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Persistent-heavy-haze (PHH) events and extreme-cold temperatures are prevalent problems confronting the Northeastern part of China (especially Harbin) during the prolonged winter season, leading to two challenging phenomena known as the urban-heat/cold-island (UHI/UCI) and urban-pollution-island (UPI) intensities (UHII/UCII and UPII) defined as the differences between urban and rural temperature/air pollution. Although UHI and UPI have been explored, the mechanisms and novel drivers (urban-stilling-island-intensity (USII), urban-dryness-island-intensity (UDII), and urban-planetary-boundary-layer-height-intensity (UPBLHI) which are by-products of wind speed (WS), relative humidity, and planetary-boundary-layer-height (PBLH), respectively; with wind direction (WD)) influencing them are still underexplored in extreme-cold regions. Using the Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF-Chem), we designed the mechanisms into non-radiative-effect (NRE), direct-radiative-effect (DRE), indirect-radiative-effect (IRE), with slope-and-shading-effect (SSE) during early-winter-heavy-haze-episode (EWHHE; December 2019) and peak-winter-persistent-heavy-haze-episode (PWPHHE; January 2020). We found that the spatial distributions of the mass concentration of pollutants (e.g., PM 2.5) dominated the downtown, with the IRE and SSE accounting for >200 μg/m3 in both episodes. In assessing the drivers impacting UHII and UPII, the USII favors the increase of UHII and UPII in the EWHHE but lowers the UCII in PWPHHE. Moreover, the UDII and UPBLHI were weaker in PWPHHE than the EWHHE, with NO 2 having the highest UDII at 7.05% (SSE), 7.00% (IRE and NRE), and 6.24% (DRE); hence, revealing that PHH lowered the PBLH. Additionally, the dominant south-to-north WD impacted the UHII and UPII. Generally, low USII, UDII, and UPBLHI with WD are major contributors to PHH in the cold region. Therefore, this work provides insight into drivers for other urban areas with severe air pollution and extreme cold problems. [Display omitted] • Novel drivers were introduced, which are by-products of meteorological conditions. • Spatial distribution of pollutants dominated the downtown, with the IRE and SSE impacting both episodes. • USII favors the increase of UHII and UPII in the EWHHE but lowers the UCII in PWPHHE. • NO 2 has the highest UDII at 7.05% (SSE), 7.00% (IRE and NRE), and 6.24% (DRE). • Low USII, UDII, and UPBLHI with WD are major contributors to PHH in the cold region. [ABSTRACT FROM AUTHOR]

At the local and regional climate scale, one of the most studied environmental issues is urban heat island (UHI). UHI is a thermal anomaly caused by temperature differences between urban and rural settings, which adds heat to the atmosphere and makes people feel uncomfortable. This study explores the influence of new land-cover data on UHI simulations using the high-resolution Weather Research and Forecasting (WRF) model coupled with the single-layer urban canopy model (SLUCM) in the city of Harbin. A comparison was performed between the new Tsinghua University (TU) land cover dataset with the default United States Geological Survey (USGS) and Moderate Resolution Imaging Spectroradiometer (MODIS) land cover datasets. The results of this study revealed that the new TU land cover data had better representation and more realistic land cover changes than the default datasets. The diurnal, seasonal, and long-term nighttime UHIs of air and surface temperatures were higher than the daytime UHIs for both downtown Harbin and the satellite towns. We discovered that coal-burning during winter had a significant influence on UHI in Harbin. Moreover, the results from our buffer revealed a rapid increase in the UHIs of satellite towns, thus revealing the need to focus on the effects of UHI in satellite towns in the future. Therefore, the timely updating of land cover datasets in the WRF model and implementing mitigation strategies will help improve the urban climatic comfort. [ABSTRACT FROM AUTHOR]

