Multimedia modeling of the PAH concentration and distribution in the Yangtze River Delta and human health risk assessment

Spatiotemporal distribution and inter-media transfer of polycyclic aromatic hydrocarbons in Shanghai, China: Historical patterns and future trends

Polycyclic Aromatic Hydrocarbons (PAHs) represent pervasive pollutants, posing health risks in urban environments. It is essential to comprehend the spatiotemporal distributions, composition profiles, and inter-media transfer processes of PAHs in various environmental compartments, influenced by both natural changes and anthropogenic activities. This study integrates historical and future spatiotemporally changing environmental parameters, including climate data, GDP, population data, land-use types, and hydrological variables, into the Multimedia Urban Model (MUM). This integration enables the simulation of spatiotemporal distributions and inter-media transfer fluxes of PAHs among six different media from the 2010s to the 2100s under two distinct Shared Socio-economic Pathways (SSP) scenarios in the megacity of Shanghai, China. The MUM model, featuring diverse gridded parameters, effectively captures PAH concentrations and movement across environmental compartments. Results indicate a decreasing trend in PAHs concentrations in the 2100s compared to the 2010s, with PAH concentrations in water, sediment, vegetation, and organic film covering impermeable surfaces under the SSP3-7.0 scenario higher than those of the SSP1-2.6 scenario. Low molecular weight PAHs dominate in the sediment, water, and air, whereas high molecular weight PAHs prevail in the organic film, vegetation, and soil. Sediment and soil serve as the predominant sinks for PAHs. The primary transport processes for PAH movement include air-film, air-soil, film-water, soil-air, and water-air. Almost all transfer fluxes exhibit a declining trend in future periods except for the air-film transport pathway. The principal input and removal routes for PAHs in Shanghai involve the advection of air and water. The study provides essential insights into the environmental behavior of PAHs and informs targeted pollution control in Shanghai. Additionally, it serves as a technical reference for similar pollution prediction research.

Cross-media transfer of polycyclic aromatic hydrocarbons in the Naples metropolitan area, southern Italy

At present, an in-depth knowledge of polycyclic aromatic hydrocarbons (PAHs) in the multimedia system of the urban environment remains limited. Taking the Naples metropolitan area (NMA) for instance, we simulated the cross-media transfer of PAHs using a multimedia urban model, involving air, water, soil, sediment, vegetation, and impervious film. The results indicated that the predicted PAH values in 2015 match well with their corresponding in-situ monitoring data. The PAH emission inventory and the simulated mass in various media all showed a downward trend from 2015 to 2020 due to national energy conservation policies and Corona Virus Disease 2019. The simulated mass of PAHs in the soil and sediment phases was 896.8 and 232.7 kg in 2020, respectively, contributing together to 96.7% of PAHs in the NMA. And they were identified as the greatest sinks for PAHs, and exhibited the longest retention duration, with values of PAH persistence reaching approximately 548.8 - 2,0642.3 hours. The results of transfer fluxes indicated that local emissions and atmospheric advection were the primary routes affecting the distribution of PAHs. The sensitivity analysis indicated that atmospheric advection rate was the most critical parameter for air, soil, vegetation, and film, whereas water concentration and sediment degradation rate were vital for water and sediment, respectively. This study offered valuable insights into how human activity contributes to the status and fate of PAHs in the urban environment.

Associations between atmospheric PM2.5 exposure and carcinogenic health risks: Surveillance data from the year of lowest recorded levels in Beijing, China

Scant research has pinpointed the year of minimum PM2.5 concentration through extensive, uninterrupted monitoring, nor has it thoroughly assessed carcinogenic risks associated with analyzing numerous components during this nadir in Beijing. This study endeavored to delineate the atmospheric PM2.5 pollution in Beijing from 2015 to 2022 and to undertake comprehensive evaluation of carcinogenic risks associated with the composition of atmospheric PM2.5 during the year exhibiting the lowest concentration. PM2.5 concentrations were monitored gradually in 9 districts of Beijing for 7 consecutive days per month from 2015 to 2022, and 32 kinds of PM2.5 components collected in the lowest PM2.5 concentration year were analyzed. This comprehensive dataset served as the basis for carcinogenic risk assessment using Monte Carlo simulation. And we applied the Positive Matrix Factorization (PMF) method to identity the sources of atmospheric PM2.5. Furthermore, we integrated this source appointment model with risk assessment model to discern the origins of these risks. The findings revealed that the annual average PM2.5 concentration in 2022 stood at 43.1 μg/m3, marking the lowest level recorded. The mean carcinogenic risks of atmospheric PM2.5 exposure calculated at 6.30E-6 (empirical 95% CI 1.09E-6 to 2.25E-5) in 2022. The PMF model suggested that secondary sources (35.4%), coal combustion (25.6%), resuspended dust (15.1%), biomass combustion (14.1%), vehicle emissions (7.1%), industrial emissions (2.0%) and others (0.7%) were the main sources of atmospheric PM2.5 in Beijing. The mixed model revealed that coal combustion (2.41E-6), vehicle emissions (1.90E-6) and industrial emissions (1.32E-6) were the main sources of carcinogenic risks with caution. Despite a continual decrease in atmospheric PM2.5 concentration in recent years, the lowest concentration levels still pose non-negligible carcinogenic risks. Notably, the carcinogenic risks associated with metals and metalloids exceeded that of PAHs. And the distribution of risk sources did not align proportionally with the distribution of PM2.5 mass concentration.

Multiple exposure pathways and health risk assessment of PAHs in Lanzhou city, a semi-arid region in northwest China

In the sparse studies for multiple pathway exposure, attention has predominantly been directed towards developed regions, thereby overlooking the exposure level and health outcome for the inhabitants of the semi-arid regions in northwest China. However, cities within these regions grapple with myriad challenges, encompassing insufficient sanitation infrastructure and outdated heating. In this study, we analyzed the characteristics and sources of polycyclic aromatic hydrocarbons (PAHs) pollution in PM2.5, water, diet, and dust during different periods in Lanzhou, and estimated corresponding carcinogenic health risk through inhalation, ingestion, and dermal absorption. Our observations revealed the concentrations of PAHs in PM2.5, food, soil, and water are 200.11 ng m-3, 8.67 mg kg-1, 3.91 mg kg-1, and 14.5 ng L-1, respectively, indicating that the Lanzhou area was seriously polluted. Lifetime incremental cancer risk (ILCR) showed a heightened cancer risk to men compared to women, to the younger than the elderly, and during heating period as opposed to non-heating period. Notably, the inhalation was the primary route of PAHs exposure and the risk of exposure by inhalation cannot be ignored. The total environmental exposure assessment of PAHs can achieve accurate prevention and control of PAHs environmental exposure according to local conditions and targets.

Effects of Chinese "double carbon strategy" on soil polycyclic aromatic hydrocarbons pollution

Polycyclic aromatic hydrocarbons (PAHs) and carbon dioxide primarily originate from the combustion of fossil fuels and biomass. The implementation of the Chinese "double carbon strategy" is expected to impact the distribution of PAH emissions, consequently influencing the spatial distribution trend of PAHs in surface soil. Therefore, it is crucial to quantitatively evaluate the effectiveness of the Chinese "double carbon strategy" on soil PAH pollution for the purpose of "the reduction of pollution and carbon emissions". This study utilized 15,088 individual PAH concentration data from 943 soil samples collected between 2003 and 2020 in China, in conjunction with PAH emissions at a 10 km resolution, for meta-analysis. The calculated PAH emissions in this study are in line with the global PAH emission inventory (PKU-PAH-2007), with a relative standard deviation at the provincial level of less than 25 %. Subsequently, a novel method was developed using emission density and Kow of PAHs to predict PAH concentrations in surface soil based on a least-squares regression model. Compared to other environmental models, the method established in this study significantly reduced the percent sample deviation to less than 70 %. Furthermore, energy consumption data for China were simulated based on the implementation plan of the "double carbon strategy" to project PAH emissions and soil PAH levels for the years 2030 and 2060. The predicted PAH emissions in China were estimated to decrease to 41,300 t in 2030 and 10,406.5 t in 2060 from 78,815 t in 2020. Moreover, the heavily contaminated areas of soil PAHs (i.e., total PAH concentrations in soil exceeding 1000 μg kg-1) were projected to decrease by 45 % and 82 % in 2030 and 2060, respectively, compared to levels in 2020. These findings suggest that the implementation of the "double carbon strategy" can fundamentally reduce the pollution of PAHs in surface soil of China.

