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The seasonal distribution coefficients of traffic volume have not been yet taken into account in asphalt pavement design in China. Through comprehensive analysis on the assessed data and the factors affecting monthly distribution coefficients of traffic volume in different areas, the monthly and seasonal distribution coefficients of traffic volume in Harbin city, China has been predicted and determined using a back propagation (BP) neural network algorithm. The research contents involve data investigation and analysis of monthly distribution coefficients of traffic volume, analysing the factors affecting the mentioned coefficients, prediction and determination of monthly and seasonal distribution coefficients of traffic volume, and application of those coefficients, etc. Through the application of monthly and seasonal distribution coefficients, the seasonal traffic volumes in a year were calculated, and the application results demonstrated that the seasonal distribution of traffic volume has a scientific rationality. In addition, this study indicated that the seasonal traffic volume could accurately evaluate the actual conditions about axle loads on the pavement, resulting in the asphalt pavement design to be more rational. Eventually, the findings could appropriately meet the requirements of actual vehicle loads passing on the road surface. [ABSTRACT FROM AUTHOR]

Metals in urban park soil are closely related to traffic emissions, which adversely affect soil quality and human health. However, little is known about the quantitative impacts of traffic on the spatial variations of metals in park soil after the banning of leaded gasoline. Herein, concentrations of Cu, Pb and Zn in surface soil of four recreational parks of Sydney (Ashfield, Robson, Lamberts and Leichhardt) were measured to evaluate their spatial characteristics in contamination, ecological and health risks and relationships with traffic emissions. Contamination of metals are assessed by contamination factor (CF). Normalized metal concentrations (<63 μm) in the park soil were 24-614, 23-3520 and 99-3060 mg kg -1 for Cu, Pb and Zn, respectively, and CFs ranged from 1.4 to 207, whose variations inter- and intra-parks were related to traffic volumes. Traffic emission accounted for 72-84% of metals contamination in soil of Ashfield, Robson and Lamberts by sites, whereas the values were 25-70% for Leichhardt due to the absence of a surrounding arterial road. In Ashfield and Robson Parks, metal concentrations from traffic decreased exponentially with distance from arterial roads. Metals in Lamberts Park and in areas near arterial roads in Ashfield and Robson Parks may raise ecological risk, and traffic sources contributed to 61-81% of the risk. The ranges of ecological risk zones away from arterial roads and average daily traffic volumes showed an exponential relationship. Copper and Zn in soil of the four parks have no non-carcinogenic health risk for children and adults, and Pb has negligible health risk for adults. Lead in Lamberts Park and in sites near arterial roads of Ashfield and Robson Parks may raise non-carcinogenic risk for children (HI > 1) due to traffic emissions. These results emphasize the remarkable influence of traffic emissions on urban soil metal, which can be predicated quantitatively by traffic volume., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Atmospheric NOx concentrations (including NO2 and NO) on the roadside environments of urban trunk, belt highway and suburban road as well as a reference in a forest area were measured. NOx concentrations on roadside environments tended to be higher than that on the reference. With the exception of suburban road, NOx concentrations over both of the urban trunk and belt highway exceeded the limited value of National Air Environmental Quality Standards. Gradient measurement of NOx on the downwind side of the belt highway shows that it declined to background level over 100 m from the road edge. [ABSTRACT FROM AUTHOR]

During 2020, the COVID-19 pandemic resulted in a widespread lockdown in many cities in China. In this study, we assessed the impact of changes in human activities on air quality during the COVID-19 pandemic by determining the relationships between air quality, traffic volume, and meteorological conditions. The megacities of Wuhan, Beijing, Shanghai, and Guangzhou were selected as the study area, and the variation trends of air pollutants for the period January-May between 2016 and 2020 were analyzed. The passenger volume of public transportation (PVPT) and the passenger volume of taxis (PVT) along with data on precipitation, temperature, relative humidity, wind speed, and boundary layer height were used to identify and quantify the driving force of the air pollution variation. The results showed that the change rates of fine particulate matter (PM 2.5 ), NO 2 , and SO 2 before and during the lockdown in the four megacities ranged from -49.9% to 78.2% (average: -9.4% ± 59.3%), -55.4% to -32.3% (average: -43.0% ± 9.7%), and - 21.1% to 11.9% (average: -10.9% ± 15.4%), respectively. The response of NO 2 to the lockdown was the most sensitive, while the response of PM 2.5 was smaller and more delayed. During the lockdown period, haze from uninterrupted industrial emissions and fireworks under the effect of air mass transport from surrounding areas and adverse climate conditions was probably the cause of abnormally high PM 2.5 concentrations in Beijing. In addition, the PVT was the most significant factor for NO 2 , and meteorology had a greater impact on PM 2.5 than NO 2 and SO 2 . There is a need for more national-level policies for limiting firework displays and traffic emissions, as well as further studies on the formation and transmission of secondary air pollutants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Near-surface atmospheric CO 2 concentration and δ 13 C value in four greenspaces and on their adjacent roads in Beijing were measured by off-axis integrated cavity output spectroscopy to analyze the influence of urban greenspace on spatial distribution of near-surface atmospheric CO 2 . The results showed that atmospheric CO 2 concentration and δ 13 C value varied substantially both temporally and spatially. The highest CO 2 concentration was found in the urban area, followed by the suburbs, and the lowest CO 2 concentration was in the outer suburbs. There was a clear near-surface atmospheric CO 2 dome, but a reverse pattern for δ 13 C value. During the non-growing season, the ΔCO 2 and Δ 13 C between greenspace and adjacent roads were low. The differences among the four experimental sites were not significant. In the growing season, the ΔCO 2 and Δ 13 C at the BLA4 th RR (Beijing Institute of Landscape Architecture and 4 th Ring Road) and BOP5 th RR (Beijing Olympic Forest Park and 5 th Ring Road) in urban areas were significantly higher than those at DPSR (Daoxianghu Park and Sujiatuo Road) and MTGMR (Mentougou forest experimental station and an adjacent road) in the suburbs. During the growing and non-growing seasons, CO 2 concentration of all examined sites was significantly positively related with the traffic volume, indicating that traffic volume was an important factor affecting the spatial distribution of CO 2 . The δ 13 C value was significantly negatively related with traffic volume during non-growing season, but no significant relationship was found during the growing season. The ΔCO 2 concentration between the four green-spaces and their adjacent roads were significantly negatively related with leaf area index (LAI). The Δ 13 C value were significantly logarithmically related to LAI. Results from stepwise regression showed that solar radiation, temperature, and LAI significantly affected ΔCO 2 in urban areas and suburbs during the growing season, and that temperature and solar radiation were the major driving factors for Δ 13 C. During the growing season, plants in the greenspaces assimilated CO 2 via photosynthesis and thus reduced the near-surface atmospheric CO 2 concentration. Our results indicate that green-spaces play a positive role in improving ecological environment in urban areas.