Large Amounts Of Particulate Matter Research Articles

Impact of anthropogenic and natural constituents on particulate matter in oasis cities on the southern margin of the Taklimakan Desert based on MERRA-2 and multi-site ground observation

Dust storms are associated with large amounts of particulate matter (PM) that can have adverse effects on health and the environment. The contribution of natural dust to atmospheric PM levels represents a scientific challenge, especially in areas with close proximity to dust sources. To improve our knowledge in this area, we collected 300 PM filter-samples across five oasis cities on the southern edge of the Taklimakan Desert in 2016, and applied the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) data to quantify the contribution of natural dust to PM on sand dust and non-sand dust days. Research has shown that the particle size distribution of mineral dust in Taklimakan dust aerosols was relatively uniform. On sand dust days, CaSO4 and Na2SO4 were directly emitted from the surface, leading to higher sulfate concentrations in PM. While the increase in the proportions of organic carbon - OC1 and OC2 was attributed to the mixed anthropogenic emissions. On non-sand dust days, SO42− concentration was significantly affected by emissions from anthropogenic sources. The automotive composite emissions and coal combustion were the main sources of elemental carbon - EC1. Based on the results of MERRA-2 reanalysis data, natural dust constituted 53 % and 70 % of the total PM2.5 and PM10, respectively. In this study, we have quantified the contribution of natural dust under different weather conditions and identifying potential sources of PM in oasis cities. This study provides support for the assessment of natural dust and PM prevention in oasis cities.

Mathematical models for traffic-source PM2.5 dispersion in an urban street canyon considering the capture capability of roadside trees

Rapid urbanization increases the densely built-up blocks, the population and vehicles. Large amounts of particulate matter (PM), especially PM2.5 (PM with an aerodynamic diameter of 2.5μm or less), from vehicle exhaust are critical to human health. In typical street canyons in hot and humid regions, traffic-source PM usually diffuses to the densely built-up blocks through roadside trees. Roadside trees are a double-edged sword, serving as “guards” to absorb PM2.5 while may lead to PM2.5 gathering in street levels, thereby influencing the PM2.5 dispersion in the densely built-up blocks. To quantify the dispersion process, this study proposed traffic-source PM2.5 dynamic dispersion models considering the capture capability of roadside trees and built-up blocks based on the OSPM model. Due to the difficulty in obtaining the adsorption and deposition rate of the proposed models, the numerical simulations by ENVI-met software were used to solve and obtain the relationship between capture capability and characteristic index of roadside trees. Subsequently, The accuracy and effectiveness of the proposed traffic-source PM2.5 dynamic dispersion models were verified through field experimental data. Results show that the calculated PM2.5 concentration significantly linearly increased with the measured values with the determined coefficient (R2) of 0.98, and the first-order coefficient close to 1. It indicates that the proposed traffic-source PM2.5 dispersion model accurately quantified the impact of roadside trees on PM2.5 and its concentration dispersion process to the built-up blocks. This study provides suggestions for designing characteristic indexes of roadside trees and built-up blocks to improve the air quality of urban street canyons.

Wildfire plume ageing in the Photochemical Large Aerosol Chamber (PHOTO-LAC).

Plumes from wildfires are transported over large distances from remote to populated areas and threaten sensitive ecosystems. Dense wildfire plumes are processed by atmospheric oxidants and complex multiphase chemistry, differing from processes at typical ambient concentrations. For studying dense biomass burning plume chemistry in the laboratory, we establish a Photochemical Large Aerosol Chamber (PHOTO-LAC) being the world's largest aerosol chamber with a volume of 1800 m3 and provide its figures of merit. While the photolysis rate of NO2 (jNO2) is comparable to that of other chambers, the PHOTO-LAC and its associated low surface-to-volume ratio lead to exceptionally low losses of particles to the walls. Photochemical ageing of toluene under high-NOx conditions induces substantial formation of secondary organic aerosols (SOAs) and brown carbon (BrC). Several individual nitrophenolic compounds could be detected by high resolution mass spectrometry, demonstrating similar photochemistry to other environmental chambers. Biomass burning aerosols are generated from pine wood and debris under flaming and smouldering combustion conditions and subsequently aged under photochemical and dark ageing conditions, thus resembling day- and night-time atmospheric chemistry. In the unprecedented long ageing with alternating photochemical and dark ageing conditions, the temporal evolution of particulate matter and its chemical composition is shown by ultra-high resolution mass spectrometry. Due to the spacious cavity, the PHOTO-LAC may be used for applications requiring large amounts of particulate matter, such as comprehensive chemical aerosol characterisation or cell exposures under submersed conditions.

