Non-heating Period Research Articles

Pollution Characteristics and Source Apportionment of Volatile Organic Compounds in Typical Solvent-using Industrial Parks in Beijing

The BCT-7800A PLUS VOC online monitor system was employed to measure ambient volatile organic compounds （VOCs） in a typical solvent-using industrial park in Beijing. From January to June 2023, the pollution characteristics, source apportionment, and ozone formation potential（OFP）of VOCs were studied, and the results of a comparative analysis were also discussed between heating and non-heating periods. The results indicated that VOC concentrations from January to June 2023 were （104.21 ± 91.31） μg·m-3 on average. The concentrations of TVOCs under the influence of southerly and northerly winds were （214.18 ± 202.37） μg·m-3 and （197.56 ± 188.3） μg·m-3, respectively. Alkanes were the species with the highest average concentration and proportion, respectively （45.53 ± 41.43） μg·m-3. The VOC concentration during the heating period was higher than those during the non-heating period, with values of （111.57 ± 83.96） μg·m-3 and （87.92 ± 75.03） μg·m-3, respectively. Propane and ethane were the species with the highest average concentration during the heating period. Compared with those in the non-heating period, the average concentrations of three species （propane, ethane, and n-butane） in the top ten species increased during the heating period, with average concentrations increasing by 51.94%, 54.64%, and 26.32%, respectively. The source apportionment results based on the positive matrix factorization （PMF） model indicated that the major sources of VOCs in the park during the monitoring period were printing emission sources （4.95%）, oil and gas evaporation sources （9.52%）, fuel combustion sources （15.44%）, traffic emissions sources （18.97%）, electronic equipment manufacturing （24.59%）, and industrial painting sources （26.52%）. Therefore, industrial painting sources, electronic equipment manufacturing sources, and traffic emissions sources were the emission sources that the park should focus on controlling. Compared with those during non-heating periods； industrial painting, traffic emission, and fuel combustion sources contributed more during the heating period, with VOC concentrations increasing by 15.02%, 16.53%, and 24.98%, respectively. The average OFP of VOCs from May to June during the monitoring period was 198.51 μg·m-3 and OVOCs, olefins, and aromatic hydrocarbons contributed the most to OFP, which were 47.41%, 22.15%, and 18.41%, respectively. The electronic equipment manufacturing source was the largest contributor to the summer OFP of the park and its contribution rate was 30.11%, which should be strengthened in the future.

Variations of black carbon, particulate matter and nitrogen oxides mass concentrations in urban environment with respect to winter heating period and meteorological conditions

The atmospheric concentrations of particulate pollution are of great scientific concern due to their impact on both human health and environment. This study aimed to investigate the concentration of black carbon (BC), particulate matter with an aerodynamic diameter of less than 10 micrometres (PM10) and nitrogen oxides (NOx) at an urban background environment throughout the year, and understand the impact of winter heating and meteorology on its concentration level. The campaign covered heating and non-heating periods, from 1 June 2021 to 31 May 2022. During the heating period, the mass concentrations of BC, PM10 and NOx were 1.17, 24.9 and 19.4 µg m–3, respectively. The analysis revealed that the mass concentrations of BC and NOx were 1.9 and 1.4 times greater during the heating period, respectively, compared to the non-heating period. In contrast, PM10 remained almost constant during the heating (19.4 µg m–3) and non-heating periods (20.0 µg m–3). Throughout the year, the BC mass concentration was dominated by BCFF (71.2%) originating from fossil fuel combustion with a maximum (8.43 µg m–3) during the heating period. Moreover, wind speed presented a weak negative correlation with BC (r = –0.40), PM10 (r = –0.19) and NOx (r = –0.40) during the heating period.

