Heavy Metal Emissions Research Articles

A city-level dataset of heavy metal emissions into the atmosphere across China from 2015–2020

The absence of nationwide distribution data regarding heavy metal emissions into the atmosphere poses a significant constraint in environmental research and public health assessment. In response to the critical data deficiency, we have established a dataset covering Cr, Cd, As, and Pb emissions into the atmosphere (HMEAs, unit: ton) across 367 municipalities in China. Initially, we collected HMEAs data and covariates such as industrial emissions, vehicle emissions, meteorological variables, among other ten indicators. Following this, nine machine learning models, including Linear Regression (LR), Ridge, Bayesian Ridge (Bayesian), K-Neighbors Regressor (KNN), MLP Regressor (MLP), Random Forest Regressor (RF), LGBM Regressor (LGBM), Lasso, and ElasticNet, were assessed using coefficient of determination (R2), root-mean-square error (RMSE) and Mean Absolute Error (MAE) on the testing dataset. RF and LGBM models were chosen, due to their favorable predictive performance (R2: 0.58–0.84, lower RMSE/MAE), confirming their robustness in modelling. This dataset serves as a valuable resource for informing environmental policies, monitoring air quality, conducting environmental assessments, and facilitating academic research.

Assessing the deposition of heavy metals in edaphotopes and synantrophy vegetation under the conditions of technological pollution of the city

The object of this study is a regional center with a developed industry and a significant traffic load. The study provides an assessment of the impact of the urbanization process on the conditions of development of urban edaphotopes and their role in the functioning of urban ecosystems. It was determined that the geochemistry of the soils of urban ecosystems is significantly different from natural landscapes, which is due to the symbiosis of natural and anthropogenic factors. The content of mobile forms of heavy metals in the soil of 14 localities of different functional zones within the city was investigated. A comparative assessment of the spatial heterogeneity of the content of heavy metals in the vegetative organs (root, shoot) of the diagnostic species Polygonum aviculare L. was performed. Based on the sources of emission of heavy metals and the formed geochemical anomalies, a direct dependence was established on their accumulation by the vegetative organs of Polygonum aviculare L. According to the calculated biological absorption coefficient (BAC), high bioavailability for the accumulation of man-made toxicants Cu, Zn, Pb, Cd by the phytomass of Polygonum aviculare L. was proven. It was determined that the content of heavy metals in different parts of the test object is due to their physiological ability to accumulate these toxicants in the root and above ground mass. Active translocation of toxicants from the soil to the roots is characteristic of localities with intense influence of man-made factors, for which the value of the bioavailability coefficient varies within 0.6>BAC<0.85. Correlation coefficients between the content of heavy metals in the atmosphere, soil, and vegetative organs of the plant were determined. The research allows us to evaluate the prospects for using Polygonum aviculare L. as a cumulative indicator of metal pollution in urban technogenic ecosystems and their high phytoremediation value under conditions of environmental pollution with heavy metals

Emission inventory of heavy metals from on-road vehicles in Xiamen, China, from 2015 to 2060

Reducing vehicle emissions to improve air quality has been widely adopted by policy makers. However, insufficient attention has been paid to non-exhaust particulate matter (PM) and the associated heavy metals (HMs) from on-road vehicles, which can cause adverse health effects. In this study, emission inventories of PM2.5 and PM10 and the associated HMs from on-road vehicles in Xiamen, China, were established from 2015 to 2060 under a business-as-usual scenario. In the base year 2021, the total emissions of HMs associated with primary PM2.5 and PM10 were 1.88 × 104 kg and 3.96 × 104 kg, respectively, with the dominant contributions from brake wear and road surface wear. The emissions of HMs were overwhelmingly dominated by light-duty passenger cars and heavy-duty trucks. Fe, Ba, Zn, Cu, Mn, and Ti together accounted for about 97% of the total HMs. High-density emission areas were concentrated in urban centers. From 2015 to 2060, an increasing trend in total HMs emissions was observed due to the superimposed effect of decreasing diesel exhaust and increasing non-exhaust brake wear and road wear. However, the trends of the individual HMs were different from each other. The U-shaped distribution patterns of the relative cancer and non-cancer risks of HMs were observed between 2015 and 2060. Vehicle electrification alone is not enough to effectively reduce the potential health risk of vehicle-related HMs in the future. Reducing HMs from brake wear should be encouraged to use in electric vehicle. Uncertainties in the emissions of HMs were quantified using the Monte Carlo simulation.

