after adjusting for children's age; and also with log MnTn (β=2.31×10-5, p<0.001) independent of age. Mn loading rates explained 18.5% and 28.5% of the variance in MnH and MnTn levels, respectively. School-aged children exposure to Mn, independently of age, increases significantly with school proximity to the ferro-manganese alloy plant.

Using regression model to identify and evaluate heavy metal pollution sources in an open pit coal mine area, Eastern Junggar, China

This study aims at identifying multi-source heavy metal pollution from natural and anthropogenic sources using a regression model, principal component analysis, and five different indices (geo-accumulation index (I geo), the modified degree of contamination, pollution load index (PLI), enrichment factor, and ecological risk factor. Results revealed that: (1) although the average concentrations of soil heavy metals (Cu, Cr, Pb, Hg, As, Zn) were generally low, Hg, As, and Cr concentrations exceeded national standard values by approximately 0.91, 1.84, and 0.91 times with maximum concentrations up to 0.41, 78.6, and 175.2 μg/g, respectively; (2) PLI results showed that the industrial park and Wucaiwan open coal mining area were the most polluted (PLI of 1.98, 1.71). The potential ecological hazards index indicated that the E i r of three heavy metals (Cu, Hg, As) in the soil were relatively high, presenting potential ecological risk factors of 74.89, 16.71, 4.15%, respectively; (3) stepwise regression model and principal component analysis suggest that Cu and Zn were primarily effected by the natural geological condition and atmospheric dust fall. Cr, Hg, Pb are mainly derived from anthropogenic sources, particularly coal mining activities and industrial sources. Results of this research have some significant implications for heavy metal pollution prevention and the sustainable development of the economy and ecology of arid regions in China.

Dust deposition from air with anomalous characteristics

A singular event related with the fall of a considerable amount of dust with anomalous characteristics is reported here, as well as the physicochemical characteristics of samples collected at the site in Lisbon—Portugal. The dust fall occurred during a rainy autumnal overnight and the geographic delimitation of the affected area, as well as the physical state in situ of the powder samples, are not compatible with the one that would be expected considering the climatic conditions registered at that time. The collected samples have been investigated, particularly by modern techniques involving nanoparticle analysis. The results prove that the samples have a very heterogeneous and granulated composition whose nanoparticle size distribution is bimodal (centered, respectively, about 90 and 120 nm) and containing some nanowhiskers and nanorods. Taking into account the official meteo data, it is likely that dust must have been transported by air and dried in the place (after rain) by unusual extremely localized-heat wave. However, the back trajectories software simulations point to a geographic source of clouds which soil chemical composition has no correlation with the chemical composition of the sample and where no industrial-relevant source is assigned.

Characteristics and Sources of Elements in Atmospheric Dust Fall in Zhuzhou City, Central China

To study the concentration characteristics as well as sources of elements and heavy metal pollution in atmospheric dust fall in Zhuzhou City, 144 samples from 12 sites in the Zhuzhou urban area were collected from January to December in 2012 and 28 kinds of elements in the samples were analyzed. The results showed that the dust fall quantities of the industrial areas and mixed commercial and residential (MCR) areas were, respectively, 89.46 g·m-2 and 33.20 g·m-2 and the range of all sample points was 23.14-114.67 g·m-2. There were 10 elements (Na, Mg, Al, K, Ca, Ti, Mn, Fe, Zn, Pb) in the industrial areas as well as 8 elements in the MCR areas, for which the contents greatly exceeded 1000 mg·m-1 in the atmospheric dust fall. The Zn and Pb contents exceeded 10000 mg·kg-1 in the dust fall of the industrial areas, which were far higher than those in the Earth's crust. The main sources of dust fall in Zhuzhou City were metal smelting, shallow ground dust, vehicle emissions, construction dust, and industrial production with specific elements (Mo, Ba). Correlation analysis, principal component analysis (PCA), and analysis of transportation characteristics showed that 13 elements (Mn, Fe, Co, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Tl, Pb) in dust fall mainly came from waste gas emissions of industrial areas in Zhuzhou, in which 7 heavy metal elements (Cu, Zn, As, Ag, Cd, Sb, Pb) caused serious pollution. The contents of heavy metals in the industrial areas were 7.4 to 4079.4 times the contents defined in China soil elements background values, whereas those in the MCR areas were 3.6 to 1413.4 times the soil background values. Cd was the highest background ratio element. The degree of contamination was clearly higher in the industrial areas than in the MCR areas.

