Coal Combustion Research Articles

Investigating effects of sintering mean residence time on engineering properties of coal ash‐based lightweight aggregate

AbstractThis study examines the effect of sintering mean residence time (MRT) on the engineering properties and morphological structure of lightweight aggregates (LWA) manufactured from waste coal combustion ash (W‐CCA). A thermodynamics‐based framework was used to tune LWA manufacturing processes. A minimum 35% liquid phase (by mass) and a lower bound viscosity of 100 Pa·s of molten material were found necessary to successfully produce LWA. Using W‐CCA's chemical composition and FactSage thermodynamic modeling, the sintering temperature for LWA was set to 1075°C. Green spherical pellets made using a pelletizer were sintered at MRT of 5.1, 14.8, and 25.9 min to test LWA physical‐mechanical properties including, unit weight, specific gravity, water absorption, and compressive strength. Results indicated that unit weight ranged from 752 to 800 kg/m3, providing desirable lightweight properties. Oven dry specific gravity ranged from 1.24 to 1.43, complying with ENI13055 specification for LWA. Water absorption capacity decreased as MRT extended from 5.1 to 14.8 min and then increased as MRT proceeded from 14.8 to 25.9 min, achieving an average absorption capacity of 26% ± 1.5%. The inverse effect was noticed for compressive strength as LWA sintered with an MRT of 14.8 min demonstrated the highest compressive strength of 14.7 ± 1.8 MPa. The initial decrease in water absorption and increase in compressive strength are attributed to the efficient sintering of the LWA's internal structure. The inverse effect observed as MRT proceeded from 14.8 to 25.9 min was believed to be a result of thermal cracking due to extensive heat exposure. MRT of 14.8 min is recommended for LWA production using the coal ash utilized in this study for its buoyancy characteristics, sufficient absorption capability, and higher compressive strength.

Substantial differences in source contributions to carbon emissions and health damage necessitate balanced synergistic control plans in China

China’s strategy to concurrently address climate change and air pollution mitigation is hindered by a lack of comprehensive information on source contributions to health damage and carbon emissions. Here we show notable discrepancies between source contributions to CO2 emissions and fine particulate matter (PM2.5)-related mortality by using adjoint emission sensitivity modeling to attribute premature mortality in 2017 to 53 sector and fuel/process combinations with high spatial resolution. Our findings reveal that monetized PM2.5 health damage exceeds climate impacts in over half of the analyzed subsectors. In addition to coal-fired energy generators and industrial boilers, the combined health and climate costs from energy-intensive processes, diesel-powered vehicles, domestic coal combustion, and agricultural activities exceed 100 billion US dollars, with health-related costs predominating. This research highlights the critical need to integrate the social costs of health damage with climate impacts to develop more balanced mitigation strategies toward these dual goals, particularly during fuel transition and industrial structure upgrading.

Adsorption of Methylene Blue using Bottom Ash: Experimental Design, Isotherm Analysis, and Optimum Conditions

<p><span lang="EN-US" style="font-size:12.0pt"><span style="line-height:107%"><span style="font-family:"Times New Roman",serif"><span style="color:black">This study investigated the removal of methylene blue (MB) via adsorption using waste bottom ash.  The bottom ash, sourced from a waste storage site in the Çorlu district of Tekirdağ province, Thrace Region, was utilized as the adsorbent. The research examined the impact of several variables on MB removal, including bottom ash dosage, pH, contact time, and agitation speed. It was found that all parameters had a single-variable effect, while pH exhibited a quadratic effect on MB removal in a model-based analysis. The optimization of the model for maximum MB removal identified the optimal conditions as 0.978 g bottom ash dosage, pH 3, 15 minutes of adsorption time, and 50 rpm agitation speed. Under these conditions, the model predicted an MB removal efficiency of 71%, which was experimentally confirmed to be 72.5%. The adsorption process was found to fit with the Freundlich isotherm, indicating a multilayer adsorption mechanism on the heterogeneous surface of the adsorbent. This research not only highlights the feasibility of using bottom ash from coal combustion as an economical adsorbent for dye-contaminated wastewater but also underscores its potential to inform and inspire future studies on waste recycling and wastewater treatment. </span></span></span></span></p>

Analysis of the Impact of Waste Fly Ash on Changes in the Structure and Thermal Properties of the Produced Recycled Materials Based on Polyethylene.