Distribution of gasification products and emission of heavy metals and dioxins from municipal solid waste at the low temperature pyrolysis stage.

Gasification is widely regarded as one of the most practical, economical, and environmentally friendly waste disposal technologies for municipal solid waste (MSW). The pyrolysis stage (300-500°C) is crucial for weight loss during MSW gasification, as a considerable amount of organic matter breaks down, producing high-value synthesis gas. This study investigated the product distribution and pollutant emission characteristics within this temperature range and its influencing factors during MSW gasification using a self-designed MSW gasification device. Results indicated that MSW underwent approximately 70% weight loss within this temperature range, yielding low amounts of inorganic and short-chain organic products, with mainly long-chain organic compounds of C16-C34. The atmosphere variation had minimal effect on the elemental composition and content of solid phase products. X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) analyses showed that Mn and Zn were the primary components of heavy metal leaching toxicity in solid phase products, with their contents increasing as temperature increased. Synthesis gas showed the highest content of heavy metal As element, reaching a peak at 400°C. Higher gasification temperature and lower oxygen flow rate significantly reduced the dioxin content and I-TEQ values, with highly chlorinated isomers being the predominant dioxin isomers. Nonetheless, low-chlorinated dioxins accounted for more than 50% of the I-TEQ. This study improves our understanding of the gasification process of MSW.

Long-term implications of municipal solid waste (MSW) classification on emissions of PCDD/Fs and other pollutants: Five-year field study in a full-scale MSW incinerator in southern China

Understanding how municipal solid waste (MSW) classification influences the physiochemical properties and incineration emission characteristics of MSW is imperative for sustainable waste management. To investigate how long-term changes in the composition and physical properties of MSW resulting from MSW classification affect the emissions of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and multiple flue gas pollutants, a five-year experiment (2018–2022) was conducted in a full-scale MSW incinerator in Shenzhen City, China. After MSW classification, the food waste in MSW was substantially reduced while the paper, textile, and wood components were notably increased. MSW classification also remarkably decreased the water and chlorine contents of MSW while concomitantly increasing the wet-based calorific value, sulfur content, and nitrogen content. Consequently, the PCDD/Fs emissions declined from 106.7 ng I-TEQ/t MSW in 2018 to 26.0 ng I-TEQ/t MSW in 2022. Moreover, a process-tracing experiment demonstrated noticeable decreases in PCDD/F synthesis in the post-combustion area, with mass-reduction efficiencies of 23.6 %–95.4 %. In a correlation analysis, the PCDD/F emissions were significantly positively correlated with food waste, water content, and chlorine and negatively correlated with the wet-based calorific value and nitrogen content. Furthermore, MSW classification reduced the emissions of conventional flue gas pollutants (SO2, CO, and HCl) and multiple heavy metals (total sum of Sb, As, Pb, Cr, Co, Cu, Mn, and Ni). In summary, the long-term study demonstrated that MSW classification can feasibly separate incombustible waste, improve combustion quality, and reduce pollutant emissions from sources. These findings offer practical guidance for promoting MSW classification.

