Highly volatile persistent organic pollutants (HV-POPs) are characterized by high volatility, environmental persistence, bioaccumulative potential, toxicity, and ability for long-range transport, posing environmental and health concerns. However, research on HV-POPs remains limited, particularly in rapidly urbanizing regions, constraining understanding of their sources, environmental fate, and risks. This study investigated 52 HV-POPs, including Stockholm Convention-listed POPs like hexachlorobutadiene (HCBD) and hexa-/pentachlorobenzene (HCB/PeCB), and nonlisted HV-POPs such as volatile methylsiloxanes (VMS) and chlorinated nitrobenzenes (CNBs), using active air samplers in six major cities across Asia and Africa. The median total concentrations of HV-POPs were highest in Guangzhou (351 ng/m3), followed by Kuala Lumpur (167 ng/m3), Accra (82.4 ng/m3), Dhaka (73.3 ng/m3), Nairobi (44.9 ng/m3), and Islamabad (33.5 ng/m3). VMS dominated at all sites, accounting for 84 ± 18% of total HV-POPs, up to 2-5 orders of magnitude higher than other compounds. Source analysis showed VMS emissions in Guangzhou were mainly from industrial activities, while in the other cities, they were from usage of personal care products. Inhalation risk assessments indicated negligible noncarcinogenic and carcinogenic risks at all sites. This study provides the first multiregional HV-POPs data set in urban air, supporting chemical risk assessment efforts and broader international regulatory initiatives.

Per- and polyfluoroalkyl substances (PFAS) are global pollutants of concern, yet their atmospheric sources and secondary formation mechanisms remain poorly understood. Here, we collected PM2.5 samples during winter and summer across nine cities in the Pearl River Delta (southern China). Among 44 targeted PFAS in PM2.5, 15 were detected with a median concentration of 222 pg/m3, with ultra-short-chain PFAS accounting for 42% of the total concentration. Higher Σ15PFAS concentrations occurred in winter (261 pg/m³) than in summer (141 pg/m³), with distinct seasonal compositional patterns. Source apportionment analysis indicated that potential secondary formation contributed an average of 16% to Σ15PFAS. Significant correlations between selected perfluoroalkyl acids (PFAAs) and atmospheric oxidants, aerosol liquid water content, and succinic acid point to aqueous-phase precursor degradation as a potential pathway for PFAS formation. These results suggest that PM2.5 may act as a sink for PFAS, especially for ultrashort-chain species during winter. Overall, our study provides field-based evidence for potential secondary PFAS formation in ambient aerosols and underscores the importance of controlling precursor emissions to mitigate atmospheric PFAS pollution.

Megacities are significant land users and major contributors to global carbon emissions. It is urgent to enhance land-use resilience of megacities through a low carbon strategy. This necessitates a comprehensive understanding of the interactions between decarbonization and land-use resilience from a systematic network perspective. Using ecological network analysis combined with scenario projection methods, this study examined the temporal trends and socioeconomic determinants of the network resilience of carbon metabolism in three Chinese megacities (i.e., Beijing, Shanghai, and Shenzhen) from 2000 to 2030. Our findings suggest that inefficient land expansion directly increased network redundancy, leading to higher carbon emissions and deteriorated land-use resilience. Furthermore, network resilience significantly declined as net carbon emissions neared their peak. Economic restructuring, driven by changes in structure- and efficiency-oriented factors, revealed both co-benefits and trade-offs between decarbonization efforts and network resilience. These improvements were mainly achieved through coupled strategies, with Beijing demonstrating the highest network resilience value (0.3524) during the last stage, compared to Shanghai (0.2810) and Shenzhen (0.2138). Scenario analysis highlighted notable fluctuations in network resilience in response to interventions, underscoring the need for adaptive measures to balance network efficiency and redundancy. To achieve low carbon and resilient development, Beijing must focus on structural transformation, Shenzhen on reducing energy intensity, and Shanghai on improving energy use efficiency. Our study provides valuable insights into the intricate relationship between urban economic resilience and low-carbon development, offering key implications for sustainable urban planning and management.