This paper presents the results of the research on the structure and thermal properties of materials made from fly ash based on high-density polyethylene (HDPE). Composites based on a polyethylene matrix with 5, 10, and 15 wt% fly ash from hard coal combustion content were examined. Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) was used to identify characteristic functional groups present in the chemical structure of polyethylene and the composites based on its matrix. Structural analysis was performed using X-ray diffraction (XRD), a differential scanning calorimeter (DSC), and microscopic examinations. Mechanical properties were also examined. Analysis of the thermal effect values determined by the DSC technique, XRD, and FTIR-ATR allowed the evaluation of the crystallinity of the tested materials. Polyethylene is generally considered to be a two-phase system consisting of crystalline and amorphous regions and is a plastic characterized by a significant crystalline phase content. Based on the FTIR-ATR spectra, DSC curves, and XRD, the effect of the filler and the changes occurring in the materials studied resulted in a decrease in the degree of crystallinity and a change in the melting point and crystallization temperature of the polymer matrix were established. Microscopic examinations were carried out to analyze the microstructure of the composites to collect information on the distribution and shape of the filler particles, indicating their size and distribution in the polymer matrix. Furthermore, the use of scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS) allowed for the microanalysis of the chemical composition of the filler particles.

Thermal Studies of Fractionated Lignite and Brown Coal Fly Ashes.

Coal fly ash (CFA), a by-product of coal combustion, is a valuable raw material for various applications. However, the heterogeneous nature of the composition and properties of CFA provides challenges to its effective usage and utilisation. This study investigates the thermal behaviour of the fly ashes of lignite (FA1) and brown coal (FA2) and their fractions obtained by dry aerodynamic separation. Thermal analysis techniques, including thermogravimetry (TG), differential scanning calorimetry (DSC), and evolved gas analysis (EGA), were used to characterise the behaviour of the fly ash fractions while heating up to 1250 °C. The results reveal distinct differences in the thermal behaviour between ash types and among their different size fractions. For the FA1 ashes, the concentration of calcium-rich compounds and the level of recrystallisation at 950 °C increased with the decrease in particle size. The most abundant detected newly formed minerals were anhydrite, gehlenite, and anorthite, while coarser fractions were rich in quartz and mullite. For the FA2 ashes, the temperature of the onset of melting and agglomeration decreased with decreasing particle size and was already observed at 995 °C. Coarser fractions mostly remain unchanged, with a slight increase in quartz, mullite, and hematite content. Recrystallisation takes place in less extension compared to the FA1 ashes. The findings demonstrate that the aerodynamic separation of fly ashes into different size fractions can produce materials with varied thermal properties and reactivity, which can be used for specific applications. This study highlights the importance of thermal analysis in characterising fly ash properties and understanding their potential for utilisation in various applications involving thermal treatment or exposure to high-temperature conditions. Further research on advanced separation techniques and the in-depth characterisation of fly ash fractions is necessary to obtain materials with desired thermal properties and identify their most beneficial applications.

Characterizing multi-pollutant emission impacts of sulfur reduction strategies from coal power plants

Fuel combustion for electricity generation emits a mix of health- and climate-relevant air emissions, with the potential for technology or fuel switching to impact multiple emissions together. While there has been extensive research on the co-benefits of climate policies on air quality improvements, few studies have quantified the effect of air pollution controls on carbon emissions. Here we evaluate three multi-pollutant emission reduction strategies, focused on sulfur dioxide (SO2) controls in the electricity sector. Traditional ‘add-on’ pollution controls like flue gas desulfurization (FGD) reduce SO2 emissions from coal combustion but increase emissions of nitrogen oxides (NO X ), volatile organic compounds (VOCs), fine particulate matter (PM2.5), and carbon dioxide (CO2) due to heat efficiency loss. Fuel switching from coal to natural gas and renewables potentially reduces all pollutants. We identified 135 electricity generation units (EGUs) without SO2 controls in the contiguous US in 2017 and quantified the unit-level emission changes using pollution control efficiencies, emission rates, fuel heat input, and electricity load. A cost-benefit analysis is conducted, considering pollution control costs, fuel costs, capital and operation and maintenance (O&M) costs, the monetized health benefits from avoided multi-pollutant, and the social cost of carbon as the benefit for carbon reduction. We find that add-on SO2 controls result in an average annual net benefit of $179.3 million (95% CI: $137.5-$221.0 million) per EGU, fuel switching from coal to natural gas, $432.7 million (95% CI: $366.4-$498.9 million) per EGU; and fuel switching from coal to renewable energy sources, $537.9 million (95% CI: $457.1-$618.9 million) per EGU. Our results highlight multi-pollutant emission reduction strategy as a cost-effective way to synergistically control air pollution and mitigate climate change.