Drivers distinguishing of PAHs heterogeneity in surface soil of China using deep learning coupled with geo-statistical approach

Although numerous studies have reported the influencing factors of polycyclic aromatic hydrocarbons (PAHs) in surface soil from source, process or soil perspectives, the mechanism of PAHs heterogeneity in surface soil are still not well understood. In this study, the effects of 16 PAHs in surface soil of China sampled between 2003 and 2020 with their 17 "source-process-sink" factors at 1 km resolution (N = 660)) were explored using deep learning (eXtreme Gradient Boosting) to mine key information from complex dataset under the optimized parameters (i.e., learning rate = 0.05, maximum depth = 5, sub-sample = 0.8). It was observed that top five factors of 16 PAH had the largest cumulative contribution (i.e., from 84.8% to 98.1%) on their soil concentrations. PAH emission was the predominant driver, and its effect on soil PAH increases with increasing logKow. Soil was the second driver, in which clay can promote the partition of PAHs with low or middle logKow. However, sand can accumulate those congeners with high logKow. Moreover, the deep learning plus geo-statistical models (with low deviation for testing dataset (N = 283)) were capable of predicting soil PAH concentrations using their drivers with high accuracy. This study improved the understanding of the environmental fate and spatial variability of soil PAHs, as well as provided a novel technique (i.e., deep learning coupled with geo-statistics) for accurate prediction of soil pollutants.

Comprehensive Assessment of Environmental Emissions, Fate, and Risks of Veterinary Antibiotics in China: An Environmental Fate Modeling Approach

China is one of the major global consumers of veterinary antibiotics. Insufficient recognition of emissions and environmental contamination hamper global efforts to prevent antibiotic resistance development. This pioneering study combined empirical data and modeling approaches to predict total 2010-2020 emissions of 80 veterinary antibiotics ranging from 23,110 to 40,850 tonnes/year, after 36-50% antibiotic removal by manure treatment. Following an initial increase of 10% from 2010 to 2015, emissions declined thereafter by 43%. While 85% of emissions discharged into soils, approximately 56%, 23%, and 18% of environmental residue were ultimately distributed in soils, freshwaters, and seawaters under steady-state conditions. In 2020, 657 (319-1470) tonnes entered the ocean from inland freshwaters. Median ∑antibiotics concentrations were estimated at 4.7 × 103 ng/L in freshwaters and 2.9 ng/g in soils, with tetracyclines and sulfonamides as the predominant components. We identified 44 veterinary antibiotics potentially posing high risks of resistance development in freshwaters, with seven exhibiting high risks in >10% of Chinese freshwater areas. Tetracyclines were the category with the most antibiotics exhibiting elevated risks; however, sulfamethylthiazole demonstrated the highest individual compound risk. The Haihe River Basin displayed the highest susceptibility overall. The findings offer valuable support for control of veterinary antibiotic contamination in China.

Environmental fate and health risks of polycyclic aromatic hydrocarbons in the Yangtze River Delta Urban Agglomeration during the 21st century

Understanding the spatiotemporal distribution and behavior of Polycyclic Aromatic Hydrocarbons (PAHs) in the context of climate change and human activities is essential for effective environmental management and public health protection. This study utilized an integrated simulation system that combines land-use, hydrological, and multimedia fugacity models to predict the concentrations, transportation, and degradation of 16 priority-controlled PAHs across six environmental compartments (air, water, soil, sediment, vegetation, and impermeable surfaces) within one of the world's prominent urban agglomerations, the Yangtze River Delta Urban Agglomeration (YRDUA), under future Shared Socio-economic Pathways (SSP)-Representative Concentration Pathways (RCP) scenarios. Incremental lifetime carcinogenic risk for adults and children exposed to PAHs were also evaluated. The results show a declining trend in PAHs concentrations and associated health risks during the 21st century. Land use types, hydrological characteristics, population, and GDP, have significant correlations with the fate of PAHs. The primary removal for PAHs is determined to be driven by advection through air and water. PAHs covering on impermeable surfaces pose a relatively higher health risk compared to those in other environmental media. This study offers valuable insights into PAHs pollution in the YRDUA, aiming to ensure public health safety, with the potential for application in other urban areas.

Spatial distribution and source apportionment of surface soil's polycyclic aromatic hydrocarbons in the Yangtze River Delta

Soil acts as a crucial reservoir of polycyclic aromatic hydrocarbons (PAHs) in the environment, and its PAH content serves as a significant indicator of regional PAH pollution. Monitoring PAH levels in soil is important for assessing the potential risks to human and environmental health. In this study, 53 surface soil samples were collected from the Yangtze River Delta. These samples were monitored for 16 priority PAHs. Pollution levels, compositional profiles, and source differences of soil PAHs were analyzed among different regions, urban and rural areas, and functional zones. The total PAH content (Σ16PAHs) in the surface soil of the Yangtze River Delta was 2326.01 ± 2901.53 ng/g. High-ring PAHs (4-6 rings) accounted for the predominant portion (85.50%) of total PAHs. The average pollution level of soil PAHs in Jiangsu Province (2651.92 ± 3242.87 ng/g) was significantly higher than that of Zhejiang Province (2001.44 ± 2621.71 ng/g) and Shanghai (1669.13 ± 1758.34 ng/g), and high-ring PAHs constituted a predominant portion in these three regions. There was no significant difference in the PAH content between urban and rural areas. In different functional areas, automobile stations exhibited the highest PAH levels among the functional zones analyzed, with traffic emissions identified as a major source of soil PAH in this area. The primary factors influencing the distribution of soil PAHs in the study area were the duration of urbanization exposure (r = 0.753, p < 0.01) and soil organic carbon content (r = 0.452, p < 0.01). This provides novel evidence for the cumulative build-up of PAHs during urbanization. The positive matrix factorization model was used to analyze the sources of PAHs in the surface soil of the Yangtze River Delta, revealing that biomass and coal combustion (60.19%) and traffic emissions and coal combustion (31.82%) were the primary sources of PAHs in the region.

Indirect Emissions from Organophosphite Antioxidants Result in Significant Organophosphate Ester Contamination in China

Organophosphite antioxidants (OPAs) have been seriously neglected as potential sources of organophosphate esters (OPEs) in environments. This study utilizes a modeling approach to quantify for the first time national emissions and multimedia distributions of triphenyl phosphate (TPHP)─a well-known flame retardant─and three novel OPEs: tris(2,4-ditert-butylphenyl) phosphate (AO168═O), bis(2,4-ditert-butylphenyl) pentaerythritol diphosphate (AO626═O2), and trisnonylphenol phosphate (TNPP). Emphasis is on the quantitative assessment of OPA source in China. TPHP has 1.1-9.7 times higher emission (300 Mg/year in 2019 with half from OPA sources) than AO168═O (278 Mg/year), AO626═O2 (53 Mg/year), and TNPP (32 Mg/year), but AO168═O is predominant in environments (63-79%) except freshwaters. About 72-99% of the studied OPEs are emitted via air, with 88-99% ultimately distributed into soils as the major sink. OPA-source emissions contribute 9.5-57% and 4.7-56% of TPHP masses and concentrations (except in sediments) in different media, respectively. Both AO168═O and AO626═O2 exhibit high overall persistence ranging between 2 and 11 years. Source emissions and environmental concentrations are elevated in economically developed areas, while persistence is higher in northern areas, where precipitation and temperature are lower. This study shows the significance of the sources of OPA to OPE contamination, which supports chemical management of these substances.