The globally massive land-use changes associated with unprecedented urbanization rate are leading to prodigious quantities of carbon emissions. Nonetheless, the dynamics of land-use carbon emissions, particularly driven by supply-chain activities across all relevant industrial sectors, remain largely unexplored, especially in non-agricultural sectors. Here, we constructed a novel methodological framework to quantify full-sector land-use carbon emissions in Shenzhen, China, an international megacity grappling with acute land resource scarcity. Then, we integrated this framework with multiregional input-output analysis to uncover the multi-scale embodied land-use emissions propelled by Shenzhen's supply-chain activities. Our results indicate a marked increase in Shenzhen's embodied carbon emissions, approximately two orders of magnitude greater than its physical emissions, tripling during 2005-2018. Remarkably, non-agriculture sectors contributed 81.3-90.5 % of physical and 46.6-58.4 % of embodied land-use emissions. The land-use changes occurred outside Shenzhen accounted for 6.5-13.3 % of Shenzhen's total embodied land-use emissions. The sectoral analysis revealed a transition from traditional manufacturing (e.g., metallurgy, chemical products, textiles, wood products) in 2010-2015 to high-tech sectors (e.g., electronic equipment and other manufacture) in 2015-2018. This shift was primarily attributed to concurrent industry transfer actions, leading to aggressive changes in land-use emission intensity discrepancies within and outside Shenzhen. This study provides a scientific basis for designing effective strategies to mitigate land-use carbon emissions associated with supply-chain activities.

AbstractAtmospheric polycyclic aromatic hydrocarbons (PAHs), which are emitted significantly by economic sectors, are closely related to the global incidence of human cancer. When assessing temporal changes in PAH emissions in a country that is vast in area, such as China, it is crucial to consider socioeconomic differences across geological regions. In this study, we developed PAH emission factors at the provincial level and used them to compile a Chinese PAH emission inventory. Subsequently, we estimated trade‐driven PAH emissions at the provincial level in 2007, 2010, 2012, 2015, and 2017, and examined the critical supply chain paths. The updated inventory reveals a distinct temporal trend in trade‐driven PAH emissions, although they remain at an order of magnitude similar to previous estimates. National total production‐, consumption‐, and income‐based PAH emissions, despite a rebound in 2012, exhibit a general decline from 59.3, 43.3, and 48.8 kt in 2007 to 52.1, 43.9, and 47.0 kt in 2017, respectively. These declines align with economic adjustments and emissions mitigation legislation. Spatial hotspots were concentrated in the most affluent Yangtze River Delta, Pearl River Delta, and Jing‐Jin‐Ji provinces on the demand side and in the northern coal resource‐rich provinces on the supply side. They primarily drive PAH emissions from the heavy industrial sectors of northern coal resource‐rich provinces. Fewer affluent provinces have experienced a rapid increase in trade‐driven PAH emissions after 2012, emphasizing the need for synergistic reduction measures to combat PAH pollution.

The intricate relationship between climate and vegetation dynamics, particularly during the late Paleozoic ice age marked by multiple icehouse-greenhouse transitions, is a compelling aspect in Earth's historical narrative. In this study, we decipher the interactions between the Permo-Carboniferous climate fluctuations and floral turn-overs within the North China Craton, based on the stratigraphic distributions of biomarkers and carbon isotopes from cored coals in Huainan coalfield, North China. Our findings reveal that the changes in n-alkane, terpane, sterane, and polycyclic aromatic hydrocarbon (PAH) distributions result from a confluence of maturation, depositional environment, and organofacies effects. Molecular maturity-sensitive ratios align with the maturity stage determined by Rock-Eval pyrolysis and petrography, categorizing the coals as high volatile bituminous A/B with a composite organic matter derived from terrestrial plants and marine algae. Notably, the 18 alpha-22,29,30-trisnorneohopane (Ts) to 17 alpha-trisnorhopane ratio (Ts/(Ts + Tm)), as well as C31-C34 22S/(22S + 22R) hopanes and C29 20S/(20S + 20R) steranes ratios exhibit moderate correlations with %Ro, indicative of epimerization reactions induced by maturation processes. The stratigraphic variations in pristane to phytane ratios (Pr/Ph), Pr/ n-C17, Ph/n-C18, C30 alpha beta/(alpha beta+beta alpha) hopanes, and organofacies sensitive PAH indices collectively capture a paleo-environmental shift from reducing to oxic conditions attributed to marine regression. The systematic changes in PAH concentrations and their maturity indices reflect condensation and dealkylation reactions during the maturation process. The 613C signature manifests a negative excursion in coals of the Artinskian Shanxi Formation and a subsequent positive excursion in the Capitanian Upper Shihezi Formation coals, respectively, reflecting changes in the 613C values of contemporaneous atmospheric CO2 in response to regional aridity fluctuations.

