Asphalt pavements release volatile organic compounds (VOCs) during the entire process from mixing to paving. Most studies focus on short-term emissions, while evaluations of VOC emission characteristics and environmental impacts under prolonged high-temperature conditions remain limited. This study investigated VOC emissions from three asphalt binders (70#, 90#, and SBS-modified asphalt) under two heating temperatures (130 °C and 180 °C) and two heating duration conditions (0.5 h and 4 h). Total VOC concentrations, composition profiles, ozone formation potential (OFP), and secondary organic aerosol formation potential (SOAP) were systematically compared. Total VOC emissions increased with both temperature and duration for all asphalts. Under long-term heating, total VOC concentrations increased by 1.4 to 5.0 times depending on binder type and temperature. Temperature had a stronger overall effect on total emissions, while duration also played an important role. Prolonged heating reduced the relative contribution of alkanes by up to 19.7 % and enriched oxygenated hydrocarbons by 7.0 %–10.3 % and alkenes or alkynes, shifting the VOC profile toward a more reactive mixture. OFP increased by 2.1 to 20.1 times and SOAP by 2.2 to 39.4 times for most conditions. OFP was driven mainly by unsaturated hydrocarbons such as propylene, while SOAP was dominated by aromatics like benzene and toluene. These findings demonstrate that prolonged heating fundamentally alters both emission magnitude and compositional reactivity, and that short-term data alone may underestimate secondary pollution potential. Heating duration should be considered alongside temperature in asphalt VOC assessments.

Extreme heat and ozone (O3) pollution are aggravating public health threats; yet their co-exposure mortality effects remain poorly characterized, particularly among vulnerable populations. Using a time-stratified case-crossover design with conditional logistic regression and Relative Excess Risk due to Interaction (RERI), we quantified the synergistic mortality risk of co-exposure to extreme heat (90th–97.5th percentiles of daily temperature) and O3 (90th–97.5th percentiles of daily maximum 8-hour average) during hot seasons (2013–2018) in Shanghai. We assessed mortality risks associated with individual and combined exposures to extreme heat and O3 for total non-accidental (TND), cardiovascular, and respiratory mortality. Our results demonstrated significant synergistic effects across all mortality categories, with RERI values of 0.062 (95% CI: 0.017–0.106) for TND, 0.106 (0.058–0.154) for cardiovascular, and 0.167 (0.081–0.253) for respiratory mortality (all p < 0.01). Co-exposures at the 90th–97.5th percentiles consistently demonstrated higher mortality risks than additive individual effects (e.g., TND RR = 1.112, 95% CI: 1.083–1.142 for co-exposure vs. 1.047 [1.024–1.070] for heat alone and 1.010 [0.992–1.029] for O3 alone at 90th percentile). Subgroups exhibiting heightened vulnerability included adults aged >60 years (RERI = 0.062, 95% CI: 0.026–0.098), females (RERI = 0.092, 95% CI: 0.048–0.136), and individuals with lower education (RERI = 0.087, 95% CI: 0.038–0.136). These findings underscore the need for integrated climate-air quality interventions to protect public health for sustainable and equitable urban governance.

This study examines how ground-level ozone (O3) exposure affects mortality in Shanghai (2013–2018), and how temperature modify this relationship in subtropical climate. Using a generalized additive model, we found: (1) A significant non-linear O3-mortality association, with risks rising sharply above 42.1 μg/m3 for cardiovascular diseases; (2) The estimated effects of O3 on mortality varied across different lag days, peaking on lag03; (3) Respiratory mortality most sensitive to O3 exposure compared with total non-accidental or cardiovascular mortality; (4) Higher vulnerability among females, adults ≥60 years, and those with low-education; and (5) Consistent effect modification by temperature, both low- and high-temperature strata have elevated O3-related mortality risks across all cause-specific and demographic subgroups. For temperatures below the 25th, between 25th and 75th, and above the 75th percentiles, a 10 μg/m3 O3 increase was associated with 0.97% (95% CI: 0.64–1.31%), 0.73% (0.30–1.16%), and 0.85% (0.38–1.32%) rises in total non-accidental mortality, respectively. Given ongoing climate change and rising O3 precursor emissions, urgent targeted interventions are needed to protect vulnerable populations from combined O3-temperature exposure.