Assessment of Particle Matter Pollution during Post-Earthquake Debris Removal in Adiyaman City

Severe earthquakes in the world and in Turkey can cause great loss of life and property, environmental problems and health problems. In addition to the loss of life and property, earthquakes are closely related to ecosystems, air, water, and soil pollution. Particularly in post-earthquake debris removal, very large amounts of particulate matter are released and may have negative effects on the health of the local population. This study aimed to detect two types of particle matter pollution during debris removal in 25 different locations in Adiyaman City using a CEM DT 9880 particle matter measuring device in May and August 2023. PM2.5 and PM10 measurements, which have a significant impact on human health, were conducted in the field. The obtained data were analyzed using the Inverse Distance Weighting (IDW) method in ArcGIS 10.7 software. Results showed that the highest particle matter pollution was identified in neighborhoods with extensive demolition. The highest PM2.5 pollution values were recorded in Barbaros Hayrettin, Hoca Omer, Yesilyurt, and Varlik neighborhoods, while the lowest was observed in Altinsehir and Yunus Emre neighborhoods with minimal demolition. As for PM10 pollution, the highest levels were observed in Alitasi, Barbaros Hayrettin, Sumerevler, and Hoca Omer neighborhoods, while the lowest was detected in Yunus Emre and Yesilyurt neighborhoods. Green areas and their surroundings in the field exhibited lower levels of PM pollution compared to other areas.

Cellulose nanofiber aerogels modified with titanium dioxide nanoparticles as high-performance nanofiltration materials

Air pollution is a major environmental and public health issue. Each year, large amounts of particulate matter (PM) and other harmful pollutants are released into the atmosphere. Conventional polymer nanofiber filters lack the functionality to capture ultrafine PM. As a sustainable alternative, this work developed titanium dioxide (TiO2) nanoparticle surface-modified cellulose nanofiber (CNF) aerogels for PM2.5 filtration. CNFs were extracted via mechanical disintegration to diameters below 100 nm. The nanofibers were functionalized with 1.0–2.5 wt% TiO2 nanoparticles using citric acid cross-linking. Cylindrical aerogels were fabricated by freezing and lyophilizing aqueous suspensions. Structural, morphological, thermal, and mechanical properties were characterized. TiO2 modification increased density (11.8–19.7 mg/cm3), specific surface area (287–370 m2/g), and Young's modulus (33.5–125.5 kPa) but decreased porosity (99.6 %–97.7 %), pore size (20.2–15.6 nm) and thermal stability compared to unmodified cellulose aerogels. At 2.5 wt% loading, the optimized aerogels achieved 100 % absorption of 0.1–5 μm particulates owing to reduced pore size. Despite enhanced filtration capabilities, the modified CNF aerogels retained inherent biodegradability, degrading over 70 % within one month of soil burial. This pioneering research establishes TiO2 functionalized CNF aerogels as promising sustainable alternatives to traditional petroleum-based air filters, representing an innovative approach to creating next-generation nanofiltration materials capable of effectively capturing fine and ultrafine particulate matter pollutants.

Effects of different external factors on urban roadside plants for the reduction of airborne fine particulate matters