Characteristics and health risks assessment of PM2.5-bound heavy metals during winter in urban areas of northern China: A case study in Kaifeng

The health impact of heavy metals in atmospheric PM2.5 has garnered increasingly widespread attention. We have collected PM2.5 samples in a typical city (Kaifeng) within the Central Plains Urban Agglomeration in China during winter and measured the mass concentration of PM2.5-bound heavy metals. The pollution of As and Cr in the urban atmosphere requires significant attention. As PM2.5 concentrations increased, the enrichment factors (EFs) of Mn, Cu, Zn, As, and Pb also rose, suggesting a growing contribution from anthropogenic emissions. The analysis showed that the hazard quotient (HQ) for the non-heating and heating periods (HQ < 1) did not result in a cumulative non-carcinogenic health risk to humans. Regarding carcinogenic effects, As and Cr exhibit significant carcinogenic impacts on both children and adults (ELCR>1 × 10−6), indicating that the carcinogenic risks posed by As and Cr under PM2.5 exposure in Kaifeng could not be overlooked. It was found that industrial and biomass combustion are the primary sources of carcinogenic risk in Kaifeng city. From the non-heating to the heating period, the industrial carcinogenic risk increased from 37.12 % to 43.39 %, while the contribution of biomass burning remained at 25 %. This result was strongly correlated with the high proportions of heavy metal elements such as As, Mn, Pb, and Ni from the metal refinery industry. The results of this study revealed the equally important source of heavy metals, compared to coal combustion in North China Plain. In addition to residential coal combustion, industrial emissions are a major source of PM2.5-bound heavy metals in Kaifeng, contributing significantly to overall air pollution and providing a useful reference to mitigating human health risks in the area.

Optimization and simulation of a novel multi-energy complementary heat pump system in cold regions

Solar-assisted ground source heat pump systems(SAGSHPSs) and solar- assisted air source heat pump systems (SAASHPSs) are recognized renewable energy technologies for clean and feasible heating and domestic hot water supply. However, in cold regions, the poor thermal comfort of SAASHPSs and the soil thermal imbalance of SAGSHPSs during heating periods must be resolved urgently. Therefore, to provide an efficient and stable heat source, a multi-energy complementary heat pump system(MECHPS) with seasonal heat storage was designed to meet the needs of building energy consumption. The system comprehensively utilizes solar energy and ambient air for seasonal heat storage during non-heating periods, and then directly provides heat coupled with the ground source heat pump during heating periods. The composition and control strategy of the system were introduced. The system was numerically modeled by the simulation software Transient System Simulation Program (TRNSYS), and the main MECHPS modules were experimentally verified. Additionally, to study the optimal capacity of MECHPS in terms of economy and energy savings, the Hooke-Jeeves algorithm was used for MECHPS capacity optimization with the objectives of minimising the annual cost and maximising the annual savings of standard coal. The results showed that compared with traditional SAASHPSs, the MECHPS exhibited better thermal comfort while maintaining the room temperature above 18 °C. Compared to SAGSHPSs, the MECHPS was able to achieve soil thermal balance, and its soil temperature remained largely constant after 15 years of operation. Finally, compared with the initial scheme, the annual cost reduction rate was 4.98 % under the annual cost optimization scheme and an additional 1310 kg of standard coal could be saved under the annual savings of standard coal optimization scheme. The proposed system provides a way to satisfy the building energy supply for widespread application in cold regions.

Prediction models for building thermal mass of intermittently heated rooms for balancing energy consumption and indoor thermal comfort

Building thermal mass (BTM) plays an essential role in maintaining a comfortable indoor environment for intermittently heated rooms (IHR). However, how to properly determine the BTM in IHR is unclear for the comprehensive consideration of the opposite effects on the reduction of heating energy consumption (HEC) as well as the improvement of indoor thermal comfort (ITC). This study aims to investigate the comprehensive impact of BTM on the HEC and ITC of IHR in the hot summer and cold winter (HSCW) zone of China using the validated EnergyPlus model. The results indicate that BTM can significantly improve the ITC of IHR, whereas increase HEC. The degree of impact is mainly related to the internal wall heat accumulation coefficient, external wall insulation layer thermal resistance, and outdoor air mean temperature during non-heating periods. Response surface methodology is further employed to quantify the effects of BTM on HEC and ITC of IHR. Based on the predictive models, the range of parameter variations for BTM that simultaneously meet HEC and ITC requirements is obtained. The predictive models can provide a theoretical basis for balancing HEC and ITC in intermittently heated buildings in the HSCW zone of China.