Chlorine (Cl) atoms generated from the photolysis of atmospheric reactive chlorine species can rapidly react with various volatile organic compounds (VOCs), forming chlorine- and non-chlorine-containing low-volatile oxygenated organic molecules. Yet, the formation mechanisms of chlorine-containing oxygenated organic molecules (Cl-OOMs) from reactions of Cl atoms with aromatics in the presence and absence of NOx are not fully understood. Here, we investigated Cl-OOMs formation from Cl-initiated reactions of three typical aromatics (i.e., toluene, m-xylene, and 1,2,4-trimethylbenzene (1,2,4-TMB)) in the laboratory and searched for ambient gaseous Cl-OOMs in suburban Shanghai. From our laboratory experiments, 19 Cl-containing peroxyl radicals and a series of Cl-OOMs originating from the Cl-addition-initiated reaction were detected, which provides direct evidence that the Cl-addition-initiated reaction is a non-negligible pathway. In addition, a total of 51 gaseous Cl-OOMs were identified during the winter in suburban Shanghai, 38 of which were also observed in laboratory experiments, hinting that Cl-initiated reaction of aromatics could serve as a source of Cl-OOMs in an anthropogenically influenced atmosphere. Toxicity evaluation of these Cl-OOMs shows potential adverse health effects. These findings demonstrate that Cl-OOMs can be efficiently formed via the Cl-addition pathway in the reactions between aromatics and Cl atoms and some of these Cl-OOMs could be toxic.

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are key reactive volatile organic compounds (VOCs) that contribute significantly to tropospheric ozone formation and secondary organic aerosol production. Despite their environmental importance, the environmental effect of BTEX remains underexplored, especially in near-road atmosphere, as most studies have focused on particulate matter and nitrogen oxides. This study continuous observed the variations in BTEX at four roadside sites under different traffic emission scenarios before and after the Spring Festival in near-road atmosphere in Shanghai, which purpose to better understand their environmental dynamics. Results indicated that BTEX and NMHCs concentrations declined substantially (41-63 % and ∼60 %, respectively) during the Spring Festival with reduced traffic, while source apportionment using ternary diagrams and B/T ratios revealed distinct shifts from traffic-dominated to non-traffic contributions during the holiday period. However, Benzene remained at a high level and the corresponding estimated carcinogenic risk remained above the acceptable threshold in both periods. This study demonstrated that short-term traffic emission reductions not only lower VOCs levels but also significantly alter BTEX composition, but benzene still had prolonged effects, which explained that identifying BTEX from different sources is crucial for developing effective strategies to control urban environmental ozone and secondary aerosols.

As a replacement for polybrominated diphenyl ethers (PBDEs), organophosphorus flame retardants (OPFRs) have been widely used and detected in different indoor environments all over the world. This paper comprehensively describes the concentration levels and distribution information of 11 kinds of OPFRs from 33 indoor dust and 10 air environments, from which TBOEP, TCIPP, and TDCIPP were observed to have higher concentrations in indoor environments. The ΣOPFRs displayed higher concentrations in indoor dust than in indoor air due to the higher molecular weight and vapor pressure of ΣOPFRs in building decoration materials, specifically for TCIPP and TDCIPP compounds. Considering that it is inevitable that people will be exposed to these chemicals in the indoor environments in which they work and live, we estimated their potential health risks through three human exposure pathways and found that the ingestion exposure to TBOEP for toddlers in Japan may reach up to 1270.80 ng/kg/day, which comprises a significant pathway compared to dermal contact and indoor air inhalation. Specifically, the combined total exposure to OPFRs by air inhalation, dust ingestion, and dermal contact was generally below the RfD values for both adults and toddlers, with a few notable higher exposures of some typical OPFRs.

为了解上海郊区大气中汞的形态分布特征,于2021年1—7月使用在线监测设备对上海郊区大气中的气态元素汞(GEM)、气态氧化汞(GOM)和颗粒态汞(PBM)进行了连续观测,分析了GEM、GOM和PBM的浓度特征,研究了不同空气质量下GEM、GOM和PBM的变化情况,并探讨了不同风速、风向条件下GEM、GOM和PBM的变化特征.结果表明:观测期间上海郊区大气中GEM、GOM和PBM小时质量浓度分别为(2.65±0.99)ng/m3、(4.84±13.84)pg/m3和(20.51±47.95)pg/m3,GEM的质量分数达到了99.1％,是大气中汞的主要存在形式.GEM与PM2.5的Pearson相关系数为0.517,呈现出较高的显著相关性.以PM10为首要污染物、空气质量恶化情况下,GEM浓度无明显变化,GOM和PBM浓度呈现下降趋势;而在以PM2.5为首要污染物、空气质量恶化情况下,GEM和PBM浓度呈现上升趋势,而GOM浓度则呈现下降趋势.GEM、GOM和PBM浓度风向—风速玫瑰图相似性较低,表明GEM、GOM、PBM的污染源不具有同源性,GEM主要是受区域工业锅炉排放影响.