A Lab-Scale Experiment on the Spontaneous Combustion Behavior of Chronic Naturally–Oxidized Coal in Re-Mining Coal Mine

ABSTRACT Spontaneous combustion of coal in re-mining coal mine is a serious threat to the safety recovery of coal resources. In this paper, six coal samples, including two raw bituminous coal samples from the new mining working face and four oxidized bituminous coal samples from the re-mining working face, are selected. The pore structures, thermogravimetric properties, and spontaneous combustion characteristics of raw coal and oxidized coal are studied. The pore structures show that the surface of oxidized coals has more cracks and higher macropore volume and porosity as compared with raw coal. The thermogravimetric experiments demonstrate that the oxidized coal has a higher combustion rate and turns to the combustion reaction zone in advance. Moreover, the oxidized coals perform a better combustion property by showing a comprehensive combustion index of 6.7 × 10−9 min−2·°C−3 and 8.9 × 10−9 min−2·°C−3, higher than the raw coal of 4.0 × 10−9 min−2·°C−3. The spontaneous combustion characteristics show that the oxidized coal performs a greater rate of oxygen consumption and more oxidation products released than raw coal. The CPT of raw coal is higher than 157°C, while the CPT of oxidized coal is between 132°C and 140°C. The research results can provide a risk assessment method for coal spontaneous combustion in the re-mining coal mine, and provide guidance for avoiding the occurrence of coal fires.

Comprehensive source identification of heavy metals in atmospheric particulate matter in a megacity: A case study of Hangzhou

Megacities face significant pollution challenges, particularly the elevated levels of heavy metals (HMs) in particulate matter (PM). Despite the advent of interdisciplinary and advanced methods for HM source analysis, integrating and applying these approaches to identify HM sources in PM remains a hurdle. This study employs a year-long daily sampling dataset for PM1 and PM1-10 to examine the patterns of HM concentrations under hazy, clean, and rainy conditions in Hangzhou City, aiming to pinpoint the primary sources of HMs in PM. Contrary to other HMs that remained within acceptable limits, the annual average concentrations of Cd and Ni were found to be 20.6 ± 13.6 and 46.9 ± 34.8 ng/m³, respectively, surpassing the World Health Organization's limits by 4.1 and 1.9 times. Remarkably, Cd levels decreased on hazy days, whereas Ni levels were observed to rise on rainy days. Using principal component analysis (PCA), enrichment factor (EF), and backward trajectory analysis, Fe, Mn, Cu, and Zn were determined to be primarily derived from traffic emissions, and there was an interaction between remote migration and local emissions in haze weather. Isotope analysis reveals that Pb concentrations in the Hangzhou region were primarily influenced by emissions from unleaded gasoline, coal combustion, and municipal solid waste incineration, with additional impact from long-range transport; it also highlights nuanced differences between PM1 and PM1-10. Pb isotope and PCA analyses indicate that Ni primarily stemmed from waste incineration emissions. This explanation accounts for the observed higher Ni concentrations on rainy days. Backward trajectory cluster analysis revealed that southern airflows were the primary source of high Cd concentrations on clean days in Hangzhou City. This study employs a multifaceted approach and cross-validation to successfully delineate the sources of HMs in Hangzhou's PM. It offers a methodology for the precise and reliable analysis of complex HM sources in megacity PM.