Analysis of the synergistic benefits of typical technologies for pollution reduction and carbon reduction in the iron and steel industry in the Beijing–Tianjin–Hebei region

With its high energy consumption and pollutant emissions, the iron and steel industry is a significant source of air pollution and carbon emissions in the Beijing–Tianjin–Hebei (BTH) region. To improve air quality and reduce greenhouse gas emissions, a series of policies involving ultra-low emission, synergistic reduction of pollution, and carbon application have been implemented in the region. This study has assessed air pollutant and CO2 emission patterns in the iron and steel industry of the region by employing co-control effects coordinate system, marginal abatement cost curve, and numerical modeling, along with the synergistic benefits of typical technologies. The results have demonstrated that: (1) the intensive production activities pertinent to iron and steel enterprises has contributed greatly to the emission in Tangshan and Handan, where the sintering process is the main source of SO2, NOx, PM2.5, and CO, accounting for 64.86%, 55.15%, 29.98%, and 46.43% of the total emissions, respectively. (2) Among the typical pollution control and reduction measures, industrial restructuring and adjustment of the energy-resource structure have led to the greatest effects on emission reduction. Technologies exhibiting great potential in emission reduction and high-cost efficiency such as Blast Furnace Top Gas Recovery Turbine Unit (TRT) need to be promoted. (3) In Tangshan city with the highest level of steel production, the iron and steel production activities contributed to the concentration of 30.51% of PM2.5, 50.67% of SO2, and 42.54% of NO2 during the non-heating period. During the heating period, pollutants pertinent to the combustion of fossil energy for heating have increased, while iron and steel induced emissions have decreased to 23.7%, 34.32%, and 29.13%, respectively. By 2030, it is speculated that the contribution of the iron and steel industry to air quality will be significantly decreased as result of successful implementation of ultra-low emission policies and typical synergistic reduction technologies.

Particulate black carbon mass concentrations and the episodic source identification driven by atmospheric blocking effects in Astana, Kazakhstan

Black carbon (BC) is a component of fine particulate matter (PM2.5) that is a key contributor to adverse human health effects and climate forcing. To date, BC mass concentrations and possible sources in Kazakhstan have not been studied. Thus, understanding the temporal variations of BC for a large developing region with a complex climate is useful. In this study, measurements of fine particulate BC mass concentrations in Astana were made from June 2020 to October 2021 by measuring light absorption of PM2.5 on filters. The mean BC concentration was 2.56 ± 1.29 μg m−3 with maximum and minimum monthly mean BC concentrations being 4.56 ± 2.03 μg m−3 and 1.12 ± 0.42 μg m−3 in January 2021 and June 2020, respectively. Temporal analyses of BC, SO2, PM10, NOx, CO, meteorological and atmospheric stability parameters were performed. Aggregated pollutant ‘episodic loadings’ during the heating and non-heating periods were identified. Their relationships with blocking anticyclones and cyclones were investigated by examining the reversal of meridional gradients at 500 hPa geopotential height (GPH) maps and identifying Omega (Ω) and Rex blocking types. Astana has some of the highest BC concentrations of cities worldwide. Seasonal BC source location identification using Conditional Bivariate Probability Function (CBPF) analysis implicated combined heat and power (CHP) plant emissions as the major BC source in Astana. Significant increases in BC concentrations were observed during the cold season due to numerous sources, generally poorer atmospheric dispersion and blocking events. The Concentration Weighted Trajectory (CWT) analysis results showed that the distribution of the 75th percentile of BC during episodic periods actively controlled by blockings exceeding than the entire measurement period, which may reflect cross-border transport and adjacent countries.