高校课程思政建设是培养社会主义人才的重要举措,在高等学校环境工程专业课的教学体系中融入"思政课程"教育,可为我国生态文明建设提供人才基础.本文以《环境监测》课程为例,通过在课程教学中融入"思政教育",并从提升教师的政治素养和优化教学模式两方面来探索课程思政教学改革,在提高大学生基础理论知识和专业技能的同时,注重思想政治的教育,引导大学生做生态文明建设的坚定践行者.

The emission of air pollutants from the municipal solid waste (MSW) incineration is one of the major concerns in air pollution. The up-to-date emission situation for Chinese MSW incineration is largely unknown. The emission factors (EFs) are the key parameters to estimate the emissions from MSW incineration. The localized EFs from MSW incineration in Shanghai, China were established using continuous emission monitoring system data from 2017 to 2019. Our results showed that the EFs were 9.80 g t-1 of PM, 46.62 g t-1 of SO2, 812.68 g t-1 of NOx, 25.84 g t-1 of CO, and 17.49 g t-1 of HCl for the period 2017-2019, nearly 1.7-24.2 times lower than those in 2010, implying that the current EFs should be updated to avoid overestimation of MSW emissions in China. Compared with 2010, the emissions of PM, SO2, CO, and HCl in 2019 were significantly reduced by 84%, 69%, 47%, and 72%, respectively, except for NOx with a 106% increase, although the corresponding MSW incineration amount increased by 356%. The current levels of air pollutants from MSW incineration have already met the current national emission standard as well as the stricter standard of the European Union (98.87%-99.91%). Our findings suggest that China should update the current standards of MSW incineration, which can be a benefit for the prevention and control of MSW incineration in the future. It is still challenging to control NOx emissions from MSW incineration for Shanghai and even greater China.

Iron and steel industry emission is an important industrial source of air pollution. However, little is known about the relationship between volatile organic compounds (VOCs) emitted and regional air pollution. In this study, VOCs emissions from a typical iron and steel plant in Yangtze River Delta (YRD, China) were monitored from April 2018 to March 2019. The ozone formation potential (OFP) and secondary organic aerosol (SOA) formation of VOCs were calculated to reveal the influence of VOCs emissions on regional ozone and particulate pollution, and the sensitivity analysis approach was performed to explore the qualitative and quantitative relationships between VOCs and O3, as well as VOCs and PM2.5. The VOCs concentration was 93.76 ± 266.97 ppbv during the study. The OFP was 760.08 ± 2391.90 μg m−3, and aromatics were the predominant precursors, contributing 54.05% of the total OFP. Furthermore, the SOA estimated by fractional aerosol coefficient (FAC) and time-resolved (TR) methods were 6.032 ± 13.347 μg m−3 and 0.971 ± 4.650 μg m−3, accounting for 8.65–26.39% (13.78 ± 7.46%) and 1.55–4.20% (2.22 ± 1.23%) of the PM2.5 concentrations, respectively. The results indicated that VOCs were more sensitive to O3 pollution in high pollution domains, whereas VOCs were more sensitive to PM2.5 pollution in low pollution domains. We concluded that reducing VOCs emissions might be effective in alleviating photochemical pollution episodes in areas around iron and steel industry, and the haze pollution occurred in these regions may be caused by the primary emission of PM, and the contribution of SOA was relatively small.

