Trace Element Emissions Research Articles

Interannual and spatial variations in acid-soluble trace elements in snow: comparison with the mineralogy of dusts from open pit bitumen mining

There is ongoing concern about trace element (TE) emissions to the global environment from the dusts generated by open pit mining of coal, iron ore, stone quarries, and aggregate extraction. However, the chemical composition and acid solubility of these dusts is highly variable. Here, TEs were determined in snow collected in 2016 and 2017 in the vicinity of open-pit bitumen mines in northern Alberta, Canada. Acid solubility was assessed quantitatively by comparing TE concentrations in leachates and acid digests. The mineralogical composition of the particles extracted from the snow was examined using SEM-EDS. The data is reproducible from one year to the next. TE concentrations were greater throughout the industrial zone compared to the reference location (UTK), with the midpoint between the two central upgraders being especially impacted. Regardless of their geochemical class (lithophile: Al, Be, Cs, La, Li, Sr, Th; chalcophile: As, Cd, Pb, Sb, Tl; or enriched in bitumen: Mo, Ni, V), all TEs showed strong, positive correlations with Y, a conservative element which serves as a surrogate for the abundance of mineral particles. The ratio V:Ni in the snow is less than the corresponding values for bitumen and petcoke, but similar to that of local road dust. The ratio La:Al in snow is elevated, relative to the earth's crust, suggesting an enrichment of heavy minerals monazite and zircon. The predominance of quartz and other stable silicates helps to explain the limited chemical solubility of the dusts, and predicts a low bioaccessibility of these TEs in the environment.

Study on the distribution, enrichment and migration characteristics of trace elements in particulate matter during solid waste combustion

Trace element emissions caused by the entrainment of particulate matter (PM) has led to serious environmental pollution. This research focuses on the distribution, enrichment and migration characteristics of trace elements in different sizes of PM during the typical solid waste combustion. The results indicate that the mass concentration of trace elements in different PM is closely related to their volatility. Volatile trace elements such as Cu, In, Ag, Pb, and Cd tend to distribute in PM1. Higher temperatures facilitate the volatilization of trace elements, promoting their migration and enrichment in finer PM. The removal effect of Si–Al-based additives on trace elements in PM1 decreases with the increase of Si/Al ratio. Among them, the removal efficiency of 5% kaolin is the best. After the addition of Si–Al-additives, Zn and In mainly migrate to PM1-10, while Cu, V, Mo, As, Se, Cr, Ba, Mn, Co, Sr, and Ti mainly migrate to PM10+. Ag, Pb, and Cd migrate to both PM1-10 and PM10+ simultaneously.

Enhancing the Fuel Properties of Spent Coffee Grounds through Hydrothermal Carbonization: Output Prediction and Post-Treatment Approaches

The reuse potential for the large annual production of spent coffee grounds (SCGs) is underexploited in most world regions. Hydrochars from SCGs produced via hydrothermal carbonization (HTC) have been recognized as a promising solid fuel alternative. To increase demand, optimization of the HTC and two post-treatment processes, washing and agglomeration, were studied to improve hydrochar in terms of energetic properties, minimizing unwanted substances, and better handling. HTC experiments at three scales (1–18.75 L) and varying process conditions (temperature T (160–250 °C), reaction time t (1–5 h), and solid content %So (6–20%) showed that the higher heating value (HHV) can be improved by up to 46%, and most potential emissions of trace elements from combustion reduced (up to 90%). The HTC outputs (solid yield—SY, HHV, energy yield—EY) were modeled and compared to published genetic programming (GP) models. Both model types predicted the three outputs with low error (<15%) and can be used for process optimization. The efficiency of water washing depended on the HTC process temperature and type of aromatics produced. The furanic compounds were removed (69–100%; 160 °C), while only 34% of the phenolic compounds (240 °C) were washed out. Agglomeration of both wet SCG and its hydrochar is feasible; however, the finer particles of washed hydrochar (240 °C) resulted in larger-sized spherical pellets (85% > 2000–4000 µm) compared to SCGs (only 4%).