The water-insoluble organic carbon in PM2.5 of typical Chinese urban areas: light-absorbing properties, potential sources, radiative forcing effects, and a possible light-absorbing continuum

Abstract. Water-insoluble organic carbon (WIOC) constitutes a substantial portion of organic carbon (OC) and contributes significantly to light absorption by brown carbon (BrC), playing pivotal roles in climate forcing. China is a hotspot region with high levels of OC and BrC, but information regarding the sources and light-absorbing properties of WIOC on a national scale remains scarce. Here, we investigated the light-absorbing properties and sources of WIOC in 10 representative urban cities in China. On average, WIOC made up 33.4 ± 7.66 % and 40.5 ± 9.73 % of concentrations and light absorption at 365 nm (Abs365) of extractable OC (EX-OC), which includes relatively hydrophobic OC (WIOC and humic-like substances, HULIS-C) and hydrophilic OC (non-humic-like substances, non-HULIS-C). The mass absorption efficiency of WIOC at 365 nm (MAE365) was (1.59 ± 0.55 m2 (g C)−1) comparable to that of HULIS (1.54 ± 0.57 m2 (g C)−1) but significantly higher than non-HULIS (0.71 ± 0.28 m2 (g C)−1), indicating that hydrophobic OC possesses a stronger light-absorbing capacity than hydrophilic OC. Biomass burning (31.0 %) and coal combustion (31.1 %) were the dominant sources of WIOC, with coal combustion sources exhibiting the strongest light-absorbing capacity. Moreover, employing the simple forcing efficiency (SFE300–700 nm) method, we observed that WIOC exhibited the highest SFE300–700 nm (6.57 ± 5.37 W g−1) among the EX-OC fractions. The radiative forcing of EX-OC was predominantly contributed by hydrophobic OC (WIOC – 39.4 ± 15.5 % and HULIS – 39.5 ± 12.1 %). Considering the aromaticity, sources, and atmospheric processes of different carbonaceous components, we propose a light-absorbing carbonaceous continuum, revealing that components enriched with fossil sources tend to possess stronger light-absorbing capacity, higher aromatic levels, increased molecular weights, and greater recalcitrance in the atmosphere. Reducing fossil fuel emissions emerges as an effective means of mitigating both gaseous (CO2) and particulate light-absorbing carbonaceous warming components.

Utilization of Nanocenospheres a waste material to improve the physical and rheological properties of SBS asphalt binders

The performance enhancement of asphalt binders by incorporating innovative additives has been a subject of significant research and industry interest. This study emphasizes the potential of Nano polymer composites as a promising additive for improving the performance of asphalt binders, providing valuable insights into developing advanced asphalt materials for sustainable road infrastructure construction and maintenance. It explores the utilization of nano cenospheres to amplify the attributes of Styrene-Butadiene-Styrene (SBS) modified asphalt binders. It introduces a novel approach by incorporating Nano polymer composites (NPC) comprising nanocenosphere particles and Styrene-butadiene-Styrene Particles. Nanocenosphere particles are the waste materials derived from coal combustion in thermal power plants. Styrene-butadiene-styrene is a type of thermoplastic elastomer, a synthetic rubber. A series of experimental tests, penetration, softening point, ductility, performance grading, temperature sweep, multiple stress and creep recovery, frequency sweep, linear amplitude sweep, and rutting aging index, is conducted to evaluate changes in physical and rheological properties. Results indicate that adding nano cenospheres particles in SBS asphalt binder enhances its softening point, elasticity recovery, rutting resistance, fatigue life, storage stability, and aging resistance compared to traditional SBS-modified asphalt binders. Statistical analyses were accomplished to comprehend the influence of the Nano polymer composites. This analysis provides valuable insights into the effects of nanocenospheres on SBS-modified binders. Through rigorous statistical analysis, a thorough interpretation of how the incorporation of nanocenospheres influences the attributes of Nano-polymer composites.

Pore-fracture structures and seepage flow characteristics during spontaneous coal combustion based on CT 3D reconstruction

To study the evolution characteristics of the pore-fracture structures and seepage properties of coal in the process of spontaneous combustion, a high-temperature tube furnace was used to heat the coal samples. The coal samples were scanned using Xray-CT scanning technology, and the CT 3D reconstruction technology was used to extract the 3D pore structure and equivalent pore network model of each group of coal samples. Firstly, the specific surface area and volume of pore cleavage is statistically characterized; the change rules of Ep, Et, Lc, and Cn are quantitatively analyzed. At 200 °C, the coal body produces a large number of pore fractures, the development of coal samples is more significant, and the pore-specific surface area and the number of pore throats reached their maximum value. In addition, the changes of fractal dimension, porosity, connectivity, and permeability of coal with temperature were discussed, and the best permeability of the coal was achieved at 200 °C. The connectivity and permeability were weakened with the further increase of temperature, and the structural changes had a close influence on the gas seepage pressure and seepage flow rate. The results of the study provide important engineering guidance for deepening fire prevention in coalfields.

