Deposition Of Particulate Matter Research Articles

Geochemical characterization and health risk assessment of surface and green barrier deposited PM particles in the proximity of a kindergarten

The particulate matter (PM) is a key health risk factor in urban areas. Different approaches have been developed worldwide to deal with PM pollution, including nature-based solutions (NBSs). This study presents the results of the geochemical characterization of a green barrier established between a kindergarten and a street. In 2018 and 2019, PM deposits on green barrier and tree leaves were investigated to reveal particle size distribution and geochemical composition. In addition, the contents of potentially toxic elements (PTEs) found in kindergarten outdoor and street dust were determined to assess the imposed health risk. The results showed that based on the chemical composition, the studied PM deposits had grouped into two clusters of major elements: carbonates and aluminosilicates clustered with Fe oxides/hydroxides. However, the presence of several PTE, including Mo, Cu, Mn, Cr and Ba was also highlighted. The efficiency of the green barrier in impeding Cu-containing particles diffusion was proven, since street dust Cu contents increased during the study period, while the Cu content in kindergarten outdoor dust displayed a decreasing trend. The non-carcinogenic risk associated to PTE in the street and outdoor dust suggested that the multi-elemental risk level in the study area was above the allowable limit, with the highest share in risk level attributed to Cr which had the tendency to decrease due to the presence of the barrier. The results of this study can serve as a basis for green barrier PM capturing efficiency monitoring and securing a healthy environment for kindergarten children.

A new efficiency calibration methodology for different atmospheric filter geometries by using coaxial Ge detectors

The study of the different pollutants present in atmospheric aerosols such as trace elements and radionuclides is essential to assess the air quality. To analyze the particulate matter (PM), atmospheric filters with different dimensions and geometries (rectangular, circular, slotted, and square filters) are usually employed. Regarding the pollutants existing in atmospheric aerosols, radionuclides are usually analyzed due to their multiple applications such as either in the environmental radiological control or as tracers of atmospheric processes. Therefore, this study aims to develop a new and general methodology to calibrate in efficiency coaxial Ge detectors to properly determine radionuclides present in the PM by gamma-ray spectrometry for several filter types. For this, granular certified reference materials (CRM) containing only natural radionuclides (238U-series, 232Th-series, and 40 K) were selected. Several granular solid CRMs were chosen allowing us to reproduce the same PM deposition geometry and to assure the homogeneity of the added CRMs. These are the main advantages in relation to the typical methods that use liquid CRMs. Furthermore, for filters whose surfaces are relatively large, they were cut in several pieces and placed one on top of the other, achieving the same geometry than the PM deposited onto the filter. Then, the experimental full-energy peak efficiencies (FEPEs) were obtained for each energy of interest (Eγ) and they were fitted versus Eγ, finding a general FEPE function for each filter type. Finally, this methodology was validated for both natural and artificial radionuclides (from 46 to 1332 keV) by using different filter types employed in proficiency test exercises, obtaining |zscore|< 2 for all cases.

Adverse impacts of Asian dust events on human health and the environment—A probabilistic risk assessment study on particulate matter-bound metals and bacteria in Seoul, South Korea

This study aimed to assess the impact of Asian dust (AD) on the human health and the environment. Particulate matter (PM) and PM-bound trace elements and bacteria were examined to determine the chemical and biological hazards associated with AD days and compared with non-AD days in Seoul. On AD days, the mean PM10 concentration was ∼3.5 times higher than that on non-AD days. Elements generated from the Earth's crust (Al, Fe, and Ca) and anthropogenic sources (Pb, Ni, and Cd) were identified as major contributors to coarse and fine particles, respectively. During AD days, the study area was recognized as “severe” for pollution index and pollution load index levels, and “moderately to heavily polluted” for geoaccumulation index levels. The potential cancer risk (CR) and non-CR were estimated for the dust generated during AD events. On AD days, total CR levels were significant (in 1.08 × 10−5–2.22 × 10−5), which were associated with PM-bound As, Cd, and Ni. In addition, inhalation CR was found to be similar to the incremental lifetime CR levels estimated using the human respiratory tract mass deposition model. In a short exposure duration (14 days), high PM and bacterial mass deposition, significant non-CR levels, and a high presence of potential respiratory infection-causing pathogens (Rothia mucilaginosa) were observed during AD days. Significant non-CR levels were observed for bacterial exposure, despite insignificant levels of PM10-bound elements. Therefore, the substantial ecological risk, CR, and non-CR levels for inhalation exposure to PM-bound bacteria, and the presence of potential respiratory pathogens, indicate that AD events pose a significant risk to both human lung health and the environment. This study provides the first comprehensive examination of significant non-CR levels for bacteria and carcinogenicity of PM-bound metals during AD events.