Migration and transformation of trace elements during sewage sludge and coal slime Co-combustion

Co-combustion of sewage sludge (SS) and coal slime (CS) could improve the combustion properties of the two materials, however, high levels of trace elements (TEs) can be released from the two wastes, resulting in secondary pollution. The migration and transformation behavior of As, Cr, Pb, Zn, and Mn during co-combustion is explored in current research. The results showed co-combustion could inhibit the emission of Zn, As, Pb, and Mn, and the effect was more pronounced for Zn, As and Mn. Meanwhile, minerals like kaolinite and gypsum were found to generated in the ash from co-combustion but not solo-combustion. Model experiments demonstrated that kaolinite captured As, Pb and Mn, while gypsum captured Zn, As and Mn but facilitated the emission of Pb and Cr. This well explained the distinct TEs emission characteristics between co-combustion and solo combustion. As the temperature elevated, kaolinite in co-combustion ash decomposed and the generation of gypsum was promoted. In this way, the emission ratios of Zn, As, and Mn initially increased but subsequently decreased between 700 and 1300 °C, whereas Pb and Cr emission ratios increased by twofold within the same temperature range. Leaching characteristics and risk assessment code on co-combustion ashes were also conducted in this study. The results indicated a marginal elevation in the risk associated with trace elements (TEs) following co-combustion, provided that all five TEs remained within the limits of national standards.

Major and trace element emission rates in hydrothermal plumes in a tropical environment. The case of La Soufrière de Guadeloupe volcano

Hydrothermal or low-temperature volcanic emissions, most commonly occurring in fumarolic environments, dominate the global volcanic landscape. This work presents physicochemical characterization of the aerosols contained in steam- and H2S-rich plumes discharged from La Soufrière volcano, in conjunction with the first report on their heavy metal degassing emission rates. Our results indicate that the plume is enriched in certain lithophile (K, Ti, Si, Al, Mn, and Mg) and siderophile (Fe) elements, related to hydrothermal rock leaching, and chalcophile (Sb, As, Zn, Pb, and Tl) elements, which are usually degassed from the magma source. Heavy metal emission rates were found to be below 15 g/d, which are modest compared to available worldwide data. Nevertheless, Cr and Sb emission rates were very similar to those of Lascar volcano (Chile), which instead has produced magmatic eruptions in recent times. We propose that the depth of the magma chamber and the input of meteoric waters play an important role in scavenging heavy metals in the hydrothermal system of magmatic-hydrothermal volcanoes. Notwithstanding low heavy metal emission rates, La Soufrière can be regarded as an important pollution source in the Lesser Antilles volcanic arc.

Effect of coal preparation on atmospheric emissions of trace elements and their cross-media environmental risk from Chinese coal-fired industrial boilers

Effect of coal preparation on atmospheric emissions of trace elements and their cross-media environmental risk from Chinese coal-fired industrial boilers

Migration and emission characteristics of trace elements in coal-fired power plant under deep peak load regulation

The trace elements (TEs) have caused great harm to the environment due to the large consumption of coal, and their emission from the coal-fired power plant (CFPP) has become a hot issue. The deep peak load regulation (DPLR) become a trend in the CFPP, which will affect the migration and emission of TEs. To explore the effect of the DLPR on the migration and emission characteristics of typical TEs in a 330 MW CFPP, the TEs field tests were carried out during the regulation period. Results showed that a higher load enhanced the migration of Pb, Mn, and Cr from bottom ash to fly ash, while it had little effect on the other TEs. More importantly, >99 % of TEs (93 % of Se) could be captured by air pollution control devices (APCDs), and the emission risk of Se and Mn increased with the load. Compared with the other TEs, it is particularly noteworthy that Se has a higher gaseous proportion in the flue gas, and the emission factor sharply increased from 165 MW to 297 MW. In addition, part of the particulate selenium transformed into a gaseous state across the ESP. This work contributes to understanding the migration characteristic of TEs during the DPLR process of CFPP and provides guidance for TEs control in the CFPP.