A simple lead dust fall method predicts children's blood lead level: New evidence from Australia

We have measured dust fall accumulation in petri dishes (PDD) collected 6 monthly from inside residences in Sydney urban area, New South Wales, Australia as part of a 5-year longitudinal study to determine environmental associations, including soil. with blood lead (PbB) levels. The Pb loading in the dishes (n = 706) had geometric means (GM) of 24µg/m2/30d, a median value of 22µg/m2/30d with a range from 0.2 to 11,390µg/m2/30d. Observed geometric mean PbB was 2.4µg/dL at ages 2–3 years. Regression analyses showed a statistically significant relationship between predicted PbB and PDD. The predicted PbB values from dust in our study are consistent with similar analyses from the US in which floor dust was collected by wipes. Predicted PbB values from PDD indicate that an increase in PDD of about 100µg/m2/30d would increase PbB by about 1.5µg/dL or a doubling PbB at the low levels currently observed in many countries. Predicted PbB values from soil indicate that a change from 0 to 1000mg Pb/kg results in an increase of 1.7µg/dL in PbB, consistent with earlier investigations. Blood Pb levels can be predicted from dust fall accumulation (and soil) in cases where blood sampling is not always possible, especially in young children. Petri dish loading data could provide an alternative or complementary “action level” at about 100µg Pb/m2/30 days, similar to the suggested level of about 110µg Pb/m2 for surface wipes, for use in monitoring activities such as housing rehabilitation, demolition or soil resuspension.

Pengaruh Jarak Sumber Pencemar Terhadap Kada Sulfat (SO4) pada Debu Terendap di Sepanjang Jalan Angkut Batubara

Abstract: The Influence Of The Distance Of Pollutant Source On Sulfate (So4) Concentrations In The Dust Along The Coal Haul Road. One of the quality parameters of coal is Sulfur. Sulfur content in coal be able to reach 4%. Sulfur content in coal at South Kalimantan mine ranges from 0.08 – 1.58%. Sulfur can be in the form of pyrite as S2 and sulfate as SO4. Sulfur content in coal dust that floats in the air will fall along with rain. This study aims to determine the effect of distance to SO4 levels on dust along coal haul roads. The sampling point was taken from variation of distance that is 1 m, 50 m, 100 m, 150 m, and 200 m from the side of coal haul road. The results showed that the highest sulfate concentration was at 1 m distance from the side of the road, that was 37.865 mg/L, and the lowest was at 200 m distance from the side of the road, that was 3.405 mg/L. These sulfate concentrations were proportional to dust fall. The farther the sampling point, the sulfate content decreases.&#x0D; &#x0D; Keywords: Dust Fall; sulfate concentration; distance.

Uptake of PAHs by cabbage root and leaf in vegetable plots near a large coking manufacturer and associations with PAHs in cabbage core.

Samples of ambient air (including gaseous and particulate phases), dust fall, surface soil, rhizosphere soil, core (edible part), outer leaf, and root of cabbage from eight vegetable plots near a large coking manufacturer were collected during the harvest period. Concentrations, compositions, and distributions of parent PAHs in different samples were determined. Our results indicated that most of the parent PAHs in air occurred in the gaseous phase, dominated by low molecular weight (LMW) species with two to three rings. Specific isomeric ratios and principal component analysis were employed to preliminarily identify the local sources of parent PAHs emitted. The main emission sources of parent PAHs could be apportioned as a mixture of coal combustion, coking production, and traffic tailing gas. PAH components with two to four rings were prevailing in dust fall, surface soil, and rhizosphere soil. Concentrations of PAHs in surface soil exhibited a significant positive correlation with topsoil TOC fractions. Compositional profiles in outer leaf and core of cabbage, dominated by LMW species, were similar to those in the local air. Overall, the order of parent PAH concentration in cabbage was outer leaf > root > core. Partial correlation analysis and multivariate linear stepwise regression revealed that PAH concentrations in cabbage core were closely associated with PAHs present both in root and in outer leaf, namely, affected by adsorption, then absorption, and translocation of PAHs from rhizosphere soil and ambient air, respectively.