Effects of terrestrial input on heavy metals in Zhanjiang Bay, a typical subtropical bay in the South China Sea

Understanding the influence of terrestrial inputs on heavy metals in bays is crucial for the environmental protection of regional estuaries and coastal systems. In this study, the concentrations, temporal and regional distribution characteristics, and fluxes of heavy metals (Cr, Cu, Zn, Cd, Pb) in the surface seawater and terrestrial sewage of Zhanjiang Bay (ZJB) in four different seasons were investigated. The results identified the heavy metal concentrations in the sewage outlet around ZJB had significant seasonal variation. The heavy metals in the surface seawater of ZJB had significant spatiotemporal variations. Terrestrial input, biological activity and hydrodynamics affected the overall distribution. The heavy metal emission fluxes indicated that riverine input was the main influencing factor for heavy metals in ZJB (96.22 %). The fluxes of heavy metals into ZJB increased significantly after the typhoon (Cu: 127 %, Zn: 63 %, Pb: 136 %), it was possible to deteriorate the seawater quality.

Emission characteristics and removal of heavy metals in flue gas: a case study in waste incineration and coal-fired power plants.

Heavy metal pollutants such as Hg, As, Pb, Cr, and Cd emitted from coal and waste combustion have received widespread attention. In this study, we systematically investigated the emission characteristics of heavy metals in waste incineration and coal-fired flue gases, focused on testing the removal effect of self-made cold electrode electrostatic precipitator (CE-ESP) on heavy metals in flue gas, and made a comparative analysis with the existing air pollution control devices (APCDs). Test results from waste incineration power plant showed that each APCD showed a certain effect on the removal of heavy metals in condensable particulate matter (CPM), with an average removal efficiency of bag filter was 86%, but its effect on Hg removal was slightly worse. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiency of CE-ESP on heavy metals in CPM was as high as 93%, including 76% for Hg. The removal efficiency of heavy metals (especially Hg) in CPM increased with the increase of flue gas temperature difference between inlet and outlet of CE-ESP. Test results from this coal-fired power plant showed that heavy metals were enriched in fly ash to a higher degree than in slag, the synergistic control of heavy metals in submicron particulate matter by the dust remover was not obvious, and there was a significant correlation between each heavy metal emission factor and its content in coal. Under the temperature field with non-electric cold electrode plate operation mode, the overall effect of CE-ESP on the removal of gaseous heavy metals was better than that of particulate heavy metals. Under the conventional electric field operation mode, CE-ESP was less effective in removing particulate Cr and gaseous Hg0. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiencies of CE-ESP for particulate and gaseous heavy metals were 82.37% and 76.16%, respectively.

Heavy metal transport with adsorption for instantaneous and exponential attenuation of concentration

Heavy metal pollutant is a serious problem in environmental pollution, and it is very difficult to eradicate once it enters the soil. As heavy metal adsorption has been proven to occur, the heavy metal’s behaviour can be modeled as a transport equation with adsorption. Previous adsorption term mostly due to the concentration alone, while in here, the desorption effect given by the rate of change of the concentration is also included. Also, the heavy metals are frequently considered to enter the soil after being dumped into the soil for a certain period of time. But, quick dumping onto the soil can introduce heavy metal instantaneously. Heavy metals entering the soil through leaching or when their concentration in the soil is influenced by chemical reactions, can all lead to the exponential decay of heavy metals entering the soil. Based on two-dimensional advection diffusion equation (ADE) with the new adsorption term, analytical solutions are obtained for the cases of instantaneous and exponential attenuation of heavy metals emission to soil by the method of Laplace transform. The results highlight the significant influence of emission type on the peak concentrations. If heavy metals are instantaneously enter the soil, the peak occurs in the range of 1–3 m radius from the point of emission on the first day, while for exponential attenuation the peak occurs close to the point of emission. Furthermore, there exists a correlation between retardation factors and heavy metal concentrations, where a decrease in retardation factors leads to an increase in heavy metal concentration. It is essential to investigate both types of heavy metals emission to provide valuable information for proper pollution management, effective environmental regulations and enforcement.