With the progress of urbanization and industrialization in China, the consumption of fossil fuels blows up. The burning of fossil fuels releases large amounts of particulate matter, leads to smog, and the air quality is gradually getting worsen. Previous studies have shown that vegetation can effectively reduce airborne particles with different size fractions. And large amounts of previous studies pointed to the adsorption ability of urban forest for particles larger than 2.5 μm. The capacity of roadside plants for the capture of fine particles, especially for those smaller than 2.5 μm has been rarely reported. In this study, five external factors including leaf orientation, leaf height, planting location, planting form, and pollution concentration were tested to evaluate their impact on the dust retention capacity of different roadside plants. The results indicate that significant interspecies was found between tested plant species, and with the change of different external factors, the capturing capacity for the same roadside plants varied. The change of leaf orientation has limited effects on the amount of captured fine particles for the tested plants. While, the amount of captured particulate matter by leaves was inversely proportional to its growth height. Plants locating in the central of the road showed significantly higher capturing capacity than they, when they was set alongside the road. The total amount of captured fine particle by Ligustrum japonicum locating in the central green belt of road was about 5 times higher than it when it was planted in the green belt alongside the road. In addition, the correlation between the capturing capacity of roadside plants and its distance to the street curb was found to be negative.

Pollution characteristics and health hazards of PAHs in PM1.0 in the cooking environment

Cooking produces a large amount of particulate matter, which can adsorb PAHs and pose serious health hazards to humans. In this study, real-time monitoring of PM1.0 concentration and measurement of PAHs concentration in PM1.0 were conducted in the urban residential building kitchen, farmhouse kitchen, fried chicken restaurant kitchen, fried stinky tofu restaurant kitchen, Yunnan cuisine restaurant kitchen, Northeast cuisine restaurant kitchen, charcoal grill restaurant kitchen, and electric grill restaurant kitchen, respectively, and the carcinogenic risks of PAHs in the air of the above eight cooking environments were analyzed. In the residential kitchen, the concentration of PAHs produced by cooking and heating with solid fuels in the farmhouse kitchen is about 5.85 times higher than that of the urban residential building kitchen. In the commercial kitchen, the highest concentrations of PAHs were found in the charcoal grill restaurant kitchen and fried chicken restaurant kitchen. Charcoal and electric grill restaurant kitchen mainly produced low to medium-ring PAHs monomer. The fried chicken restaurant kitchen mainly generated high-ring PAHs monomer. The health risk assessment found that PAHs in eight cooking environments posed a high carcinogenic risk to both males and females. The risk of cancer caused by PAHs through the skin was the highest, followed by the intake route. The carcinogenic risk of the inhalation route was negligible. The high carcinogenic risk in males and females through the skin and ingestion was only associated with BaP and DBA.

Source apportionment of potentially toxic PM10 near a vast metallic ore mine and health risk assessment for residents exposed

Mining is an economic activity that traditionally releases large amounts of particulate matter into the atmosphere because of the procedures required to process the mineral. In particular, polymetallic ores are environmentally harmful as they can enrich potentially toxic elements, which may cause adverse effects to humans and ecosystems due to their toxicity. The aim was to assess the impact on health of this type of mining on nearby populations. Accordingly, it was conducted an extensive PM10 sampling campaign during the entirety of 2021 through a total of 248 filters placed in three villages close to the Rio Tinto district (Southwest Spain), which is one of the largest Cu mines in the world. A total of 58 major and trace elements were analysed, along with organic carbon/elemental carbon, cations, and anions. The mean PM10 concentrations were high during spring (47 μgPM10⋅m−3) and summer (56 μgPM10⋅m−3) in the population closest to the mine, wherein values surpassed the annual and daily limit values, but were lower in the other two villages. Moreover, high enrichment of As (annual maximum mean of 6.2 ng⋅m−3), Cu (70 ng⋅m−3), Pb (19 ng⋅m−3), and Zn (50 ng⋅m−3) was observed in all locations. A positive matrix factorization (PMF) was primarily used to assess the origins of this particulate matter, revealing that the impact of the mine reduced considerably over a long distance, with contributions ranging from 36% at the mine's outskirts to 8% further away from it, which coincides with the features of the mine during the abandonment phase (2001–2015). Despite this, the risk assessment revealed that the carcinogens were within the permissible exposure limits even in the closest village, indicating a minor concern for the inhabitants from a toxicological perspective.