Experimental study of factors affecting dust accumulation and their effects on the transmission coefficient of glass for solar applications

Solar collectors and Photovoltaic panels are the most common applications of solar energy. Although how to increase the efficiency of these systems in different ways has been vastly studied and analyzed, the effect of dust accumulation on panel’s and collector’s efficiency has been largely ignored. To overcome this deficit, an experiment was developed in Isfahan, Iran, to investigate the factors affecting dust accumulation and their effects on the transmission coefficient of glass. The results indicate factors such as installation tilt, azimuth angle, dominant wind direction and the time in which samples are placed within the environment, are related to dust accumulation density on surface and transmission coefficient reduction. Up to 25% decline in the transmission coefficient caused by the accumulation of dust on the surface was observed during the 70-day test period. Given that the dust fall density is strictly depended on weather conditions during the test period, unlike previous studies, in this article the transmission reduction relation, instead of time is derived in terms of dust accumulation density on the surface. This equation is generalized and applicable to other regions and even different weather conditions.

Petrographic and mineralogical studies of fossil charcoal from Sierra de Bahoruco (Barahona Province, Dominican Republic)

The volcanic formations of the Sierra de Bahoruco mountain range (Barahona Province, Dominican Republic) contain charred fragments of plants, mainly tree trunks, which are composed of dense concentrations of hard mineralized fusain, with diverse microstructures. Petrographic examinations confirmed occurrence of two types of fusinite - structural fusinite with well-preserved tree tissue fragments, and detrital fusinite originating probably from softer tissues of tree phloem. In addition to the fusinite varieties developed from tree trunks and roots, charred tissues of dead external part of trunk epidermis affected by the microbiological process of rotting were identified. Poorly marked seasonal growth rings of trees, the shape and distribution of tree tissues, as well as the degrees of tissue destruction, indicated that the fragments originated from tropical trees growing in specifically marked rain and dry seasons, while wood tissues, charred by the fall of hot volcanic dust, suggested the existence of a monsoon tropical forest on the area. Fusinite was strongly impregnated with calcite and pectolite, sometimes zeolites (prehnite) and chlorite. It was accompanied by iron and copper sulphides, i.e. pyrite, chalcopyrite, and chalcocite. The latter minerals occurred in magma and pyroclastic formations, strongly associated with hydrothermal activities.

Impact of coal-carrying trains on particulate matter concentrations in South Delta, British Columbia, Canada

Transport of coal by train through residential neighborhoods in Metro Vancouver, British Columbia, Canada may increase the possibility of exposure to particulate matter at different size ranges, with concomitant potential negative health impacts. This pilot study identifies and quantifies train impacts on particulate matter (PM) concentrations at a single location. Field work was conducted during August and September 2014, with the attributes of a subset of passing trains confirmed visually, and the majority of passages identified with audio data. In addition to fixed ground based monitors at distances 15 and 50 m from the train tracks, an horizontally pointing mini-micropulse lidar system was deployed on three days to make backscatter and depolarization measurements in an attempt to identify the zone of influence, and sources, of train-generated PM. Ancillary wind and dust fall data were also utilized. Trains carrying coal are associated with a 5.3 (54%), 4.1 (33%), and 2.6 (17%) μgm−3 average increase in concentration over a 14 min period compared to the average concentrations over the 10 min prior to and after a train passage (“control” or “background” conditions), for PM3, PM10, and PM20, respectively. In addition, for PM10 and PM20, concentrations during train passages of non-coal-carrying trains were not found to be significantly different from PM concentrations during control conditions. Presence of coal dust particles at the site was confirmed by dust fall measurements. Although enhancements of PM concentrations during 14 min train passages were generally modest, passing coal trains occasionally enhanced concentrations at 50 m from the tracks by ∼100 μgm-3. Results showed that not every train passage increased PM concentrations, and the effect appears to be highly dependent on wind direction, local meteorology and load related factors. LiDAR imagery suggests that re-mobilization of track-side PM by train-induced turbulence may be a significant contributor to coarse particle enhancements.