In China, the corresponding control directives for volatile organic compounds (VOCs) have been based on primary emissions, rarely considering reactive speciation. To seek more effective VOCs control strategies, we investigated 107 VOC species in a typical coastal city (Beihai) of South China, from August to November 2018. Meanwhile, a high-resolution anthropogenic VOCs monthly emission inventory (EI) was established for 2018. For source apportionments (SAs) reliability, comparisons of source structures derived from positive matrix factorization (PMF) and EI were made mainly in terms of reaction losses, uncertainties and specific ratios. Finally, for the source–end control, a comprehensive reactivity control index (RCI) was established by combing SAs with reactive speciation profiles. Ambient measurements showed that the average concentration of VOCs was 26.38 ppbv, dominated by alkanes (36.7%) and oxygenated volatile organic compounds (OVOCs) (29.4%). VOC reactivity was estimated using ozone formation potential (52.35 ppbv) and propylene-equivalent concentration (4.22 ppbv). EI results displayed that the entire VOC, OFP, and propylene-equivalent emissions were 40.98 Gg, 67.98 Gg, and 105.93 Gg, respectively. Comparisons of source structures indicated that VOC SAs agreed within ±100% between two perspectives. Both PMF and EI results showed that petrochemical industry (24.0% and 33.0%), food processing and associated combustion (19.1% and 29.2%) were the significant contributors of anthropogenic VOCs, followed by other industrial processes (22.2% and 13.3%), transportation (18.9% and 12.0%), and solvent utilization (9.1% and10.5%). Aimed at VOCs abatement according to RCI: for terminal control, fifteen ambient highly reactive species (predominantly alkenes and alkanes) were targeted; for source control, the predominant anthropogenic sources (food industry, solvent usage, petrochemical industry and transportation) and their emitted highly reactive species were determined. Particularly, with low levels of ambient VOC and primary emissions, in this VOC and NOx double-controlled regime, crude disorganized emission from food industry contributed a high RCI.

Volatile organic compounds (VOCs) are important precursors of ozone and atmospheric particulates that have attracted extensive attention worldwide. Cooking emissions, the chemical characteristics of which vary dramatically due to different cooking styles, are a main source of ambient VOCs, especially in large cities. This research focused on the emission characteristics of VOCs from six types of restaurants in Shanghai: hot pot (HP), Sichuan cuisine (SC), Cantonese cuisine (CS), seafood (SF), Western fast food (WFF), and authentic Shanghai cuisine (ASC). It was found that HP, which discharged cooking fumes indoors, produced the highest mass concentration of VOCs (1900.2 ± 364.8 μg m −3 ), followed by SC (1403.7 ± 403.8 μg m −3 ), WFF (656.0 ± 156.9 μg m −3 ), SF (638.6 ± 145.1 μg m −3 ), CC (632.7 ± 127.7 μg m −3 ), and ASC (612.3 ± 51.3 μg m −3 ), the cooking fumes from which were collected by emission extraction stacks. Additionally, the VOC species from each cuisine were mainly low carbon substances. Alkanes were the major VOC pollutants from all six cuisines, accounting for 34.4–71.7%. The coefficient divergence values were 0.287–0.593, suggesting that there were differences between the cuisines in the present study. Ozone formation potential and secondary organic aerosol formation potential indicated that O-VOCs and aromatics were the largest contributors. Health risk assessment of VOCs via non-carcinogenic risk values (HQ) and carcinogenic risk values (RISK) indicated that frying, grilling, and stir-frying had relatively large impacts on human health. VOCs collected in emission extraction stacks were significantly higher risk compared with those in the indoor environment, but the RISK score of the HP restaurant was larger, second only to SC. The HQ and RISK values of 1,3-butadiene, acetaldehyde, and trichloroethylene in the HP restaurant all exceeded US EPA standards, indicating that long-term exposure in an HP restaurant would have a significant impact on human health and might carry a potential cancer risk.

Traceability and authenticity is crucial to the food safety of scallop. The present study investigated the possibility of using stable isotope analysis to identify the origins and species of scallops (Patinopecten yessoensis, Chlamys farreri, and Argopecten irradians) in the coastal areas of China. The δ13C and δ15N values of a total of 575 samples from seven sites around China were determined and additional 150 samples were tested by fisher linear discrimination analysis (LDA) to estimate the accuracy of origin identification and species prediction. The results show that the stable C and N isotope composition differed significantly depending on the origin, season and species of scallops. Meanwhile, the LDA shows that 92% of the samples were correctly classified for origin prediction, and an accuracy of 98.3% was obtained for species prediction. This study reveals that stable isotope ratio is an effective technique to trace the geographical origin and identify the species of scallops.