Formation and migration of trace elements in condensable particulate matter with the finest particle size distribution

There is a lack of existing studies on the effect of particle size distribution on the condensation behavior of trace elements (TEs) in condensable particulate matter (CPM) surfaces. The effects of TEs on the formation of PM10 and CPM10 with different particle sizes in coal-fired flue gas were studied using an entrained flow reactor. Hg and Se were enriched in ultra-fine CPM. As, Pb, and Cr were enriched in sub-micron and ultra-micron PM. For Hg2+, As3+ and Cr6+, a higher toxicity state was observed in PM10. For Se4+, a higher toxicity state was observed in CPM10. TEs in the form of volatile elements and oxides tend to be enriched in ultra-fine particle sizes, while TEs in the form of metal salts tend to be enriched in sub-micron and ultra-micron particle sizes. The formation mechanism of TEs on PM and CPM surfaces was closely related to the volatility and speciation of TEs and the particle sizes of PM and CPM. The results established the qualitative (speciation of TEs) and quantitative (concentration of TEs) correlation between TEs and the finest particle sizes. This study will help to better control the emission of TEs and CPM during coal combustion.

Emission and transformation behaviors of trace elements during combustion of Cd-rich coals from coal combustion related endemic fluorosis areas of Southwest, China

Long-term combustion of low-quality coal may release hazardous elements into the environment causing serious environmental problems. This phenomenon is particularly prevalent in the Three Gorges Region of Southwest (SW), China. Cadmium (Cd), as well as other harmful elements are found to be highly enriched in coals and supergene environments in this area. In the existing literature, the behavioral issue of emission and transformation of the elevated trace elements during simulated household stove combustion from Cd-rich inferior coal remains unknown. This study investigated the emission of toxic elements, mineral assemblages, and provided technical guidance for reducing pollution by means of optimization combustion tests on inferior coals. The research may improve the understanding of geochemical characteristics from toxic elements emission in coal combustion endemic diseased areas. For this purpose, a series of simulated coal combustion experiments were conducted to reveal the release, mobility, and distribution of elevated elements in Cd-rich coal combustion products. The results showed that Cd, Mo, Cr, Cu, Zn, As, and Sb were significantly enriched in the inferior coals of the study area. Furthermore, large amounts of toxic elements were released as fly ash into the environment during the combustion process. In particular, combustion conditions played an important role in the emission and transformation of elevated elements. For example, higher temperatures promoted the release of Cd, Sb, Zn, and Tl into the environment. Oxygen-deficient combustion was found to liberate more Cd, Sb, and Tl to the atmosphere and generated complex mineral assemblages of lizardite, calcite, dolomite, forsterite, and enstatite. Moreover, toxic elements were found to be absorbed in the fine particle matter of fly ash from the endemic fluorosis area of SW, China. The findings of this work may aid to control the emission of toxic elements from inferior coals and mitigate the effect of toxic elements in the environment to protect human health.

The migration and transformation characteristics of particulate matter and trace elements in a cement plant

ABSTRACT The particulate matter (PM) and trace elements (TEs) from industrial kilns have attracted extensive attention due to serious harm to the environment. In this work, the emissions of PM and TEs were investigated in a new dry-process cement plant. The PM was collected through a particle sampling system, and the TEs were determined by inductively coupled plasma mass spectrometry in the collected particle. The results showed significant differences of PM and TEs in the flue gas and hot air. The content of PM10 in flue gas was an order of magnitude higher than that in hot air. The TEs in flue gas were mainly Mn. In hot air, Cr accounted for more than half of the mass concentration of TEs. The conditioning tower could reduce PM10 and TEs in the flue gas. The removal efficiencies were 33.77% and 50.37%, respectively. PM10 and TEs at the end of the kiln were 18.91 mg·m−3 and 77.53 μg·m−3, respectively. The gravity settler could remove PM10 and TEs well through sedimentation, and the removal efficiencies were 31.11% and 68.18%, respectively, while the exhaust heat boiler of air quenching cooler had little effect on PM10 and TEs in the hot air.