Pace of heavy metal pollution in the anthropogenically altered and industrialized Nakdong River Estuary, South Korea: Implications for the Anthropocene

Estuaries, vital coastal ecosystems, face growing threats from industrialization. To understand the pace of sedimentary changes and heavy metal pollution at the anthropogenically altered and industrialized Nakdong River Estuary in South Korea, we used sediment coring to reconstruct environmental change. Estuarine dam construction in 1934 shifted the sedimentary system from sand to mud, coinciding with a post-1930s mercury increase due to coal burning. Mercury concentrations in other South Korean regions surged in the 1970s, indicating proximity to emission sources matters. However, most heavy metal levels (Cu, Cd, Zn, Ag) sharply rose in the 1960s and 1970s with regional industrialization. Modern heavy metal concentrations doubled pre-industrial levels, underscoring human activities as the primary driver of Nakdong Estuary environmental changes. This emphasizes the need for a balanced approach to development and environmental preservation.

Distribution and bioaccumulation status of polycyclic aromatic hydrocarbons (PAHs) in Veraval coastal waters using copepods as bio-indicators.

The study investigates the pollution characteristics of 16 priority PAHs, accumulated in copepods from a major fishing harbour and its adjacent coastal waters of Veraval, west coast of India. The total PAH accumulation is in the range of 922.16-27,807.49ngg-1 dw, with the mean concentration of 5776.59ngg-1 dw. High concentrations of PAHs were present in the copepod samples from inside the harbour. Notably, there was no significant correlation between the lipid content of copepods and the accumulation of PAHs. The molecular diagnostic ratio method (MDR) indicates that the PAH sources are petrogenic in origin, while principal component analysis (PCA) points to petroleum, coal combustion and vehicular emission sources. Total cancerous PAHs (C-PAHs) in the study area dominate by 40% of the total PAHs identified; moreover, the bioaccumulation factor (BAF) is very high in the offshore area, which is also a fishing ground. The global relevance and magnitude of the present study in the Veraval, one of the prime seafood exporting hubs in India, should be dealt with utmost avidity as the accumulation status of PAHs in the zooplankton has never been explored in the Indian coastal waters. Moreover, the current study gives the foremost data on the bioaccumulation status of PAHs in copepods from the tropical waters of India.

Compositions and sources of fluorescent water-soluble and water-insoluble organic aerosols

Brown carbon (BrC), the light-absorbing component of organic aerosols, plays a significant role in climate change and atmospheric photochemistry. However, the water-insoluble fractions of BrC have not been extensively studied, limiting the assessment of the overall climate effects of BrC. In this study, water-soluble and -insoluble organic carbon (i.e., WSOC and WIOC) in wintertime aerosols in Hefei were subsequently fractionated, and their fluorescence properties were comparatively investigated with the excitation–emission matrix method. WIOC contributing 57.1 % was the major component of organic carbon. WSOC with the largest contribution from humic-like regions exhibited a redshift compared to WIOC. Three humic-like substances (HULIS) with different oxidation degrees and one protein-like substances (PRLIS) were identified as the major fluorescent components by the parallel factor analysis. WSOC had more highly oxygenated HULIS, whereas low-oxygenated HULIS dominated WIOC. Nighttime WIOC contained more less-oxygenated species. The positive matrix factorization analysis suggested that biomass burning (43 %) was the largest source of both fluorescent WSOC and WIOC. Coal combustion contributed much more to fluorescent WIOC (40 %), whereas secondary formation contributed more to fluorescent WSOC (12 %). During aerosol pollution episodes, the increase in fluorescence efficiency was much greater for WIOC (25 %) than for WSOC (12 %), and WSOC and WIOC experienced a redshift and blueshift in emission wavelength, respectively. WSOC had more highly oxygenated HULIS, while WIOC had more less-oxygenated HULIS in aerosol episodes than the non-episodic periods. In addition, aerosol pollution was accompanied by the increased contributions of biomass burning and coal combustion to both fluorescent WSOC and WIOC, while the decreased relative contribution of secondary formation to fluorescent WSOC. Our findings highlighted the different fluorescence properties, compositions and sources of fluorescent WSOC and WIOC, providing a comprehensive view of BrC aerosols.