COVID-19 Pandemic: Impacts on Air Quality during Partial Lockdown in the Metropolitan Area of São Paulo

Air pollution has become one of the factors that most affect the quality of life, human health, and the environment. Gaseous pollutants from motor vehicles have a significantly harmful effect on air quality in the Metropolitan Area of São Paulo (MASP)—Brazil. Motor vehicles emit large amounts of particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOCs), the last three acting as the main tropospheric ozone (O3) precursors. In this study, we evaluated the effects of these pollutants on air quality in the MASP during the partial lockdown that was imposed to ensure the social distancing necessitated by the COVID-19 pandemic. We compared the monthly data for nitrogen dioxide (NO2) from the Ozone Monitoring Instrument (OMI) and CO, SO2, and BC from MERRA-2 for the period between April and May 2020 (during the pandemic) with the average for the same period for the (pre-pandemic) years 2017 to 2019 in the southeast region of Brazil. The meteorological and pollutant concentration data from the CETESB air quality monitoring stations for the MASP were compared with the diurnal cycle of three previous years, with regard to the monthly averages of April and May (2017, 2018, and 2019) and the same period in 2020, when the partial lockdown was first imposed in southeast Brazil. Our findings showed that there was a decrease in NO2 concentrations ranging from 10% to more than 60% in the MASP and the Metropolitan Area of Rio de Janeiro (MARJ), whereas in the Metropolitan Area of Belo Horizonte and Vitoria (MABH and MAV, respectively), there was a reduction of around 10%. In the case of the concentrations of CO and BC from MERRA-2, there was a considerable decrease (approx. 10%) during the period of partial lockdown caused by COVID-19 throughout almost the entire state of São Paulo, particularly in the region bordering the state of Rio de Janeiro. The concentration of SO2 from MERRA-2 was 5 to 10% lower in the MASP and MARJ and the west of the MABH, and there was a decrease of 30 to 50% on the border between the states of São Paulo and Rio de Janeiro, while in the MAV region, there was an increase in pollutant levels, as this region was not significantly affected by the COVID-19 pandemic. Sharp reductions in the average hourly concentrations of CO (38.8%), NO (44.9%), NO2 (38.7%), and PM2.5 (6%) were noted at the CETESB air quality monitoring stations in the MASP during the partial lockdown in 2020 compared with the hourly average rate in the pre-pandemic period. In contrast, there was an increase of approximately 16.0% in O3 concentrations in urban areas that are seriously affected by vehicular emissions, which is probably related to a decrease in NOx.

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 > Ficus pumila Linn > 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 > autumn > spring > 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.

Deposition of heavy metals in biological tissues of workers in metal workshops.

Welding and cutting of metals produce large amounts of particulate matter (PM), which poses a significant health risk to exposed workers. Appropriate biological markers to estimate exposure are of great interest for occupational health and safety. Here, hair and nail samples from metal workers were analyzed, which appear to be more suitable than blood or urine samples for assessing long-term exposure. Four workshops working with steel components were included in the study. The hair and nail samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to measure the concentrations of 12 elements. At the workplaces, the concentrations of 15 elements in particulate matter were determined using X-ray fluorescence (XRF) and particle-induced X-ray emission (PIXE) techniques. The hair and nail samples of the workers contained significantly higher metal concentrations than the analytical results of a nonexposed control group. The most significant difference between the groups was found for Ti, Mn, Fe, and Co.

Numerical Study on Particulate Fouling Characteristics of Flue with a Particulate Fouling Model Considering Deposition and Removal Mechanisms

Due to a large amount of particulate matter in industrial flue gas, the formation of particulate deposits on the flue wall will increase the instability of equipment operation, which needs to be solved urgently. In this paper, a numerical investigation on the characteristics of particulate deposition and removal in the furnace flue was carried out for waste heat and energy recovery. This research adopted a comprehensive fouling model combined with the discrete phase model (DPM) which was performed by the CFD framework and extended by user-defined functions (UDFs). Firstly, the particulate deposition and removal algorithms were proposed to develop the judgment criterion of particle fouling based on the Grant and Tabakoff particle–wall rebound model and the Johnson–Kendall–Roberts (JKR) theory. This model not only considered the particles transport, sticking, rebound, and removal behaviors, but also analyzed the deposition occurring through the multiple impactions of particles with the flue wall. Then, the influence of furnace gas velocity, particle concentration, and inflection angle α of the tee section on the particulate fouling were predicted. The results show that the furnace gas velocity, particle concentration, and flue structure have significant effects on particle fouling and distribution, and the particle fouling mainly occurs in the blind elbow section and the tee sections of the flue. In addition, the fouling mass of particles decreases with an increasing furnace gas velocity and the decrease in particle concentration. Lastly, the fouling mass of particles decreases with the increase in the inflection angle α of the tee section, and the location of particle fouling gradually transfers from the blind elbow section to the tee section.

