Search Results (66)

Exposure of propulsion gas turbines to inlet flow contaminated with dust, sand, or ash particulates can lead to a myriad of complex and interrelated damage modes that reduce engine operational life, increase maintenance costs, and pose a safety risk to passengers and hardware assets. Experimental and computational research is ongoing to better understand the fundamental physics underlying this phenomenon, but data from full-scale engine tests with particles are needed for anchoring and validation under fully representative conditions. In this study, compressor blade/particle interactions are investigated at field-relevant conditions using Rolls-Royce/Allison M250-C20C turboshaft engines in an instrumented engine test cell. A novel experimental dataset was produced, yielding a qualitative visualization of particle impact regions on blades and vanes of an on-engine full six-stage axial compressor at transonic tip speeds for two particle compositions and two inlet particle delivery configurations. This investigation contributes the first experimental dataset of its kind for a rotating frame at transonic blade tip speeds (nominal Mach 1.0). By comparing the resulting impact patterns produced in this work to those of fielded hardware, it is shown that for field-relevant high-Stokes number particle conditions at the first-stage rotor, particle/engine dynamics simplify significantly due to ballistic inertial particle behavior. In addition, the spatial distribution of particle concentration and particle velocities across the compressor inlet plane was found to have only minor effects on the resulting particle/blade impact patterns for the two dust injection configurations tested. Full article

Cutting fluids are widely used in mechanical engineering to reduce friction and heat generation during metal machining. However, during operation, these fluids become contaminated with metal particles, dust, and microorganisms, leading to degradation of their functional properties and environmental concerns. This study investigates the ultrasonic cleaning and regeneration of contaminated cutting fluids. A rheological model of the elastic–viscous medium was analyzed, and a physical model describing the ultrasonic cleaning mechanism was proposed. Experimental investigations were conducted to validate the theoretical assumptions. The results confirmed that ultrasonic treatment promotes dispersion and phase separation of the fluid, removes putrefactive odor, and partially destroys microorganisms. The regenerated fluid exhibited enhanced clarity and stability compared with the contaminated samples. The findings contribute to a deeper understanding of the physicochemical processes occurring during ultrasonic treatment and demonstrate the potential of this method for sustainable reuse of cutting fluids in industrial applications. Full article

The widespread production and application of per- and polyfluoroalkyl substances (PFASs) have created a global environmental and public health crisis. This review aimed to consolidate the foundational knowledge on PFASs by synthesizing research on their environmental fate, human health impact, analytical methods, and regulatory status and by highlighting their critical challenges. A comprehensive literature search focusing on publications from the last five years (2020–2025) was conducted using global scientific databases (e.g., PubMed, Web of Science) and regulatory reports (e.g., EPA, ECHA). The persistent and pervasive nature of PFASs stems from the highly stable carbon–fluorine (C-F) bond, leading to their widespread release from diverse industrial and consumer products into water, soil, and air. Key outcomes reveal significant analytical challenges in their detection, including sample matrix complexity, widespread laboratory contamination, and a lack of standards for the vast number of specific compounds. Critical research gaps were identified, particularly the limited data on PFAS concentrations in air and dust, the need for standardized analytical methods and reporting units, and the urgent necessity for developing scalable, sustainable remediation strategies. The ongoing environmental contamination and associated health risks necessitate continued, focused interdisciplinary research to improve detection, risk assessment, and the effective management of this complex class of pollutants. Full article

The central objective of this study was to investigate metals accumulating in water at the bottom of roof-harvested drinking water tanks in rural inland NSW, located from 220 km west to 420 km northwest of Sydney. Two of three study areas contained mining operations. The Narrabri study area contained five coal mines, the Cadia study area a large gold and copper mine. A third region (Mendooran) had no mines. In this study, turbidity, pH, salinity and the total concentration of 15 metals were measured in water tank samples. Four metals (cadmium, lead, nickel and manganese) and arsenic from the bottom of tanks often exceeded Australian Drinking Water Guidelines. Of drinking water samples, 90% exceeded lead guidelines (<10 µg L⁻¹), with 54% exceeding by 100 times and 3.6% of samples exceeding lead guidelines by 1000 times. Contamination was generally greater in Cadia area tanks. It is likely that metal-enriched mine particulate emissions contribute through fallout onto roofs used to harvest drinking water. Improved environmental monitoring and governance to address metal-contaminated dust emissions from mines and improved information on fallout plumes are needed. Action is also needed to encourage regular cleaning of drinking water tanks. Full article