Sources and formation of fine particles and organic aerosols during autumn-winter period in the southern edge of northern China plain

The North China Plain (NCP) experienced significant improvements in air quality in 2018–2022. However, severe pollution episodes still occur frequently during the cold season. The limitations of highly time-resolved measurements hinder understanding the sources and formation mechanisms of pollution episodes, especially the role of organic aerosols (OA). Therefore, we used a Time-of-Flight Aerosol Chemical Speciation Monitor to characterize the aerosol chemical species, variation, and sources of OA during autumn and winter in Luohe, a city in the southern part of the NCP. The results showed that nitrates and organics were the main species of fine particles (PM2.5), accounting for an average of 38.4% and 29.6% of its total mass, respectively. Furthermore, the positive matrix factorization model analyzed the OA in PM2.5 and identified three primary OA and secondary OA related to photochemistry. Primary OA was the dominant contributor throughout the study period (55%), increasing from 50% during the non-heating period to 59% during the heating period. The contribution of photochemically generated oxidized OA remained high (41%) during heavy pollution episodes in the heating period, indicating strong photochemical production during winter. Additionally, most aerosol species and OA factors showed distinct diurnal variations, with lower concentrations during the day, suggesting the influence of the planetary boundary layer and primary emissions. By analyzing the chemical species features of five heavy particulate matter pollution episodes during the study period, we identified three main driving mechanisms for severe pollution events: photochemical processing, photochemical and aqueous-phase production, and local emissions.

Pollution characteristics, source apportionment and absorption spectra of size-resolved PAHs in atmospheric particles in a cold megacity of China

Polycyclic aromatic hydrocarbons (PAHs) have the capability for solar radiation absorption related to climate forcing. Herein, pollution characteristics and absorption spectra of size-resolved PAHs in atmospheric particles in a cold megacity were comprehensively investigated. The mean concentrations of Σ18PAHs in all the 11 particle size ranges were 3.95 ± 4.77 × 104 pg/m3 and 2.17 ± 1.54 × 103 pg/m3 in heating period (HP) and non-heating period (NHP), respectively. Except for most PAHs with 2 and 3 benzene rings in NHP, most other PAHs showed a unimodal distribution pattern with the peak at 0.56–1.0 µm in both periods, which was caused by PAH emission sources. The PAH-related climate forcing was mainly caused by the solar radiation absorptions at ∼325 (∼330) nm and ∼365 nm. In general, the absorption intensities were higher in HP than NHP. The absorption intensity in the particle size range of 0.56–1.0 µm was the highest, and benzo[e]pyrene was the dominant contributor. In colder periods in HP, higher PAH concentrations caused more intensive PAH-related climate forcing. This study provided new insights for pollution characteristics and absorption spectra of size-resolved PAHs in atmospheric particles, which will be useful for better understanding PAH-related climate forcing.

Influence of heat storage on performance of multi-borehole mid-deep borehole heat exchangers

Storing heat underground is an effective method to solve the problem of apparent ground temperature decrease due to long-term operation of a multi-borehole mid-deep borehole heat exchanger (MMBHE), which will cause heating capacity decrease and even heating failure. To understand the influence of heat storage on the MMBHE operation performance, based on the proposed model considering heat storage and extraction, this research comprehensively analyzes the influence of heat storage on the MMBHE heat extract capacity, ground temperature distribution, fluid temperature variation along flow path. The influential factors analyzed include borehole layout, borehole amount, borehole spacing, and borehole depth. The results indicate that adopting heat storage in non-heating seasons significantly improves the ground temperature and the heat extraction capacity of the MMBHE. The MMBHE can extract more heat with heat storage than that without heat storage when the heat storage fluid temperature is higher than the critical heat storage temperature which is much less the borehole bottom temperature. As the case discussed in this paper, the mean heat extraction capacity with heat storage is 24.25 % higher than that without heat storage. As the borehole depth increases, there is a substantial increase in the heat extraction capacity of the MMBHE with no heat storage, and the heat storage effect is weakened when heat storage adopted in non-heating period. Less borehole number and larger borehole spacing make larger mean borehole heat extraction capacity of an MMBHE with no heat storage. However, when the borehole layout, borehole amount, borehole spacing, and borehole depth change, fluctuation of the mean borehole heat extraction capacity with heat storage is much smaller compared to those with no heat storage. When the borehole spacing increases from 25 m to 45 m with no heat storage, the mean heat extraction capacity of the MBHE is increased by 27.67 kW, while that is 11.88 kW with heat storage. This research can provide some inherent understanding of the heat storage on MMBHE performance and reference for designing MMBHE with heat storage systems.

