scholarly journals Spatial-Temporal Variations and Socio-Economic Influencing Factors of Air Quality in China’s Major Cities During COVID-19

2021 ◽  
Author(s):  
Xinlin Yan ◽  
Tao Sun
Keyword(s):  
Air Quality ◽  
Influencing Factors ◽  
Central Government ◽  
National Level ◽  
Temporal Variations ◽  
Yangtze River Delta ◽  
River Delta ◽  
Added Value ◽  
The Government ◽  
Pm2.5 And Pm10

Abstract Due to the emergence of COVID-19 in Wuhan in January 2020, the central government of China announced that Wuhan was in "lockdown," the activities of the country's citizens were restricted. This study selected three standard air quality indexes AQI, PM2.5, and PM10 of 2017-2021 in 40 major cities of seven regions in China to analyze their changes, spatial-temporal distributions, and socio-economic influencing factors. Compared with 2019, AQI, PM2.5, and PM10 decreased by 22.54%, 13.94%, and 22.30%, respectively, and the days with AQI level "A" increased from 89% to 100% during the "lockdown" in 2020. Due to different degrees of industrialization, the decline range of Northeast, Yangtze River Delta, and Pearl River Delta areas is more than that of the Southwest, BTH, Northwest, and Central areas, the concentration of air pollutants shows significant regional characteristics. The AQI before and after the "lockdown" in 2020 showed significant spatial autocorrelation, and the cities' AQI in the north present high aggregation, and the cities in the south are in low aggregation. From the data at the national level, the changes of the four socio-economic factors of roadway passenger volume (RPV), construction area (CA), coal-fired power (CP), and the proportion of industrial added value in GDP (IND) significantly influenced AQI. This study gives regulators confidence that if the government implements regionalized air quality improvement policies according to the characteristics of each region in China and reasonably plans socio-economic activities, it is expected to improve China's air quality sustainably.

scholarly journals The Spatio-Temporal Analysis of Urban-Rural Coordinated Development and Its Driving Forces in Yangtze River Delta

Land ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 495
Author(s):  
Daizhong Tang ◽  
Mengyuan Mao ◽  
Jiangang Shi ◽  
Wenwen Hua
Keyword(s):  
Influencing Factors ◽  
Yangtze River ◽  
Driving Forces ◽  
Yangtze River Delta ◽  
River Delta ◽  
Urban Agglomeration ◽  
System Level ◽  
Actual State ◽  
Coordinated Development ◽  
Urban Rural

This paper conducts an analytical study on the urban-rural coordinated development (URCD) in the Yangtze River Delta urban agglomeration (YRDUA), and uses data from 2000–2015 of 27 central cities to study the spatial and temporal evolution patterns of URCD and to discover the influencing factors and driving forces behind it through PCA, ESDA and spatial regression models. It reveals that URCD of the YRDUA shows an obvious club convergence phenomenon during the research duration. The regions with high-level URCD gather mainly in the central part of the urban agglomeration, while the remaining regions mostly have low-level URCD, reflecting the regional aggregation phenomenon of spatial divergence. At the same time, we split URCD into efficiency and equity: urban-rural efficient development (URED) also exhibits similar spatiotemporal evolution patterns, but the patterns of urban-rural balanced development (URBD) show some variability. Finally, by analyzing the driving forces in major years during 2000–2015, it can be concluded that: (i) In recent years, influencing factors such as government financial input and consumption no longer play the main driving role. (ii) Influencing factors such as industrialization degree, fixed asset investment and foreign investment even limit URCD in some years. The above results also show that the government should redesign at the system level to give full play to the contributing factors depending on the actual state of development in different regions and promote the coordinated development of urban and rural areas. The results of this study show that the idea of measuring URCD from two dimensions of efficiency and equity is practical and feasible, and the spatial econometric model can reveal the spatial distribution heterogeneity and time evolution characteristics of regional development, which can provide useful insights for urban-rural integration development of other countries and regions.

scholarly journals Absorption coefficient of urban aerosol in Nanjing, west Yangtze River Delta, China

2015 ◽  
Vol 15 (23) ◽  
pp. 13633-13646 ◽  
Author(s):  
B. L. Zhuang ◽  
T. J. Wang ◽  
J. Liu ◽  
Y. Ma ◽  
C. Q. Yin ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Urban Area ◽  
Yangtze River ◽  
Temporal Variations ◽  
Yangtze River Delta ◽  
River Delta ◽  
Near Surface ◽  
Absorbing Aerosols ◽  
The Impact ◽  
532 Nm