Investigation of chemical characteristics and spatiotemporal quantitative changes of dust fall using GIS and RS technologies; a case study, Yazd city, central plateau of Iran

Background: 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. Methods: 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: 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. Conclusion: 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. Keywords: ArcGIS, ENVI, Remote sensing, Air pollution, Dust fall, Zoning

Evaluation of some heavy metals loading in dust fall of three universities motor parks in Western Nigeria

The high density of vehicles that run to and fro University campus to town has become of great concern for assessment of health status of the ambient air around the Universities motor parks. Moreover, some of the University’s parks are unpaved while the paved ones are old and unmaintained. Dust fall samples in parks of Universities of Ilorin, Ibadan and Kwara State University were collected for five months spanning from 1st November 2014 to 31st March, 2015 using open bucket sampler based on ASTM D 1739 of 1998 (2010). A 0.1 g of dust sample was digested with 20 ml of HNO3, HClO4 and HF in ratio of (3:2:1) respectively and heavy metals (Mn, Cu, Zn, Cd, Pb, and Ni) were analysed using atomic absorption spectrophotometer (Buck Scientific model 210 VGP). Results of heavy metal concentrations showed decrease in the following order: 1479.75, 1255.68, 241.50, 128.00, 85.25, and 9.63 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively for University of Ibadan. The decreased in concentrations of heavy metals obtained for University of Ilorin motor park dust-fall were found to be 1145.75, 797.75, 219.63, 133.51, 58.25 and 23.13 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively. For Kwara State University, decrease in the following order: 778.5, 323.88, 259.38, 101.38, 34.38, and 4.63 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively were obtained. Generally for the three sites used, the heavy metal concentrations decreased in the following order: Mn&gt;Zn&gt;Pb&gt;Ni&gt;Cu&gt;Cd. This implies that dust-fall in the parks are heavily loaded with some heavy metals that are of concentrations above Romania standard threshold limit for Cd and Pb while concentration values obtained for Ni are higher than US- EPA values (75 mg/kg). The regulatory agent or management should ensure that the roads are paved and there should be intermittent wetting of the roads with water.Keywords: Dust Fall; Heavy Metals; University Motor Parks

Assessment of Heavy Metals Pollution and Its Health Risk of Atmospheric Dust Fall from East Part of Junggar Basin in Xinjiang

In order to evaluate the contamination and health risk of heavy metals from atmospheric dust fall in Zhundong opencast coalfield in Xinjiang, samples of atmospheric dust fall were collected from 52 sampling sites covering the entire region and the contents of Zn, Cu, Cr, Pb, Hg and As were tested and analyzed. The contamination was assessed by geo-accumulation index method, and the risk to human health was assessed using the US EPA Health Risk Assessment Model. The results showed that:The contamination of heavy metals from atmospheric dust fall had a significant difference, in the order of Zn > Cr > Cu > As > Pb > Hg, and the average contents were higher than the soil background of Changji. The coefficient of variation of Hg, Cu and As was 381.91%, 99.94% and 97.82%, and human activities had a greater impact on them. The correlation coefficients in 6 heavy metals were complex, the correlation coefficients among Zn-Cu-Cr were more relevant than Hg-As-Pb. The assessment results of geo-accumulation index indicated that the Zn pollution in the atmospheric dust fall should be classified as extreme degree, and that of Cu, Pb, As as between slight and extreme degrees, and Hg as practically uncontaminated. The exposure content of carcinogenic risk and non-carcinogenic risk of the study area had little difference. It was HQCr > HQAs > HQZn > HQPb > HQCu > HQHg, the total non-cancer hazard index was 0.258, the non-cancer hazard indexes were both lower than their threshold values, suggesting that they would not harm the health. The carcinogenic risk hazard indexes were in the order of CRAs > CRCr > CRPb, suggesting that Pb had no cancer risk, while As was the most important carcinogenic factor. The average TCR was 1.95E-05, indicating that the risk was within the limit that human can tolerate.