Reduction in solar PV soiling loss using hydrophobic coating with and without dew suppression

The deposition of particulate matter (PM) on PV surfaces reduces energy generation, which results in huge losses to the PV industry. Hydrophobic coatings are known to reduce PM deposition on PV surfaces. Covering panels during the night is expected to reduce the PM deposition as well as suppress the dew formation on the surface. The objective of the present study is to compare the soiling on the hydrophobic coating with and without dew suppression. Uncoated and hydrophobic coated slides were kept for PM deposition in a 70-day field study. The dew formation was suppressed on some of the uncoated and coated slides by covering them from sunset to sunrise. The results show that the % reduction in soiling of coated slides under dew suppression is higher (50 ± 13%) compared to the coated slides without dew suppression (31 ± 15%) (statistically different; two-tailed p-value < 0.05). In addition, the particle size analysis using optical microscopy shows that the hydrophobic coating (under dew suppression) reduces the particles deposition by 60.0 ± 8.1% (mainly 10 to 30 μm range) compared to the uncoated slides (under dew suppression) over the entire sampling period. However, the dust potency (soiling loss per unit deposited mass loading) for uncoated and coated samples is found to be statistically similar (5 to 6 % g−1 m2; two-tailed p-values > 0.05). Overall, the present study advances the understanding of the impact of dew on hydrophobic coating, thereby adding to the existing knowledge of soiling mitigation approaches for solar PV industries.

Estimating the mortality attributable to indoor exposure to particulate matter of outdoor origin in mainland China

Previous estimations on the premature deaths attributable to indoor ambient particulate matter (PM) with aerodynamic diameter < 2.5 μm (PM2.5) of outdoor origin only considered the indoor PM2.5 concentration, which always neglected the impact from the distribution of particle size and the PM deposition in human airways. To tackle this issue, we first calculated the premature deaths due to PM2.5 was approximately 1,163,864 persons in mainland China in 2018 by using the global disease burden approach. Then, we specified the infiltration factor of PM with aerodynamic diameter < 1 μm (PM1) and PM2.5 to estimate the indoor PM pollution. Results showed that average concentrations of indoor PM1 and PM2.5 of outdoor origin were 14.1 ± 3.9 μg/m3 and 17.4 ± 5.4 μg/m3, respectively. The indoor PM1/PM2.5 ratio of outdoor origin was estimated to be 0.83 ± 0.18, which was 36 % higher than the ambient PM1/PM2.5 ratio (0.61 ± 0.13). Furthermore, we calculated the premature deaths from the indoor exposure of outdoor origin was approximately 734,696, accounting for approximately 63.1 % of total deaths. Our results are 12 % higher than previous estimations neglecting the impact from the distribution disparities of PM between indoor and outdoor. Regarding the cause-specific diseases, indoor PM2.5 exposure of outdoor origin accounted for 293,379 deaths to ischemic heart disease, followed by 158,238 deaths to chronic obstructive pulmonary disease, 134,390 deaths to stroke, 84,346 cases to lung cancer, 52,628 deaths to lower respiratory tract infection, and 11,715 deaths to type 2 diabetes. In addition, we for the first time estimated the indoor PM1 of outdoor origin has led to approximately 537,717 premature deaths in mainland China. Our results have well demonstrated the health impact may be approximately 10 % higher when considering the effects from infiltration and respiratory tract uptake and physical activity levels, comparing to the treatment that only used outdoor PM concentration.

Potential Airborne Releases and Deposition of Radionuclides from the Santa Susana Field Laboratory during the Woolsey Fire.