Urban industrial complexes have been expanding worldwide, reducing the spatial separation between agricultural, residential, and industrial zones, particularly in developing nations. Urban road dust contamination, a sensitive indicator of urban environmental quality, primarily originates in urbanization and industrialization. Its detrimental impacts on human health arise not only from particulate matter itself but also from toxic and harmful substances embedded within dust particles. Toxic metals in road dust can pose health risks through inhalation, ingestion and contact. To investigate the seasonal patterns, bioaccessibility levels and the potential human health risks linked to toxic metals (Cadmium (Cd), Nickel (Ni), Arsenic (As), Lead (Pb), Zinc (Zn), Copper (Cu), and Chromium (Cr)), 34 dust samples were collected from key roads in proximity to representative industrial facilities in Wuhan’s Qingshan District. The study found that the concentrations of Cd, Pb, and Cu in road dust were within the limits set by the national standard (GB 15618-2018), while Ni and As were not. Seasonally, Ni, As, Pb, Zn, and Cr exhibited higher concentrations during the summer than in other seasons, whereas Cd levels were lowest in spring and highest in autumn, the opposite of Cu. According to the Simplified Bioaccessibility Extraction Test (SBET), the average bioaccessibility rates of toxic metals were Cd > Zn > Cu > Ni > Cr > As > Pb. An improved health risk assessment model was developed, integrating metal enrichment, bioaccessibility, and parameter uncertainty. Results indicated that Cd, Ni, Zn, Cu, As, and Cr posed no significant non-carcinogenic risk. However, for children, the carcinogenic risks of Cd and As were relatively high, identifying them as priority control metals. Therefore, it is recommended to periodically monitor As and Cd and regulate their potential emission sources, especially in winter and spring. Full article

Heavy metals are among the most toxic and persistent environmental pollutants, accumulating in soils and living organisms. Phytoremediation, the use of plants to remove contaminants, is considered one of the promising methods for cleaning soils contaminated with metals. This study assessed the effectiveness of phytoremediation of heavy metals in soil using lettuce (Lactuca sativa) as a phytoaccumulative species. Despite the successful extraction of significant amounts of metals by the plants, post-harvest soil analysis revealed persistently elevated concentrations of elements such as iron (Fe), lead (Pb), and zinc (Zn). To clarify the reasons behind the limited improvement in soil quality, additional field investigations were conducted and identified a nearby highway as a continuous source of heavy metal emissions. In the next phase of the study, metal concentrations were analyzed in dust deposited along the highway, confirming their significant contribution to ongoing secondary soil contamination. The findings emphasize the importance of considering both environmental and anthropogenic factors when designing long-term phytoremediation strategies in urban and traffic-impacted areas. Full article

In megacities, the rapid development of construction entails threats to the environment, in particular, to the health of urban residents. One of the main sources of danger is microscopic dust particles PM_2.5 and PM₁₀, resulting from construction projects that can seriously impair people’s health. To minimize these risks, it is necessary to actively implement control over the level of dust in the air and carry out scientific work to study the impact of construction on the environment. These measures should become mandatory aspects in the planning of modern cities, given that the degree of air pollution in large cities has already reached critical levels. In modern megacities, where development is intensive and, in some places, very dense, there is a key importance of environmental audit of territories intended for construction, for creating effective and safe development projects. The lack of adequate risk control during the construction stages can lead not only to emergencies, but also have a harmful impact on the natural environment. It is worth noting that environmental hazards can vary significantly depending on the unique characteristics of each specific construction site. As a result of an in-depth analysis of the ecological state of the region, which included an assessment of various levels of pollution and their impact on the health of residents, it was found that intensive construction in some areas of the city significantly worsens the ecological situation. In particular, it was found that the level of dust pollution in areas with active construction exceeds the regulatory indicators by two times, which indicates a serious environmental problem. These data highlight the need for targeted actions to improve air quality and reduce harmful air emissions. Thus, the study raises the alarm about the point-pattern housing development as a source of high environmental danger and underlines the development of strategies for air purification in the city. The PM₁₀ contamination level was 671.6 micrograms per cubic meter, while PM_2.5 was at 368.2 micrograms per cubic meter. These data indicate that the main cause of pollution is local dust exposure. Full article