Environmental mobility of trace elements present in dusts emitted from Zn–Pb metallurgical processes

The paper presents results of investigations into possibility of migration to the soil and water environment of trace elements present in one of the main phases, zinc sulphide, emitted in dusts from various operations of pyrometallurgical extraction of Zn and Pb at the Miasteczko Śląskie Zinc Smelting Plant. The quantity of elements was estimated on the basis of: (1) dust fall, (2) zinc sulphide content in dust, (3) element content in zinc sulphide and (4) mobility of zinc sulphide under the hypergenic conditions of the soil and water environment of the Smelting Plant area. Among the elements considered, arsenic emitted with zinc sulphide contained in dusts from the Sintering Machine will pose a potential hazard for the soil and water environment of the Miasteczko Śląskie Zinc Smelting Plant area.

Variations of Nutrients in Gross Rainfall, Stemflow, and Throughfall Within Revegetated Desert Ecosystems

Revegetation in arid desert ecosystems is emerging as a practical strategy to cease sand dune encroachment and combat desertification worldwide. The revegetation is expected to affect the spatial distribution of rainfall to the ground within vegetation communities. However, the impact of revegetation on the temporal distribution of dry and/or wet dust fall trapped by shrub canopies via stemflow and throughfall remains a topic of concern for shrub “fertile islands.” This study investigated whether xerophytic shrub community acts as a sink of various cations (Na+, K+, Ca2+, and Mg2+), inorganic anions (Cl− and SO4 2−), total nitrogen, and total phosphorus to the revegetated desert ecosystems. Gross rainfall, the stemflow, and throughfall of two codominated xerophytic shrubs (Caragana korshinskii and Artemisia ordosica) were volumetrically measured after natural rainfall events, and their samples were chemically analyzed in the laboratory. Results showed that ions had higher concentrations in stemflow than in throughfall, followed by gross rainfall. Ion concentrations in stemflow and throughfall strongly depends on the first flush effect, rainfall depth, and the antecedent dry period before a rainfall event occurring. Concentrations of most of the ions in stemflow and throughfall collected after the first rainfall event of a year were obviously higher than other rainfall events for both shrub species, suggesting a first flush effect. Ion concentrations generally decreased with the increasing depth of gross rainfall, stemflow, and throughfall, while increased with prolonged antecedent dry period. Based on nutrient input by stemflow and throughfall at the community scale, we conclude that chemical enrichment of stemflow and throughfall plays an important role in forming the shrub fertile islands and contributes significantly to a sustainable succession of the revegetated desert ecosystems.

Manganese and lead in dust fall accumulation in elementary schools near a ferromanganese alloy plant

Previous studies have shown elevated airborne manganese (Mn) in villages adjacent to a Mn alloy production plant in Brazil and negative associations between biomarkers of Mn and children's cognition and behavior. Since small Mn particles may be carried for long distances, we measured manganese (Mn) and lead (Pb) dust fall accumulation in 15 elementary schools, located between 1.25 and 6.48km from the plant in the municipality of Simões Filho, Bahia, Brazil. Passive samplers (polyethylene Petri dishes) were set in interior and exterior environments. After 30 days, the samplers’ content was solubilized with diluted nitric acid and Mn and Pb levels were analyzed by electrothermal absorption spectrometry. The overall geometric mean and range of Mn and Pb accumulation in dust fall (loading rates) were 1582μg Mn/m2/30 days (37–37,967) and 43.2μg Pb/m2/30 days (2.9–210.4). A logarithmic decrease in interior and exterior Mn loading rates was observed with distance from the ferro-manganese alloy plant. Multiple regression analyses of log-transformed Mn loading rate within the schools showed a positive association with Mn levels in outdoor dust, a negative association with distance from the plant; as well, wind direction (downwind>upwind) and school location (urban>rural) entered significantly into the model. For the interior school environments, located within a 2-km radius from the plant, loading rate was, on average, 190 times higher than the Mn levels reported by Gulson et al., (2014) in daycare centers in Sydney, Australia, using a similar method. Pb loading rates were not associated with distance from the plant and were lower than the rates observed in the same daycare centers in Sydney. Our findings suggest that a significant portion of the children in this town in Brazil may be exposed to airborne Mn at concentrations that may affect their neurodevelopment.