Environmental performance of different end-of-life alternatives of wood fly ash by a consequential perspective

The increasing demand for bioenergy has intensified the pressure to utilise forest residues. Consequently, wood ash production has increased, which has prompted the need to find environmentally friendly alternatives for its end-of-life processes. However, studies assessing the environmental impacts of wood ash valorisation have assumed a static market while disregarding the potential environmental consequences and economic causalities of producing new products from wood ash. Therefore, this study assesses the outcomes of changing the conventional end-of-life of wood fly ash from its disposal in sanitary landfills to valorisation alternatives through its incorporation in construction materials (mortar and concrete) or soil amelioration. First, a consequential life cycle assessment was applied to identify the most environmentally sustainable choices for two types of wood fly ash (namely, those derived grate furnaces and fluidised bed furnaces). The characterisation factors used in this study are those that have been suggested for conducting a Product Environmental Footprint (PEF). The results show that mortar production is the best alternative for fly ashes generated in grate furnaces. Meanwhile, concrete and mortar production are the best alternatives for fly ashes generated in fluidised bed furnaces, concrete production has a slight advantage (smaller than 1%) over mortar production. Valorisation is less beneficial for soil amelioration than the incorporation in construction materials, and the impacts are higher than those of ash landfilling in some impact categories (human toxicity, freshwater eutrophication and ecotoxicity) due to the emission of trace elements into soil. A sensitivity analysis was carried out by changing the market trend of the conventional materials displaced from stable to strongly declining. This analysis showed that market trends could affect the net environmental performance of the investigated alternatives and modify their rankings.

Moss Biomonitoring of Atmospheric Pollution with Trace Elements in the Moscow Region, Russia.

For the first time, moss biomonitoring covering the territory of the entire Moscow region, without including Moscow, was performed in 2020. Moss Pleurozium schreberi collected at 156 sampling sites were analyzed using neutron activation analysis and atomic absorption spectrometry. A total of 34 elements were determined in moss samples. Obtained data were compared with the results of the moss surveys performed in the Vladimir and Yaroslavl regions in 2018 and with the data of moss surveys conducted in the Moscow region on a limited number of sampling sites in 2004 and 2014. The Moscow region showed to be more polluted than the Vladimir and Yaroslavl regions. In the the Moscow region, the decrease of the content of the main part of the elements over time was noted. Trace elements emission sources were identified and characterized using factor analysis. Contamination Factor, Pollution Load Index, and Ecological Risk were calculated to assess the level of the region contamination and elements effect on human health. In general, the Moscow region can be characterized as unpolluted to moderately polluted with a low ecological risk of human exposure. The cities satellites around Moscow were determined to experience particular environmental stress, even in the period of the COVID-19 restrictions.

A Role of Mineral Oxides on Trace Elements Behavior during Pulverized Coal Combustion

The issues of trace element emissions during coal combustion has been a concern in recent years due to their environmental pollutant. To study the trace element transformation, the thermodynamic calculation (FactSage 7.2) was used. Five kinds of pure mineral oxides (Al2O3, CaO, Fe2O3, K2O, and MgO) and As, B, Cr, F, and Se in fly ash were considered for trace elements. The results confirm that all mineral oxides have a good correlation with arsenic to form Ca3(AsO4)2, FeAsO4, K3AsO4, and Mg3(AsO4)2. Boron has a good relationship with Al, Ca, and Mg to form (Al2O3)9(B2O3)2, Ca3B2O6, and Mg3B2O6. Chromium has a good correlation with K and Ca to form K2CrO4, CaCr2O4. Furthermore, FeF3(s) KF(s), and AlF3(s) are predicted from the interaction of fluorine with Fe2O3, K2O, and Al2O3. The effect of mineral oxides on selenium partitioning are not observed. The inhibition order of trace elements by mineral oxides is as follow: As (Al2O3 > MgO > CaO > Fe2O3 > K2O), B (Al2O3, CaO, Fe2O3, K2O, > MgO), Cr (CaO > K2O > Al2O3, MgO, Fe2O3), F (CaO > MgO > Al2O3 > Fe2O3 > K2O). The results will be useful to control the trace element emissions.