Study on Safety Mining Technology of Gob in Stopping Face by Replacing Pressure Equalization with Gob Pumping—A Case Study of Sitai Mine

Gas control in the upper corner of the natural coal mining face with high gas is always a difficult problem that troubles the safe production of the working face. Among them, a high gas-prone natural coal mining face with ground air leakage is more likely to cause gas and CO to exceed limits in the corner of the working surface and is difficult to control. The traditional treatment methods often have some problems; for example, it is easy to increase air leakage in the gob with the method of gas extraction in the gob, which is not conducive to the prevention and control of spontaneous combustion of coal in the gob. At present, the more effective method is the pressure-equalization method. However, the pressure-equalization measures need to establish a complex pressure-equalization system, and close cooperation between the systems is required; once the system power fails or equipment failure occurs, the pressure-equalization state changes randomly, and it is easy to cause gas over-limits and other faults. Therefore, this paper presents a new method to control gas in the gob of a coal seam by pumping the gob of the upper-adjacent layer, using the negative pressure of pumping, and balancing the negative pressure of the upper-adjacent layer and the gob of the coal seam to form a new pressure-equalization relationship. This method can prevent the toxic and harmful gases in the goaf of the upper-adjacent layer from escaping into the passageway of the gob of the local coal seam, reduce the air leakage in the goaf, and benefit the gas control and spontaneous coal combustion prevention in the goaf.

Research regarding the influence of size on the compressive strength of spontaneous combustion coal gangue concrete utilizing the diffusion model

This passage employs the U2-Net model to segment images of spontaneous combustion gangue coarse aggregate (SCGCA) concrete cross-section and randomly placed aggregate library. These methods are used to construct the dataset and subsequently establish and train the diffusion model. Based on this model, a two-dimensional micro-mechanical model of SCGCA concrete was constructed, accurately reproducing the distribution, grading, and shape of the aggregate in the concrete. The size effect of SCGCA concrete is analyzed through experimentation and numerical simulation of two-dimensional micro-models. The findings of the study reveal that the dimension conversion factors for the 100 mm and 200 mm cubic specimens are 0.92 and 1.12 respectively, which demonstrates the evident size effect of SCGCA concrete. The remarkable coherence between the empirical results and the computational simulation results serves as a powerful validation of the durability and efficacy of the model delineated in this paper. In accordance with the theory of Bažant's size effect, this paper elucidates the size effect law of uniaxial compressive strength in SCGCA concrete models ignited spontaneously at different dimensions.

Oxidation and spontaneous combustion characteristics of particulate coal under stress–heat–gas interactions

Coal spontaneous combustion (CSC) is disturbed by complex downhole conditions. However, current research by scholars mainly focuses on the impact of single conditional disturbances on CSC, which is difficult to comprehensively characterize the oxidation and spontaneous combustion characteristics of granular coal in a complex environment. For this reason, a temperature-programmed gas chromatographer (TP-GC) hyphenated instrument and a C600 high-precision microcalorimeter was used for analysis. The variation rules of derived gas and oxidizing thermodynamic parameters in the coal oxidizing and heating process under stress-heat-gas interaction were obtained. The intrinsic action mechanism of stress-heat-gas interaction to increase the risk of spontaneous combustion of granular coal is described. The results showed that as the level of air leakage (AL) rate increased, the concentration of derived gases in the coal sample showed a “˄”-shaped trend, and the heat release intensity and heat release varied in stages, both reaching their peak at a leakage rate of 150 mL/min. Under different stress conditions, the heat release intensity and heat release of coal also reach their maximum at 150 mL/min, indicating a higher risk of spontaneous combustion of coal at 150 mL/min. As the stress increases, the coal‑oxygen reaction is inhibited, leading to a decrease in the concentration of derived gases and a reduction in the average heat release of the coal sample. This indicates that particulate coal is prone to spontaneous combustion when subjected to high air leakage rate and low stress conditions. The experimental results provide a theoretical basis for the prevention of CSC under complex conditions.