EFFECTIVE DEVELOPMENT OF INDUSTRY THROUGH USE OF NEW TOOLS AND MECHANISMS

The development of the industry stimulates the functioning of environmental projects related to agriculture, renewable energy sources, and environmentally friendly industry. Improving the system of “green” lending in banks contributes to the development of the private sector on new terms, which implies maximum preservation of natural resources and receiving more profit than from traditional projects. When issuing loans for the development of sustainable entrepreneurship, the banking sector seeks to support clients in the transition to sustainable solutions, since the conservation of resources and the creation of energy-saving technologies determine the future capabilities of the state. Green loans are an effective and significant tool for the development of sustainable entrepreneurship in the industry. And the conditions and procedure for issuing them are the mechanism through which the industry develops. Green loans can also be issued for projects of large clients in support of the industry, which meets the requirements of the SEB system. By choosing a green loan to finance a project, the enterprise becomes part of a sustainable management system. The most relevant areas for obtaining "green" loans are: renewable energy (solar, wind, tidal energy, bioenergy; energy efficiency - in relation to district heating or cooling; clean transport - non-fossil fuels or hybrid transport solutions; waste management - energy from waste and methane capture projects, as well as projects to reduce waste through process improvement; emission reduction - reduction of emissions of particulate matter, heavy metals and dioxins through physical, chemical, mechanical means; sustainable forestry - forestry projects with a forest management certificate or equivalent scheme certification; water and wastewater treatment – drinking water production, wastewater treatment, water resources management.

Enhanced chromium (VI) removal: A remediation study employing nano zero-valent iron supported by sawdust

The rapid expansion of industry leads to the emission of heavy metals into the environment, posing a significant global concern presently. The management of heavy metals holds particular significance due to their resilience and persistence in the environment. Removal technologies of heavy metals include physical and chemical treatments. Chromium (VI) was utilized as a representative of heavy metals in this research. Sorption experiments were conducted using a composite material consisting of supported nano zero-valent iron on sawdust, designated as NZVI/SD. The NZVI/SD composite was prepared through a two-step process involving the impregnation of sawdust with ferrous sulfate, followed by a chemical reduction using Sodium borohydride (NaBH4). The adsorbent was characterized with the help of Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), X-Ray Diffraction analysis (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and chemical test. The adsorption characteristics have been investigated under various conditions, including different pH values, adsorbent dosages, initial metal ion concentrations, contact times, and varying temperatures. The optimal conditions for employing NZVI/SD for the removal of Cr(VI) were observed at a pH of 3.0, an adsorbent dosage of 0.5 g/L, an initial metal ion concentration of 61.45 mg/L, a contact time of 180 min, and a temperature of 50 °C. Sorption of Cr(VI) on NZVI/SD followed Langmuir Isotherm model. The maximum monolayer sorption capacity on NZVI/SD was 39.8 mg/g at 298 K temperature (equilibrium pH of 3.0) estimated from the Langmuir isotherm. Kinetics and thermodynamic studies on the sorption of Cr (VI) on NZVI/SD were done to understand the sorption mechanism. Sorption kinetics of Cr (VI) on NZVI/SD confirmed that pseudo second order reaction kinetics was followed concluding that the rate of adsorption depends on the analyte and the available free site of adsorbent. By employing the Langmuir isotherm model and Van't Hoff equation, the determination of thermodynamic parameters such as Gibbs free energy, enthalpy change, and entropy change of the adsorption process was facilitated. It was found that the sorption of Cr(VI) was spontaneous (∆G° = −10.36 kJ.mol−1) on NZVI/SD and the process was endothermic (∆H = +4.609 kJ/mol). NZVI/SD can be effectively regenerated by elution with 1 M NaOH for 4 h.

