Windblown Dust Research Articles

The Potential Health Costs of PM10 Impacts on a Gold Mine Village, during Company Liquidation: An Analysis of 2013–2017

Windblown dust from tailings storage facilities (TSFs), particularly in towns with liquidated mining companies, exacerbate air pollution. Companies of suddenly closed mine operations evade the responsibility of environmental and socio-economic care required by law. It is common for suddenly closed mines to have poorly rehabilitated TSFs which become a significant source of pollution by dust for the surrounding communities. There is strong evidence that acute exposure to high levels of air pollutants causes significant mortality and morbidity. However, very few studies have estimated the externalities of PM10 emanating from gold TSFs especially when a mine closes suddenly owing to company liquidation. By exploring the externalities of PM10 arising from wind erosion of suspended particulate matter from TSFs, this study fills an existing gap in the literature. A ‘bottom-up’ approach was implemented in this study following the External Energy (ExternE) project, and a gold mine operation that was liquidated between 2013 and 2017, was used as the case study. In this study, the externality of PM10 estimated was the cost of illness focusing specifically on respiratory-related illnesses. The results showed that the estimated cost of illness associated with PM10 inhalation was a total of R 5,560,022 including assessments of both neighboring Wedela and the Gold mine village based on the threshold concentration set by the South African National Ambient Air Quality Standards (NAAQS) guideline and R 66,092,760 when considering the Fund for Research into Industrial Development Growth Equity (FRIDGE), Airshed and Infotox. Thus, it was concluded that air pollution by windblown dust from partially rehabilitated TSFs has the potential to significantly affect surrounding mining communities’ socio-economic status through poor health and the costs thereof.

Land Surface Parameterization at Exposed Playa and Desert Region to Support Dust Emissions Estimates in Southern California, United States

Remote sensing technologies provide a unique opportunity to identify ground surfaces that are more susceptible to dust emissions at a large scale. As part of the Salton Sea Air Quality Mitigation Program (SSAQMP) of the Imperial Irrigation District (IID), efforts have been made to improve our understanding of fugitive, wind-blown dust emissions around the Salton Sea region in Southern California, United States. Field campaigns were conducted for multiple years to evaluate surface conditions and measure the dust emissions potential in the area. Data collected during the field work were coupled with remote sensing imagery and data mining techniques to map surface characteristics that are important in identifying dust emissions potential. Around the playa domain, surface crust type, sand presence, and soil moisture were estimated. Geomorphic surface types were mapped in the desert domain. Overall accuracy ranged from 91.7% to 99.4% for the crust type mapping. Sand presence mapping showed consistent and slightly better accuracy, ranging from 96.2% to 99.7%. Soil moisture assessment agreed with precipitation records. Geomorphic mapping in the desert domain achieved accuracy above 93.5%, and the spatial pattern was consistent with previous studies. These land surface condition assessments provide important information to support dust emissions estimates in the region.

Study of Planetary Boundary Layer, Air Pollution, Air Quality Models and Aerosol Transport Using Ceilometers in New South Wales (NSW), Australia

The planetary boundary layer height (PBLH) is one of the key factors in influencing the dispersion of the air pollutants in the troposphere and, hence, the air pollutant concentration on ground level. For this reason, accurate air pollutant concentration depends on the performance of PBLH prediction. Recently, ceilometers, a lidar instrument to measure cloud base height, have been used by atmospheric scientists and air pollution control authorities to determine the mixing level height (MLH) in improving forecasting and understanding the evolution of aerosol layers above ground at a site. In this study, ceilometer data at an urban (Lidcombe) and a rural (Merriwa) location in New South Wales, Australia, were used to investigate the relationship of air pollutant surface concentrations and surface meteorological variables with MLH, to validate the PBLH prediction from two air quality models (CCAM-CTM and WRF-CMAQ), as well as to understand the aerosol transport from sources to the receptor point at Merriwa for the three case studies where high PM10 concentration was detected in each of the three days. The results showed that surface ozone and temperature had a positive correlation with MLH, while relative humidity had negative correlation. For other pollutants (PM10, PM2.5, NO2), no clear results were obtained, and the correlation depended on the site and regional emission characteristics. The results also showed that the PBLH prediction by the two air quality models corresponded reasonably well with the observed ceilometer data and the cause and source of high PM10 concentration at Merriwa can be found by using ceilometer MLH data to corroborate back trajectory analysis of the transport of aerosols to the receptor point at Merriwa. Of the three case studies, one had aerosol sources from the north and north west of Merriwa in remote NSW, where windblown dust is the main source, and the other two had sources from the south and south east of Merriwa, where anthropogenic sources dominate.