The fatty acid composition in organisms is mainly determined by food sources and environmental conditions. They can reflect the specific living environment of organisms. In this work, we studied the regional differences in fatty acid composition of sea cucumber (Apostichopus japonicus) and scallop (Patinopecten yesoensis) in the coastal regions of China, and analyzed the effects of different geographical and environmental conditions on the fatty acid composition of A. japonicus and P. yesoensis. Principal component analysis (PCA) was applied to reveal the differentiating effects of fatty acid composition on A. japonicus and P. yesoensis from different regions and evaluate the feasibility of using fatty acid composition to origin identification of A. japonicus and P. yesoensis. The results showed that there were significant differences in the fatty acid compositions of A. japonicus and P. yesoensis in different regions and seasons, mainly because of the regional differences and seasonal changes of the food sources. On the basis of the analysis of characteristic fatty acid, the main food sources of A. japonicus were diatoms, and the main food sources of P. yesoensis were diatoms and dinoflagellates. We concluded that the fatty acid composition can reflect the living environment of A. japonicus and P. yesoensis, and the combined use of fatty acid composition and PCA can be an effective method for identifying the geographical origins of A. japonicus and P. yesoensis. The conclusions of this study can provide technical support for the origin traceability of sea cucumber and scallop. (C) 2019 Published by Elsevier B.V.

As one of the highest energy consuming and polluting industries, the power generation industry is an important source of particulate matter emissions. Recently, implementation of ultra-low emission technology has changed the emission characteristic of fine particulate matter (PM2.5). In this study, PM2.5 emitted from four typical power plants in China was sampled using a dilution channel sampling system, and analyzed for elements, water-soluble ions and carbonaceous fractions. The results showed that PM2.5 concentrations emitted from the four power plants were 0.78 ± 0.16, 0.63 ± 0.09, 0.29 ± 0.07 and 0.28 ± 0.01 mg m-3, respectively. Emission factors were 0.004-0.005 g/kg coal, nearly 1-2 orders of magnitude lower than those reported in previous studies. The highest proportions of PM2.5 consisted of organic carbon (OC), SO42-, elemental carbon (EC), NH4+, Al and Cl-. Coefficients of divergence (CDs) were in the ranges 0.22-0.41 (for an individual plant), 0.43-0.69 (among different plants), and 0.60-0.99 (in previous studies). The results indicated that the source profiles of each tested power plant were relatively similar, but differed from those in previous studies. Enrichment factors showed elevated Se and Hg, in accordance with the source markers Se and As. Comparing source profiles with previous studies, the proportion of OC, EC and NH4+ were higher, while the proportion of Al in PM2.5 were relatively lower. The OC/EC ratio became concentrated at ∼5. Results from this study can be used for source apportionment and emission inventory calculations after implementation of ultra-low emission technologies.

Currently, studies on the characteristics, reactivity and source apportionment of volatile organic compounds (VOCs) are mainly focused on large cities, however, information about the source characteristics of VOCs in less developed regions is insufficient. In this study, ambient air samples (n = 352) were collected from 11 sampling sites (including urban areas, suburban areas, outer suburb areas, and background areas) in Guilin, a typical tourist city located in southwest China, during the period 1st May to 30th November 2018 to determine the concentrations, temporal and spatial distribution, and activity of VOCs and to identify their sources. The results showed that the concentration of VOCs was 23.67 +/- 9.77 ppbv, and aromatics were the most abundant VOCs, accounting for 65.75% of the total VOCs concentrations. The propylene-equivalent concentration and the ozone formation potential (OFP) of VOCs were 10.08 ppbv and 158.02 ppbv, respectively, and aromatics contributed the largest, accounting for 88.87% and 93.00%, respectively. Moreover, the ratios of T/B and X/E were 1.44 +/- 0.92 and 0.74 +/- 1.10, respectively. The temporal and spatial distribution of VOCs showed that there were significant differences of the VOCs concentrations between seasons (higher in autumn and lower in summer) and the VOCs concentrations were both high in urban areas and outer suburb areas. Based on the positive matrix factorization (PMF) method, 5 sources were identified as fuel evaporation, vehicle exhaust, industrial productions, solvent use, and biogenic emissions, contributing 35.32%, 28.29%, 15.65%, 11.20%, and 9.54%, respectively. Results indicated that a high proportion of aromatics in ambient VOCs and a large contribution of aromatics to O-3 generation are the main characteristics that differentiate Guilin as a typical tourist city from other types of cities. We concluded that the VOCs in Guilin mainly come from the emissions of fuel evaporation and vehicle exhaust, and the impact of industrial emissions is relatively small, which is consistent with the characteristics of a tourist city. Moreover, our results revealed that the aging degree of air mass in Guilin is relatively higher than other cities, which inferred that the VOCs in Guilin may be affected by transmission from external sources.