Particle collection and heavy metals migration during high-temperature electrostatic precipitation in copper smelting: A pilot-scale study

Recently, large amounts of particulate matter (PM) and heavy metals (HMs) have been generated in the processes of non-ferrous metal smelting (NFMS). High-temperature electrostatic precipitator (HT-ESP) was the key method to capturing PM while extensive HMs enriched. In this work, the PM collection and migration of HMs in the HT-ESP process of copper smelting were investigated through an established pilot-scale platform. The excellent performance of the pilot-scale HT-ESP could achieve a particle collection efficiency of 99.5 %. The distribution patterns of HMs in various particle sizes revealed that the volatile heavy metals, arsenic (As) and selenium (Se) were predominantly distributed in PM1.0 and PM1-2.5 with a moderately dispersed distribution, whereas copper (Cu) and lead (Pb) were densely concentrated on particles. When the temperature difference between the inlet and the outlet of the HT-ESP narrowed to 23 K, the original As and Se enriched in hopper particles partially volatilized and migrated into the gas phase and adhered to tiny size particles. The enrichment ratio in the gas phase (ERG) of As and Se increased by 2.7 % and 18.5 %, respectively. The results were beneficial to reducing the enrichment of volatile HMs in copper smelting ash and provided guidance for resource utilization of the copper smelting industry.

Electronic Cigarette Nicotine Flux, Nicotine Yield, and Particulate Matter Emissions: Impact of Device and Liquid Heterogeneity.

Electronic cigarettes (ECIGs) heat a nicotine-containing liquid to produce an inhalable aerosol. ECIG power (wattage) and liquid nicotine concentration are two factors that predict nicotine emission rate ("flux"). These factors can vary greatly across devices and users. The purpose of this study was to examine ECIG device and liquid heterogeneity in "real world" settings and the association with predicted nicotine flux, nicotine yield, and total particulate matter (TPM) emissions. Past 30-day ECIG users (n = 84; mean age = 23.8 years [SD = 9.6]) reported device and liquid characteristics. Device power was measured via multimeter, device display screens, or obtained via labeling. Liquid nicotine concentration was obtained via labeling or through chemical analysis. Predicted nicotine flux, nicotine yield, and TPM associated with 10 4-second puffs were calculated for participants' primary devices. Participants' primary devices were box mods (42.9%), disposable vapes (20.2%), and pod mods (36.9%). Most participants (65.5%) reported not knowing their primary device wattage. Rebuildable/box mods had the greatest power range (11.1-120.0 W); pod mod power also varied considerably (4.1-21.7 W). Unlike device wattage, most participants (95.2%) reported knowing their liquid nicotine concentration, which ranged from 3.0 to 86.9 mg/ml (M = 36.0, SD = 29.3). Predicted nicotine flux varied greatly across products (range =12.0-160.1 μg/s, M = 85.6 μg/s, SD = 34.3). Box mods had the greatest variability in wattage and predicted nicotine flux, nicotine yield, and TPM yield. ECIG device and liquid heterogeneity influence nicotine and other toxicant emissions. Better measurement of ECIG device and liquid characteristics is needed to understand nicotine and toxicant emissions and to inform regulatory policy. ECIG device and liquid heterogeneity cause great variability in nicotine flux and toxicants emitted. These data demonstrate the need to examine device and liquid characteristics to develop empirically informed, health-promoting regulatory policies. Policies may include setting product standards such that ECIG products cannot (1) have nicotine fluxes much greater than that of a cigarette to decrease the risk of dependence, (2) have nicotine fluxes that are very low and thus would have minimal appeal to cigarette smokers and may serve as starter products for youth or nontobacco users, and (3) emit large amounts of particulate matter and other toxicants.