The role of off-highway vehicle activity in augmenting dust emissions at the Oceano Dunes State Vehicular Recreation Area, Oceano, CA

The Oceano Dunes State Vehicular Recreation Area (ODSVRA) allows off-highway vehicle (OHV) activity on this coastal dune system. Three sources of data were examined to determine if OHV activity increased wind-blown dust emissions originating from the ODSVRA. Measurements of emissivity (mg m −2 s −1 ) of particulate matter (PM) from dune sands were made using the PI-SWERL® instrument from 2013 through to 2020 in the area with OHV activity and in areas where OHV access is not permitted. These measurements indicated that the mean emissivity of the riding area was two to three times higher than the mean of the non-riding areas, for wind shear velocity ( u ∗ , m s −1 ) conditions well-above threshold ( u ∗ > 0.5 m s −1 ). Measurements of Wind Power Density (WPD, W m −2 ) and suspended particulate matter (PM, μg m −3 ) at monitoring stations in the riding areas and downwind of the riding areas made between May and September 2019 indicate that PM concentrations increased 12% per month for similar WPD conditions. In 2020, OHV activity was prohibited beginning in March due to the SARS-CoV-2 pandemic. Network measurements of PM and WPD, April to August 2020 indicated a 12% decrease in PM concentrations per month for similar WPD conditions, suggesting the cessation of OHV activity resulted in the dunes becoming less emissive through time. Measurements of wind speed and suspended PM at a monitoring station downwind of a dune preserve area (no OHV activity allowed) for 2019 and 2020 indicate that PM and WPD measurements do not follow the same temporal trends for the in-Park and downwind of riding area influenced area stations, further suggesting that OHV activity influences dune emissivity. • Measurements of emissivity on areas without riding have significantly lower emissivity than areas with riding. • PM 10 decreased by 12% per month during COVID19 closure for similar values of wind power density. • These environmental measurements provide compelling evidence that OHV activity augments the amount of PM 10 mineral dust.

Assessment and development of air quality forecasting models by the combination of PCA and ANN at metropolis Kolkata, India

PM10, PM2.5, SO2, NO2, Pb, As and Ni were monitored at Jadavpur, Kolkata over the time span of October 2016 to March 2017. The air quality of the study area was assessed in terms of air quality index (AQI) which is calculated on the assessed concentration of the pollutants. The result of the study showed significant seasonal variance and the ambient air of the study area is highly polluted in terms of particulate matters, NO2 and metallic pollutants. AQI study reveals that PM2.5 was found responsible for this degraded air quality of Kolkata. Principal component analysis (PCA) was used to identify possible contributors i.e. i) construction work, windblown dust, road dust and earth crust (variance- 28.98%); ii) automobile exhaust (variance- 20.47%); iii) brake wear source, road dust and tire wear (variance- 18.07%) of air pollution in the study area. Multiple linear regression (MLR) and feedforward backpropagation artificial neural network (FFBPANN) were used in combination with PCA to predict the future PM2.5 concentrations. Several performance indexes were used to assess the degree of accuracy and the magnitude of error in the model predicted values. Overall performance index establishes the fact that PCA-FFBP-ANN model most accurately predicts the future PM2.5 concentrations.