Revealing transmissions of atmospheric heavy metals hidden in the Chinese supply chain

Heavy metals (HMs) pose significant risks to human health and the environment. Identifying the sectors that play a significant role in the transmission of HMs has rarely been considered and represents an efficient method to control and manage HMs. By combining atmospheric HM emission inventories, the multi-regional input-output approach, and a betweenness-based method, this study revealed the transmission of HMs (comprehensively evaluated by the Heavy Metal Pollution Load, HMPL) in 2017. In 2017, 119.86 million tons of HMPL were transmitted through China's supply chain, and Cr was the main contributor to HMPL transmission. The results suggest that metal smelting is the primary contributor to HMPL transmission, and metal smelting in Jiangsu, Hebei, Henan, Shandong, and Anhui are the top five critical nodes. These results suggest that the sector's role changes dramatically with respect to HM control under this perspective. The role of HM emission-intensive sectors changed the most, as their production-based HMPLs accounted for 84% of the total HMPL; however, the HMPL transmitted by these sectors accounted for only 45% of the total. The critical HMPL transmission sectors identified in this study provide a basis for policy-making from a transmission perspective.

Hemispheric-scale heavy metal pollution from South American and Australian mining and metallurgy during the Common Era

Records from polar and alpine ice reflect past changes in background and industrial toxic heavy metal emissions. While Northern Hemisphere records have been used to evaluate environmental effects and linkages to historical events such as foreign conquests, plagues, economic downturns, and technological developments during the past three millennia, little is known about the magnitude and environmental effects of such emissions in the Southern Hemisphere or their historical linkages, especially prior to late 19th century industrialization. Here we used detailed measurements of the toxic heavy metals lead, cadmium, and thallium, as well as non-toxic bismuth, cerium, and sulfur in an array of five East Antarctic ice cores to investigate hemispheric-scale pollution during the Common Era. While thallium showed no anthropogenic increases, the other three metals increased by orders of magnitude in recent centuries after accounting for crustal and volcanic components. These first detailed records indicate that East Antarctic lead pollution started in the 13th century coincident with Late Intermediate Period metallurgy in the Andes and was pervasive during the Spanish Colonial period in parallel with large-scale exploitation of Andean silver and other ore deposits. Lead isotopic variations suggest that 19th-century increases in lead, cadmium, and bismuth resulted from Australian lead and Bolivian tin mining emissions, with 20th century pollution largely the result of the latter. As in the Northern Hemisphere, variations in heavy metal pollution coincided with plagues, cultural and technological developments, as well as global economic and political events including the Great Depression and the World Wars. Estimated atmospheric heavy metal emissions from Spanish Colonial-era mining and smelting during the late 16th and early 17th century were comparable to estimated European emissions during the 1st-century apex of the Roman Empire, with atmospheric model simulations suggesting hemispheric-scale toxic heavy metal pollution during the past five centuries as a result.

Modifying national industrial structure for reducing heavy metals in China: A nexus-based multi-objective optimization approach

Heavy metals (HMs) exhibit significant toxicity and can lead to a range of health issues. Certain HMs share common emission sources, necessitating an exploration of the nexus among various HMs for achieving collaborative reductions. Considering the efficacy and feasibility of industrial modification to environmental pressures, this paper proposes a novel nexus-based optimization approach based on nexus analysis, multi-region input-output (MRIO) table, and multi-objective optimization to mitigate atmospheric HMs. The atmospheric HM emission inventory in 2017 is first compiled. Subsequently, the Integrated Nexus Strength of HMs Risk (HMR-INS) is proposed and employed to determine the range of sectoral output variations. Finally, a multi-objective optimization approach is employed based on the MRIO table in 2017. Compared with the traditional optimization method, the proposed approach performs better regarding HM-related risks and total output, leading to a 1.9 million tons increase in reduction on HM-related risks and a 1.37 trillion yuan increment in total output. Some further analyses are also given to provide feasible solutions for industrial modification, which considers both the economic efficiency and the stability of the industrial structure.