Ornithogenic sediment may contain important paleoecological information concerning past bird population dynamics. In this paper, we analyse the distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in two sedimentary profiles collected from abandoned penguin colonies at Cape Bird, Ross Island, Antarctica. The geochronology of the sediment profiles was determined using 210Pb and AMS 14C dating techniques, and spans the past 1500 years. We observe low levels of n-alkanes (0.93-2.67 mu g g-1) and PAHs (20.5-46.8 ng g-1) concentrations dominated by short-chain n-alkanes, low-molecular-weight and alkyl PAHs. Principal Component Analysis (PCA) shows that the PC 1 scores for n-alkanes and PAHs are significantly correlated with the input intensity of penguin guano and penguin bioelements. Using these proxies in combination with Generalized Additive Model (GAM), we reveal that breeding penguin population growth reaches a historical peak during the Medieval Climate Anomaly (MCA) prior to 1550 CE. This growth in population size corresponds to the extent of sea ice cover and the activity of the local atmospheric-ocean circulation. Warming induced by El Nino and the positive phase of the Southern Annular Mode, along with the expansion of ice-free zones and increased oceanic nutrient and food availability, are considered primary factors contributing to the growth of breeding penguin populations. Additionally, variations in sea ice extent and Amundsen Sea Low significantly influence penguin population dynamics. Our study suggests that n-alkanes and PAHs may be valuable organic proxies for reconstructing historical changes in breeding penguin populations, with the local sea ice extent and atmosphericoceanic circulation exerting a major influence on Antarctic penguin population dynamics.

China, as the largest global emitter of atmospheric polycyclic aromatic hydrocarbons (PAHs), exhibits significant variation in energy structure and technological capabilities among provinces. It is vital to construct a provinciallevel emission inventory of PAHs, fully considering these provincial disparities, for assessing the environmental budgets and instituting effective mitigation measures. This study constructed a dataset of provincial PAHs emission factors based on downscaling estimates by incorporating the Human Development Index (HDI). These emission factors were combined with the latest activity rate data to estimate PAHs emissions from individual provinces in China from 2007 to 2017. The national total PAHs emissions in our study were 11.8-12.3% higher than the previous emission inventory results. The validation results indicated that the inventory-based PAHs emissions were significantly correlated with the simulated emissions by an atmospheric box model and watershed model. From 2007 to 2017, nearly three-quarters of provinces declined in PAHs emissions resulting from technological advancements and environmental standard improvements, leading to a 34.4% reduction (from 118.5 to 77.8 Gg) of the national total. The industrial sector was consistently the dominant contributor (51.9-66.4%) with a growing trend in its share. This growth was dominantly contributed by less developed provinces, such as Heilongjiang, Ningxia, and Qinghai, indicating that there was a shift of industrial sectors and associated PAHs emissions from highly concentrated industrial regions to nascent industrial regions. This study provides essential data support for a comprehensive understanding of each province's emission responsibilities regarding PAHs and for assessing the potential risks that PAHs pose to human health and ecosystems in these provinces.