Climate change and human impacts on aquatic communities at Etoliko Lagoon in western Greece

The Etoliko Lagoon in western Greece has experienced extensive human modification since the 20th century, both on the surrounding land and in the aquatic environment. To examine human impacts and disentangle climatic from anthropogenic changes, we present a suite of biomarker records that span the past two centuries (∼1790–2011). Specifically, we use terrigenous (n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and phytosterols) and aquatic (dinosterol, brassicasterol, cholesterol, and stigmasterol) biomarkers to document changes in nutrient inputs, combustion, and algal productivity. During most of the 19th and 20th centuries, aquatic communities respond to temperature, forced mainly by solar irradiance and volcanic activity, and precipitation, controlled largely by summer and winter North Atlantic Oscillation (NAO) patterns that determine freshwater runoff. PAHs illustrate the acceleration of coal combustion during the 1800s, and declining concentrations since the 1950s correspond to the implementation of emission controls and reductions in rainfall that likely inhibited PAH transport. As human pressures increased in the late 1900s and water column anoxia grew, the absence of a clear human waste and eutrophication signal suggests that other factors also contributed to limited oxygen availability. Overall, environmental degradation of the late 20th and early 21st centuries is clear and can be attributed to a combination of especially arid conditions and human interferences that altered lagoon hydrography, trophic state, and aquatic community composition.

Ecological and human health impact assessments based on long-term monitoring of soil PAHs near a coal-fired power plant.

The combustion of coal in power plants releases significant amounts of polycyclic aromatic hydrocarbons (PAHs), which are highly toxic and carcinogenic. This study assesses the ecological and human health impacts of PAHs contamination from a coal-fired power plant over 8years. The monitoring site selection considered the distance from the power plant and the prevailing wind direction in the investigated area. The results reveal that, during the monitoring period, PAH levels increased on average by 43%, 61%, and 37% in the zone of the prevailing wind direction, in the area proximate to the power plant, and the zone distant from it, respectively. The site, which has a radius of 4.5km in the prevailing wind direction, exhibited the highest ecological and human health impacts. Additionally, a strong correlation was observed between environmental and human health impacts, depending on the distance from the power plant, particularly in areas with the prevailing wind direction. These insights contribute to a comprehensive understanding of the intricate dynamics linking power plant emissions, PAHs contamination, and their far-reaching consequences on the environment and human health.

P‑Phenylenediamine antioxidants in PM2.5: New markers for traffic in positive matrix factorization source apportionment

The extensive utilization of rubber-related products can lead to a substantial release of p-phenylenediamine (PPD) antioxidants into the environment. In recent years, studies mainly focus on the pollution characteristics and health risks of PM2.5-bound PPDs. This study presents long-time scale data of PPDs and N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPD-Q) in PM2.5 and proposes the innovative use of PPDs as new markers for vehicular emissions in the Positive Matrix Factorization (PMF) source apportionment. The results indicate that PPDs and 6PPD-Q were detectable in 100 % of the winter PM2.5 samples, and the concentration ranges of PPDs and 6PPD-Q are 15.6–2.92 × 103 pg·m−3 and 3.90–27.4 pg·m−3, respectively, in which 6PPD and DNPD are the main compounds. Moreover, a competitive formation mechanism between sulfate, nitrate, ammonium (SNA) and 6PPD-Q was observed. The source apportionment results show that the incorporation of PPDs in PMF reduced the contribution of traffic source to PM2.5 from 13.5 % to 9.5 %. In the traffic source factor profiles, the load of IPPD, CPPD, DPPD, DNPD and 6PPD reaches 91.8 %, 91.6 %, 92.9 %, 80.6 % and 87.2 %, respectively. It`s amazing that traditional markers of traffic source, which often overlap with coal burning and industrial sources, over-estimated the contribution of vehicles by one third or more. The discovery of PPDs as specific markers for vehicular emissions holds significant utility, particularly considering the growing proportion of new energy vehicles in the future. The results may prove more accurate policy implications for pollution control. SynopsisPPDs are excellent indicators of vehicle emissions, and PMF without PPDs over-estimated the contribution of traffic source to PM2.5.