Co-combustion of bituminous coal and industrious sludge under non-isothermal and isothermal conditions: Thermal behaviors, kinetic analyses, and heavy metals migration

Considering the environmental pollution caused by the direct stacking or landfilling of various sludge, the combustion characteristics of bituminous coal, Fe-rich industrious sludge, and their blend were studied using thermogravimetric analysis at non-isothermal and isothermal conditions. It was found that the volatile matter in sludge with low C/H ratios will be released and burned in the low-temperature stage, then the generated heat will promote extra heat for the combustion of fixed carbon in coal when the addition of sludge was greater than 60%. The used Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods were more accurate for coal, sludge, and their blend with low sludge addition. After comparing the activation energy, a suitable addition of sludge was found to improve the combustion and kinetic characteristics of fixed carbon but do less help to volatile matter in coal. As to the heavy metals emission, the synthetic effect of the blend combustion enhanced the Pb emission when sludge addition was more than 60% but almost did not affect Cr, Ni, Zn, and Cu. By sampling dynamically during the co-combustion, it was found that the leaching toxicity of heavy metals was greatly related to the combustion degree. The stabilization of Al, Ca, Cr, and Zn was finished as their leaching toxicity decreased to a constant value before the burnout of fixed carbon (100∼120s) while that of Ni was slightly delayed, especially when the coal was added. Besides, the leaching concentration of Cu gradually increased with combustion time and its stabilization cost more time. Such a time-controlled combustion strategy may also be worthy of further research to help dispose of other solid wastes with similar composition.

Assessment and Exposure Analysis of Trace Metals in Different Age Groups of the Male Population in Southern Punjab, Pakistan.

In developing countries, like Pakistan, the pursuit of urbanization and economic development disrupts the delicate ecosystem, resulting in additional biogeochemical emissions of heavy metals into the human habitat and posing significant health risks. The levels of these trace elements in humans remain unknown in areas at higher risk of pollution in Pakistan. In this investigation, selected trace metals including Copper (Cu), Chromium (Cr), Lead (Pb) Cadmium (Cd), Cobalt (Co), Nickel (Ni), and Arsenic (As) were examined in human hair, urine, and nail samples of different age groups from three major cities (Muzaffargarh, Multan, and Vehari) in Punjab province, Pakistan. The results revealed that the mean concentrations (ppm) of Cr (1.1) and Cu (9.1) in hair was highest in Muzaffargarh. In urine samples, the mean concentrations (μg/L) of Co (93), As (79), Cu (69), Cr (56), Ni (49), Cd (45), and Pb (35) were highest in the Multan region, while As (34) and Cr (26) were highest in Vehari. The mean concentrations (ppm) of Ni (9.2), Cr (5.6), and Pb (2.8), in nail samples were highest in Vehari; however, Multan had the highest Cu (28) concentration (ppm). In urine samples, the concentrations of all the studied metals were within permissible limits except for As (34 µg/L) and Cr (26 µg/L) in Vehari. However, in nail samples, the concentrations of Ni in Multan (8.1 ppm), Muzaffargarh (9 ppm), Vehari (9.2 ppm), and Cd (3.69 ppm) in Muzaffargarh exceeded permissible limits. Overall, the concentrations of metals in urine, nail, and hair samples were higher in adults (39-45 age group). Cr, Cu, and Ni revealed significantly higher concentrations of metals in hair and water in Multan, whereas As in water was significantly (p < 0.001) correlated with urinary As in Multan, indicating that the exposure source was region-specific.