Introducing a land use-based weight factor in regional health risk assessment of PAHs in soils of an urban agglomeration

The high heterogeneity of land uses in urban areas has led to large spatial variations in the contents and health risks of polycyclic aromatic hydrocarbons (PAHs) in soils. A land use-based health risk assessment (LUHR) model was proposed for soil pollution on a regional scale by introducing a land use-based weight factor, which considered the differences in exposure levels of soil pollutants to receptor populations between land uses. The model was applied to assess the health risk posed by soil PAHs in the rapidly industrializing urban agglomeration of Changsha-Zhuzhou-Xiangtan Urban Agglomeration (CZTUA). The mean concentration of total PAHs (∑PAHs) in CZTUA was 493.2 μg/kg, and their spatial distribution was consistent with emissions from industry and vehicles. The LUHR model suggested the 90th percentile health risk value was 4.63 × 10-7, which was 4.13 and 1.08 times higher than those of traditional risk assessments that have adopted adults and children as default risk receptors, respectively. The risk maps of LUHRs showed that the ratios of the area exceeding the risk threshold (1 × 10-6) to the total area were 34.0 %, 5.0 %, 3.8 %, 2.1 %, and 0.2 % in the industrial area, urban green space, roadside, farmland, and forestland, respectively. The LUHR model back-calculated the soil critical values (SCVs) for ∑PAHs under different land uses, resulting in values of 6719, 4566, 3224, and 2750 μg/kg for forestland, farmland, urban green space, and roadside, respectively. Compared with the traditional health risk assessment models, this LUHR model identified high-risk areas and drew risk contours more accurately and precisely by considering both the spatial variances of soil pollution and their exposure levels to different risk receptors. This provides an advanced approach to assessing the health risks of soil pollution on a regional scale.

Atmospheric benzo[a]pyrene in the Yangtze River Delta, China: pollution level and lung cancer risk in 2016 and future predictions

The Yangtze River Delta (YRD) has undergone widespread polycyclic aromatic hydrocarbon (PAH) pollution. In this study, we simulated the spatial distribution of atmospheric benzo[a]pyrene (BaP, the most carcinogenic PAH) in the YRD in 2016 and 2030 under different emission scenarios using a 3-D atmospheric transport model and evaluated the lung cancer risks posed by BaP during the study years. The purpose of this study is to suggest targeted policy recommendations for policy-makers to mitigate BaP pollution through numerical simulation. Our results showed that the average BaP concentration in the YRD was 0.30 ng/m3 in 2016; however, a significant spatial variation was observed, with the highest BaP concentration in Shanghai (0.59 ng/m3). The population-weighted incremental lifetime lung cancer risk (PILCR) was 6.67 × 10-6 in 2016, whereas it ranged from 2.70 × 10-6 to 1.05 × 10-5 in 2030 under the five emission scenarios. A higher future population density in the YRD region could increase lung cancer risk. In all scenarios, Shanghai had the highest number of lung cancer cases (range: 208-476). The results suggest that BaP pollution could be effectively improved through the synergistic effect of reducing activity levels and improving technology. Finally, we provide specific suggested pollution control strategies (e.g., accelerating the use of clean energy in rural areas) for atmospheric BaP in the YRD.

Long-term spatiotemporal variation and lung cancer risk of atmospheric polycyclic aromatic hydrocarbons (PAHs) in the Yangtze River Delta, China

The Yangtze River Delta (YRD), which is the most developed region in China, suffers from atmospheric polycyclic aromatic hydrocarbons (PAH) pollution. However, the long-term spatiotemporal variation of atmospheric PAHs and the lung cancer risk caused by PAH exposure in the YRD remain unclear. Herein, we simulated the daily atmospheric concentration of benzo[a]pyrene (BaP, the most carcinogenic PAH) from 2001 to 2016 using an atmospheric transport model. During this period, the atmospheric BaP concentration showed a general trend of first increasing and then decreasing (average BaP concentration = 0.50 ± 0.12 ng/m³) and was highest in 2005 (0.72 ng/m³). Moreover, the BaP concentration in Jiangsu and Shanghai was 5.17- and 4.98-fold higher than that in Zhejiang. BaP pollution was severe in Jiangsu during the winter. The average area proportion of BaP exceeding the national standard in winter in Jiangsu was 69.09%. The population-weighted incremental lifetime cancer risk from 2001 to 2016 ranged 6.67 × 10^-6-1.50 × 10^-5, and the excess lung cancer cases ranged 1054-2130. Compared with 2005, excess lung cancer cases in the YRD decreased by 49.49% in 2016. Reducing BaP pollution in winter in Jiangsu is crucial for reducing lung cancer risk in the YRD.

Polycyclic Aromatic Hydrocarbons Pollution Characteristics in Agricultural Soils of the Pearl River Delta Region, China

In order to investigate the pollution status of polycyclic aromatic hydrocarbons (PAHs) in the agricultural soil, 240 agricultural soil topsoil samples were collected from nine Pearl River Delta cities from June to September 2019. In addition, 72 samples were collected for vertical soil profiles, which soil profiles were excavated to a depth of 80 cm. After sample preparation, GC-MS was used for the separation of compounds on a HP-5MS quartz capillary column. ArcGIS software was used to map the spatial distribution. Health risk assessment was conducted using USEPA standard. The results showed that the total concentration of 16 PAHs ranged from 43.4 to 5630 ng/g, with an average of 219 ng/g. The spatial distribution showed that most of the seriously polluted areas were in the coastal area, near the port, and there was point source pollution in the Gaoming of Foshan. Vertically distributed display Zhuhai, Jiangmen, Zhaoqing, Shenzhen and Dongguan increased and then decreased from bottom to bottom, showing a low-high-low pattern, the concentration of PAHs in Zhongshan and Foshan decreased with the soil depth, while the concentration of PAHs in Guangzhou and Huizhou was enriched with human activities. The PAHs components in soil samples were mainly medium and high rings (4−6 rings). The analysis of the origin of PAH in soil samples showed that the mixture of incomplete combustion sources of fossil fuels such as coal and biomass and traffic emission sources were the main sources of soil PAHs. A small amount can be attributed to oil sources such as oil spills. The human health risk assessment showed no cancer risk for children, while for adults, may cause a potential risk of cancer, which needs to be noticed. Spearman correlation analysis showed that PAH content was significantly correlated with SOC (p < 0.01) and pH (p < 0.05). Port transport, road emissions and industrial production make the area a pollution hot topic, and supervision should be strengthened to protect the environment and food safety.

Engineered microbes as effective tools for the remediation of polyaromatic aromatic hydrocarbons and heavy metals

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) have become a major concern to human health and the environment due to rapid industrialization and urbanization. Traditional treatment measures for removing toxic substances from the environment have largely failed, and thus development and advancement in newer remediation techniques are of utmost importance. Rising environmental pollution with HMs and PAHs prompted the research on microbes and the development of genetically engineered microbes (GEMs) for reducing pollution via the bioremediation process. The enzymes produced from a variety of microbes can effectively treat a range of pollutants, but evolutionary trends revealed that various emerging pollutants are resistant to microbial or enzymatic degradation. Naturally, existing microbes can be engineered using various techniques including, gene engineering, directed evolution, protein engineering, media engineering, strain engineering, cell wall modifications, rationale hybrid design, and encapsulation or immobilization process. The immobilization of microbes and enzymes using a variety of nanomaterials, membranes, and supports with high specificity toward the emerging pollutants is also an effective strategy to capture and treat the pollutants. The current review focuses on successful bioremediation techniques and approaches that make use of GEMs or engineered enzymes. Such engineered microbes are more potent than natural strains and have greater degradative capacities, as well as rapid adaptation to various pollutants as substrates or co-metabolizers. The future for the implementation of genetic engineering to produce such organisms for the benefit of the environment andpublic health is indeed long and valuable.