Small-scale district heating system as heat storage for decentralized solar thermal collectors during non-heating period

Solar thermal energy usage in the Baltic countries is currently low, so there is a need to find technically and economically feasible solutions to increase the appeal of this technology. Integration of solar energy into existing district heating systems is a way to increase the share of renewable energy sources while utilizing the existing infrastructure, thereby reducing capital investments, as well as mitigating the risk of solar collector overheating and eliminating the need for local storage tanks in buildings. This study presents a parametric study for evaluating the effectiveness of using a district heating system to store heat produced by decentralized solar thermal collectors and comparing the district solution to the traditional local solution. The TRNSYS 18 model was developed for this purpose. The model investigates the impact of different hot tap water demand profiles as well as pipeline diameters and lengths on system energy efficiency, showing a statistically significant difference (p < 0.05) between installing solar collectors on residential and restaurant or office roofs, and no significant difference (p = 0.24) between restaurant and office. The model shows that solar energy can be shared within a 500 m distance between neighborhoods and that a larger main pipeline diameter can increase overall system efficiency.

Environmental impact assessment of the coal yard and ambient pollution.

This study investigates the vertical distribution of pollutants emitted from coal yards using unmanned aerial vehicles (UAVs). Vertical concentration measurements of black carbon (BC) and particulate matter (PM) inarange of 1m to 100m above ground level (AGL) in the central coal yard showed clear spatial patterns and gradients of these pollutants. In addition, measurements were taken at specific heights (1 m, 30 m AGL, and60mAGL) at seven locations approximately 3 km from the yard. Thirteen measurements were carried out during the non-heating period under similar weather conditions. The measured BC concentrations decreased significantly with increasing altitude, with ground-level concentrations reaching 1.88 ± 0.61µg/m3 and decreasing by over 46% at 80 m AGL. Similarly, PM10 concentrations at 60 m AGL decreased by 21.7%, with values of25.99 ± 9.24µg/m3 measured near the ground level and 16.52 ± 8.31µg/m3 at 60 m AGL. The maximum coal particle pollution from the coal depot ranges from 500 to 1,000 m. The study showed a significant decrease in BC concentrations with height above the coal yard surface. Concentrations of PM10 and PM10-TSP showed a complex distribution influenced by local emissions and long-range particle transport. Meteorological factors, especially wind speed and direction, significantly influenced the pollutant dispersion. In addition, higher pollutant concentrations were measured during dry periods than after rainfall. The findings of this study contribute to abetter understanding of the dispersion patterns and potential impacts of coal dust, enabling the implementation of targeted mitigation strategies and improved pollution control measures.

Investigation of Indoor Airborne Bacteria in the Severe Cold Region in China: Genera, Levels, and the Influencing Factors of Concentration