Submicron particle formation from co-firing of coal and municipal sewage sludge

With the increasing production of municipal sewage sludge (MSS) in China every year, the co-firing of MSS and pulverized coal is getting more and more widely applied in large coal-fired power plants. The co-firing of MSS and pulverized coal will produce a large amount of particulate matter (PM) emissions, especially submicron particles. In this paper, the formation characteristics of submicron particles in the co-firing process of coal and MSS were studied in a drop tube furnace. The influence of the furnace temperature and the addition ratio of sludge on the particle size distribution and element composition of submicron particles in MSS, pulverized coal combustion and co-firing was mainly studied. The experimental results show that the furnace temperature has an influence on the formation of PM0.4. For sludge combustion, increasing the furnace temperature will promote the formation of PM0.4. The main reason is that increasing the furnace temperature promotes the gasification of Si, S, Fe, and P to form the precursor of PM0.4 or PM0.4. At same furnace temperature, the volume concentration and mass concentration of PM0.4 produced from pulverized coal combustion are less than that of sludge. Different from sludge combustion, co-firing of pulverized coal and sludge has a synergistic effect on eliminating PM0.4 formation. Increasing the addition ratio of sludge can decrease the volume concentration and mass concentration of PM0.4. This is because that aluminosilicates formed during co-firing promotes the scavenge Si, Ca, Fe, thereby reducing the precursors of PM0.4 and the mass yield of PM0.4. Increasing the furnace temperature in co-firing can inhibit the formation of PM0.4. When the furnace temperature is between 1100 °C and 1300 °C, increasing the furnace temperature will reduce the Fe content and increase the content of Si, Ca, Na, K, and P in PM0.4. However, the reduction of Fe and the increase of Si, Ca, Na, K, and P in PM0.4 offset each other, resulting in an insensitive relationship between the mass yield of PM0.4 and the furnace temperature.

Influence of Natural Processes and Bottom Trawling in the Nepheloid Layer Structure Off Vancouver Island (British Columbia, Canada, NE Pacific)

Continental margins are transitional areas between the land and the deep ocean where large amounts of particulate matter are supplied, transported, and ultimately deposited in the deep sea. High-energy hydrodynamic processes such as storms, ocean currents, or internal waves and tides, as well as bottom trawling activities contribute to the resuspension and remobilization of these particles. These mechanisms favor their transference from the continental shelf to the continental slope and maintain high concentrations of particulate matter in the water column forming nepheloid layers. The temporal evolution of the hydrographic and nepheloid structure in the upper slope off Vancouver Island (British Columbia, Canada, NE Pacific) was assessed by analyzing 4 months (from mid-August to late-November 2018) of sensor data from Ocean Networks Canada (ONC) NEPTUNE cabled seafloor observatory. The distribution of particulate matter during the study period illustrated a well-defined turbidity structure consisting of surface nepheloid layers (SNLs) at <100 m depth associated to primary and secondary productivity, intermediate nepheloid layers (INLs) between 150 and 300 m depth at the shelf-break and upper slope domain, and bottom nepheloid layers (BNLs) developed at >400 m depth. Moderate storm events occurred during fall when the more intense INLs were recorded at shelf-break depths. However, not all the INLs recorded during this period occurred in coincidence with these storms, indicating that these INL detachments were modulated by a different sediment resuspension mechanism. Analyses of fishing vessel activity during the study period revealed that trawlers operated over the same depth range as these INLs. Our results suggest that, in combination with the regional currents, the presence of continuous fishing along the continental slope off Vancouver Island contributes to the advection of suspended sediment particles, playing a major role in their transfer as nepheloid layers.

Retraction Note: Ambient particulate matter concentration levels of Ahvaz, Iran, in 2017.

Dust storm in Khuzestan region is strongly influenced by transportation and influx of large amount of particulate matter from internal sources (Hawizeh Marshes and East Ahwaz) and external sources (the Arabian Desert in Saudi Arabia, Jordan, Syria and the Sahara Desert). Particulate matter is one of the main components of indoor and outdoor air quality that can be very dangerous for human. The principal objective of this study was the pinpoint of the source of airborne particulate matter by the NOAA HYSPLIT model in Ahvaz City, southwest of Iran. The investigation of dust storm and their origin was performed by the GFSG Meteorological Data (backward trajectories ending analysis of the NOAA HYSPLIT model) and collecting particulate samples with high-volume air samplers during the fall and winter seasons. The results showed the average ambient particulate matter concentration in the cold and warm seasons was 158 and 161 µg/m3, respectively. Moreover, the average particulate matter concentration in the cold season was significantly higher than the standard level as presented in the National Ambient Air Quality Standard. Consequently, it seems essential to develop green space, decrease particulate emission from source and make determined efforts to control dust at governmental and international scales.