Plastic waste management, deeply intertwined with our economy, presents a global challenge. Plastic pollution pervades both aquatic and terrestrial ecosystems worldwide. In a vast country like China, establishing a comprehensive plastic flow regime that accounts for socioeconomic disparities between urban and rural areas is essential for effectively reducing s plastic waste. This study aims to map the life-cycle of China's plastic flows from 2001 to 2040, distinguishing between urban and rural sources, through integrating dynamic probabilistic material flow analysis with scenario analysis. The results indicate that from 2001 to 2020, cumulative plastic waste generation was 1001 +/- 14.6 million tonnes (Mt), with a higher proportion originating from urban areas (706 +/- 10.3 Mt) compared to rural areas (218 +/- 3.2 Mt). The rate of increase in mismanaged plastic wastes (MPWs) in rural areas outpaced that in urban areas, peaking in 2016, five years after the peak in urban areas. Consequently, the cumulative total of rural MPWs, including littering (103.5 +/- 2.0 Mt) and open dumping (74.8 +/- 1.5 Mt), was higher than that in urban areas (littering: 83.0 +/- 4.0 Mt; open dumping: 70.3 +/- 1.4 Mt). The scenario analysis forecasts a reduction of 96.5 +/- 0.4 % and an 83.0 +/- 2.1 % in MPW generations in urban and rural areas by 2040, respectively, if all interventions are implemented. However, strategies like reuse&recycling and reduce&substitute are less effective in rural areas compared to urban areas. Therefore, we recommend establishing a collection system with both penalties and incentives to reduce rural MPWs.

2021年10月在淮河沿岸采集了 19个农田表层土壤样品,利用气相色谱-质谱联用仪测定土壤中多环芳烃(PAHs)的含量,并对其残留、组成、分布和污染来源进行了分析.结果表明,淮河沿岸表层土壤中PAHs的含量范围为 92.7-893.2 ng·g-1,均值为515.3 ng·g-1.16种美国优控的PAHs,只有苊、蒽、荧蒽和芘未全部检出.PAHs的组成以2-4环为主.其中2环和3环PAHs所占比例为17.8％-53.3％(平均31.7％);4环 PAHs 的比例为 18.6％-40.2％(平均 30.1％);5 环和 6 环 PAHs 的比例为 18.3％-58.3％(平均28.6％).通过浓度比值法判定PAHs主要来源于石油源以及煤和木材的燃烧;另外淮河沿岸周边的生活燃烧和汽车尾气排放也是土壤中PAHs的来源之一.生态效应区间法评价显示淮河沿岸周边土壤中PAHs具有一定的生态风险.

Marine plastic pollution poses a potential threat to the ecosystem, but the sources and their magnitudes remain largely unclear. Existing bottom-up emission inventories vary among studies for two to three orders of magnitudes (OMs). Here, we adopt a top-down approach that uses observed dataset of sea surface plastic concentrations and an ensemble of ocean transport models to reduce the uncertainty of global plastic discharge. The optimal estimation of plastic emissions in this study varies about 1.5 OMs: 0.70 (0.13-3.8 as a 95% confidence interval) million metric tons yr-1 at the present day. We find that the variability of surface plastic abundance caused by different emission inventories is higher than that caused by model parameters. We suggest that more accurate emission inventories, more data for the abundance in the seawater and other compartments, and more accurate model parameters are required to further reduce the uncertainty of our estimate.

Understanding the molecular structural evolution mechanism during coal pyrolysis can help better regulate coal conversions for developing clean coal technology. This study investigated changes in functional groups and polycyclic aromatic hydrocarbons (PAHs) during pyrolysis of a perhydrous bituminous coal at temperature of 75-600 degrees C. Results indicated that aliphatic, C-O, C=O, OH, aromatic C=C, and aromatic C-H groups declined in relative abundance below 300 degrees C. These declines were attributed to cracking of hydrogen bonds and devolatilization. Meanwhile, the alkyl side chains of alkylated PAHs, i.e., alkyl-naphthalenes and alkyl-phenanthrenes, were continuously detached. Pyrolysis at 300-450 degrees C was characterized by elevated aromaticity, reflected by increments in the relative abundances of aromatic C-H, aromatic carbon, pyridine nitrogen, and protonated carbon. PAH evolutions at this stage exhibited relative increases of 4--6-ring PAHs with relative decreases of 2-3-ring PAHs. Pyrolysis at 450-600 degrees C was characterized by an increment of aromatic C=C and significant increases in relative abundances of 4--6-ring PAHs in emitted particulate and gaseous phases. The elevation of pyrolysis temperature transformed coal macromolecules into more compact structure. The molecular structural units of chars were formulated as C245H227N3O14S, C239H193N3O8S, C228H152N2O3S, and C221H113NO3S for coal and chars produced at 300, 500, and 600 degrees C, respectively. Changes in three-dimensional molecular structural units reflected step-by-step intense deformation and condensed process.