In regions experiencing severe cold, inadequate ventilation during winter months often leads to increased concentrations of indoor pollutants. While there have been several studies on indoor particulate matter and inorganic pollutants in such regions, bioaerosol pollution has not been as extensively investigated. This study examines the indoor bioaerosol situation in a university located in one of the severe cold regions in China, focusing on bacteria as a representative pollutant. It investigated random samples of an office and a dormitory (including washrooms) and spanned heating and nonheating periods. The findings indicated that bacterial abundance in the dormitory and office was approximately equivalent. The predominant airborne bacterial communities identified were Proteobacteria, Bacteroidota, Actinobacteriota, Firmicutes, and Myxococcota. Opening windows effectively reduced bacterial concentrations during both heating and nonheating periods. When windows remained closed, bacterial concentrations exceeded the standard by 9.1% during the nonheating period and by 14.3% during the heating period. Furthermore, temperature and relative humidity influenced bacterial particle size, activity, and consequently, aerosol concentrations. In the office, the highest percentage of bioaerosols was observed in particle sizes &lt;1.1 and 1.1–2.1 μm, with smaller percentages observed in other particle sizes. Conversely, the percentage of particle sizes 2.1–3.3 μm in the dormitory was higher. The highest bacterial aerosol concentrations were detected in the morning in both the dormitory and office, during heating and nonheating periods. Bacterial concentrations in the office were lower on weekends than on weekdays, whereas in the dormitory, concentrations were higher on weekends than on weekdays. The above results indicate that indoor bacterial aerosol pollution is serious in winter in severe cold regions, which needs more attention.

Machine learning revealing key factors influencing HONO chemistry in Beijing during heating and non-heating periods

Nitrous acid (HONO) is of great interest due to its contribution to hydroxyl (OH) radicals by self-photolysis. Nowadays, machine learning (ML) algorithms are good at capturing complicated non-linear relationships between predictors and dependent variables. Here, using the whole year of 2018 of observed HONO and related pollutant data at an urban site in Beijing, an ML-RF (random forest) model is carried out to predict HONO concentrations and explore the main factors influencing HONO formation mechanisms. ML-RF models show satisfactory performance during the heating, non-heating and whole year periods with R values of 0.95, 0.96 and 0.95, respectively. Primary emissions and diffusion have an obvious influence on ambient HONO during the heating period, while chemical formation processes such as NO2 heterogeneous reaction and photolysis of nitrate are important for HONO during the non-heating period with higher RH and stronger solar intensity. O3 and NH3 are the most important variables for HONO in both periods, indicating the close relationship of HONO with atmospheric oxidation and the important role of NH3 in HONO formation processes. Although there are deviations due to some variability in HONO formation mechanisms between years, ML-RF models based on 2018 data are able to roughly predict HONO for three periods in 2017 and 2021. Overall, machine learning with limited meteorological and pollutant parameters offers great advantages in HONO prediction, and it can also provide some clues to improve the chemical mechanisms of HONO by finding related variables of ambient HONO.

Oxidative potential in rural, suburban and city centre atmospheric environments in central Europe

Abstract. Oxidative potential (OP) is an emerging health-related metric which integrates several physicochemical properties of particulate matter (PM) that are involved in the pathogenesis of the diseases resulting from exposure to PM. Daily PM2.5-fraction aerosol samples collected in the rural background of the Carpathian Basin and in the suburban area and centre of its largest city of Budapest in each season over 1 year were utilised to study the OP at the related locations for the first time. The samples were analysed for particulate matter mass, main carbonaceous species, levoglucosan and 20 chemical elements. The resulting data sets were subjected to positive matrix factorisation to derive the main aerosol sources. Biomass burning (BB), suspended dust, road traffic, oil combustion mixed with coal combustion and long-range transport, vehicle metal wear, and mixed industrial sources were identified. The OP of the sample extracts in simulated lung fluid was determined by ascorbic acid (AA) and dithiothreitol (DTT) assays. The comparison of the OP data sets revealed some differences in the sensitivities of the assays. In the heating period, both the OP and PM mass levels were higher than in spring and summer, but there was a clear misalignment between them. In addition, the heating period : non-heating period OP ratios in the urban locations were larger than for the rural background by factors of 2–4. The OP data sets were attributed to the main aerosol sources using multiple linear regression with the weighted least squares approach. The OP was unambiguously dominated by BB at all sampling locations in winter and autumn. The joint effects of motor vehicles involving the road traffic and vehicle metal wear played the most important role in summer and spring, with considerable contributions from oil combustion and resuspended dust. In winter, there is temporal coincidence between the most severe daily PM health limit exceedances in the whole Carpathian Basin and the chemical PM composition causing larger OP. Similarly, in spring and summer, there is a spatial coincidence in Budapest between the urban hotspots of OP-active aerosol constituents from traffic and the high population density in central quarters. These features offer possibilities for more efficient season-specific air quality regulations focusing on well-selected aerosol sources or experimentally determined OP, rather than on PM mass in general.