The Santa Susana Field Laboratory (SSFL), located in southern California, is a former research facility, and past activities have resulted in residual radioactive contamination in Area IV of the Site. The Woolsey Fire burned across the site, including some of the contaminated areas, on 8-11 November 2018. Atmospheric transport modeling was performed to determine where the smoke plume went while the fire burned across the SSFL and the deposition footprint of particulates in downwind communities. Any radionuclides on vegetation and in surface soil released by the fire were assumed to follow particulate matter transport path and deposition. The predicted deposition footprint was used to guide confirmatory soil sampling at 16 locations including background. Highest offsite deposition was determined to be northeast of the Oak Park community, which is located about 6 km southwest of SSFL. Depth-profile sampling was used to evaluate whether radionuclides of SSFL origin were potentially emitted and deposited during the Woolsey Fire. If radionuclides had been deposited from the Woolsey Fire at sufficient concentrations, then they would be detected in the surface layer and would be expected to be higher within the plume footprint than outside it. An upper bound estimate of the hypothetical effective dose to a person in Oak Park based on measured radionuclide concentrations in soil and vegetation on the SSFL was less than 0.0002 mSv. The occurrence of naturally occurring radionuclides at concentrations above the established background for the SSFL was attributed to natural variability in geologic formations and not SSFL. No anthropogenic radionuclides were measured at levels above those expected from global fallout. The soil sampling confirmed that no detectable levels of SSFL-derived radionuclides migrated from SSFL at the locations sampled because of the Woolsey Fire or from past operations of the SSFL.

Hydrodynamic effects on the ability of bottom traps to capture nutrient-rich sediments in shallow eutrophic lakes

Hydrodynamics are the key factor influencing sediment resuspension, transport and nutrient release in large shallow lakes. However, the hydrodynamic responses of bottom traps during pollutant capture remain unclear. In this study, a large eutrophic shallow lake was selected to carry out a field test of deep traps at the lake bottom. Based on observations of the lake current around the trap, the sedimentation rate of the particles in the trap and the nutrient content of the captured sediments, combined with the numerical simulation of the waves outside the trap, the effects of lake currents and waves on the sediment deposition in the traps were studied, and the response of the nutrient content of the sediments captured in the deep traps to the changes in lake currents and waves was analyzed. The results showed that the strong hydrodynamic force significantly promoted sediment deposition in the trap and enhanced the ability of the trap to capture sediments with high nutrient contents. The influences of waves and lake currents on the bottom trap capture of polluted sediments varied among different periods. Waves played the leading role in winter and spring, accelerating sediment capture in the bottom traps near the southern shore of eastern Lake Chaohu during this period. In summer, the lake current was the main dynamic factor contributing to the rapid deposition of particulate matter and the capture of sediments with high nutrient contents in the bottom traps of western Lake Chaohu. The multiple stepwise linear regression model based on lake current and wave data explained 37.6 % of the sediment deposition in the trap, and the model built for a single bottom trap explained more than 80 % of the deposition. After correcting the sediment deposition thickness in the trap by considering the water content of the sediment, the quantitative relation yield better inversion results for the sediment deposition process, and different thicknesses in the bottom trap were linked to different sediment deposition periods. According to the hydrodynamic strength in 2020, the thickness of the highly contaminated sediments captured by traps CC1-CC5 was calculated to be 1.09–1.93 m, and the corresponding TN and TP were 26.66–68.53 kg and 6.84–19.89 kg, respectively. This study provides a scientific analysis and guidance for the evaluation of endogenous nutrients captured by lake bottom trap methods.

The impact of puff frequency on respirable particulate matter in mainstream cigarette smoke.

Inhalation of particulate matter (PM) from cigarette smoke is hazardous to smokers and non-smokers. This contribution simulates the deposition of cigarette PM on the lung surface by trapping tobacco smoke particulates on Croton megalocarpus biochar. This study investigated one commercial cigarette (MM) and one local cigarette (RR). Biochar was incorporated into the filters of MM and RR cigarettes in order to adsorb PM from mainstream cigarette smoke. A weighed 5mg of biochar with adsorbed cigarette PM was analyzed using a scanning electron microscope and a Fourier transform infrared spectrometer. The size distribution of cigarette smoke particulates was processed using ImageJ software. At 15 s puff time, the mean particulate diameters for the commercial and the local cigarettes, respectively, can be classified as coarse ≈PM10 . Conversely, the mean particulate diameter at 2s puff time for the commercial cigarette falls under the ultrafine classification of ≤PM2.5 , whereas at the same puff time, the mean particulate diameter for the local cigarette was approximately PM2.5 . Data from Fourier transform infrared spectroscopy indicate the PM in the two model cigarettes contains aromatic structures that feature the C=C bond characterized by an intense absorption band at δs (1600 cm-1 ). This study found that PM in mainstream cigarette smoke depends on puff time. Although cigarette smoking was conducted for two model cigarettes, this study can be extended to any other form of cigarette. Moreover, this study emphasizes the need for comprehensive studies on real-world cigarette smoking conditions, taking into account cigarette smokers who use larger puff volumes.