Health risks of PM2.5-bound polycyclic aromatic hydrocarbon (PAH) and heavy metals (PPAH&HM) during the replacement of central heating with urban natural gas in Tianjin, China

To investigate the health effects of fine particulate matter (≤ 2.5 μm in aerodynamic diameter; PM_2.5)-bound heavy metals and polycyclic aromatic hydrocarbons (PAHs) before and after the implementation of the Urban Natural Gas Heating Project (UNGHP), the lifetime cancer risks, hazard quotients (HQs) of heavy metals and PAHs were calculated. Seven kinds of heavy metals (Al, As, Cd, Cr, Mn, Ni and Se) and 12 kinds of PAHs including acenaphthylene (ANY), acenaphthene (ANA), fluoranthene (FLT), pyrene (PYR), chrysene (CHR), benz[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), dibenz[a,h]anthracene (DBA), benzo[ghi]perylene (BPE) and indeno[1,2,3-cd]pyrene (IPY) were analyzed and used for the health risk assessments. It was found that HQ of Mn fell from 1.09 in the coal-burning period to 0.72 in the gas-burning period in the suburban area. And lifetime cancer risks of PAHs fell from 35.7 × 10^-6 in the coal-burning period to 17.22 × 10^-6 in the gas-burning period in the urban area. It could be concluded that, during the gas-burning period, downward trends were observed for the lifetime cancer risks and HQs of most kinds of heavy metals and PAHs in all regions of Tianjin compared to those during the coal-burning period. The UNGHP was effective, and we should also take other measures to control the pollution.

Modeling multimedia fate and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the coastal regions of the Bohai and Yellow Seas

Using an improved multimedia fate model, this study simulated the spatial distributions, partitioning behaviors, and mass exchanges of PAH₁₆ (16 species with priority by the USEPA) in multiple environmental compartments in the coastal regions of the Bohai and Yellow Seas, Northern China. The model predictions generally matched well with the measured results, as the deviations of most points were within one order of magnitude in the air, freshwater, and 3 soil compartments. The estimated concentrations of ΣPAH₁₆ in the northern part were higher than those in the southern part, which was consistent with the emissions of each part. Approximately 97.6% of the ΣPAH₁₆ mass was distributed in soils; therefore, soils served as the dominant sink of PAH₁₆. The estimated net flux of ΣPAH₁₆ from air to soil ranged from 0.4 to 10.7 mg/m²/year (an average of 3.2 mg/m²/year), and the estimated flux of deposition from air to soil fell in the range of 0.4-10.8 mg/m²/year (an average of 3.2 mg/m²/year), which served as the dominant process at the air-soil interface. The estimated net flux of ΣPAH₁₆ from air to freshwater ranged from -15.3 to 9.4 mg/m²/year (an average of -0.3 mg/m²/year), and the reversed volatilization flux from freshwater to air ranged from 0.01 to 21.1 mg/m²/year (an average of 3.7 mg/m^2/year). This situation indicated notable spatial variations and volatilization as the main process affecting the direction of net flux at the air-freshwater interface. Deterministic risk assessment and probabilistic risk assessment were conducted. The overall health risks of the studied regions were acceptable, while the excess lifetime cancer risk (ELCR) by air inhalation was greater than that by soil ingestion. CAPSULE: Multimedia fate model-predicted distributions and compositions of PAH₁₆ in different compartments, compartmental exchange fluxes and directions, and deterministic and probabilistic ELCR via different exposure pathways were assessed.

Spatially resolved environmental fate models: A review

Spatially resolved environmental models are important tools to introduce and highlight the spatial variability of the real world into modeling. Although various spatial models have been developed so far, yet the development and evaluation of these models remain a challenging task due to several difficulties related to model setup, computational cost, and obtaining high-resolution input data (e.g., monitoring and emission data). For example, atmospheric transport models can be used when high resolution predicted concentrations in atmospheric compartments are required, while spatial multimedia fate models may be preferred for regulatory risk assessment, life cycle impact assessment of chemicals, or when the partitioning of chemical substances in a multimedia environment is considered. The goal of this paper is to review and compare different spatially resolved environmental models, according to their spatial, temporal and chemical domains, with a closer insight into spatial multimedia fate models, to achieve a better understanding of their strengths and limitations. This review also points out several requirements for further improvement of existing models as well as for their integration.

Air pollutant emissions from the asphalt industry in Beijing, China

Improving our understanding of air pollutant emissions from the asphalt industry is critical for the development and implementation of pollution control policies. In this study, the spatial distribution of potential maximum emissions of volatile organic compounds (VOCs) in the complete life cycle of asphalt mixtures, as well as the particulate matter (PM), asphalt fume, nonmethane hydrocarbons (NMHCs), VOCs, and benzoapyrene (BaP) emissions from typical processes (e.g., asphalt and concrete mixing stations, asphalt heating boilers, and asphalt storage tanks) in asphalt mixing plants, were determined in Beijing in 2017. The results indicated that the potential maximum emissions of VOCs in the complete life cycle of asphalt mixtures were 18,001 ton, with a large contribution from the districts of Daxing, Changping, and Tongzhou. The total emissions of PM, asphalt fume, NMHC, VOCs, and BaP from asphalt mixing plants were 3.1, 12.6, 3.1, 23.5, and 1.9 × 10^-3 ton, respectively. The emissions of PM from asphalt and concrete mixing stations contributed the most to the total emissions. The asphalt storage tank was the dominant emission source of VOCs, accounting for 96.1% of the total VOCs emissions in asphalt mixing plants, followed by asphalt heating boilers. The districts of Daxing, Changping, and Shunyi were the dominant regions for the emissions of PM, asphalt fume, NMHC, and BaP, while the districts of Shunyi, Tongzhou, and Changping contributed the most emissions of VOCs.

Application of a fugacity model to estimate emissions and environmental fate of ship stack PAHs in Shanghai, China

The understandings of environmental activities and regional inventory of ship stack PAHs are very limited in Shanghai due, in part, to the lack of source-segregated analysis. To address this, measured PAHs in organic film on ship surfaces were employed to reconstruct concentrations in various compartments through a fugacity model to investigate the level, transport, fate and annual emission of ship stack PAHs in Shanghai. The results revealed that ship stack PAHs results in 11.2-181 ng L^-1 and 71.0-1710 ng g^-1 in water and sediment of Shanghai, respectively. After being released into air, ship stack PAHs mainly concentrated in organic films and sediments while sunk in water and sediment. Crucial mass transfer pathways include deposition of airborne and sediment PAHs. The mass loss of ship stack PAHs was primarily through air advection, followed by degradation in sediment. The ship emissions (53.7 tons annually) accounted for approximate one tenth of the regional total in Shanghai (in 2017). Additionally, shipping was estimated to release 127 tons of PAHs annually into the Shanghai section of Yangtze River. Our results suggest our fugacity-based approach can be used to estimate the regional emissions and inventory of ship stack PAHs in the surrounding environment.

Spatial distributions and sources of PAHs in soil in chemical industry parks in the Yangtze River Delta, China

The Yangtze River Delta (YRD) is one of the fastest developing areas in eastern China and contains many chemical industry parks. The profiles and sources of polycyclic aromatic hydrocarbons (PAHs) in soil in chemical industry parks and surrounding areas in the YRD were investigated by analyzing soil samples (n = 64) were collected in the YRD and Rudong chemical park (RD), a typical chemical park in the Yangtze River Delta. The total concentrations of 19 PAHs in the YRD soil samples were 16.3-4694 ng g^-1 (mean 688 ng g^-1), and the total concentrations of PAHs in RD were 21.6-246 ng g^-1 (mean 75.4 ng g^-1). The PAHs in soil in YRD were dominated by four-ring and five-ring PAHs, and the PAHs in RD were dominated by two-ring and three-ring PAHs. It suggested that PAHs may have been supplied to soil in YRD predominantly through coal combustion and vehicle emissions, PAHs in the soil of RD may be due to the volatilization and leakage of chemical raw material. According to the different distribution characteristics of PAHs, the ratio (1.5) of (2 + 3) rings/4 rings was proposed to identify the chemical source of PAHs. The PAH isomer ratios and principal component analysis/multiple linear regression (PCA/MLRA) results indicated that PAHs concentrations in soil in the YRD and RD are mainly supplied by industrial and traffic emissions. Incremental lifetime cancer risks (ILCRs) indicated that PAHs in soil pose negligible cancer risks to children and adults, but much stronger risks to children than adults.