Plastic mulch film induced soil microplastic enrichment and its impact on wind-blown sand and dust

Microplastics (MPs) pollution is being increasingly recognized as a global concern in all environments. Wind-blown sand and dust contaminated by MPs are an important pathway of MPs transport across different environments, which can result in on-site and off-site potential MP pollution. Here, we designed field experiments to detect MPs in surface soil and wind-blown sand and dust in farmlands with and without film mulch in a semi-arid region of northern China. This study provides the first insights into MPs enrichment in wind-blown sand and dust deposited by natural storms. The results reveal that fibers, fragments, and films constitute the major types of MPs in farmland soil and wind-blown sand and dust. The MPs abundances of 1–3 mm, <1 mm, and 3–5 mm items kg−1 successively decrease. The enrichment of MPs in wind-blown dust is one to two orders of magnitude higher than that in wind-blown sand. For the farmlands with (without) film mulch, the MPs enrichment ratios ranged from 0.22 (0.29) to 1.35 (2.26) in the wind-blown sand and that varied from 1.79 (1.01) to 16.6 (25.79) in the wind-blown dust. Fibers are preferentially transported by wind erosion compared to fragments and films. Soil aggregating processes, wind speed, and MPs shape may influence enrichment in wind-blown sand and dust. Film mulch debris and the application of manure may be the primary sources of MPs in farmland soils. This study further highlights the importance of the transport of airborne MPs from surface soil into the atmosphere. Future research is required to establish the quantitative relationships between the MPs shape, wind speed, and surface soil properties and the MPs enrichment in wind-blown sand and dust.

Chemical isolation and isotopic analysis of terrigenous sediments with emphasis on effective removal of contaminating marine phases including barite

The radiogenic isotope composition (e.g. 87Sr/86Sr and εNd) of the terrigenous fraction is commonly used to determine the provenance and transport history of sediments. In ocean sediments, the terrigenous fraction must be isolated prior to analysis to avoid contamination by marine phases. While the removal of calcium carbonate, organic matter, biogenic opal, authigenic coatings and adsorbed cations is widely advised, steps to remove all these phases are not consistently employed, and there is no standard procedure for the effective removal of marine barite. Marine barite is found throughout the world's oceans, particularly in regions of high export production, is highly enriched in strontium (Sr) and therefore has the potential to bias measurements of terrigenous 87Sr/86Sr towards seawater. Here we present results from sequential leaching experiments on marine sediments from the Atlantic and the Pacific Oceans to quantitatively determine the contaminating effect on 87Sr/86Sr and εNd exerted by the presence of barite and develop a protocol to successfully isolate the terrigenous fraction. Our results show that marine barite can skew measurements of terrigenous 87Sr/86Sr by >0.01 towards the 87Sr/86Sr value of seawater, and we highlight the importance of assessing the location-specific impact of barite contamination on terrigenous 87Sr/86Sr. Our results show that marine barite can severely contaminate terrigenous 87Sr/86Sr, even where marine barite accumulation rates are modest (< ~5 mg/m3/yr and <~20 g C/m2/yr, respectively). Barite contains Nd in very low concentrations so barite contamination of terrigenous εNd is not a major concern but an important aspect of our protocol is that it has minimal effect on terrigenous εNd, allowing 87Sr/86Sr and εNd to be analysed on identically cleaned aliquots. Our systematic graduated approach will help standardise 87Sr/86Sr data, allow for robust comparisons between sites, and will contribute to an improved understanding of the provenance, transport and weathering histories of windblown continental dust and riverine sediments.

Wind-blown dust and its impacts on particulate matter pollution in Northern China: current and future scenarios