Accelerated settling velocity of airborne particulate matter on hairy plant leaves

Phytoremediation has emerged as an ecofriendly technique to reduce hazardous particulate matter (PM) in the air. Although previous studies have conducted statistical analyses to reveal PM removal capabilities of various plant species according to their leaf characteristics, the underlying physical mechanism of PM adsorption of plants remains unclear. Conventional methodologies for measuring PM accumulation usually require long-term field tests and provide limited understanding on PM removal effects of individual leaf traits of various plants. In this study, we propose a novel methodology which can compare the electrostatic interactions between PMs and plant leaves according to their trichome structures by using digital in-line holographic microscopy (DIHM). Surface characteristics of Perilla frutescens and Capsicum annuum leaves are measured to examine electrostatic effects according to the morphological features of trichomes. 3D settling motions of PMs near the microstructures of trichomes of the two plant species are compared in detail. To validate the PM removal effect of the hairy microstructures, a polydimethylsiloxane (PDMS) replica model of a P. frutescens leaf is fabricated to demonstrate accelerated settling velocities of PMs near trichome-like microstructures. The size and electric charge distributions of PMs with irregular shapes are analyzed using DIHM. Numerical simulation of the PM deposition near a trichome-like structure is conducted to verify the empirical results. As a result, the settling velocities of PMs on P. frutescens leaves and a PDMS replica sample are 12.11 ± 1.88% and 34.06 ± 4.19% faster than those on C. annuum leaves and a flat PDMS sample, respectively. These findings indicate that the curved microstructures of hairy trichomes of plant leaves increase the ability to capture PMs by enhancing the electric field intensity just near trichomes. Compared with conventional methods, the proposed methodology can quantitatively evaluate the settling velocity of PMs on various plant leaves according to the morphological structure and density of trichomes within a short period of time. The present research findings would be widely utilized in the selection of suitable air-purifying plants for sustainable removal of harmful air pollutants in urban and indoor environments.

Impacts of autochthonous particulate organic matter on redox-conditions and elimination of trace organic chemicals in managed aquifer recharge

Autochthonous carbon fixation by algae and subsequent deposition of particulate organic matter can have significant effects on redox conditions and elimination of trace organic chemicals (TOrCs) in managed aquifer recharge (MAR). This study investigated the impacts of different algae loadings (0–160 g/m2) and infiltration rates (0.06–0.37 m/d) on overall oxygen consumption and elimination of selected TOrCs (diclofenac, formylaminoantipyrine, gabapentin, and sulfamethoxazole) in adapted laboratory sand columns. An infiltration rate of 0.37 m/d in conjunction with an algae load of 80 g/m2 (dry weight) sustained oxic conditions in the sand bed and did not affect the degradation of TOrCs. Thus, the availability of easily degradable organic carbon from algae did not influence the removal of TOrCs at an influent concentration of 1 µg/L. In contrast, a lower infiltration rate of 0.20 m/d in combination with a higher algae loading of 160 g/m2 caused anoxic conditions for 30 days and significantly impeded the degradation of formylaminoantipyrine, gabapentin, sulfamethoxazole, and diclofenac. Especially the elimination of gabapentin did not fully recover within 130 days after pulsed algae deposition. Hence, measures like micro-sieving or nutrient control are required at bank filtration or soil aquifer treatment sites with low infiltration rates.

Optimization of the energy dispersive x‐ray fluorescence spectrometer for determination of elemental composition of air particulate matter samples

AbstractElemental composition of air particulate matter samples was determined by energy dispersive x‐ray fluorescence technique utilizing in‐house constructed secondary target excitation system. The system, based on 3 kW Mo‐anode x‐ray tube with Ni and Mo secondary targets, was operated in air at atmospheric pressure. The sensitivities of the measurement system were determined for a number of elements in the atomic number range from Z = 13 to Z = 39 (K‐series characteristic radiation) and from Z = 44 to Z = 82 (L‐series characteristic radiation). The results of measurement of reference material samples confirmed that the in‐house constructed system is well suited for analysis of air particulate matter deposits on filter substrate with application of the thin‐layer sample model, with sufficiently good detection limits also for low‐Z elements such as Al, Si, P, S, and Cl.