Technology transition strategies for textile-dyeing sludge management in China from the environmental and economic perspectives

Textile-dyeing sludge reutilization is considered as an effective management scheme in the transition to low-carbon and sustainable development from the conventional incineration or landfilling. However, few studies have focused on its assessment from environmental and economic perspectives. In this study, a bin-to-grave life cycle thinking is applied to compare the environmental and economic performances of four promising and newly industrialized sludge reutilization technologies (i.e., pyrolysis-gasification-incineration, co-combustion in coal-fired power plants, sludge-to-brick, and sludge-to-biochar) with the traditional landfill option. Results indicate that technology transition to sludge-to-biochar option outperforms other transition strategies. The sludge-to-biochar option could gain environmental benefits in 7 categories i.e., primary energy demand (−6.1 × 103 MJ/t sludge), abiotic depletion potential (−4.9 × 10−4 kg antimony eq./t sludge), eutrophication (−0.15 kg PO43− eq./t sludge), ozone depletion(−1.67 × 10−5 kg CFC-11 eq./t sludge), photochemical ozone formation (−2.25 kg NMVOC eq./t sludge), ionizing radiation-human health effects (−3.1 kg U235 eq./t sludge), and ecological toxicity (14.4 CTUe/t sludge). Direct emissions of GHG in sludge reutilization technologies contribute to >70 % of the global warming potential category. Adopting the preferred sludge-to-biochar option at the provincial scale could mitigate approximately 0.81 million t of CO2 eq./year, which is equivalent to the amount of CO2 annually absorbed by 44.1 million trees in China. Feedstock (i.e., chemicals) contributes to about 77.9 %–97.9 % of toxicity-related environmental loads (i.e., human toxicity-cancer effects and ecological toxicity) for sludge-to-biochar, whereas in other utilization technologies, the key factor is heavy metal emission. The sludge reutilization technologies could break even within 3 years except pyrolysis-gasification-incineration (7 years). Meanwhile, contribution, sensitivity, and scenario analyses indicate that reducing primary energy consumption and improving the product quality and yield could effectively alleviate environmental burdens. A reasonable sludge disposal fee could help with the circular regeneration of textile-dyeing sludge. Despite that sludge-to-biochar stands as the foremost advantageous option for the technology transition in managing textile-dyeing sludge, certain aspects (for example, product quality and feedstock consumption) still necessitate further enhancements before its large-scale application in China.

Thermal Destruction of Waste and the Impact of the Presence of Cl and S in Waste on the Emissions of Cu, Ni, and Pb and Their Immobilisation in the Ash Residue

This study addresses the pressing environmental problem of the emissions of ecotoxic heavy metals from high-temperature waste combustion processes, including incineration and pyrolysis. Such emissions pose a serious threat to ecosystems and human health. This study investigated the behaviour of the heavy metals Cu, Ni, and Pb during the combustion of various waste materials such as plastic waste, pharmaceutical waste, and pesticide waste. To limit the release of heavy metals into the exhaust gas stream, various additives were used: divanadium pentoxide (V2O5), borax (Na2B4O7), and their mixtures with calcium oxide (CaO). Additionally, this study examined the impact of the content of chlorine heteroatoms (Cl) in burned waste materials on the emission levels of Cu, Ni, and Pb. The findings shed light on the mobility of ecotoxic heavy metals in high-temperature waste incineration processes (1273, 1373 K) and offer insight into strategies to improve their immobilisation in grate residues. At a temperature of 1273 K, V2O5 with CaO reduced Pb emissions by ~65% for plastic waste and by ~40% for pesticide.

Atmospheric iron deposition in a megacity of northwest China: Solubility, speciation, and deposition fluxes

Atmospheric iron has crucial effects on biogeochemical cycles, atmospheric processing, global climate, and human health. In this study, atmospheric dustfall samples were collected from six functional areas in Xi'an, China, from 2020 to 2021. The spatiotemporal distributions and deposition fluxes of total and water-soluble (ws) Fe as well as the speciation and potential sources of ws-Fe were characterized. Industrial areas had the highest concentrations of total Fe and ws-Fe, which were mainly due to copious emissions of heavy metals during manufacturing. The total Fe concentrations peaked in spring, primarily due to the substantial input of crustal dust, which also led to the lowest Fe solubility in this season. By contrast, the highest levels of ws-Fe occurred during winter due to an increase in biomass combustion. Among the water-soluble forms, ws-Fe (II) was dominant and accounted for 74.8% of the total amount of ws-Fe. Crustal dust was the main contributor to total Fe, whereas biomass burning primarily contributed to peak ws-Fe concentrations. The average total and ws-Fe deposition fluxes in Xi'an were the highest in spring and lowest in autumn, which were related to the distributions of the dustfall deposition fluxes and their Fe contents during these periods. Our study provided a broader and comprehensive understanding of atmospheric iron deposition in Chinese urban area, which is of positive significance for understanding atmospheric chemistry and global climate change.