Soil-Derived Dust PM10 and PM2.5 Fractions in Southern Xinjiang, China, Using an Artificial Neural Network Model

Soil-derived dust emissions have been widely associated with health and environmental problems and should therefore be accurately and reliably estimated and assessed. Of these emissions, the inhalable PM10 and PM2.5 are difficult to estimate. Consequently, to calculate PM10 and PM2.5 emissions from soil erosion, an approach based on an artificial neural network (ANN) model which provides a multilayered, fully connected framework that relates input parameters and outcomes was proposed in this study. Owing to the difficulty in obtaining the actual emissions of soil-derived PM10 and PM2.5 over a broad area, the PM10 and PM2.5 simulated results of the ANN model were compared with the published results simulated by the widely used wind erosion prediction system (WEPS) model. The PM10 and PM2.5 emission results, based on the WEPS, agreed well with the field data, with R2 values of 0.93 and 0.97, respectively, indicating the potential for using the WEPS results as a reference for training the ANN model. The calculated r, RMSE and MAE for the results simulated by the WEPS and ANN were 0.78, 3.37 and 2.31 for PM10 and 0.79, 1.40 and 0.91 for PM2.5, respectively, throughout Southern Xinjiang. The uncertainty of the soil-derived PM10 and PM2.5 emissions at a 95% CI was (−66–106%) and (−75–108%), respectively, in 2016. The results indicated that by using parameters that affect soil erodibility, including the soil pH, soil cation exchange capacity, soil organic content, soil calcium carbonate, wind speed, precipitation and elevation as input factors, the ANN model could simulate soil-derived particle emissions in Southern Xinjiang. The results showed that when the study domain was reduced from the entire Southern Xinjiang region to its five administrative divisions, the performance of the ANN improved, producing average correlation coefficients of 0.88 and 0.87, respectively, for PM10 and PM2.5. The performances of the ANN differed by study period, with the best result obtained during the sand period (March to May) followed by the nonheating (June to October) and heating periods (November to February). Wind speed, precipitation and soil calcium carbonate were the predominant input factors affecting particle emissions from wind erosion sources. The results of this study can be used as a reference for the wind erosion prevention and soil conservation plans in Southern Xinjiang.

Optimize configuration of multi-energy storage system in a standalone microgrid

Aiming at the integrated energy microgrid, an important part of the energy internet, this paper constructs a multi-energy storage system optimization configuration model of the integrated energy microgrid in an independent mode, and proposes a configuration method that includes the rated power and capacity of the storage system and the heat storage system. The storage system model includes the estimation of battery life during heating and non-heating periods. The model takes economy as the index, and considers the relevant constraints of thermoelectric coupling of thermoelectric units, including thermal and electrical balance, unit climb, energy storage system and self-sufficiency probability, etc., and uses a The bacterial colony chemotaxis (BCC) algorithm model based on unit output and energy storage system power distribution strategy to solve the problem. The operation characteristics of cogeneration units equipped with energy storage system are discussed. The results show that the proposed multi-energy storage system configuration method has significant economic and environmental benefits in both heating and non-heating periods, and promotes the uptake of wind power.