Biomarkers in coal can evolve dramatically in terms of their concentration and distribution during coalification, limiting their use in source allocation of coal-derived pollution. Here we analyzed a broad range of aliphatics (i.e., 26 n-alkanes, 6 isoprenoids, 32 terpanes, 19 steranes) and 77 polycyclic aromatic compounds (PACs) in the Permo-Carboniferous and Late Triassic coals from the Chinese Huainan and Da Baoding coalfields, respectively. These coals, classifying as high volatile bituminous B to low volatile bituminous with vitrinite reflectance (Rr) values ranging from 0.71 to 1.74 %, show variable organic geochemical features owing to the combined effects of thermal maturity and organofacies. Changes in the n-alkanes and isoprenoids indicate the loss of aliphatic fractions associated with maturation owing to cracking of the long-chain alkanes. The stratigraphic changes in the pristane to phytane ratios (Pr/Ph), Pr/n-C17, and Ph/n-C18 reflect a control exerted by the depositional environment in the Huainan coals. In addition, principal component analysis (PCA) recognizes the Pr/n-C17, Ph/n-C18, carbon preference index (CPI), and odd-to-even predominance 2 (OEP 2) as organofacies sensitive indices. Intercomparison of the PAC distributions suggest different maturation pathways for the coals from the Huainan and Da Baoding coalfields. The demethylation processes related to coalification preferentially occur on the polymethyl substitutes that occur to a greater degree in the Da Baoding coals than in the Huainan coals. Nine PAC indices display distinctive patterns when plotting against Rr. The DMP-2 vs DBT:DBF cross-plot explicitly separates the Huainan and Da Baoding coals into three distinctive zones representing different depositional environments and sources of organic matter. Moreover, PCA explicitly discriminate the maturation sensitive indices (i.e., MNR, DNR-1, TrMN-1, TrMN, TeMN, MPR, and MPI-1) from organofacies sensitive indices (i.e., DMP-2 and DBT:DBF).

To meet the global need for carbon neutrality, we must first understand the role of urban carbon metabolism. In this study, we developed a land–energy–carbon framework to model the spatial and temporal variation of carbon flows in Beijing from 1990 to 2018. Based on the changes in carbon sequestration and energy consumption, we used ecological network analysis to identify the critical paths for achieving carbon neutrality during land-use changes, thereby revealing possible decarbonization pathways to achieve carbon neutrality. By using GIS software, changes in the center of gravity for carbon flows were visualized in each period, and future urban construction scenarios were explored based on land-use policy. We found that the direct carbon emission peaked in 2010, mostly due to a growing area of transportation and industrial land. Total integrated flows through the network decreased at an average annual rate of 3.8%, and the change from cultivated land to the socioeconomic sectors and the paths between each socioeconomic component accounted for 29.5 and 31.7% of the integrated flows during the study period. The socioeconomic sectors as key nodes in the network should focus both on their scale expansion and on using cleaner energy to reduce carbon emissions. The center of gravity gradually moved southward, indicating that the new emission centers should seek a greener mixture of land use. Reducing carbon emission will strongly relied on transforming Beijing’s energy consumption structure and increasing green areas to improve carbon sinks. Our results provide insights into carbon flow paths that must be modified by implementing land-use policies to reduce carbon emission and produce a more sustainable urban metabolism.