To investigate the differences in characteristics of heavy metals associated with different levels of ambient air quality, we collected road dust samples from Beihai (BH) and Shanghai (SH). The mean concentrations of Ni, Cr, Zn, and Cu in BH samples were one to four times the background concentrations in soil, whereas the concentrations of Cd, Cr, Mn, Zn, Cu, and Pb in SH were one to three times the background concentrations. The geo-accumulation index (Igeo) indicated widespread moderate contamination by Zn and high contamination near industrial areas by Ni and Cr in BH, whereas in SH was partly moderately contaminated by Pb, Cu, and Zn. The potential ecological risk index ( $$ {E}_r^i $$ ) indicated the low risk posed by all metals in both BH and SH. However, special attention should be given to the maximal $$ {E}_r^i $$ values, such as considerable risk for Hg ( $$ {E}_r^i $$  = 148.7) and high risk for Ni (254.1) in BH, respectively. According to the health risk assessment results, there were no non-carcinogenic or carcinogenic risks (CR) posed by heavy metals in road dust collected from BH and SH. Non-carcinogenic risks due to Cr for children in both BH (0.36) and SH (0.24) were relatively high compared to other metals, and a maximal CR value for Cr (2.7 × 10−6) was found to pose a potential carcinogenic risk near the industrial area in BH. Compared with those in developed cities, the health risks in BH related to Cu, Pb, and Zn from motor vehicle emissions were relatively low, but those related to Ni and Cr from local industrial activity in road dust were relatively high.

Human activities have huge impact on the aquatic environment. Knowledge on sources of the contaminants provides guidelines to determine the ideal location and maintenance of monitoring stations, thus advancing environmental monitoring and pollution control. Factor analysis (FA) may be the most popular method for source identification, but the results should be affirmed. Following this logic, in this research, firstly the potential sources were determined, and secondly the contaminant concentrations in the source regions and the non-source regions were compared. To identify the potential sources, 75 meteorological, economic and social indicators were used to group the study regions. FA was used to reduce dimensionality and factor scores were calculated. The grouping was based on the weighted factor scores while the weight was variance explained by each factor respectively. Each group was supposed to correspond to a factor; that is, a potential source. The results indicated that the concentrations of chemical oxygen demand (COD), ammonia nitrogen, phosphorus and arsenic in wastewater were significantly different between groups. Animal husbandry, mining and/or energy industry were the main sources of COD, ammonia nitrogen and phosphorus; animal husbandry, mining, energy industry, and/or heavy and chemical industry were the main sources of phosphorus; humid climate and/or secondary industry were the main sources of arsenic.

Perfluoroalkyl acids (PFAAs) are a form of toxic pollutant that can be transported across the globe and accumulated in the bodies of wildlife and humans. A nationwide geographical investigation considering atmospheric PFAAs via a passive air sampler (PAS) based on XAD (a styrene–divinylbenzene copolymer) was conducted in 23 different provinces/municipalities/autonomous regions in China, which provides an excellent chance to investigate their occurrences, spatial trends, and potential sources. The total atmospheric concentrations of 13 PFAAs (n=268) were 6.19–292.57 pg m−3, with an average value of 39.84±28.08 pg m−3, which were higher than other urban levels but lower than point source measurements. Perfluorooctanoic acid (PFOA) was the dominant PFAA (20.6 %), followed by perfluorohexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS), and perfluoroheptanoic acid (PFPeA). An increasing seasonal trend of PFAA concentrations was shown as summer < autumn < spring < winter, which may be initiated by stagnant meteorological conditions. Spatially, the content of PFAAs displayed a declining gradient trend of central China > northern China > eastern China > north-eastern China > south-western China > north-western China > southern China, and Henan contributed the largest proportion of PFAAs. Four sources of PFAAs were identified using a positive matrix factorization (PMF) model, including PFOS-based products (26.1 %), products based on PFOA and perfluorononanoic acid (PFNA; 36.6 %), degradation products of fluorotelomer-based products (15.5 %), and an unknown source (21.8 %).