Advances in nutrient metabolism and emission of livestock and poultry dietary trace elements

<p indent=0mm>Trace elements, including iron, copper, manganese, zinc, selenium, and iodine, comprise less than 0.01% of animals, yet are essential nutrients and key factors in the plant-animal-soil cycle. Trace elements have important physiological functions and are often required for enzymatic reactions, energy metabolism, and synthesis of materials, immune defense, and other activities necessary for life. Micronutrient deficiency causes developmental disorders and decreased immunity in young animals, and even leads to nutritional metabolic diseases and death. Supplementation of the diet of livestock and poultry with trace elements is closely related to growth and reproductive performance. Many studies have demonstrated that dietary supplementation with trace elements improves production performance and the content of these elements in livestock and poultry products. Due to the low bioavailability of dietary trace elements, excess trace elements may be added to livestock and poultry diets. However, animals generally have self-regulatory mechanisms of absorption and metabolism to maintain the homeostasis of trace elements. Excess dietary trace elements that are not absorbed are discharged in the excrement and pollute farm soil and water sources. In particular, heavy metals, such as copper, zinc, manganese, chromium, and cadmium, detrimentally affect the growth of crops and change the composition and structure of soil microorganism. Human health can also be affected when heavy metals bioaccumulate through the food chain. Breeding and consumption of livestock and poultry occur on a large scale in China, the excrement from livestock and poultry is an important source of heavy metals in the environment. Soil, water, and crops in most areas of China are seriously affected by heavy metal pollution. Clarifying the nutrient metabolism and emission of dietary trace elements to reduce environmental con-tamination is crucial to improve the economic benefits of breeding, protect the ecological environment of breeding areas, and promote the healthy and sustainable development of the breeding industry. In recent years, increasing attention has focused on reducing environmental pollution caused by heavy metals from livestock and poultry, while maintaining the efficiency of breeding production. Appropriate reductions of trace elements in livestock and poultry diets do not impact growth performance and reduce the content of trace elements in excreta. In addition, organic trace element additives demonstrate higher bioavailability with less emission. This article summarizes the nutritional function, absorption and metabolism mechanism, enrichment characteristics of livestock and poultry products, and fecal excretion patterns of trace elements. The appropriate lower levels, improved dosage form of supplemented dietary trace elements, and a model of combined planting and breeding may alleviate trace element pollution in livestock and poultry breeding.

Ash formation and trace elements associations with fine particles in an ultra-low emission coal-fired power plant

To meet the strict environmental requirements, air pollutions control devices are commonly installed in coal-fired power plants in China. Better understanding of porperties of particulate matters and trace elemetns associations are important for comprehensive evaluations on environmental impacts caused by the ultra-low emiission retrofits. This work have analyzed ash formaion and trace elements emissions as well as their associations with particulate matters in an ultra-low emission coal-fired power plant. The results indicate that ultra-low emission retrofits would greatly reduce particulate matters emissions, and trace elements distributions in bottom ash, fly ash, and fine particles are not significant changed. However, it would affect trace elements distributions in particulate matter from different sampling sites, which is due to the alternations on ash fromation caused by the change of local reaction conditions, thus affecting the particualte matter properties and trace elements migration behaviors. Electrostatic precipitator and wet electrostatic precipitator are capable for most of trace elements laden particle matter removal, but the particulate matters escaped from wet electrostatic precipitator are enriched in As, Cu, Zn, and Pb. Particle size would affect those 4 kinds of trace elements distributions in fly ashes. As and Pb would accumulate in particles with size decreasing in the fractions from 10 μm to 0.5 μm. While Cu and Zn enrich in particles in size fractions of 1 μm. The associations of As, Cu, and Pb with other species in a single particle are also presented, which would be helpful for understanding the trace elements migration and accumulation behaviors in particulate matter.