The structure and distribution of biomarkers residing in coal evolve in measurable ways during coalification, marking study of their chemical alteration applicable to thermal history assessment of coal-forming sedimentary basins. However, such alternations are frequently accompanied by post-depositional effect that modify the biomarker performance as different kinetics, which remains poorly constrained. Here we present measurements of a broad range of aliphatics and 77 polycyclic aromatic compounds (PACs) in the Permo-Carboniferous and Late Triassic coals from the Chinese Huainan and Da Baoding coalfields, respectively. These coals show variable organic geochemical features as a function of combined effects of the thermal maturity and organofacies. The changes in n -alkane and isoprenoid concentrations and compositions indicate loss of aliphatic fractions associated with maturation owing to cracking of the long-chain alkanes and formation of short-chain alkanes. The pristane to phytane ratios (Pr/Ph) in the Da Baoding coals vary as a consequence of maturation, but reflect a control exerted by the depositional environment in the Huainan coals. In addition, principal component analysis (PCA) recognizes the Pr/ n -C 17 , Ph/ n -C 18 , carbon preference index (CPI), and odd-to-even predominance 2 (OEP 2) as organofacies sensitive indices. Intercomparison of the distributions of total amounts and compositions of PACs for the coals from the Huainan and Da Baoding coalfields suggest different maturation ways. Demethylation performs as a higher rapid degree in polymethylated aromatics (i.e., tri- and tetra-methylated naphthalenes and di- and tri-methylated phenanthrenes) than do mono-methylated homologues in both the Huainan and Da Baoding coals, with the latter having a more demethylation degree than do the Huainan coals. A total of nine PAC indices are estimated and they display four distinctive shapes when plotting against thermal maturity expressed as R r values. The DMP-2 and DBT:DBF cross-plot explicitly separates the Huainan and Da Baoding coals into three distinctive zones that represent different depositional environments and sources of organic matters. Moreover, PCA explicitly discriminate the maturation sensitive indices (i.e., MNR, DNR-1, TrMN-1, TrMN, TeMN, MPR, and MPI-1) from organofacies sensitive indices (i.e., DMP-2 and DBT:DBF).

自2010年,中国燃煤电厂大范围普及的大气污染物净化设备极大地改变了多环芳烃(PAHs)的排放格局.本研究以中国煤炭重要产地安徽为例,建立自下而上的PAHs历史排放清单,分析2010年到2017年间PAHs的排放规模、强度和特征的变化.2017年煤粉炉和循环流化床锅炉的PAHs排放总量近似,分别为8600 kg和7800 kg.细分至不同城市,PAHs排放量最大的城市分别为淮南(3600 kg),淮北(3100 kg),马鞍山(1800 kg).不同锅炉类型的年均排放速率和排放强度产生极大的差异,循环流化床炉的年均排放速率和排放强度(7.2 kg·t-1和2.1 kg·MW-1)分别是煤粉炉(1.1 kg·t-1和0.19 kg·MW-1)的7倍和11倍.这主要是由于循环流化床的较低燃烧温度和不完全的燃烧条件所导致.PAHs排放量的时间尺度变化也较为显著,在2012年至2017年间,随着燃煤电厂对小锅炉的关闭和大气污染净化设备的革新升级,单位锅炉的PAHs排放强度不断降低.此外,PAHs的排放格局还受到气温变化的影响,在相对较热的夏季和较冷的冬季,过度使用空调也会造成电力的额外消耗,增加区域PAHs的排放强度.

The transformation of heavy metals in ash from waste incineration plants is significant for ash management. The migration behavior of trace elements in ash after combustion, semidry deacidification, fabric filtration, and chelating agent stabilization was investigated from one waste incineration plant. The hazardous elements Zn, Pb, and As were enriched in raw fly ash (ash produced at a combustion temperature of 850-1100 °C) due to their relatively high volatility. Mercury, Cd, and Pb were captured in fly ash2 and processed by activated carbon and fabric filters. The removal rate of As (71%) was the highest among all studied elements due to a large amount of quinquevalent As removed. However, the average removal rate of elements in fly ash was only 13%. In the finally obtained fly ash3 (after chelating agent stabilization), a larger particle size (~100 μm) was found than that of raw ash. Furthermore, fly ash3 contains HgSO4 and trivalent As, which are toxic and likely to be precipitated when the fly ash3 is next utilized or deposited in a landfill, causing environmental risks.