Harbin-Changchun megalopolis (HCM) is a typical representative of the cold urban agglomeration region in China. Although the average annual PM 2.5 concentration has experienced an evolutionary process continuous deterioration to gradual improvement in the past decade, but severe haze episodes still occur during cold winter periods. WRF-CMAQ model and observed dataset of surface PM 2.5 concentration were conducted in this study to identify the drivers of 2015–2021 trends in cold winter surface PM 2.5 in the HCM by separating contributions from anthropogenic emissions and meteorology changes. Meteorological condition change was the dominant driver of 2015–2021 trends in cold winter surface PM 2.5 in the HCM. The years with most unfavorable, typical, and most favorable meteorological conditions for PM 2.5 concentration reduction during January from 2015 to 2021 for the whole HCM region were 2020, 2017, and 2018, respectively. The major controlling meteorological factors that affect the surface PM 2.5 concentration change were relative humidity, maximum wind direction and speed in cold winter in the HCM. In addition, we found that the emission cut policy began to play a practical role in the air quality improvement in the HCM from year of 2018. The emission reduction during the 2017–2021 resulted in an approximately 19% (15.7 μg/m3) decrease of PM 2.5 concentrations in January. Furthermore, sensitivity experiments demonstrated that residential emission cut was the key measures for future air quality improvement in cold winter in the HCM. [Display omitted] • Drivers of 2015–2021 trends in cold winter surface PM 2.5 in the HCM was identified. • RH and wind are dominant meteorological factors affecting PM 2.5 in cold winter. • Residential emission cut was the key measures for future air quality improvement in the HCM. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To analyze the allergic status to common inhalant allergens and food allergens in clinical patients in Harbin in northeastern China and provide evidence to develop the prevention strategy of allergic disease. Methods: The data were collected from 5 473 patients with clinical suspected allergic diseases seeking medical care in the Second Affiliated Hospital of Harbin Medical University. Among these patients, 2 530 (46.2%) were males aged 0-86 years, the youngest was only 1 month old and 2 579 (47.1%) were young children and teenagers. The serum specific Immunoglobulin E (sIgE) to 14 kinds of common allergens and serum total IgE were detected by using AllergyScreen test (Mediwiss Analytic GmbH, Moers, Germany). Results: In 5 473 subjects the positive rate of sIgE was 33.1% (n=1 813). Cow milk (6.9%) and wheat (3.1%) were the most common food allergens, followed by house dust mite mix (12.5%) and mould mix (9.4%) and the age and gender specific differences in the positive rate were significant. For the children aged <7 years the positive rates to cow milk, beef-mutton, and egg white/egg yolk were high, but the positive rates to house dust mite mix, ragweed estragon, and mould mix were low (P<0.05). For the adults the positive rates to aeroallergens were high while the rates to food allergens were low. Conclusion: The results from this study showed that the food allergens in Harbin had geographic characteristics, which support the viewpoint that the environment factors play an important role in the incidence of allergic diseases. Also, the detection of sIgE and total IgE are essential to identify relevant allergens for the purpose of early diagnosis, management and prevention of allergic disease. [Copyright &y& Elsevier]

The hourly concentration of six criteria air pollutants in the Harbin-Changchun region were used to investigate the status and spatiotemporal variation of target air pollutants and their relationships with meteorological factors. The annual concentrations of particulate matters during 2013–2017 were two times higher than the Chinese Ambient Air Quality Standards (CAAQS) Grade Ⅱ. The annual O 3 concentration increased by two times during 2013–2018 in Harbin. The concentration of PM, SO 2 , NO 2 , and CO depicted a similar seasonal trend with an order of winter > autumn > spring > summer. The consistent interannual variation trends of PM 2.5 /CO, NO 2 and SO 2 indicated that the formation of secondary inorganic aerosols in the annual scale was dominated by the concentrations of NO 2 and SO 2. The interannual variations of the individual meteorological factors causing on PM 2.5 and O 3 during 2013–2018 varied significantly in seasonal scale. The interannual variations were stable in annual scale indicating that the continuous decline of PM 2.5 during 2014–2018 can be attributed to the comprehensive and strict prohibition of small coal-fired boilers and straw burning in the study area. Meanwhile, the increase in O 3 during 2013–2018 in the study area were mainly attributed to the rapid growth of the emission of its precursor (VOCs and NOx). The influence of meteorology on PM 2.5 and ozone were the most stable and strongest in winter than that in the other three seasons. Image 1 • The annual O 3 concentration has increased by two times during 2013–2018 in Harbin. • The dominant source of SO 2 was attributed to the point sources. • Strongest influence of meteorology on PM 2.5 /O 3 was found in winter. • Temperature was the key factor with strong influence on air pollutants. The characteristics of criteria air pollutants and their causal relationship with individual meteorological factors were comprehensively understood. [ABSTRACT FROM AUTHOR]

Bioaerosols have received extensive attention due to their impact on climate, ecological environment, and human health. This study aimed to reveal the driving factors that structure bacterial community composition and the transmission route of antibiotic resistance genes (ARGs) in PM 2.5. The results showed that the bacterial concentration in spring (8.76 × 105 copies/m3) was significantly higher than that in summer (1.03 × 105 copies/m3) and winter (4.74 × 104 copies/m3). Low temperatures and air pollution in winter negatively affected bacterial concentrations. Keystone taxa were identified by network analysis. Although about 50 % of the keystone taxa had low relative abundances, the strong impact of complex interactions between keystone taxa and other taxa on bacterial community structure deserved attention. The bacterial community assembly was dominated by stochastic processes (79.3 %). Interactions between bacteria and environmental filtering together affected bacterial community composition. Vertical gene transfer played an important role in the transmission of airborne ARGs. Given the potential integration and expression of ARGs in recipients, the human exposure risk due to high concentrations of ARGs and mobile genetic elements cannot be ignored. This study highlights human exposure to inhalable bacterial pathogens and ARGs in urban areas. [Display omitted] • Airborne bacteria and ARGs were characterized in different seasons in cold city. • Null model was introduced for the exploration of the community assembly process. • Airborne bacterial community assembly was dominated by stochastic processes. • bla TEM and qnrS were the main airborne ARGs in PM 2.5. • The transmission route of ARGs showed seasonal differences. [ABSTRACT FROM AUTHOR]