Leaching of Carbon Reinforced Concrete—Part 1: Experimental Investigations

The composite material ‘carbon concrete composite (C3)’ is currently capturing the building sector as an ‘innovative’ and ‘sustainable’ alternative to steel reinforced concrete. In this work, its environmental compatibility was investigated. The focus of this research was the leaching behavior of C3, especially for the application as irrigated façade elements. Laboratory and outdoor exposure tests were run to determine and assess the heavy metal and trace element emissions. In the wake of this work, the validity of laboratory experiments and the transferability to outdoor behavior were investigated. The experimental results show very low releases of environmental harmful substances from carbon concrete composite. Most heavy metal concentrations were in the range of <0.1–8 µg/L, and higher concentrations (up to 32 µg/L) were found for barium, chromium, and copper. Vanadium and zinc concentrations were in the range of 0.1–60 µg/L, boron and nickel concentrations were clearly exceeding 100 µg/L. Most of the high concentrations were found to be a result of the rainfall background concentrations. The material C3 is therefore considered to be environmentally friendly. There is no general correlation between laboratory leaching data and outdoor emissions. The results depend on the examined substance and used method. The prediction and evaluation of the leaching of building elements submitted to rain is therefore challenging. This topic is debated in the second part of this publication.

Chemistry of Trace Inorganic Elements in Coal Combustion Systems: A Century of Discovery.

Coal fueled the Industrial Revolution and the global expansion of electrification in the 20th century. In the 21st century, coal use has declined in North America and Europe, but continues to increase in Asia. Coal contains many of the elements of the Periodic Table, in percent-levels or in trace amounts (ppm, ppb). The impact of many of these elements on the environment via air and water discharges from coal-fired plants has been studied with decades of research on their chemical transformations within combustion systems and on their fates upon reintroduction into the environment. The transformations of the trace elements present in coal burned during combustion can be categorized as thermal volatilizations from the coal in the furnace; thermal decomposition of trace element compounds inside the coal; encapsulation inside ash structures through high-temperature vitrification; oxidation of the trace elements with the myriad species contained in flue gas through gas phase (homogeneous) reactions or catalytic (gas-solid) reactions; adsorption and/or reactions with active sites on entrained fly ash particulates contained in the flue gas; and absorption into solutions. These transformations can, in many cases, impact the fraction of these trace elements that are removed by various pollution control devices compared to the fraction released into the environment. The sampling and measurement of trace elements, in the inlet coal, outlet flue gas, aqueous scrubber solutions, and ash matrices, represents a significant challenge. This review focuses on the behavior of trace elements in industrial coal combustion systems with an emphasis on what has been learned over the past century uniquely related to the use of coal in boilers for electricity and heat production. Key accomplishments in measurement, modeling and control of trace element emissions in coal-fired systems are highlighted.

Atmospheric trace metal deposition to remote Northwest Ontario, Canada: Anthropogenic fluxes and inventories from 1860 to 2010

