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Simple Summary: This study explored how urbanization (urban heat island effect and air pollution) affects urban tree growth. The radial growth and xylem anatomical characteristics of trees in urban and rural areas of Harbin were compared by means of tree-ring anatomy. Results showed that there were significant differences in the growth of both broadleaf trees and conifers between urban and rural areas. Urbanization may have the effect of slowing down tree growth, and conifers may be more sensitive to urbanization. Warming and drying climate in Harbin may be an important factor affecting tree growth. Our findings provide a theoretical basis for the future evaluation of the effect of urbanization on tree growth and ecological benefits, as well as the selection of tree species in urban forests. In the context of the intensification of global urbanization, how urbanization (urban heat island effect and air pollution) affects urban tree growth is not fully understood. In this paper, the radial growth and xylem anatomical characteristics of three different tree species (Quercus mongolica, Fraxinus mandshurica, and Pinus sylvestris var. mongolica) in urban and rural areas of Harbin were compared by means of tree-ring anatomy. The results showed that there were significant differences in the growth of both broadleaf trees and conifers between urban and rural areas. The vessel number, cumulative area of vessels, and theoretical hydraulic conductivity of all tree species in rural areas were higher than those in urban areas, indicating that urbanization may have the effect of slowing down growth. However, broadleaf trees in urban areas had higher vessel density and a greater percentage of a conductive area within xylem and theoretical xylem-specific hydraulic conductivity. The thickness of cell walls and cell wall reinforcement index of P. sylvestris var. mongolica were strongly reduced by air pollution, implying that it may be more sensitive to urbanization. Compared to Q. mongolica, F. mandshurica showed less sensitivity to urbanization. Warming and drying climate in Harbin may be an important factor affecting tree growth. [ABSTRACT FROM AUTHOR]

Abstract: Taxis share a high proportion of urban traffic volume and contribute a large proportion to urban air pollution. This paper addressees this context by exploring urban taxi air pollution emissions and possible reduction countermeasures. Based on a survey of Harbin taxis, we have developed different urban taxi pollution emissions models and considered taxi passenger occupancy and taxi average vacant ratio. To reduce taxi air pollution emission, this paper sets a reduction goal and puts forward three kinds of transport management policies. These are taxi market regulation, introduction of electric and Liquefied Petroleum Gas powered vehicles, and the introduction of dial-a-ride services. The paper provides recommendations for managing urban taxi development using these strategies. [Copyright &y& Elsevier]

The floating catkins generated by willow and poplar trees have been criticized for spreading germ and causing fire for decades. It has been found that catkins are with a hollow tubular structure, which made us wonder if the floating catkins can adsorb atmospheric pollutions. Thus, we conducted a project in Harbin, China to investigate whether and how willow catkins could adsorb atmospheric polycyclic aromatic hydrocarbons (PAHs). The results suggest that both the catkins floating in the air and on the ground preferred to adsorb gaseous PAHs rather than particulate PAHs. Moreover, 3- and 4-ring PAHs were the dominating compositions adsorbed by catkins, which significantly increased with exposure time. The gas/catkins partition (K CG) was defined, which explained why 3-ring PAHs are more easily adsorbed by catkins than by airborne particles when their subcooled liquid vapor pressure is high (log P L > −1.73). The removal loading of atmospheric PAHs by catkins were estimated as 1.03 kg/year in the center city of Harbin, which may well explain the phenomenon that levels of gaseous and total (particle + gas) PAHs are relatively low in the months with catkins floating reported in peer-reviewed papers. [Display omitted] • The natural floating catkins could remove atmospheric PAHs. • Catkins prefer to adsorb gaseous PAHs rather than particulate PAHs. • Adsorbing ability of catkins to low-rings PAHs was higher than airborne particles. • Atmospheric level of PAHs declined during the catkin-floating season. [ABSTRACT FROM AUTHOR]

With rapid economic development, the problem of air pollution has become increasingly prominent. Countries have paid attention to PM2.5, one of the main air pollutants, and have gradually addressed this issue. Based on the 2015–2019 air quality data, meteorological data, and aerosol optical depth data from Harbin, China, this study investigated the relationship between PM2.5, a number of influencing factors, and their temporal changes using a machine-learning method. It can be seen from the analysis that the random forest model can predict PM2.5 concentration. In this model, the mean RH and AOD have a high impact on PM2.5 concentration, but there was negligent correlation with PM2.5. The results indicated that the level of PM2.5 pollution continuously decreased from 2015 to 2019, and there were significant seasonal differences in PM2.5 concentration and its variations. In 2019, due to the impact of heating and adverse meteorological conditions, PM2.5 pollution during the heating period increased significantly. This study provides theoretical and data support for the analysis of PM2.5 pollution in Harbin and formulation of air pollution control policies. [ABSTRACT FROM AUTHOR]