Abstract Climate–vegetation interactions belong to the most intriguing relationships in Earth’s history, especially for the late Paleozoic ice age with multiple icehouse-greenhouse climate transitions. Biomarkers preserved in coals provide evidence for potential taxonomic relationships among taxa with large scale paleoclimatic and paleofloral interpretations. In this study, we decipher the interactions among Permo-Carboniferous paleoclimate change and floral turnovers in the North China Craton. This is achieved by comprehensive investigation of the stratigraphic distribution of biomarkers in cored coals from Huainan coalfield, North China. Results indicated that the concentration and composition of biomarkers in coal, though irrevocably altered by diagenetic transformation and epigenetic activities, are closely related to the source of organic matter, depositional environment, and/or post-depositional change. The estimated molecular parameters of aliphatic and aromatic compounds are consistent with the maturity stage determined by Rock-Eval and organic petrology, which characterized the coals as high volatile bituminous A/B primarily consisting of mixed organic matters originating from marine algae and terrestrial higher plants. Enhanced maturity of coal results in the isomerization reactions of sterane isomers, tricyclic and tetracyclic diterpanes due to thermal stress and obscures the relationships between biomarker parameters and their biological precursors. The n-alkane distributions, though profoundly affected by thermal maturation, point towards the terrestrial higher plant inputs reflecting by the odd predominance of long-chain n-alkanes. The parallel stratigraphic patterns of C30 βα/(αβ + βα) with those of Pr/Ph ratios suggest that redox conditions is likely responsible for epimerization reactions of the hopane that converting βα to geologically preferred αβ isomers. The abrupt increase of 4- to 7-ring PAHs at the boundary of Lower and Upper Shihezi formations argue for a period of enhanced wildfire frequency. Moreover, the stratigraphic distribution patterns of biomarker parameters are consistent with the floral turnovers from initial warm and humid climate adaptive plant groups to semi-arid adaptive plant groups, and finally to dry climate adaptive plant groups.

Coal-fired power plants (CFPPs) and waste incineration power plants (WIPPs) represent a large portion of polycyclic aromatic hydrocarbons (PAHs) sources in the environment, among which halogenated PAHs (HPAHs) are more toxic to the human body compared with their corresponding parent PAHs. In the current work, we investigated the occurrence, formation mechanism, and toxicity effects of HPAHs in the coal and waste combustion products from three CFPPs and one WIPP. The results indicate that the contents of chlorinated PAHs (Cl-PAHs) in the fly ash from the CFPPs and WIPP were 1.06-1.67 ng·g-1 and 2.76 ng·g-1, respectively, and the contents of brominated PAHs (Br-PAHs) in the fly ash from the CFPPs and WIPP were 26.4-44.2 ng·g-1 and 6.31 ng·g-1, respectively. The HPAH contents in the fly ash from the WIPP were significantly higher than those from the CFPPs primarily due to the abundant plastics in the domestic waste, represented by polyvinyl chloride, resulting in the formation of Cl-PAHs during combustion. The HPAH contents in the fly ash from the pulverized coal-fired (PC) boiler were significantly higher than those from the circulating fluidized bed (CFB) boiler mostly due to the higher combustion temperature operated in the PC boiler. The HPAHs in the fly ash from coal combustion were predominantly 7-BrBaA and 9-ClPhe, and those from domestic combustion were predominantly 9-BrPhe and 2-ClAnt. In addition, the contents of 7-BrBaA and 9,10-Br2 Ant in the coal combustion fly ash were significantly higher than those in domestic waste combustion fly ash, whereas 2-BrFle exhibited a contrasting profile. The content of Br-PAHs in the fly ash treated by semi-dry deacidification was twice that in dust removal fly ash but significantly increased in the chelating agent stabilization fly ash. The Pearson correlation analysis indicated the the formation mechanism of Cl-PAHs and Br-PAHs were the same but a secondary formation of HPAHs during the chelating agent stabilization of the fly ash was deduced. The TEQ values of the HPAHs in the fly ash (8.87×10-3-15.0×10-3 ng·g-1) from the WIPP were similar to those in the fly ash from the CFPPs (10.0×10-3 ng·g-1), which were significantly reduced in the fly ash treated by semi-dry deacidification due to the removal of 7-BrBaA. Moreover, the TEQ values of the HPAHs in the fly ash increased 5.4 times after the chelating agent stabilization. The ecological risk should be considered for the CFPP fly ash due to their massive amount of discharge and high TEQ values.