Northern China experienced two intense dust storms in March 2021, leading to reduced visibility and excessive particulate pollution. Understanding the cause of such extreme phenomena is important for further prevention. This study successfully reproduced the extreme dust storms using the Community Multiscale Air Quality model with refined bulk density of different soil types and improved spatial resolution. The wind-blown PM2.5 and PM10 are estimated to be around 15 and 120 μg m−3 in dust source areas (equal 9.6% and 31.0% in average of China), resulting in 1.1 and 2.0 times increases in PM2.5 and PM10 concentrations in populated regions of the Middle Yellow River Basin and the Beijing-Tianjin-Hebei area. The critical threshold friction velocity is the key parameter to judge whether wind-blown dust occurs. Dust flux is sensitive to the bulk soil density (increased by 4.2% and 12.6% for PM2.5 and PM10 after refined soil bulk density) and resolution (increased by 13.5% and 3.5% for PM2.5 and PM10 from 27 km to 9 km). Such results demonstrated the strong correlation between wind speed, frequency, and intensity of dust phenomena from 2013 to 2021. The wind speed can be further enhanced in dust source areas even in the context of a decline in the national average, leading to more frequent and persistent dust storms in March 2050. Only relying on coordinated emission reductions to mitigate climate change, wind-blown dust in northern China still poses considerable potential risks to air quality. Urgent actions should also be taken to improve land-use and land-cover to reduce the area of dust sources.

A critical review of the ecological status of lakes and rivers from Canada's oil sands region

We synthesize the information available from the peer‐reviewed literature on the ecological status of lakes and rivers in the oil sands region (OSR) of Canada. The majority of the research from the OSR has been performed in or near the minable region and examines the concentrations, flux, or enrichment of contaminants of concern (CoCs). Proximity to oil sands facilities and the beginning of commercial activities tend to be associated with greater estimates of CoCs across studies. Research suggests the higher measurements of CoCs are typically associated with wind‐blown dust, but other sources also contribute. Exploratory analyses further suggest relationships with facility production and fuel use data. Exceedances of environmental quality guidelines for CoCs are also reported in lake sediments, but there are no indications of toxicity including those within the areas of the greatest atmospheric deposition. Instead, primary production has increased in most lakes over time. Spatial differences are observed in streams, but causal relationships with industrial activity are often confounded by substantial natural influences. Despite this, there may be signals associated with site preparation for new mines, potential persistent differences, and a potential effect of petroleum coke used as fuel on some indices of health in fish captured in the Steepbank River. There is also evidence of improvements in the ecological condition of some rivers. Despite the volume of material available, much of the work remains temporally, spatially, or technically isolated. Overcoming the isolation of studies would enhance the utility of information available for the region, but additional recommendations for improving monitoring can be made, such as a shift to site‐specific analyses in streams and further use of industry‐reported data. Integr Environ Assess Manag 2022;18:361–387. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Combining Optical and Radar Satellite Imagery to Investigate the Surface Properties and Evolution of the Lordsburg Playa, New Mexico, USA

Driven by erodible soil, hydrological stresses, land use/land cover (LULC) changes, and meteorological parameters, windblown dust events initiated from Lordsburg Playa, New Mexico, United States, threaten public safety and health through low visibility and exposure to dust emissions. Combining optical and radar satellite imagery products can provide invaluable benefits in characterizing surface properties of desert playas—a potent landform for wind erosion. The optical images provide a long-term data record, while radar images can observe land surface irrespective of clouds, darkness, and precipitation. As a home for optical and radar imagery, powerful algorithms, cloud computing infrastructure, and application programming interface applications, Google Earth Engine (GEE) is an invaluable resource facilitating acquisition, processing, and analysis. In this study, the fractional abundance of soil, vegetation, and water endmembers were determined from pixel mixtures using the linear spectral unmixing model in GEE for Lordsburg Playa. For this approach, Landsat 5 and 8 images at 30 m spatial resolution and Sentinel-2 images at 10–20 m spatial resolution were used. Employing the Interferometric Synthetic Aperture Radar (InSAR) techniques, the playa’s land surface changes and possible sinks for sediment loading from the surrounding catchment area were identified. In this data recipe, a pair of Sentinel-1 images bracketing a monsoon day with high rainfall and a pair of images representing spring (dry, windy) and monsoon seasons were used. The combination of optical and radar images significantly improved the effort to identify long-term changes in the playa and locations within the playa susceptible to hydrological stresses and LULC changes. The linear spectral unmixing algorithm addressed the limitation of Landsat and Sentinel-2 images related to their moderate spatial resolutions. The application of GEE facilitated the study by minimizing the time required for acquisition, processing, and analysis of images, and storage required for the big satellite data.