Harbin is a northmost megacity in the cold regions of China and experiences severe PM2.5 pollution. However, comprehensive investigations for severe haze formation are few. In this study, we simultaneously measured aerosol composition in real time to assess the sources apportionment, regional transport and its interaction with meteorology from 1 October 2018 to 1 May 2019 by using the single particle aerosol mass spectrometer (SPAMS). The daily average PM2.5 concentration was 51.21 µg/m3 with the hourly maximum of 900.45 µg/m3. Winter coal combustion was the largest source of PM2.5 aerosols during this period. Open straw burning from surrounding and adjacent areas by short-distance transport could aggravate air quality deterioration in Harbin. Three extreme haze events (i.e., Ep1, Ep2 and Ep3) were observed in this study, showing the typical characteristics of local winter pollution. The pollutants of PM2.5 and SO2 emitted from coal combustion played an important role in haze episode during Ep1, whereas Ep2 was caused by the joint effect of coal combustion and straw burning. Ep3 was characterized by long-distance transport of windblown dust from southeast Inner Mongolia and northwest Harbin. Real-time source apportionment of fine particulate matter highlights the importance of joint control of coal and straw burning from the surrounding cities of Harbin. [ABSTRACT FROM AUTHOR]

To improve the analysis ability of residue levels of persistent toxic substances (PTS) in environment, this paper investigated the distribution characteristics of air concentrations of polycyclic aromatic hydrocarbons (PAHs) during the Spring of 2007 (January to April) in 4 different functional areas (urban, suburban, rural, and remote areas) in and near the Haring metropolitan by using the fuzzy C -means clustering algorithm, and got the cluster centers of different samples and a membership matrix which offered quantity foundation for analysis of samples description. Results showed that the contamination level in the urban industrial area was the highest, followed by those in the other urban places and rural area, and the contamination levels in the remote area and in the places on the windward were the lowest. PAHs in Harbin urban atmospheric were mainly from coal - burning and industrial emissions, those in rural areas were mainly from the burning of crop stalks. PAHs in air in this region have imposed a potential threat on human health. [ABSTRACT FROM AUTHOR]

Despite the growing interest in understanding haze formation in Chinese megacities, air pollution has been largely overlooked for the Harbin–Changchun (HC) metropolitan area, located in the severe cold climate region in northeast China. In this study, we unfolded significant variations of fine particulate matter (PM 2.5) in HC's central city (Harbin) during two sequential heating seasons of 2018–2019 and 2019–2020, and we explored major drivers for the observed variations. The two campaigns showed comparable organic carbon (OC) levels but quite different OC sources. The biomass burning (BB) to OC contribution decreased substantially for 2019–2020, which was attributed primarily to the transition of local policies on agricultural fires, i.e., from the "legitimate burning" policy released in 2018 to the "strict prohibition" policy in 2019. Meanwhile, the contribution of secondary OC (OC sec) increased significantly, associated with the much more frequent occurrences of high relative humidity (RH) conditions during the 2019–2020 measurement period. Similar to OC sec , the major secondary inorganic ions, i.e., sulfate, nitrate and ammonium (SNA), also exhibited RH-dependent increases. Given the considerable aerosol water contents predicted for the high-RH conditions, heterogeneous reactions were likely at play in secondary aerosol formation even in the frigid atmosphere in Harbin (e.g., with daily average temperatures down to below - 20 ∘ C). In brief, compared to 2018–2019, the 2019–2020 measurement period was characterized by a policy-driven decrease of biomass burning OC, a RH-related increase of OC sec and a RH-related increase of SNA, with the first two factors generally offsetting each other. In addition, we found that open burning activities were actually not eliminated by the strict prohibition policy released in 2019, based on a synthesis of air quality data and fire count results. Although not occurring during the 2019–2020 measurement period, agricultural fires broke out within a short period before crop planting in spring of 2020, and this resulted in off-the-charts air pollution for Harbin, with 1 h and 24 h PM 2.5 concentrations peaking at ∼ 2350 and 900 µ g/m 3 , respectively. This study indicates that sustainable use of crop residues remains a difficult challenge for the massive agricultural sector in northeast China. [ABSTRACT FROM AUTHOR]

Because of the unique geographical, climate, and anthropogenic emission characteristics, it is meaningful to explore the air pollution in the Harbin-Changchun (HC) metropolitan area. In this study, the Air Quality Index (AQI) and the corresponding major pollutant were investigated for the HC cities, based on the air quality data derived from the China National Environmental Monitoring Center. The number of days with the air quality level of "good" gradually increased during recent years, pointing to an improvement of the air quality in HC. It was also found that ozone, a typical secondary pollutant, exhibited stronger inter-city correlations compared to typical primary pollutants such as carbon monoxide and nitrogen dioxide. In addition, for nearly all the HC cities, the concentrations of fine particulate matter (PM2.5) decreased substantially in 2020 compared to 2015. However, this was not the case for ozone, with the most significant increase of ozone observed for HC's central city, Harbin. This study highlights the importance of ozone reduction for further improving HC's air quality, and the importance of agricultural fire control for eliminating heavily-polluted and even off-the-charts PM2.5 episodes. [ABSTRACT FROM AUTHOR]