Atmospheric ammonium and ammonia have brought negative environmental impacts and adverse health effects. However, ammonia emissions are generally less regulated worldwide. This study analyzed ammonium pollution character, quantified the dominant ammonia emission sources, and assessed ammonia reduction potential in urban Harbin (China). The results showed that ammonium recorded low concentration in the non-heating season (1.34 ± 1.57 μg/m3), and recorded sharply increased concentration (6.50 ± 7.02 μg/m3) and relative abundance in the heating season. It was closely correlated with vehicle-related pollutants (CO) in non-heating season, while with biomass burning-related pollutants (K+, Cl−) in the heating season. Bayesian Mixing Model emphasized the increasing contribution of biomass burning and decreasing contribution of fertilizer as the pollution levels escalate. The results from the thermodynamic equilibrium model showed that a 50%–60% ammonium decrease could bring marketable decrements of the aerosol pH, aerosol water content, ammonium nitrate concentration, and inorganic ion mass. The results of this study would provide scientific bases for ammonia emission reduction and haze pollution control in urban Harbin. • Ammonium recorded sharply increased concentration and fraction in heating season. • NH 4 + was scarcely modulated by climate factors, but by anthropogenic emissions. • NH 3 reduction from waste treatment and biomass burning could curb severe pollution. • NH 3 emission has greater reduction potential than SO 2 and NO x for PM 2.5 alleviation. [ABSTRACT FROM AUTHOR]

The meteorological conditions in northeast China exhibit particular characteristics associated with snow cover in winter and dramatic land cover transformations. In this study, the Weather Research and Forecasting Model (WRF) is used to assess the influences of snow albedo and land cover changes on wind speed, temperature, relative humidity, and planetary boundary layer height (PBLH). Two new static geographical datasets, a maximum snow albedo dataset (MSA) developed by Beijing Normal University (BNU_MSA) and a land cover dataset developed by Tsinghua University (TU_LC), are employed for updating previous datasets in WRF. Besides, a case study for local anthropogenic heat (AH) parameters is conducted to examine its influences on temperature in winter. Modeled scenarios for 13 December 2017 to 15 January 2018 show that TU_LC yields a lower mean absolute error of 0.55 m/s for simulated wind speed, suggesting the usefulness of the TU_LC in modeled 10-m wind speed. The change in the wind speed is closely related to land cover transformations occurring over urban and forest regions. The spatially varying temperature agrees well with changes in the MSA. Simulation with updated AH parameters induces higher temperature over downtown Harbin and Changchun. Increasing PBLH is observed as compared with that using default datasets because of increasing temperature and heat fluxes induced by the decreases in MSA. The maximum differences of the wind speed and temperature between updated and default datasets in the verticle direction are confined within 600-m height above the ground surface. • The new land cover and maximum snow albedo datasets show good effects on different modeled meteorological variable as compared with WRF default datasets. • The changes of meteorological variables are significant in urban and forest regions in winter. • The maximum differences of the wind speed and temperature between updated and default datasets in the vertical direction are identified in 600 m height. [ABSTRACT FROM AUTHOR]

Haze pollution in Harbin has been gradually alleviated in recent years, but it is still far from eliminated. Thus, precise and effective emission abatement of main chemical components like nitrate is urgently needed for further haze pollution control. This study aimed to estimate nitrate formation pathways, and the contributions of the emission sources of nitrogen oxide in urban Harbin, based on the measurement of isotope signatures in nitrate and the utilization of an improved Bayesian mixing model. The results showed that nitrate significantly aggravated particulate pollution in the heating season, and its driving role was enhanced as the pollution level increased. This study suggested that homogeneous reaction and heterogeneous reaction were the dominant conversion pathways of nitrate formation in non-heating season and heating season respectively, and the contribution of heterogeneous reaction increased as pollution levels increased. By considering isotope fractionation value (δ15N), this paper emphasized coal combustion as the dominant contributor of nitrogen oxide in urban Harbin, while biomass burning, mobile sources, and biogenic soil emissions played relatively weak roles in nitrate pollution. This study has critical importance to provide scientific theoretical bases for nitrogen oxide reduction in urban Harbin and air quality improvement reference in other severely polluted regions in China. Image 1 • Considering δ15 N fractionation is necessary for accurate NO x source apportionment. • Heterogeneous reaction played a vital role in nitrate formation in heating season. • Coal combustion was the dominant contributor to nitrate pollution in urban Harbin. [ABSTRACT FROM AUTHOR]