The contribution of commercial fireworks to both local and personal air quality in Auckland, New Zealand.

Firework displays produce large amounts of particulate matter (PM), contributing to poor air quality in local areas. Since short-term exposure to particulate matter correlates with increased mortality risks, these celebrations may impact both human health and the environment. Little is known about the particulate matter produced from recreational fireworks, as most studies have focused on professional large-scale events. In New Zealand, it is common for consumer fireworks to be ignited within residential areas during the Guy Fawkes celebration around 5 November. To better understand the contribution of individual fireworks on local air quality, ambient PM10 sampling was conducted in the 10 days surrounding Guy Fawkes Day in Auckland, New Zealand. These data were supplemented with measurements of firework emissions from 11 different individual products, including smoke bombs, sparklers, and Roman candles. Filter sampling results indicated that personal fireworks can contribute to ground level ambient air quality during celebrations, increasing ambient PM10 concentrations by 21.6 μg m-3 over a 12-h sampling period. The use of personal fireworks can expose consumers to PM10 concentrations much higher, up to 9.51 mg m-3 from individual sparkler use under worst-case scenario assumptions. The inhalation of sparkler emissions for just 8 min can lead to an exposure to PM10 mass greater than that from daily recommended limits (50 μg m-3 exposure over 24 h). X-ray fluorescence (XRF) analysis indicated that potassium (K) and strontium (Sr) can be used as tracers for local firework use and that arsenic (As) may be an important contaminant during Guy Fawkes celebrations. The PM from personal fireworks contained large amounts of chlorine (Cl), which may be indicative of perchlorate oxidizers. In addition, lead (Pb) was observed in the PM generated from two of the colored sparklers, which were marketed as "safer" alternatives to more explosive firework products.

Death of Coal and Breath of Life: The Effect of Power Plant Closure on Local Air Quality

The number of U.S. coal-fired power plants declined by nearly 250 between 2001 and 2018. Given that burning coal generates large amounts of particulate matter, which is known to have adverse health effects, the closure of a coal-fired power plant should improve local air quality. Using spatial panel data from air quality monitor stations and coal-fired power plants, we estimate the relationship between plant closure and local air quality. We find that on average, the levels of particulate matter within 25 and 50 mile buffers around air quality monitors declined between 7 and 14 percent with each closure. We estimate that closure is associated with a 0.6 percent decline in local mortality probabilities. In terms of the value of a statistical life, the median local benefit of a coal power plant closure has ranged between $1 and $4 billion or 5 to 15 percent of local GDP since the early 2000s. (This abstract was borrowed from another version of this item.)

Approaches to evaluate spatial and temporal variability of deep marine sediment characteristics under the impact of dense water formation events

Dense shelf water cascading and open-ocean convection frequently occurs in the Gulf of Lions, northwestern Mediterranean Sea. These intense dense water formation events are capable of supplying large amounts of particulate matter as well as remobilizing and dispersing local sediments and, therefore, are thought to leave an imprint on superficial deposits. Here, we compared the spatial variability of the superficial sediment composition (grain size, organic parameters, and metals) at different scales (from decimetric to kilometric) on the continental slope and rise with the temporal variability linked to the occurrence of intense dense water formation events. The spatial and temporal variability of the geochemical composition of deep sediments was assessed using multivariate and geostatistical analysis. The results indicate that, on the outer reach of the Cap de Creus Canyon, where both processes interact, no clear relation was found between the temporal variability of the superficial sediment and the deep-water formation events, and that the small-scale spatial variability of the sediment is masking the temporal variability. Measurements across the southern slope indicate the presence of a somehow distinct geochemical signature that likely results from the influence of recurrent intense, dense water formation events as well as an unabating bottom trawling activity.