Evaluation of PAHs in edible parts of vegetables and their human health risks in Jinzhong City, Shanxi Province, China: A multimedia modeling approach

Knowledge of the origins of polycyclic aromatic hydrocarbon (PAH) in vegetables is essential to reduce human health risks induced by dietary exposure. The current study developed a vegetation-advanced multimedia model, SESAMe-Veg, to identify the major uptake pathway of 15 priority PAHs in vegetables and assess the PAHs in edible parts of cabbages and carrots in Jinzhong City, Shanxi Province, China. The model was well evaluated against site- and plant-specific measurements. Edible parts exhibited lower PAH concentrations than the other parts for both vegetables. The estimated concentrations of ΣPAH15 were 79 ng/g in cabbage shoots and 83 ng/g in carrot roots. Higher concentrations were estimated in shoots of the leafy vegetable than in roots of the root vegetable for most PAHs. Although air-shoot is the major transport pathway, 98% was deposition of particles, which was attached outside and could be removed relatively easily by washing. Soils might be the origin of PAHs inside vegetables, especially for lighter PAHs. PYR was more likely to be stored in roots than other congeners. The translocation of PAHs inside vegetables was negligible. Adulthood dietary exposure to local vegetables probably caused a high health risk; however, contributions from consuming cabbages and especially carrots were low. Females generally exhibited slightly higher risks than males of exposure to PAHs in local vegetables. Considering the dominant role of particle deposition, carefully vegetable washing before ingestion could reduce this risk. This study has provided a functional tool to evaluate vegetable contamination by PAHs. CAPSULE: A vegetation-advanced multimedia model of PAHs in different parts of vegetables and other environmental media was developed to evaluate the potential health risk to local populations of different sexes and ages via vegetable ingestion.

Fate and Occurrence of Polycyclic Aromatic Hydrocarbons and Their Derivatives in Water and Sediment from Songhua River, Northeast China

The Songhua River is one of the most populated and oldest industrial areas in Northeast China. To understand the sources and distribution of polycyclic aromatic hydrocarbons and their derivatives, such as 16 priority (PAHs), 33 methylated (Me-PAHs), and 12 nitrated (NPAHs) in river water and sediment, were noticed. The concentrations of ∑PAHs, ∑Me-PAHs, and ∑NPAHs in river water scaled from 135 to 563, 9.36 to 711, and 1.26 to 64.7 ng L−1, with mean values of 286, 310, and 17.9 ng L−1, and those in sediments were from 35.8 to 2000 ng g−1, 0.62 to 394 ng g−1, and 0.28 to 176 ng g−1 (dry weight) with mean values of 283, 103, and 21.7 ng g−1. The compositions proved that two-ring and three-ring compounds of PAHs, NPAHs, and four-ring, six-ring of Me-PAHs were prevalent in water samples; in contrast, four-ring dominated in sediments. Principal components analysis (PCA) and diagnostic ratios confirmed that pollutant source was mixed petrogenic and pyrogenic origin. The fugacity fraction (ƒƒ) was also calculated to explain the trend of sediment–water exchange, high ƒƒ values found in summer, for most HMW PAHs and Me-PAHs that these substances acted as a secondary source of emissions from sediment to water. The risk assessment for water was categorized as high.

Spatial distribution of polycyclic aromatic hydrocarbons in the water-sediment system near chemical industry parks in the Yangtze River Delta, China

The Yangtze River Delta (YRD) is one of the most populated and economically prosperous regions in China and contains numerous chemical industry parks. To understand the distribution and sources of polycyclic aromatic hydrocarbons (PAHs), surface water and sediment samples were collected from areas around the industrial parks. The total concentrations of 19 PAHs in water and sediment were 32.98-286 ng L^-1 and 15.14-5355 ng g^-1, respectively. The highest PAH concentrations in water and sediment were found in samples from Wuxi city, which were dominated by high molecular weight (HMW) PAHs, and strongly influenced by fine chemical parks. HMW compounds dominated in the sediment with PAHs containing four and five rings accounting for 61% of the sedimentary ΣPAHs, PAHs in water were dominated by low molecular weight (LMW) compounds (PAHs with two and three rings represented >68% of ΣPAHs). The results of isomeric ratio analysis and principal component analysis with multiple linear regression indicated that the PAH concentrations in water and sediment near the YRD chemical parks are strongly influenced by industrial emissions. The fugacity fraction approach was applied to explain the trend for water-sediment exchange of 16 priority PAHs, which showed that net fluxes for most were from the sediment into water. The results indicated that the LMW PAHs were in a non-steady state in the sediment-water system. An ecological risk assessment showed that most sites were low to medium risk, but one site was high risk.

Sediment records of polybrominated diphenyl ethers (PBDEs) in Yangtze River Delta of Yangtze River in China

The spatial and temporal distributions of polybrominated diphenyl ethers (PBDEs) were investigated in five sediment cores from the Yangtze River Delta of Yangtze River in China. The surficial concentrations of nine tri- through hepta-BDE congeners (Σ₉BDEs) and BDE209 were highest at urban sites S3 and S2, followed by rural site S1 and estuary sites S5 and S4, respectively, based on dry sediment weight. Both BDE209 and ∑₉BDE concentrations exponentially increased between 1990 and 2008. Commercial deca-BDE, penta-BDE, and octa-BDE products were likely PBDE sources in the study area. The relative abundances of BDE209 were higher in sediment cores from estuary than those from urban and rural locations, ascribing to the atmospheric transport from the adjacent densely populated northern and eastern coastal regions. This conclusion was further confirmed by the higher ratios of BDE47/BDE99 and BDE100/BDE99 in cores from the estuary than those from other locations.

Household air pollution from cooking and heating and its impacts on blood pressure in residents living in rural cave dwellings in Loess Plateau of China

Cave dwelling is an ancient and unique type of residence in the Loess Plateau of Northern China, where the economics are less-developed. The majority of the local dwellers rely on traditional solid fuels for cooking and heating, which can emit large amounts of particles into both indoor and outdoor environments. In this study, we measured the real-time household concentrations of PM_2.5 and explored the association between personal daily PM_2.5 exposure and blood pressure (BP). Cooking and heating activities with different energies made a great variation in the household PM_2.5 air pollution, and residents using biomass had the highest personal PM_2.5 exposure. Temperature and relative humidity are both significantly linear correlated with household PM_2.5 air pollution. Besides, systolic blood pressure (SBP) was demonstrated to be positively associated with personal PM_2.5 exposure: with each 10-μg/m³ incremental PM_2.5 concentration when controlling all the other factors, SBP will increase by 0.36 mmHg (95% confident interval (CI) 0.05-0.0.77 mmHg). If solid fuels could be replaced with clean energies, personal PM_2.5 exposure and SBP would reduce by more than 21% and 3.7%, respectively, calling for efficient intervention programs to mitigate household air pollution of cave dwellings and protect health of those residents.