The ability of three climbing plant species to capture particulate matter and their physiological responses at different environmental sampling sites

The adsorption of particulate matter (PM) by the leaves of urban plants can effectively reduce the particulate matter concentration in the atmosphere. The use of climbing plants to abate particulate matter is an important means of urban greening in China, which is rich in climbing plant species. In this study, three evergreen climbing plants were selected to assess their ability to adsorb particulate matter and determine their physiological responses to particulate pollution. PM deposition was determined gravimetrically. There were four key results. 1) The adsorption capacity of the three evergreen climbers followed the order of Hedera nepalensis var &amp;gt; Ficus pumila Linn &amp;gt; Euonymus fortunei, and was significantly higher in an overpass environment than in a campus environment for all three species. 2) The seasonal characteristics of particulate adsorption by the three types of climbers in both the overpass and campus environments followed the order of winter &amp;gt; autumn &amp;gt; spring &amp;gt; summer. 3) The net photosynthetic rate of the three climbing plants was significantly affected by particulate matter in a size dependent manner, with fine particulate matter on the plant leaf surface and coarse particulate matter in the leaf waxy layer being important factors affecting plant photosynthesis. 4) Particulate pollution led to changes in the activities of plant protective enzymes in plants, with increases in the superoxide dismutase (SOD) and peroxidase (POD) activity, and the malondialdehyde (MDA) and soluble protein contents. There were different trends in the soluble sugar content among the different plant species. In conclusion, F. pumila had a strong resistance to particulate pollutants, while H. nepalensis was considered suitable for planting in polluted areas where it could improve ambient air quality by adsorbing large amounts of particulate matter.

Particulate Matter Phytoremediation Effectiveness of Japanese Prunus × Yedoensis Tree Through Spring and Summer Season

Using green biofilters can help eliminate air pollutants and improve urban air quality. In the current study, Prunus × Yedoensis capacity of phytoremediation was investigated as a bio filter of Particulate matter (PM) in spring and summer seasons in Japan. Two samples were analysed to extract three fractions of PM (coarse, fine and ultra-fine). Results showed lower deposition of PM in spring season with total of 20.2 μg.cm-2 and high proportion for fine fraction (2.5-10μm), comparing with summer season which showed a higher deposition of PM with total of 31.9 μg.cm-2. Ultra-fine fraction (0.2–2.5μm) recorded the highest values with a percentage of 23.9% of the total PM deposition. Leaf micromorphological characteristics such as, rough surface and serrated margin can enhance the Prunus × Yedoensis ability of particulate matter accretion. This study confirms that vegetation has an efficient role in improving the quality of urban air. Further structural analysis should be included to deepen the understanding of phytoremediation phenomena in plants.

SPATIAL AND TEMPORAL QUANTIFICATION OF PARTICULATE MATTER (PM10) AND ASSOCIATED HEAVY METALS IN URBAN ENVIRONMENT OF DELHI

Atmospheric concentrations of PM10 and associated heavy metals were quantified to study the air pollution load of two distinct location of Delhi viz. (1) Agricultural farms of Indian Agricultural Research Institute (IARI) and (2) Yamuna flood plains (YFP). The air sampling has been done for two consecutive years in winter season, comprising the months from November to April in 2020- 21 and 2021-22 respectively. The glass fiber filter paper was used for the particulate matter deposition in high volume sampler. The monthly average concentration of PM10 varies from 112µg/ m3 to 187µg/m3 at IARI and 205 µg/m3 to 364 µg/m3 at YFP. The highest concentration of PM10 was recorded in the month of January. The concentration of PM10 and associated heavy metals were significantly higher at the YFP area. The heavy metal concentration load was 18% and 27% more in the YFP in comparison to the IARI farms in the year 2020-21 and 2021-22 respectively. The higher concentration of heavy metals recorded at YFP because of its location which is cross section of roads having very heavy traffic throughout 24 hrs. and a thermal power plant nearby. The heavy metals concentration trend at each location was in the order of Zn &gt; Fe&gt;Pb&gt;Ni&gt;Cd. The concentration of Pb, Ni, and Cd was significantly less at IARI in comparison to YFP.