Influences of Windblown Particulate Matter on Children’s Respiratory Health Residing Near the Salton Sea, California

BACKGROUND AND AIM: The production of wind-blown dust and dust storms is expected to accelerate as climate change drives land use changes and diminishes water resources. For instance, in the rural U.S./Mexico border region of the Imperial Valley, sources of wind-blown particulate matter (PM) are growing due to anthropogenic activities and the shrinking of the Salton Sea, a land-locked saline “sea” situated in the Southern California region. Residents of this environmental justice community have expressed growing concern about these environmental changes, including the health implications of worsening air quality. METHODS: To assess the impacts of PM on children’s respiratory health in a structurally marginalized community, we administered a survey to parents of elementary school children (n=456). We estimated children’s exposure to PM2.5 and PM10 using air monitoring data from governmental regional monitors based on residence at time of survey. RESULTS:22% of children reported wheeze in the past 12 months. Individual annual exposure estimates for children were on average 7.55μg/m3 (SD: 1.9) and 42.44μg/m3 (SD: 6.75) for PM2.5 and PM10, respectively. In models adjusted for age, sex, parental education, and survey language, a 1SD increase in PM10 was associated with an increased risk of wheezing in the last 12 months (OR: 1.35, 95% CI: 0.9-1.8, P=0.06). Among asthmatics, a 1SD increase in PM2.5 or PM10 was associated with an increased risk of wheezing (PM2.5 OR: 2.2, 95% CI: 1.4-3.4, P=0.0006; PM10 OR: 1.9, 95% CI: 0.9-4.0, P=0.07), and any asthma medication usage (PM2.5 OR: 1.9, 95% CI: 1.2-2.9, P=0.005; PM10 OR: 2.4, 95% CI: 1.1-4.9, P=0.01). CONCLUSIONS:These results suggest that PM2.5 and PM10 air pollution may influence children’s risk of wheezing in this rural border region. Future work aims to identify additional environmental and modifiable risk factors to facilitate implementation of targeted intervention programs to improve health. KEYWORDS: Environmental Justice, rural health, border health, respiratory health

Quantifying the impact of cropland wind erosion on air quality: A high-resolution modeling case study of an Arizona dust storm

Dust storms fueled by wind erosion of desert and cropland soils in south-central Arizona have caused numerous highway accidents and health risks by creating hazardous air quality conditions. Despite much speculation that a major fraction of windblown dust during these storms originates at an active or abandoned cropland surface over the region, its quantification is largely missing in the literature. This study estimated the contribution of cropland wind erosion to the regional air quality degradation, in terms of concentration of particulate matter with diameter 10 μm and smaller (PM10), during a typical springtime dust storm, by conducting high-resolution (1 km horizontally) simulations utilizing the Weather Research and Forecasting-FENGSHA (a dust emission model)-Community Multiscale Air Quality (WRF-FENGSHA-CMAQ) modeling framework. The dust model for this study employed up-to-date and very high-resolution data on land use, soil texture, and vegetation index. The modeling system used in this study simulated reasonably well a regional dust storm (that raised concerns for air quality and highway safety) of 08–09 April 2013 compared against ground (station) observations of PM10 and satellite observations of dust optical depth and vertical structure of aerosol subtypes. The model evaluations also included the use of radar observations.Furthermore, the model results from this study revealed that the cropland wind erosion was responsible for 55% and 51% of total PM10 over Phoenix (33.35°N–33.85°N, 112.36°W–111.485°W) and western Pinal County (32.50°N–33.35°N, 112.2°W–111.2°W), respectively, during the simulated dust storm. The large contributions suggest that the inclusion and accurate representation of cropland dust sources are crucial in preparing emission inventories and in air quality modeling for the region. Such representation is particularly important in view of the projected future aridity over this region (that is already under a long-term drought), which may lead to fallowing of currently active farmlands, making them potential hotspots of dust emission. The modeling approach developed for this work can be used to carry out more comprehensive studies, over extended spatial and temporal extents, to identify the sources of windblown dust and quantify their climatological dust emission potentials for this region or elsewhere. Such studies are highly desirable to help decision-making processes to reduce windblown dust and the associated health and safety risks.