Structural equation modeling of PAHs in surrounding environmental media and field yellow carrot in vegetable bases from Northern China: In comparison with field cabbage

During a harvest period, a set of field samples, including ambient air (gaseous and particulate phases), dust fall, surface soil and peel-surrounding soil, and yellow carrot tissues (leaf, peel, and core), were collected in a vegetable bases near a large coking manufacturer in Shanxi Province, Northern China. Based on the determinations of the concentrations and compositions of 15 USEPA priority polycyclic aromatic hydrocarbons (PAHs), the statistical results determined by a factor analysis (FA), combined with the isomeric ratios of paired species and the local emission inventory, indicated that coal combustion and vehicular exhaust served as the main emission sources of PAHs in the local environment and in yellow carrot tissues and that the coking industry was a secondary source. In terms of the transport pathways of PAHs in the surrounding media and yellow carrot tissues, the simulation results of a structural equation model (SEM) showed that the PAHs in ambient air were closely associated with those in dust fall, and these in turn had a positive correlation with the PAHs in surface soil, due to air-soil exchange. Furthermore, the PAHs in yellow carrot leaf were mainly derived from those in dust fall via leaf surface absorption, while peel uptake played a dominant role in the accumulation of PAHs in the edible core of yellow carrot. This was different from the case of cabbage, which was characterized by the prevailing contribution from leaf surface absorption. The current study supplied additional evidence to explore the transport pathways of PAHs from environmental media to tissues of different vegetables (leafy vegetables and root vegetables). CAPSULE: A combination of structural equation modeling with factor analysis was employed to quantitatively identify the dominant transport pathways of PAHs among multiple surrounding media and the different tissues of yellow carrot.

Estrogens in municipal wastewater and receiving waters in the Beijing-Tianjin-Hebei region, China: Occurrence and risk assessment of mixtures

The potentially high release of estrogens to surface waters due to high population density and local livestock production in the Beijing-Tianjin-Hebei region may pose adverse effects on reproductive systems of aquatic organisms. This study found that total measured concentrations of estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2) and diethylstilbestrol (DES) were 468 ± 27 ng/L in treated wastewater and 219 ± 23 ng/L in river waters in this region. E2, E3 and EE2 were the predominant estrogens in river waters. The restriction of DES for human use should have been enforced, however concentrations of DES were relatively high compared to other studies. Haihe and Yongdingxin Rivers delivered approximately 1.8 tonnes of estrogens to the Bohai Bay annually. Concentrations of individual estrogens were significantly higher in river waters in the dry season, however, mass loadings were significantly higher in the wet season. The average E2-equivalent concentrations reached 1.2 ± 0.2 and 0.64 ± 0.08 μg-E2/L following long-term and short-term exposure estimates, respectively, in river waters with an EE2 contribution of over 90 %. This could give rise to high risks to fish. Estrogens in river waters largely derived from human excretion. Field studies on estrogenic effects on fish reproductive systems are required locally considering high estrogen contamination levels.

Indoor polybrominated diphenyl ethers in urban China: An exposure and risk assessment based on settled dust from selected urban regions

In this study, measurements of seven typical polybrominated diphenyl ethers (PBDEs) in indoor settled dust were summarized in selected urban regions of China. BDE-209 was the most dominant congener in settled dust (1.4-101 μg/g), with a mean contribution of 95%. Indoor exposures to PBDEs were estimated via inhalation, dust ingestion, and dermal absorption. The average daily intake of ΣPBDE was 4.9 to 19.1 ng/day/kg for all the population groups, with >80% of the total exposures from dust ingestion. Exposures in commuting environments (contributing 60%-80% of the total exposures) were higher than those in other microenvironments. The means of hazard indexes ranged from 1.66 × 10^-3 to 5.26 × 10^-3, which were mainly as a result of exposure to BDE-209, BDE-47, and BDE-99. The average lifetime cancer risks were from 0.03 × 10^-9 to 2.37 × 10^-9, which indicated the acceptable health risks resulting from indoor PBDE exposure for the Chinese population. The present study could provide valuable information that could be helpful for decision-makers, analysts and researchers to develop, implement and evaluate the effectiveness of interventions for the reduction of exposures to semi-volatile organic compounds (SVOCs) for large population groups in China.

External interference from ambient air pollution on using hair metal(loid)s for biomarker-based exposure assessment

Hair metal(loid)s are often measured as biomarkers to evaluate population internal exposure, however, hair samples could be easily contaminated by ambient particulate matter (PM) pollution. Here, we evaluated the potential external interference from ambient PM pollution on using hair metal(loid)s for population biomarker-based exposure assessment. The raw hair samples were strictly washed and placed under various indoor and outdoor scenarios for ~6 months at sites with high PM pollution. The contaminated hair was then washed using the same method. A total of 33 hair elements were quantified by inductively coupled plasma-mass spectrometry. The surface residual PM on hair after washing was observed by scanning electron microscopy. In addition, we chose a practical exposure scenario including 77 housewives in Shanxi Province, China for validation. The results for the hair exposure experiment revealed that external contamination of some elements that had relatively high concentrations in hair was generally mild in both indoor and outdoor exposure scenarios (i.e., Zn, Mg, Se, Fe, Sr, Ti, Mn, Sn, Ge, U, Co, Mo, and As). A relatively higher external contamination of other elements (e.g., Al, Cr, Pb, Cd, Li, and most rare earth elements (REEs)) was observed, especially for those elements with relatively low hair concentrations (e.g., Cd, and REEs) in the outdoor environment. This finding was due mainly to some small ambient PM not being fully removed by the current washing strategy when the hair sample was heavily contaminated. However, results from practical exposure scenario of the housewives showed that there were overall no significant differences of hair metal(loid)s between the housewives using coal and clean energy for cooking. We concluded that the external interference on hair internal metal(loid) analysis could be negligible when hair was efficiently washed, especially for population with relatively longer indoor activities. It is therefore promising to use hair analysis for their population exposure assessment.

Association of prenatal exposure to PAHs with anti-Müllerian hormone (AMH) levels and birth outcomes of newborns

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are chemicals that cause serious concerns because of their carcinogenicity and endocrine disrupting ability.

OBJECTIVE

In the current study, we studied how urinary PAH metabolites are related with the dose-effects of hormone levels and birth outcomes.

METHOD

163 pregnant women without health problems and 163 newborns were enrolled in hospitals in Guiyu (e-waste-exposed area) and Haojiang (reference area) from May 2016 to May 2017. Urine samples were collected to measure hydroxylated PAH (OH-PAH) metabolite levels. Umbilical cord blood was used for measurement of hormone levels. Anthropometric parameters of newborns, such as anogenital distance (AGD), were also measured.

RESULTS

Eight of ten urinary PAH metabolites in the exposed group were significantly higher than in the reference group. Levels of umbilical cord serum estradiol (E2) and testosterone (T) in the exposed group were significantly lower than those in the reference group. Birth weight was positively correlated with 2-OHFlu (2-hydroxyfluorene). Head circumference was negatively correlated with 9-OHFlu, 3-OHPhe (3-hydroxyphenanthrene), 9-OHPhe, and ƩOHFlu (sum of 2-OHFlu and 9-OHFlu). Serum E2 and T levels were negatively correlated with most OH-PAHs. In addition, we found that serum anti-Müllerian hormone (AMH) level was positively correlated with AGD, and serum E2 level was negatively correlated with neonatal head circumference.

CONCLUSIONS

PAH exposure in pregnant women may adversely affect the birth outcomes of newborns, especially AGD; and AMH may be involved in the process. Establishing a baseline for the relationship between PAH exposure and health is important to protect the health of mothers and children living in electronic waste (e-waste) recycling areas.

Maternal ambient air pollution exposure with spatial-temporal variations and preterm birth risk assessment during 2013-2017 in Zhejiang Province, China

Preterm birth (PTB) can give rise to significant neonatal morbidity and mortality, as well as children's long-term health defects. Many studies have illustrated the associations between ambient air pollution exposure during gestational periods and PTB risks, but most of them only focused on one single air pollutant, such as PM_2.5. In this population-based environmental-epidemiology study, we recruited 6275 pregnant mothers in Zhejiang Province, China, and evaluated their gestational exposures to various air pollutants during 2013-2017. Time-to-event logistic regressions were performed to estimate risk associations after adjusting all confounders, and Quasi-AQI model and PCA-GLM analysis were applied to resolve the collinearity issues in multi-pollutant regression models. It was found that gestational exposure to ambient air pollutants was significantly associated with the occurrence of PTB, and SO₂ was the largest contributor with a proportion of 29.4%. Three new variables, prime factor (a combination of PM_2.5, PM₁₀, SO₂, and NO₂), carbon factor (CO), and ozone factor (O₃), were generated by PCA integration, contributing 63.4%, 17.1%, and 19.5% to PTB risks, respectively. The first and third trimester was the most crucial exposure window, suggesting the pregnant mothers better to avoid severe air pollution exposures during these sensitive periods.