Role of morphology and chemical composition of PM for particle deposition in human respiratory system: A case study over megacity-Delhi

Morphology and chemical composition altogether determine the fate of atmospheric particulate matter(PM) deposition and inhalation. Site-wise(#20 sites) and cumulative variations in morphology and chemical composition of PM5 in Delhi showed dominance of non-spherical (sharp-edged, angular and flattened) particles followed by spherical ones, rich in elements like C, O, S, N, Al, Si, Cu, Ca, Na, Cl, Fe, Ni, Cr, Zn, Hg, Pb, Mo, etc. having potential health effects. #2650 individual particles analyzed for the morphological parameters like aspect ratio(AR), circularity factor(CIR), surface equivalent radius(SER) and area. Dominant AR and SER values found between ≥1–1.60 and > 0–0.50 μm, respectively showing dominance of non-spherical and fine-size particles in Delhi. The Multiple Path Particle Dosimetry (MPPD) Model used to study variations in deposition potential (regional deposition, lobar deposition, mass deposition and mass flux) of different PM sizes (PM0.4, PM1, PM2.5 and PM5) at different AR values which suggested that AR is an important input parameter of health models to get realistic and unbiased output health data. In addition, study revealed higher coarse particles deposition in the head region affecting upper respiratory tract with their non-spherical shapes whereas higher fine particles deposition in TB and pulmonary regions affecting inner parts of the lungs.

Relationship between Leaf Traits and PM-Capturing Capacity of Major Urban-Greening Species

High concentrations of airborne particulate matter (PM) in urban areas are of great concern to human health. Urban greening has been shown to be an effective and eco-friendly way to alleviate particle pollution, and attention to its role in mitigating particle pollution has increased worldwide. The species-specific PM-capturing capacity of ten urban-greening species in Seoul was evaluated by leaf functional traits (average leaf area (ALA), specific leaf area (SLA), and leaf width-to-length ratio (W/L)), microstructures (roughness, stomata, and trichomes), and physicochemical traits (contact angle (θw), surface free energy (rs), the work of adhesion for water (Wa), and epicuticular wax loads (EWL)). The relationships between leaf traits and PM adsorption by leaves were revealed by Pearson’s correlations and principal component analysis (PCA). A gravimetric method was used to quantify, by particle size, the PM adsorbed on leaf surfaces or embedded in leaf epicuticular wax layers. The key factors for PM adsorption on leaf surfaces were the SLA, the mean roughness value (Ra), and stomatal size. The SLA and Ra of adaxial leaf surfaces were negatively correlated with PM accumulation on leaf surfaces, while stomatal length and width were positively correlated with surface PM load. The rs and EWL positively affected the in-wax PM load. Species-specific PM deposition was the result of complicated mechanisms of various leaf traits. Three evergreen shrub species, Buxus sinica (Rehder &amp; E.H. Wilson) M.Cheng var. insularis (Nakai) M.Cheng, Taxus cuspidata Siebold &amp; Zucc., and Euonymus japonicus Thunb., were efficient in capturing both surface PM and in-wax PM. The PCA revealed that the high PM accumulation efficiency of these three species might be attributable to the interaction between stomatal size and EWL. Aesculus turbinata Blume, Chionanthus retusus Lindl. &amp; Paxton, and Rhododendron schlippenbachii Maxim. had intermediate PM adsorption ability, which might be a result of interactions among stomatal density, the Wa of adaxial surfaces, and ALA. Magnolia denudata Desr., Styphnolobium japonicum (L.) Schott, Liriodendron tulipifera L., and Ginkgo biloba L. had low PM accumulation efficiency. These four species exhibited correlations among SLA, the Ra of adaxial leaf surfaces, and W/L, which had negative effects on PM adsorption.

Interactions of airborne graphene oxides with the sexual reproduction of a model plant: When production impurities matter

The increasing use of graphene-related materials (GRMs) in everyday-life products raises concerns for their possible release into the environment and consequent impact on organisms. GRMs have widely varying effects on plants and, according to recent evidences, graphene oxide (GO) has the potential to interfere with the sexual reproduction owing to its acidic properties and production residues. Here, stigmas of the model plant Cucurbita pepo (summer squash) were subjected to simulated dry depositions of GO and GO purified from production residues (PGO). Stigmas were then hand-pollinated and GRM deposition was checked by ESEM and confocal microscopy. Analysis of stigma integrity, pH homeostasis and pollen-stigma interactions did not reveal negative effects. Fruit and seed production were not affected, but GO depositions of 22.1 ± 7.2 ng mm−2 affected the normal development of seeds, decreasing seed dimensions, seed germination and germination speed. The elemental analysis revealed that GO has significant quantities of production residues, such as strong acids and oxidants, while PGO has only traces, which justifies the differences observed in the effects caused by the two materials. Our results show that GO depositions of up to 11.1 ± 3.6 ng mm−2, which fall within the variation range of total dry particulate matter depositions reported in the literature, are safe for reproduction of C. pepo. This is the first “safety” limit ever recorded for depositions of “out-of-the-box” GO concerning the reproduction of a seed plant. If confirmed for wind-pollinated species, it might be considered for policymaking of GRMs emissions in the air.