Determination of Elements due to Atmospheric Deposition on Barbula indica Moss at Dalat, Vietnam using NAA and TXRF Techniques

In this paper, two multielement analysis techniques, Neutron Activation Analysis (NAA) and Total Reflection X-ray Fluorescence (TXRF), are combined to detect elemental concentrations in Barbula indica moss collected at Dalat, Vietnam. Combining these two techniques has improved the qualitative detection of elements due to atmospheric deposition on moss samples. The concentrations of 40 elements, including Na, Mg, Al, Si, P, S, Cl, K, Ar, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Kr, Rb, Y, Sb, I, Cs, Ba, La, Ce, Sm, Eu, Tb, Dy, Yb, Hf, Ta, Pb, Th, and U in the Barbula indicamoss samples collected at 19 locations at Dalat have been determined. It is shown that the air in Dalat is suspected of contamination by Na, Mg, Si, P, S, V, Mn, Cu, Se, Br, and U; slightly contaminated by Mg, Cl, K, Cr, Ni, S, and Ni; moderately contaminated by Sc, Fe, Co, Zn, As, Kr, Rb, Y, Sb, Cs, Ba, La, Ce, Sm, Eu, Dy, Yb, Ta, Pb, and Th; and seriously contaminated by Tb. Factor analysis has been used to explain the contamination sources of these elements, including V, As, Fe, Zn, Se, Rb, Sb, Cs, Al, Cu, and Pb in the investigated area. Four factors have been extracted that can explain 86% of the total variance, and the results suggest that the main sources of atmospheric pollution in Dalat originate from traffic and windblown dust.

Grain size characteristics and genesis of the Muxing loess in the Muling-Xingkai Plain, Northeast China

Thick loess is deposited on the platform in the piedmont zone of Muling-Xingkai Plain (Muxing Plain), but the genesis of the Muxing loess is still unclear. The aims of this study are to analyze the grain size characteristics of Muxing loess collected from the cores of a typical borehole (ZK1) in the piedmont zone of Muxing Plain, and to verify its genesis. The Muxing loess is mainly composed of the particles with diameter less than 50 μm, with an average content of 92.48%. The coarse silt particles with diameter of 10-50 μm are the basic composition of aeolian sediments, and their average content is 44.34% for the Muxing loess, which is the mode class among the particles with different diameters. The grain size parameters and frequency curves are similar to those of the typical aeolian sediments. The distribution characteristic of the Muxing loess in the C-M scatter diagram is consistent with that of the Xi Feng loess. In addition, the discriminant analysis shows the Muxing loess mostly consists of aeolian sediments. Therefore, it can be concluded that the Muxing loess mainly resulted from aeolian deposition based on the grain size characteristics. Muxing Plain is dominated by the monsoon climate, and the wind-blown dusts are gradually deposited after being transported over long distances.

Baseline for rainwater chemistry and quality as influenced by Nyiragongo volcano permanent plume, East Africa