Abstract. Absorbing aerosols can significantly modulate short-wave solar radiation in the atmosphere, affecting regional and global climate. The aerosol absorption coefficient (AAC) is an indicator that assesses the impact of absorbing aerosols on radiative forcing. In this study, the near-surface AAC and absorption Ångström exponent (AAE) in the urban area of Nanjing, China, are characterized on the basis of measurements in 2012 and 2013 using the seven-channel Aethalometer (model AE-31, Magee Scientific, USA). The AAC is estimated with direct and indirect corrections, which result in consistent temporal variations and magnitudes of AAC at 532 nm. The mean AAC at 532 nm is about 43.23 ± 28.13 M m−1 in the urban area of Nanjing, which is much lower than that in Pearl River Delta and the same as in rural areas (Lin'an) in Yangtze River Delta. The AAC in the urban area of Nanjing shows strong seasonality (diurnal variations); it is high in cold seasons (at rush hour) and low in summer (in the afternoon). It also shows synoptic and quasi-2-week cycles in response to weather systems. Its frequency distribution follows a typical log-normal pattern. The 532 nm AAC ranging from 15 to 65 M m−1 dominates, accounting for more than 72 % of the total data samples in the entire study period. Frequent high pollution episodes, such as those observed in June 2012 and in winter 2013, greatly enhanced AAC and altered its temporal variations and frequency distributions. These episodes are mostly due to local emissions and regional pollution. Air masses flowing from northern China to Nanjing can sometimes be highly polluted and lead to high AAC at the site. AAE at 660/470 nm from the Schmid correction (Schmid et al., 2006) is about 1.56, which might be more reasonable than from the Weingartner correction (Weingartner et al., 2003). Low AAEs mainly occur in summer, likely due to high relative humidity (RH) in the season. AAC increases with increasing AAE at a fixed aerosol loading. The RH–AAC relationship is more complex. Overall, AAC peaks at RH values of around 40 % (1.3 < AAE < 1.6), 65 % (AAE < 1.3 and AAE > 1.6), and 80 % (1.3 < AAE < 1.6).

scholarly journals The influence of spatiality on shipping emissions, air quality and potential human exposure in Yangtze River Delta/Shanghai, China

2018 ◽  
Author(s):  
Junlan Feng ◽  
Yan Zhang ◽  
Shanshan Li ◽  
Jingbo Mao ◽  
Allison P. Patton ◽  
...  
Keyword(s):  
Air Quality ◽  
Yangtze River ◽  
Human Exposure ◽  
Regional Scale ◽  
Yangtze River Delta ◽  
River Delta ◽  
Population Exposure ◽  
Inland Water ◽  
The Yrd ◽  
The Impact

Abstract. The Yangtze River Delta (YRD) and the megacity of Shanghai are host to one of the busiest port clusters in the world, the region also suffers from high levels of air pollution. The goal of this study was to estimate the contributions of shipping to emissions, air quality, and population exposure and characterize their dependence on the geographic spatiality of ship lanes from the regional scale to city scale for 2015. The WRF-CMAQ model was used to simulate the influence of coastal and inland-water shipping, in port emissions, shipping-related cargo transport on air quality and, population-weighted concentrations, a measure of human exposure. Our results showed that the impact of shipping on air quality in the YRD was attributable primarily to shipping emissions within 12 NM of shore, but emissions coming from the coastal area of 24 to 96 NM still contributed substantially to ship-related PM2.5 concentrations in YRD. The overall contribution of ships to PM2.5 concentration in YRD could reach to 4.62 μg/m3 in summer when monsoon winds transport shipping emissions onshore. In Shanghai city, inland-water going ships were major contributors (40–80 %) to the shipping impact on urban air quality. Given the proximity of inland-water ships to urban populations of Shanghai, the emissions of inland-water ships contributed more to population-weighted concentrations. These research results provide scientific evidence to inform policies for controlling future shipping emissions; in particular, stricter standards could be considered for the ships on inland rivers and other waterways close to residential regions.