Comparing Economics, Environmental Pollution and Health Efficiency in China

As the modern economy develops rapidly, environmental pollution and human health have also been threatened. In recent years, relevant research has focused on subjects such as energy and economic, environmental pollution and health issues. Yet this has not considered the use of water resources and the impact of wastewater pollutant emissions on the economy and health. This article has combined the following factors like water consumption with wastewater discharge, pollutant concentration in sewage and local medical care expenditure and put them into the model of water resources, energy and health measurement, and a two-stage dynamic data envelopment analysis (DEA) model considering undesirable outputs is applied to 30 provinces (including autonomous regions and municipalities) to calculate the total efficiency, production efficiency and health efficiency in 2014-2017.The results show that the total efficiency values of most provinces are between 0.2 and 0.4, providing large room for improvement. Production efficiency and health efficiency have increased in recent years, but the health efficiency values of most provinces are still so low that they have dragged back the overall efficiency. The key impact indicators of different provinces are different, and each province should formulate different policies according to its own specific conditions so as to purposefully to deepen the energy, economic and medical reforms in each province, and also to promote sustainable economic development while improving health efficiency.

Characterization of polycyclic aromatic hydrocarbons in urban-rural integration area soil, North China: Spatial distribution, sources and potential human health risk assessment

The promotion of urbanization has accelerated the development of small manufacturing workshops and brought serious environmental problems. In this study, spatial distribution, sources and potential health risk for polycyclic aromatic hydrocarbons (PAHs) in urban-rural integration area soil in North China (800 km²) were discussed. The average total concentration of 16 PAHs was 225 μg kg^-1, and range from 25 to 15155 μg kg^-1 (n = 250). According to the European soil quality standards, more than 70% of the samples don't reach the pollution level, while around the small workshop concentration area and non-ferrous metal smelter were more contaminated than other area. The spatial distribution of soil PAHs concentration shows that low molecular weight, medium molecular weight and high molecular weight is very similar to the distribution of total PAHs, indicating that is likely to be caused by point source pollution. The sources of PAHs were identified by positive matrix factorization. The main six sources in the region are coal and biomass combustion, creosote, coke tar, vehicle and oil, which is consistent with the local energy consumption structure. Finally, a deterministic assessment of the cancer risk showed that the range for children was 5.94 × 10^-8 to 2.53 × 10^-5, and adults it ranged from 2.11 × 10^-8 to 9.01 × 10^-6. There is not a carcinogenic risk value greater than 10^-4 in the entire region, but potential carcinogenic risks persisted in some areas. We conclude that PAHs pollution of soil in the area is an issue that deserves urgent attention for the relevant departments.

Polycyclic aromatic hydrocarbons in urban soils of China: Distribution, influencing factors, health risk and regression prediction

Polycyclic aromatic hydrocarbons (PAHs) in urban soils are a risk to the health of residents. To predict those risks, the distribution and the factors influencing the concentration of PAHs were studied by collecting 1120 records of soil PAHs published during 2006-2017 from 26 cities. The mean concentrations of 16 PAHs (∑PAHs) in soil varied from 123 μg/kg to 5568 μg/kg, with a mean value of 1083 μg/kg, suggesting that a few cities were polluted. The distribution of ∑PAHs in the cities followed two gradients, namely from northern China through eastern China to southern China and from industrial cities through developed cities to cities that are main tourist attractions. The concentrations were significantly correlated to annual temperature, the efficiency of energy use, and to such measures of air quality as PM₁₀ and NO₂ concentrations. A regression equation developed to predict the concentration of ∑PAHs in soil and the corresponding health risks to residents of 35 major Chinese cities of China showed that the risks to adults and children were slight in most cities but those in a few industrial cities were of concern, and field investigations are recommended to assess the risk in greater detail. The method offers a useful tool for predicting such risks in other cities even when data on soils PAHs are not available.

The impact of heating season factors on eight PM2.5-bound polycyclic aromatic hydrocarbon (PAH) concentrations and cancer risk in Beijing

In 2015, 443 atmospheric PM_2.5 samples were collected at five sampling sites in Beijing. The concentrations of PM_2.5-bound PAH₈ (Chr, BaA, BbF, BkF, B[a]P, DBA, BghiP, and IND) were determined via high performance liquid chromatography (HPLC). The annual concentration of PM_2.5-bound PAH₈, lifetime cancer risk, and the increasing value due to heating season factors (heating and meteorological conditions) were analyzed. The results showed that the sum concentration of PM_2.5-bound PAH₈ during heating season was 72.6 ng/m³ and higher than the non-heating season concentration of 4.77 ng/m³. The annual concentration was 10.6 ng/m³, which increased 5.83 ng/m³ due to heating season factors. The B[a]P annual concentration was 1.67 ng/m³ and higher than the limit of 1 ng/m³, which was 15.2 times that of non-heating season. Diesel vehicles and gasoline vehicles were the primary PAH₈ sources during non-heating season, while the mixed sources of diesel vehicles, gasoline vehicles, and combustion were the dominant PAH₈ sources during heating season. The most significant health hazard pollutant was B[a]P, which accounted for 72%, 74%, and 69% of the B[a]P equivalent concentration (B[a]Peq) of PAH₈ during heating season, non-heating season, and throughout 2015, respectively. The lifetime cancer risk was 2.67 × 10^-6, which increased 1.36 × 10^-6 due to heating season factors. Therefore, heating season factors nearly doubled the annual concentration of PM_2.5-bound ∑PAH₈ and lifetime cancer risk. The results indicated that to protect human health, it is very important to control PM_2.5-bound ∑PAH₈ emissions during heating season, especially B[a]P emissions.

Recommended acceptable levels of maternal serum typical toxic metals from the perspective of spontaneous preterm birth in Shanxi Province, China

Preterm birth is an important issue of public reproductive health worldwide. The effects of the toxic metals on the likelihood of spontaneous preterm birth (SPB) are still under discussion. Our study aimed to investigate the association between maternal exposure to the five typical toxic metals or metalloid (i.e. arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb)) and the SPB likelihood. The mothers delivering fetus with SPB (cases) and those with term healthy birth (controls) were chosen from a prospective birth cohort of 3201 women carried out in Shanxi Province, China. A total of 147 SPB cases and 381 controls were included in our nested case-control study. We collected maternal general information by questionnaire and collected their blood sample during recruitment. The serum concentrations of the five toxic metals were measured by inductively coupled-plasma mass spectrometry. We found that the demographic information between the cases and controls were well balanced. The participants in our study had relatively higher serum As concentration. For the other toxic metals (i.e. Cd, Cr, Hg, and Pb), their serum concentrations were overall in the middle range of those from general population. There were no significant associations of the serum concentrations of the five concerned toxic metals with the SPB likelihood. Our study results overall did not support that maternal exposure to As or Cd significantly contribute to the SPB risk in the current exposure level, as well as the other three toxic metals. We further proposed their upper concentration limits in maternal serum from the perspective of SPB likelihood during the early pregnant period, i.e. 18.2 ng/mL of As, 1.05 ng/mL of Cd, 0.96 ng/mL of Cr, 1.07 ng/mL of Hg, and 1.54 ng/mL of Pb.