Single rainwater samples were collected in the city of Goma (~1,1 million inhabitants), eastern Democratic Republic of the Congo, from January to June 2013 to draw a baseline for rainwater chemical composition and quality as influenced by the permanent plume of Nyiragongo volcano. This was a better period for a baseline as the neighboring Nyamulagira volcano, only 15 km apart, had no important degassing from its central crater, and hence the recorded volcanic influence on the rainwater chemistry was solely from Nyiragongo's lava lake which has been active since May 2002. The baseline for the rainwater chemistry and quality is important for this highly populated region where rainwater is the unique potable water source for the inhabitants of many villages surrounding the volcanoes, and for some of the inhabitants of the city of Goma. Our results show that samples collected at the crater rim of Nyiragongo were more acidic with pH ranging from 3.70 to 3.82, while the majority of rainwater samples collected in downtown Goma city and to the northeastern zone of the volcano had pH close to 5.7; which represents the value for rainwater from unpolluted continental areas (Berner and Berner, 2012). However, the pH was as low as 3.93 to the west of Nyiragongo volcano because the volcanic plume is directed westward by the dominant local wind direction. The western part of the city of Goma as well as the small town of Sake and many villages (e.g. Rusayo, Mubambiro, Kingi, …) are located in this zone, and experience endemic fluorosis caused by high fluoride in the available water. The mean F− in this zone was 0.38 mg/L, while the southern and northeastern zones had mean F− concentrations on 0.44 and 0.01 mg/L respectively; even though concentrations higher than the WHO guidelines were found in few samples from the western zone (1.69 mg/L) and from the southern zone (3.44 mg/L). Compared to data from Cuoco et al. (2012) obtained during the Nyamulagira 2010 eruption, and from Balagizi et al.2017 and Liotta et al., 2017 obtained during the intense degassing of both Nyiragongo and Nyamulagira lava lakes; we have noted similarity in the spatial variation of the pH, but samples from the present study showed notable lower concentrations of major elements. This is the case for fluoride which is strictly of volcanic origin. For the other major elements, anthropogenic sources, mainly the traffic and wind-blown dust; or other non-volcanic natural sources influenced their concentrations. Thus, the anions (Cl− and SO42−) and cations (Na+, K+, Mg2+, and Ca2+) from the present study are either lower compared to that previously reported in the literature for the Virunga, or are both comparable for the zones impacted by anthropogenic activities.

Sensitivity analysis of the dust emission treatment in CMAQv5.2.1 and its application to long-range transport over East Asia

East Asian Dust (EAD) has had a measurable impact on global climate and air quality, including visibility and human health, in numerous locations around the globe over the past decade. The accuracy of an air quality modeling system to simulate dust events is vital for early warning systems. The most significant dust event observed in 6 years for northern Taiwan occurred during 4th–9th April 2018, and was characterized by high wind speeds (9–13 m s−1) upon arrival to the region. We assessed the windblown dust emission treatment across various modifications and found better model performance by decreasing the soil moisture factor and updating the aerosol speciation profile over East Asia. In the optimized CMAQ simulation, uplifted dust particles reached a maximum height of 500–700 hPa, which is crucial for effective transport of the dust plume to the downwind Taiwan region. However, by tracking the vertical distribution profile, we found the model was insufficient to estimate dust aerosol after exiting from over the continent and entering the marine boundary layer. Our simulation indicated the dust event consisted of two plumes, where the first one was significantly impacted by wet deposition (−70.65%) from a rainfall belt stretching across Japan, Korea and the East China Sea. Then, low wind speed during a period of no precipitation over the marine area led to even greater dust deposition (−89.11%) from the second plume, resulting in a consistent negative bias for the simulation. This modeling study highlights the importance of improving the dust emission treatment for a better simulation of dust aerosol transport over the marine boundary layer. To reduce the uncertainty in the dust outflow region, the deposition mechanisms for the CMAQ dust treatment should be revised.

The imprint of windblown dust from the North American Southwest on the California Channel Islands and Pacific Ocean sediments