Oxygen concentrators (OCs) are essential medical devices providing oxygen in various settings, especially low-resource settings (LRSs). Despite their adaptability and cost-effectiveness, challenges arise in such environments due to factors like dust, temperature, and humidity, leading to premature OC failure. While efforts have been made to address these issues, understanding the primary contributing factor remains unclear. This study aims to shed light on this matter through the analysis of exhausted zeolite samples from Uganda, Ethiopia, and South Africa alongside a commercial virgin sample. The samples were comprehensively characterized through powder X-ray diffraction (PXRD) analysis, wavelength dispersive X-ray fluorescence (WDXRF) elemental analysis, Brunauer–Emmett–Teller (BET) surface analysis, and thermo-gravimetric analysis (TGA) coupled with mass spectrometry (MS). The characterization results confirmed a low silicon X-type framework (FAU-LSX) for all the samples. The maximum mass loss during TGA tests occurred at 130–160 °C, suggesting that water is the main component released from the zeolites. This was confirmed by MS analysis, which revealed the predominance of water in all the sample matrices. A correlation was found between OC efficiency and the amount of water adsorbed by the zeolites, proving that humidity has a key role in causing OC malfunctioning. No evidence for the presence of dust as a contaminant in the zeolites was found by the absence of the expected chemical elements in WDXRF. Since the outcomes of the study are independent of the geographical origin of the zeolites, its findings provide general guidance for engineers to modify OCs and prevent zeolite moisture poisoning. Full article

Phytostabilization of metals involves the inactivation of metals in the soil through the use of various materials as soil amendments, which reduces the bioavailability of metals, and then the introduction of vegetation. There are limited data comparing the effectiveness of different phytostabilization amendments under the same soil and environmental conditions. Therefore, the aim of this research was to compare the effectiveness of a range of soil amendments on reducing the extractability of metals, metal uptake by plants, microbial activity in soil and nutrient availability to plants. Eight materials potentially limiting metal availability were used in a pot experiment: two composts (CG, CM), municipal biosolids (SB), bentonite (BEN), phosphorus fertilizer (PF), amorphous iron oxide (FE), waste rock material (WR), calcium carbonate (LM); and these materials were compared with typical fertilization (NPK) and an untreated soil as the control (CTL). The following trace metal-contaminated soils were used in the pot experiment: soil taken from the area of strong dust fall from the zinc and lead smelter (soil P); soil taken from an outcrop of ore-bearing rocks near a smelter waste heap (soil H); soil artificially polluted through smelter dust spill in the 1990s (soil S). In general, the greatest yields of plants (oat and white mustard) were recorded for compost-treated soils. Changes in the solubility of zinc (Zn) and cadmium (Cd) after the application of various amendments largely reflected changes in soil pH. Biosolids caused a significant increase in extractable Zn and Cd, which was related to the decrease in soil pH, while a significant reduction in Cd extractability was observed across soils after the application of both composts, especially the compost characterized by alkaline pH. Interestingly, low extractability of Cd in the soil with the addition of another compost was observed, despite the pH decrease, as compared to the control pots. This fact proves the high sorption capacity of the compost towards Cd. The microbiological analyses revealed the highly beneficial effect of composts for dehydrogenases and nitrification activities, and for soil respiration, whereas soil amendment with iron oxide caused an increase in respiration activity across soils. Full article

Lead (Pb) poses a significant risk to human health and the environment. Global Pb production and consumption have markedly risen due to unregulated development and urbanization, Pb smelting, and Pb-acid battery processing. This study addresses the issue of elevated heavy metal concentrations in dust, soil, and groundwater in Shubra Al Khaymah due to the Awadallah Pb smelter. Pb concentration in soil and groundwater escalates in proximity to the Awadallah smelter and diminishes with distance from it—the surface soil functions as a repository for heavy metals. The concentrations of Pb (50–1500 µg/L), manganese (Mn) (1–750 µg/L), iron (Fe) (200–1250 µg/L), and boron (B) (250–1750 µg/L) in the groundwater stratum exceeded drinking and irrigation standards. A solution to the groundwater system issue is proposed by employing pumping wells adjacent to the riverbed to recover the contaminated water from the hydrogeological environment. Processing Modflow Path (PMPATH) program may delineate groundwater protection zones according to the travel time of 150 days (Zones 1 and 2) and the whole watershed source (Zone 3). An injection well was constructed to replenish excellent water quality in the groundwater aquifer in the upstream region. A 3D model of dissolved matter transport was created to examine the concentration distribution across remediation time in the contaminated region. This model demonstrates that, after 365 days of injection, the C/Co concentration ratio exceeded 70% in the downstream area, rendering it appropriate for drinking and irrigation. The alternate strategy is to encapsulate the severely contaminated zone. All measures aim to decrease the piezometric pressure in the vicinity, directing groundwater flow towards the contaminated zone, as accomplished by Processing Modflow Windows (PMWIN). Full article