Marble Chromatic Alteration Study Using Non-Invasive Analytical Techniques and Evaluation of the Most Suitable Cleaning Treatment: The Case of a Bust Representing Queen Margherita di Savoia at the U.S. Embassy in Rome

In spite of the application of different cleaning procedures, the marble used for the portrait bust of Queen Margherita di Savoia continued to show permanent discoloration, consisting of an unevenly distributed grayish alteration, mainly on the front part. In this work, a multi-analytical, non-invasive approach was proposed using spectrocolorimetry, reflectance spectroscopy and multispectral imaging. The initial assumption, suggesting the presence of altered protective materials based on organic products (such as waxes or oils,) applied in the past according to traditional practices, was excluded, revealing instead the presence of deposits of particulate matter, which penetrated inside the crystalline structure of the marble, leading to a variation in its shade. Cleaning tests were also carried out to define the best product, using sustainable chemicals such as Polar Varnish Rescue®, alkoxyde surfactant, disodium EDTA, GLDA and Politect® Base in order to identify the best methodology and materials for sustainable cleaning, respecting the integrity of the original matter. Politect® Base demonstrated better action in comparison to the other products tested, and similar results were obtained with GLDA, which could be applied in areas where the Politect® is less efficient (e.g., lace).

Atmospheric deposition of particulate matter from beef cattle feedlots is a likely contributor of pyrethroid occurrence in isolated wetland sediment: Source apportionment and ecological risk assessment

Industrial cattle feeding operations (feedlots) have been subject to public scrutiny in recent decades regarding environmental impacts of site runoff and aerial dispersion of agrochemical-laden particulate matter (PM). However, source apportionment of multi-use pesticides is challenging in mixed agricultural settings. Beef cattle on feed and row crop production are heavily concentrated in the Southern Great Plains of North America, where playa wetlands are vulnerable to agrochemical inputs and sedimentation from surrounding land use. In the current study, playa basin sediment (n = 33) was analyzed via UHPLC-MS for 21 agrochemicals spanning eight classes (macrocyclic lactones, neonicotinoids, organophosphates, pyrethroids, triazoles, β-methoxyacrylates, a carboximide, and phenylpyrazole). Pyrethroids were detected most frequently (75.8% of basins). Sediment pyrethroid concentrations were also significantly correlated (R2 = 0.178, p = 0.007) with feedlot proximity (<1–50 km). Principal component analysis (PCA) of land use metrics extracted three principal components (74.3% of total variance), with principal component regression (PCR) showing the greatest agrochemical occurrence in basins heavily weighted by cropland buffer acreage (≤1 km) and feedlot proximity. Sediment toxicity benchmarks protective of two benthic invertebrates (Hyallela azteca and Chironomus spp.) identified λ-cyhalothrin, fenvalerate, and esfenvalerate as individual compounds exceeding levels of acute (RQ > 0.5) and chronic (RQ > 1) concern in >5% and >50% of cases, respectively. However, additive toxicity of co-occurring pyrethroids represents an acute high risk (RI > 1; median RI; acute = 2.4, chronic = 38.6) to benthic invertebrates in >75% of cases, which may threaten higher-order wetland taxa via bioaccumulation and trophic transfer.

Exposure Assessment of Air Pollution in Lungs

In this article, a comprehensive literature survey on air pollution and its effects on the human respiratory system is carried out. Based on the knowledge gaps, a computational assessment is proposed to find the impact of air quality on respiratory suspended particulate matter (RSPM) deposition in the human airways. A realistic 3D geometric model of the human airway was constructed to study the airflow characteristics and RSPM (PM2.5 and PM10) transport and deposition in it for normal and moderate inhalation patterns (corresponding to natural breathing) of air having an unhealthy air quality index (AQI). The results identify inertial impact as the primary mechanism of particle deposition in the human airways. They also reveals the significant differences in the deposition patterns of PM2.5 and PM10 in the right and left bronchial airways.