Government cooperation, market integration, and energy efficiency in urban agglomerations—Based on the quasi-natural experiment of the Yangtze River Delta Urban Economic Coordination Committee

2021 ◽  
pp. 0958305X2110474
Author(s):  
Da Gao ◽  
Ge Li ◽  
Yi Li
Keyword(s):  
Energy Efficiency ◽  
Yangtze River ◽  
Market Integration ◽  
Natural Experiment ◽  
Yangtze River Delta ◽  
River Delta ◽  
Urban Agglomeration ◽  
The Yangtze River ◽  
The Government ◽  
The Yangtze River Delta

Energy efficiency is the key to green development, and the government plays a vital role in energy efficiency. This paper clarifies the mechanism by which the Yangtze River Delta Economic Coordination Committee affects the energy efficiency of urban agglomeration by promoting market integration. Based on panel data of China's prefecture-level cities from 2004 to 2017, we take the Yangtze River Delta Economic Coordination Committee as a quasi-natural experiment of government cooperation and use the difference-in-difference method to test whether this organization has enhanced the energy efficiency of urban agglomeration. The results show that the Yangtze River Delta Economic Coordination Committee can significantly improve energy efficiency in urban agglomerations. The mechanism analysis shows that it reduces the energy consumption per unit of gross domestic product by enhancing the marketization level, perfecting the relationship between the government and the market, and improving the factor market development. The heterogeneity analysis shows that cities with lower city size, lower level of innovation, and cleaner industrial structures gain more benefits in energy efficiency from government cooperation in urban agglomeration. This paper provides empirical evidence for cities to realize integrated energy conservation through government cooperation and market integration.

scholarly journals Influence of Thermal Effects on Qinghai-Tibet Plateau on Air Quality in Typical Regions of China in Winter

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 50
Author(s):  
Yanjun Li ◽  
Xingqin An ◽  
Guangzhou Fan ◽  
Chao Wang ◽  
Yang Zhao ◽  
...  
Keyword(s):  
Air Quality ◽  
Heat Source ◽  
Yangtze River Delta ◽  
River Delta ◽  
Tibet Plateau ◽  
Southeast Region ◽  
Cold Source ◽  
Heavy Pollution ◽  
Northwest Region ◽  
Qinghai Tibet Plateau

In this paper, the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) monthly average reanalysis data from 1954 to 2017, haze days observation data from 1954 to 2017, and PM2.5 daily average mass concentration data from 2013 to 2017 are collected and collated. Firstly, the atmospheric apparent heat source on the Qinghai-Tibet Plateau is estimated based on thermodynamic equations. The correlation between the atmospheric apparent heat source (Q1) on the Qinghai-Tibet Plateau and the air quality in China, especially in the five typical regions (Beijing-Tianjin-Hebei, Fen-Wei Plain, Yangtze River Delta, Pearl River Delta, and Sichuan-Chongqing regions) is analyzed and studied. Through comprehensive diagnosis and synthesis, the differences of the three-dimensional spatial distribution of the circulation field and temperature field (planes and sections) in China and the typical regions in the strong and weak years of the apparent heat source Q1 on the Qinghai-Tibet Plateau in winter are compared, and the different distribution characteristics of the climate circulation background causing the strong and weak years of Q1 on the Qinghai-Tibet Plateau and the influence mechanism on the air quality in different regions in China are discussed. The results show that the spatial distribution of correlation between Q1 on the Qinghai-Tibet Plateau and PM2.5 in December has a northeast-southwest boundary. There is a negative correlation in the southeast region of the boundary, with heavy pollution when the cold source is strong and light pollution when the cold source is weak, while there is a positive correlation in the northwest region of the boundary, with light pollution when the cold source is strong and heavy pollution when the cold source is weak. The Q1 on Qinghai-Tibet Plateau is negatively correlated with air pollution in Beijing-Tianjin-Hebei and Fen-Wei Plain located in the northwest region of the boundary but positively correlated with air pollution in the Yangtze River Delta, Pearl River Delta, and Sichuan-Chongqing regions located in the southeast region of the boundary. In the cold source strong year, the northerly winds are stronger in the middle and high latitudes, and there is an abnormal northerly downward flow in the southeast region, thus the pollution is aggravated by the suppression of convection–diffusion in a downward flow. However, abnormal updraft in the northwest region exists, reducing pollution. In the cold source weak year, the situation is just the opposite.

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