Feasibility Analysis of Municipal Solid Waste Incineration for Harmless Treatment of Potentially Virulent Waste

The outbreak of major health emergencies, such as the COVID-19 pandemic, has posed numerous challenges to waste management. Environmentally sound treatment of such epidemic-related municipal solid waste (MSW) plays a vital role in interrupting virus transmission. In this study, the furnace type, incineration process and control parameters of an MSW incinerator were comparatively analyzed with those of a medical waste incinerator and hazardous waste incinerator according to China’s MSW incineration pollution control standards. In addition, changes in flue gas emissions data before, during and after the outbreak of the pandemic were empirically analyzed. The study revealed the following: (1) the feasibility of MSW incinerators to meet the harmless disposal of potentially viral municipal solid waste (PVMSW); (2) the priority order of incinerator types for MSW incinerators in the disposal of potentially virulent waste was grate furnace incinerator &gt; fluidized bed incinerator &gt; cement kiln; and (3) when MSW incinerators treated PVMSW, the emissions of dioxin compounds in the flue gas fluctuated between 0.00052 and 0.031 ng TEQ/m3, HCl emissions fluctuated between 1.6 and 23.742 mg/m3, CO emissions fluctuated between 0.18 and 59.15 mg/m3, heavy metal emissions fluctuated between 0.000008 and 0.855 mg/m3, and particulate matter emissions fluctuated between 0.64 and 12.13 mg/m3. All emissions met the flue gas emission standards. This study verified the feasibility of using MSW incinerators to treat PVMSW during a sudden major pandemic and provided a theoretical basis for the environmentally sound collaborative treatment of PVMSW and a reference for the emergency management and sustainable development of MSW.

Research on the presence of cigarette butts and their leaching of chemical pollutants and microparticles: the case of Dalian, China

Cigarette butts (CBs) can contain high amounts of toxic substances such as heavy metals, polycyclic aromatic hydrocarbons (PAHs) and microplastics, all of them can result from the incomplete decomposition of CBs. However, limited research exists on the pollution caused by littered CBs in China and the emissions of toxic substances from different Chinese cigarette brands.Therefore, the main objective of this study was to assess the quantity of CBs littered in Dalian city, China, and to evaluate the emissions of heavy metals, PAHs, and microplastics from different cigarette brands. During the survey, a total of 10,591 CBs items and 35 cigarette brands were collected. ICP-MS analysis confirmed the presence of 17 types of heavy metals in the highest abundance brand of CBs, with concentrations ranging from 0.02 μg/L (U and La) to 395 μg/L (Mn). In the lowest abundance brand of CBs, 15 types of heavy metals were detected, with concentrations ranging from 0.08 μg/L (U) to 297 μg/L (Mn). Additionally, a total of 9 PAHs, including compounds such as naphthalene and acenaphthylene, were detected in both the highest and lowest abundance brands of CBs using HPLC-MS/MS, with concentrations ranging from 0.40 ng/L (Anthracene) to 92.12 ng/L (Naphthalence). Microplastics and particles were also identified by light microscopy and SEM. Based on cigarette consumption data in China, it is estimated that annually 360,000 tons of plastic waste are generated by CBs in the environment. Considering the presence of CBs in urban and beach environments, the release of these toxic substances poses a threat to water resources.