The use of a high concentration of biodiesel blends has been implemented nationally in Indonesia as part of the government’s program to increase energy security and improve environmental quality. However, a high concentration of biodiesel, specifically a blending volume of 30% (B30), leads to a shorter fuel filter lifetime compared with pure diesel fuel (B0), due to the precipitation of impurities from biodiesel and the presence of contaminants from the environment. A study was conducted involving a rig test to evaluate the effect of using B30 on filter lifetime, referred to as JIS D1617:1998. The results showed that the temperature and cleanliness of the biodiesel had a strong influence on filter blocking. B30 with an ISO cleanliness of 22/21/17 without added standard dust contaminants at 15 °C for 48 h produced larger amounts of deposits compared to B0 with an ISO cleanliness of 16/13/7 with the addition of 1 g of contaminant for the same treatment. B30 with 1 g of additional contaminants soaked at 15 °C produced a larger amount of deposit than B30 with 2 g of added contaminant soaked at ~27 °C. The weighing of the used filters showed that deposits that originated from biodiesel impurities and precipitations were the dominant material causing a reduced fuel filter lifetime. In addition to the cleanliness factor, a decrease in the micron rating of the filter resulted in a shorter filter lifetime. Full article

Dust containing lead and zinc is a harmful contaminant, which causes serious harm to the natural environment and human health. At present, it is believed that the microscopic morphology of lead-zinc dust is intimately related to its biological toxicity. Chemical composition serves as a pivotal factor influencing the structural characteristics of dust. However, research on the impact of chemical composition variations on the microscopic morphology of dust containing lead and zinc remains inadequate. The particle size analysis reveals that as PbO content increases and ZnO content decreases, the particle size of the dust diminishes, but some samples exhibit a larger agglomeration structure. Combined with the results of the box number method, it is evident that at lower magnifications, an increase in PbO content leads to a decrease in image complexity and a loosening of aggregated structures. The similarity in pile shapes amplifies this trend, resulting in a decline in the box-counting dimension (D value) within the PbO/ZnO ratio range of 26.45 to 138, accompanied by an inverse change in the corresponding goodness of fit R-sq value. At the observation multiple of 30,000 times (30 K), smaller particles within the sample become visible, and the presence of relatively larger particles and complex sizes enhances the fractal characteristics of the sample, leading to a higher D value. Within the PbO/ZnO ratio range of 90/10 to 99/1, a coupling relationship exists between the chemical composition of the sample and the morphology of the dust. Specifically, the PbO/ZnO ratio exhibits a positive correlation with the D value. Conversely, the diversity of corresponding fractal features is negatively correlated with the D value. When the PbO content surpasses 99%, this correlation weakens, and the diversity of graphical representations displays an alternating pattern of growth and decrease. Notably, the D value and the goodness of fit (R-sq) of the D value are negatively correlated, indicating that as the complexity of the graph increases, the goodness of fit decreases. Full article

Atmospheric particulate matter (PM) samples were collected in Riyadh, Saudi Arabia, to assess air quality, quantify, heavy metal concentrations, and evaluate related ecological and health risks. This study’s uniqueness stems from its focused and detailed analysis of PM pollution in Riyadh, including an extensive assessment of heavy metal concentrations across different PM sizes by applying diverse pollution and health indices. This brings to light critical health and ecological issues and provides foundation for targeted pollution control efforts in the region. The study focused on two PM size fractions, PM_2.5 and PM₁₀ and analyzed the presence of heavy metals, including iron (Fe), nickel (Ni), chromium (Cr), zinc (Zn), cobalt (Co), copper (Cu), silver (Ag), arsenic (As), cadmium (Cd), and lead (Pb), using inductively coupled plasma emission spectrometry. Results showed significantly higher levels of PM₁₀ (223.12 ± 66.12 µg/m³) compared to PM_2.5 (35.49 ± 9.63 µg/m³), suggesting that local dust is likely a primary source. Air quality varied from moderate to unhealthy, with PM₁₀ posing substantial risks. Heavy metal concentrations in PM_2.5 followed the order Fe (13.14 ± 11.66 ng/m³) > As (2.87 ± 2.08 ng/m³) > Cu (0.71 ± 0.51 ng/m³) > Zn (0.66 ± 0.46 ng/m³) > Cr 0.50 ± 0.23 ng/m³) > Pb (0.14 ± 0.10 ng/m³) > Ni (0.03 ± 0.04 ng/m³) > Cd (0.004 ± 0.002 ng/m³) > Ag (0.003 ± 0.003 ng/m³) > Co (0.002 ± 0.004 ng/m³). In PM10, they followed the order Fe (743.18 ± 593.91 ng/m³) > As (20.12 ± 13.03 ng/m³) > Cu (10.97 ± 4.66 ng/m³) > Zn (9.06 ± 5.50 ng/m³) > Cr (37.5 ± 2.70 ng/m³) > Ni (1.72 ± 01.54 ng/m³) > Pb (1.11 ± 0.64 ng/m³) > Co (0.25 ± 0.28 ng/m³) > Ag (0.10 ± 0.26 ng/m³) > Cd (0.04 ± 0.02 ng/m³). Enrichment factor analysis revealed elevated levels for the metals Cu, Zn, As, Ag, Cd, and Pb. Pollution indices indicated various contamination levels, with Ag and As showing particularly high contamination and ecological risks. The study highlighted significant health concerns, especially from As, which poses a substantial long-term carcinogenic threat. The findings emphasize the urgent need to reduce hazardous metal levels in Riyadh’s air, especially with high child exposure. Full article