Unveiling the pollution and risk of atmospheric (gaseous and particulate) polycyclic aromatic hydrocarbons (PAHs) in a heavily polluted Chinese city: A multi-site observation research

Linfen, one of the most polluted cities in China, releases huge amounts of polycyclic aromatic hydrocarbons (PAHs) into the atmosphere. The pollution characteristics of Linfen's PAHs, along with their emission sources and health risks, were scarcely discussed. This study conducted a multi-site observation campaign in Linfen during the non-heating and heating periods (2018–2019) using passive air samplers. Sixteen PAHs were analyzed for the gaseous and particulate samples collected at the 15 sites in the urban, rural, and background areas. The PAH concentrations in Linfen's atmosphere were 225.7 ± 81.9 ng m−3 during the heating period and 139.9 ± 47.5 ng m−3 during the non-heating period, annually averaged to 168.1 ± 58.6 ng m−3, which was predominantly contributed by the rural and urban emissions. Combustion was highly responsible for the PAHs, including the burning of coal for industrial production and winter heating, coupled with the utilization of oils by automobile engines. The spatiotemporal variations of PAHs were associated with the discrepancy of emission intensity rather than that of emission type. The BaP equivalent concentrations for the rural and urban areas were 1-2 orders of magnitude higher than the various international standards, indicating the considerable carcinogenic risk for the majority of local residents. These findings are informative for better understanding the atmospheric PAH pollution in a typical resource-based Chinese city.

Thermoeconomic analysis and multiple parameter optimization of a combined heat and power plant based on molten salt heat storage

The global energy supply is transitioning to sustainable, low-carbon energy. Power-to-heat technology with molten salt thermal energy storage (TES) is a potential way to accommodate renewable power, and the stored heat can be converted to heat and electricity for residential heating and power supply with a combined heat and power plant (CHP). In this study, a CHP-TES system with valley electricity as the input energy source is proposed. Thermodynamic models are developed, and an economic evaluation index is established by considering electricity price, heat price, TES scale, and CHP layout. Then, multiparameter optimization of the proposed CHP-TES system is conducted with the genetic algorithm, and the energy-exergy-economic feasibilities of the system are evaluated. The CHP-TES system can operate under CHP and condensing modes in heating and non-heating periods, and its output power can be regulated during peak and valley load time, respectively. The exergy efficiency of the CHP-TES system is 45.07% and 36.67% in condensing modes with the peak and valley output power, respectively. The exergy efficiency of the CHP-TES system is 46.16% and 42.96% in CHP modes with the peak and valley output power, respectively. The exergy is mainly destructed in the electric heater, which accounts for over 65% of the total exergy loss in all operation modes. The equipment investment of the TES, steam generator, and CHP systems account for 87.59%, 3.53%, and 8.88% of the total, respectively. The electric heater takes the largest portion of the total equipment investment, which accounts for 37.99%. When the peak-valley electricity price changes from 0.121 $ kWh−1 to 0.259 $ kWh−1, the net present value increases from $592 million to $5.79 billion.

Inhalation bioaccessibility and risk assessment for PM-bound organic components: Co-effects of component physicochemical properties, PM properties, and sources

Inhalation bioaccessibility and deposition in respiratory tracts of organic components in atmospheric particulate matter (PM) are key factors for accurately estimating health risks and understanding human exposures. This study evaluated the in-vitro inhalation bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) and PAH derivatives, phthalic acid esters (PAEs), polychlorinated biphenyls (PCBs), and organophosphate flame retardants (OPFRs) in size-resolved PM from a Chinese megacity. The bioaccessibility ranged from 0.2% to 77.8% in the heating period (HP), and from 0.7% to 94.2% in the non-heating period (NHP). Result suggests that less hydrophobic organics might be more bioaccessible. Bioaccessibility of medium logKow organics in sizes > 0.65 µm was significantly inhibited by high carbon fractions, indicating the co-effects. Then, this is the first study to explore effects of sources on inhalation bioaccessibility of organics. Coal and biomass combustion in HP and traffic emission in NHP negatively correlated with bioaccessibility. Secondary particles also negatively correlated with bioaccessibility of medium logKow organics. Incremental lifetime cancer risk (ILCR) and non-cancer risk (HQ) for all measured components in PM10 were estimated after considering the bioaccessibility and deposition efficiencies and the HQ and ILCR were within the acceptable range. BaP and DEHP were strong contributors to HQ and ILCR, respectively.