Climate projections for the North American Southwest (NASW) predict an increasing frequency and duration of droughts over the 21st century in response to human-induced warming, with potentially severe economic and social consequences. The geological record provides a way to contextualise this prediction because of the past occurrence of abrupt hemispheric warming events and sustained intervals of atmospheric carbon dioxide loading equivalent to those projected for AD 2100 (between ∼500 and 900 ppmv). Yet, terrestrial climate archives are typically too short and incomplete to provide a full record of these events. In principle, drill cores from deep sea sediments in the eastern Pacific Ocean can be used to overcome this problem because they contain long records of continental dust and distal riverine-supplied sediments from North America. Yet our limited understanding of the provenance and transport pathways of these sediments impedes use of these marine archives for this purpose. Here we present radiogenic isotope data (Sr, Nd and Pb) from known NASW dust-producing hot spots – playa lakes in the Mojave Desert, Quaternary silts mantling the California Channel Islands and the terrigenous fraction from marine sediments of the eastern Pacific Ocean, supported by new maps of bedrock isotopic composition in the NASW. We use these and published data sets to infer the origin of playa lake silts in the Mojave Desert and the source of windblown sediments to the California Channel Islands and nearby ocean basins. Our Results rule out a significant contribution from the distal tails of either the Pacific Asian dust plume or the North African dust plume to the Quaternary Channel Island silt mantles, corroborating the suggestion that they are aeolian in origin and sourced from the NASW on the Santa Ana winds. We identify the Outer California Borderland basins as an attractive proposition for studying past dust flux and palaeoaridity in the North American Southwest.

Attraction in the Dark: The Magnetism of Speleothems

No matter how quiet and pristine a cave setting may appear, all speleothems contain assemblages of magnetic minerals. These iron oxide minerals are derived largely from overlying soils, though minor fractions may come from the residuum of dissolved bedrock, reworked sediment carried by episodic floods, geomicrobiological activity, and even windblown dust. Regardless of their origin, these minerals become aligned with Earth’s ambient magnetic field before they are fixed within a speleothem’s growing carbonate matrix. Here, we describe how the magnetism of stalagmites and flowstone can be used to chronicle high-resolution geomagnetic behavior and environmental change.

Meteorological feedback and eco-environmental impact of Asian dust: A simulation study

Wind-blown dust plays a crucial role in air quality, biogeochemical cycles, and climate change. In East Asia, one of the main dust source regions in the world, dust storms frequently engulf eastern China, with a substantial negative effect on air pollution and the ecological environment. By integrating multiple observations and the online coupled meteorology-chemistry model WRF-Chem, a severe dust storm event originating from the Gobi Desert in early May 2017 is comprehensively analyzed from the perspective of emission estimation, meteorological feedback, and the possible impact on the ecological environment. We optimize the size distribution of dust aerosol by applying local observations to better represent dust emission and regional transport in the model. Both the observations and simulations indicate that the dust storm broke out with PM10 concentrations exceeding 1500 μg/m3 in the source region of the Gobi Desert, and was quickly transported downwind, deteriorating the air quality of cities in northern and eastern China. Moreover, we find that the dust storm significantly perturbed the temperature stratification, since mineral dust is a radiatively active aerosol and can absorb both short- and long-wave radiation. The upper dust layer at an altitude of around 2–3 km became warmer by 1–2 °C while the surface temperature decreased by about 2 °C, making the planetary boundary layer more stable and indirectly aggravating local air pollution near the ground in eastern China. Furthermore, during this event, a large amount of dust deposition increased ocean primary productivity, with the maximum Chlorophyll-a concentration rising from 4 to 14 mg/m3 in the central area of the Yellow Sea. This study highlights the critical impact of Asian dust pollution on air quality and marine ecosystems in downwind areas.

Could the exception become the rule? ‘Uncontrollable’ air pollution events in the US due to wildland fires

Exceptional events occur when air pollution in a specific location exceeds the National Ambient Air Quality Standards (NAAQS) due to an event that cannot be reasonably attributed to human activities, such as a wildland fire. Ground-level ozone (O3) and particulate matter (PM) are Environmental Protection Agency (EPA) criteria pollutants regulated under the NAAQS. Smoke from wildland fires can increase PM and O3 concentrations downwind of fire and impact air quality, visibility, and health. Our analysis shows that the frequency of exceptional event reporting for PM with aerodynamic diameters smaller than 2.5 μm or 10 μm (PM2.5 and PM10) had increased since 2007 when the air quality standards became more stringent. We also show that wildland fires and windblown dust drive many exceptional events in several EPA regions. We note the importance of growth in the number of exceptional event days due to wildfire smoke in the future due to climate change and point to possible changes to the NAAQS and implementations.