With the development of electronic packaging technology toward miniaturization, integration, and high reliability, the diameter and pitch of solder joints continue to shrink. Adjacent solder joints are highly susceptible to electrochemical migration (ECM) due to the synergistic effects of high-density electric fields, water vapor, and contaminants. Dust has become one of the non-negligible causal factors in ECM studies due to air pollution. In this study, 0.2 mM/L NaCl and Na₂SO₄ solutions were used to simulate soluble salt in dust, and the failure mechanism of an Sn-58Bi solder ECM in the soluble salt in dust was analyzed by a water-droplet experimental method. It was shown that the mean failure time of the ECM of an Sn-58Bi solder in an NaCl solution (53 s) was longer than that in an Na₂SO₄ solution (32 s) due to the difference in the anodic dissolution characteristics in the two soluble salt solutions. XPS analysis revealed that the dendrites produced by the ECM process were mainly composed of Sn, SnO, and SnO₂, and there were precipitation products—Sn(OH)₂ and Na₂SO₄—attached to the dendrites. The corrosion potential in the NaCl solution (−0.351 V) was higher than that in the Na₂SO₄ solution (−0.360 V), as shown by a polarization test, indicating that the Sn-58Bi solder had better corrosion resistance in the NaCl solution. Therefore, an Sn-58Bi solder has better resistance to electrochemical migration in an NaCl solution compared to an Na₂SO₄ solution. Full article

Mining activities, particularly in large excavations like the Bingham Canyon Copper Mine in Utah, have been increasingly linked to respiratory conditions due to heavy-metal-enriched waste and dust. Operating continuously since 1906, the Bingham Canyon Copper Mine contributes 4.4% of the Salt Lake Valley PM2.5 pollution. However, the extent of its contributions to larger-sized particulate matter (PM10) dust, soil and water contamination, and human health impacts is largely unknown. Aerosol optical depth data from Sentinel-2 imagery revealed discernible dust clouds downwind of the mine and smelter on non-prevailing-wind days, suggesting potential heavy metal dispersion from this fugitive dust and subsequent deposition to nearby surface soils. Our analysis of topsoils from across the western Salt Lake Valley found mean arsenic, copper, lead, and zinc concentrations to be well above global background concentrations. Also, the minimum values for arsenic and maximum values for lead were well above the US EPA regional screening levels for residential soils. Thus, arsenic is the metal of greatest concern for impacts on human health. Elevated concentrations of all metals were most notable near the mine, smelter, and tailings pond. Our study linked these elevated heavy metal levels to regional asthma outcomes through cluster analysis and distance-related comparison tests. Significant clusters of high asthma rates were observed in regions with elevated topsoil heavy metal concentrations, impacting both low- and high-income neighborhoods. The findings of this preliminary study suggest that the mine, smelter, and recent construction activities, especially on lands reclaimed from former tailings ponds, could be contributing to atmospheric dust containing high levels of heavy metals and exacerbating asthma outcomes for residents. However, the methods used in the study with aggregated health outcome data cannot determine causal links between the heavy metal contents of soil and health outcomes; they can only point to potential links and a need for further investigation. Such further investigation should involve individual-level data and control for potential confounding factors, such as socioeconomic status, access to healthcare, and lifestyle factors, to isolate the effect of metal exposures on asthma outcomes. This study focused on atmospheric deposition as a source of heavy metal enrichment of topsoil. However, future research is also essential to assess levels of heavy metals in subsoil parent materials and local surface and groundwaters to be able to assess the links between the sources or methods of soil contamination and health outcomes. Full article