National and global inventories of anthropogenic trace element emissions to air is a comparatively recent phenomenon (post-1993 in Canada) as is the monitoring of atmospheric metal deposition, the latter being also very spatially limited. Paleo-reconstructive methods offer a contiguous record of environmental contamination providing a needed framework to establish locally relevant “pre-industrial” (~natural) conditions which can be compare with relative and quantitative deviations away from reference conditions. In this study, we reconstruct the history of the long-range, anthropogenic sourced atmospheric trace element deposition to the remote region of Northwestern Ontario Canada (Experimental Lakes Area (ELA)) using dated sediment records from five lakes. Several elements are shown to be highly enriched in lake sediments relative to pre-1860 sediments (Antimony, Lead, Tellurium, Tin, Arsenic, Bismuth, Cadmium and Mercury) and moderately (Zinc, Tungsten, Thallium, Copper, Silver, Selenium, Nickel and Vanadium). Mean decadal anthropogenic atmospheric fluxes (mg m-2 yr-1) are reconstructed for 1860–2010 and compare well with available local (ELA), regional (NW Ontario Canada, N Michigan USA) monitoring data, as well as global assessments of anthropogenic contribution to atmospheric trace metal burdens. Quantitative paleo reconstructions of atmospheric contamination history using the collective signal from multiple lakes provide a rigorous methodology to assess trends, uncertainties, evaluation with monitoring data and, provide an opportunity to explore landscape processes of contaminant transport and storage. Further study of the latter is recommended to understand the latency of legacy anthropogenic contamination of the environment.

Distribution and emissions of trace elements in coal-fired power plants after ultra-low emission retrofitting

Various hazardous trace elements emitted from anthropogenic activities are attracting increasing public awareness. This study comprehensively explored the distribution and emissions of trace elements in coal-fired power plants (CFPPs) after ultra-low emission retrofitting by conducting field experiments, literature surveys, and model calculations. High levels of volatile Hg and semi-volatile As/Pb were mainly observed in fly ash and gypsum (96.6%–98.5%), while the proportion of non-volatile Cr in bottom ash was 9.23%. The Hg and As/Pb removal efficiencies were remarkably improved by ultra-low emission retrofitting, increasing by 5.67% and 2.08%/2.63%, respectively. However, ULE retrofitting only slightly affected (0.17%) non-volatile elements. These improvements were mainly attributed to the low-low-temperature electrostatic precipitator. Owing to the enhanced particle-capturing efficiencies, the concentrations of trace elements in the emitted gas of the tested CFPPs were low, ranging from 0.21–1.50 μg/m3, but accounted for a high proportion of the gas phase (61.8%–100%). Based on the national database of coal quality and their behaviour in CFPPs, we found that most of the concentrations of trace elements emitted from Chinese CFPPs were significantly lower than the internationally existing emission limits. However, owing to the skewed distribution characteristics of the emitted concentrations, we suggest issuing or revising the corresponding emission limits and improving the control of intense trace element pollution in China.

PM10-bound trace elements in the Great Lakes Basin (1988–2017) indicates effectiveness of regulatory actions, variations in sources and reduction in human health risks

Limited studies focus on the effectiveness of regulatory actions on changes in sources and temporal trends of human health risks for trace elements in atmospheric particles < 10 μm (PM10). To address this knowledge gap, PM10 samples were collected at three stations in the Great Lakes Basin over a thirty-year time span and analyzed for 19 representative elements. Temporal trends of trace elements in PM10 were derived using the Digital Filtration Technique and sources of these elements were determined using multiple statistical techniques, namely enrichment factor analysis, positive matrix factorization (PMF) and potential source contribution function (PSCF). Non-carcinogenic and carcinogenic risks by chronic exposure were assessed using US EPA reference concentrations and inhalation unit risk. Our results showed a strong relationship between element concentrations and local populations, which suggested that the emissions of trace elements were anthropogenically-related and was confirmed by the enrichment factor analysis. The concentrations of most elements were significantly decreasing with halving times ranging from 10 to 48 years in response to national and international regulatory actions. Specific origins of atmospheric trace elements were from the copper refining industry, refuse incineration, coal combustion, vehicle emissions, oil/coal-fired power plants, and crustal/soil dust. Potential source region analysis indicates dominant sources south of the sampling sites in the US, associated with a higher population and more industrial and transportation activities. The possibility of non-cancer health effects due to inhalation were mostly within acceptable levels. However, potential cancer risk posed by inhalation of some elements cannot be ignored, with values approaching or higher than the acceptable level. Considering that the sampling locations are remote and regionally-representative, our finding emphasizes the importance of continued monitoring of metals in air to assess the effectiveness of control strategies.