Spatiotemporal distribution, source apportionment and ecological risk assessment of PBDEs and PAHs in the Guanlan River from rapidly urbanizing areas of Shenzhen, China

In this study, nine congeners of polybrominated diphenyl ethers (PBDEs) and sixteen congeners of polycyclic aromatic hydrocarbons (PAHs) were measured in water samples to elucidate their spatial distribution, congener profiles, sources and ecological risks in the Guanlan River during both the dry season (DS) and the wet season (WS). The concentration of Σ₉PBDE ranged from 58.40 to 186.35 ng/L with an average of 115.72 ng/L in the DS, and from 8.20 to 37.80 ng/L with an average of 22.15 ng/L in the WS. Meanwhile, the concentration of Σ₁₆PAHs was ranged from 121.80 to 8371.70 ng/L with an average of 3271.18 ng/L in the DS and from 1.85 to 7124.25 ng/L with an average of 908.11 ng/L in the WS. The concentrations of PBDEs and PAHs in the DS were significantly higher than those in the WS, probably due to the dilution of the river during the rainy season. Moreover, the spatial distribution of pollutants revealed decreasing trend in the concentration from upstream to downstream and almost identical pattern was observed during both seasons. The source apportionment suggested that penta-BDE and to some extent octa-BDE commercial products were major sources of PBDEs in the study area. However, the sources of PAHs were mainly comprised of fossil fuels and biomass burning, followed by the petroleum products and their mixtures. The results of the ecological risk assessment indicated PBDEs contamination posed high ecological risks, while PAHs exhibited low or no ecological risks in the study area. Consistent with the environmental levels, the ecological risks of pollutants were relatively lower in the WS, compared to that in the DS. The results from this study would provide valuable baseline data and technical support for policy makers to protect the ecological environment of the Guanlan River.

Exposure to commonly-used phthalates and the associated health risks in indoor environment of urban China

Rapid urbanization and modernization have increased exposures to phthalates from synthetic materials used indoors in China. However, exposure to phthalates from indoor environment and the associated health risks to the urban population have not been adequately characterized and documented. In this study, we summarized the recent measurements of five commonly-used phthalates in indoor environment in urban China and documented their distributions. Based on the activity patterns and exposure factors of Chinese population, Monte-Carlo simulation was used to derive their exposures. On average, the daily intake of all the targeted phthalates was 3.6 μg/kg/day for adults; and for children it ranged from 4.4 μg/kg/day to 8.1 μg/kg/day. For children, the total risk from exposures inside residences and offices was 32%-90% and 4%-19%, respectively. From commuting environments and other indoor environments, it was 5%-31%, and 3%-26%, respectively. For adults, the total risk from residences and offices was 26%-78% and 9%-35%. Additionally, from commuting environments and other indoor environments, it was 8%-35% and 5%-11%, respectively. The non-carcinogenic risk assessment was based on a cumulative Tolerable Daily Intake (TDI_cum), with means ranging from 0.18 to 0.41, which was mainly as a result of exposure to DiBP and DnBP. The means for lifetime cancer risk resulting from DEHP exposure ranged from 0.4 × 10^-6 to 2.0 × 10^-6 for urban population groups. For 80% of working adults and 40%-75%% of children, their cancer risks exceeded the EPA's benchmark (1.0 × 10^-6). The present study could provide important information for decision makers to reduce indoor phthalate exposures as well as the associated health risks for larger population groups in Chinese cities.

A multimedia fugacity model to estimate the fate and transport of polycyclic aromatic hydrocarbons (PAHs) in a largely urbanized area, Shanghai, China

Increasing PAHs pollution is creating more complex urban pollution system. However, the availability of sufficient monitoring activities for PAHs in multicompartment and corresponding multi-interface migration processes is still not well understood. In this study, a Level III steady state fugacity model was validated to evaluate the detailed local variations, and mass fluxes of PAHs in various environmental compartments (i.e., air, soil, sediment, water, vegetation and organic film). This model was applied to a region of Shanghai in 2012 based on a large number of measured data and brings model predictions in 2020. The model results indicate that most of the simulated concentrations agreed with the observed values within one order of magnitude with a tendency of underestimation for vegetation. Direct emission is the main input pathway of PAHs entering the atmosphere, whereas advection is the main outward flow from Shanghai. Organic film was achieved the highest concentration of PAHs compared to other compartments up to 58.17 g/m³. The soil and sediment served as the greatest sinks of PAHs and have the longest retention time (2421.95-78642.09 h). Importantly, a decreasing trend of PAHs was observed in multimedia from 2012 to 2020 and the transfer flux from the air to vegetation to soil was the dominant pathways of BaP intermedia circulation processes. A sensitivity analysis showed that temperature was the most influential parameter, especially for Phe. A Monte Carlo simulation emphasized heavier PAHs were overpredicted in film and sediment, but lighter PAHs in air and water were generally underestimated.

Assessing pollution and risk of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants in China's top coal-producing region

Managing and disposing of sewage sludge have been a severe environmental challenge around the world. China produces hundreds of million tons of sewage sludge annually, and a better understanding of the extent and risk of the associated pollution is of critical importance for implementing environmentally safe regulations and practices. The present study examined the quantity, composition, source, and risk of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge from 18 wastewater treatment plants (WWTPs) in Shaanxi, one of China's top coal-producing provinces. The total concentrations of 16 PAHs varied from 778 to 3264 ng/g dry weight, which is below the upper safety limit (5000 ng/g dry weight) set for the disposal of sludge from municipal wastewater treatment plants for agricultural use in China. However, the concentration of individual PAH compound exceeded the acceptable level prescribed by the Netherland Soil Standard. Three-ring PAHs were the most abundant constituent (50% of total PAHs on average), followed by four-ring PAHs averaging 25%. Relative to sludge PAHs in the same region a decade ago, the total concentrations decreased by more than 27% and the composition shifted to a more pronounced dominance by low molecular weight compounds. This compositional shift suggests higher contributions of petrogenic sources, which may reflect China's increasing consumption of petroleum products over the past decade. The flux of sludge PAHs from each WWTP was positively correlated with the corresponding city's GDP and population, and the total flux amounted to over 100 kg each year for WWTPs in the Xi'an city. The mean toxicity equivalent quantity (TEQ) value was more than twice higher than the value recommended by the Netherlands Soil Standard, and seven carcinogenic PAHs were the primary contributor (i.e., 89-99%) of the TEQ. Collectively, our findings demonstrate that sewage sludge PAHs in Shaanxi constitute a significant source of environmental pollution and toxicity, which cautions against the direct discharge and reuse of sewage sludge and further highlights challenges in managing and disposing of the vast quantities of sewage sludge in China.

A New Study on Air Quality Standards: Air Quality Measurement and Evaluation for Jiangsu Province Based on Six Major Air Pollutants

China’s current Air Quality Index (AQI) system only considers one air pollutant which has the highest concentration value. In order to comprehensively evaluate the urban air quality of Jiangsu Province, this paper has studied the air quality of 13 cities in that province from April 2015 to March 2018 based on an expanded AQI system that includes six major air pollutants. After expanding the existing air quality evaluation standards of China, this paper has calculated the air quality evaluation scores of cities in Jiangsu Province based on the six major air pollutants by using the improved Fuzzy Comprehensive Evaluation Model. This paper has further analyzed the effectiveness of air pollution control policies in Jiangsu Province and its different cities during the study period. The findings are as follows: there are distinct differences in air quality for different cities in Jiangsu Province; except for coastal cities such as Nantong, Yancheng and Lianyungang, the southern cities of Jiangsu generally have better air quality than the northern cities. The causes of these differences include not only natural factors such as geographical location and wind direction, but also economic factors and energy structure. In addition, air pollution control policies have achieved significant results in Nantong, Changzhou, Wuxi, Yangzhou, Suzhou, Yancheng, Zhenjiang, Tai’an and Lianyungang. Among them, Nantong has seen the biggest improvement, 20.28%; Changzhou and Wuxi have improved their air quality by more than 10%, while Yangzhou, Suzhou, and Yancheng have improved their air quality by more than 5%. However, the air quality of Nanjing, Huai’an, Xuzhou, and Suqian has worsened by different degrees compared that of the last period within the beginning period, during which Suqian’s air quality has declined by 20.07% and Xuzhou’s by 16.32%.