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

2015 ◽  
Vol 15 (12) ◽  
pp. 16175-16213
Author(s):  
B. L. Zhuang ◽  
T. J. Wang ◽  
J. Liu ◽  
Y. Ma ◽  
C. Q. Yin ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Yangtze River ◽  
Temporal Variations ◽  
Yangtze River Delta ◽  
River Delta ◽  
Entire Study ◽  
Near Surface ◽  
Absorbing Aerosols ◽  
The Impact ◽  
532 Nm

Abstract. Absorbing aerosols can significantly modulate shortwave solar radiation in the atmosphere, affecting regional and global climate. Aerosol absorption coefficient (AAC) is an indicator to assess the impact of absorbing aerosols on radiative forcing. In this study, the near-surface AAC and absorption angstrom exponent (AAE) in urban Nanjing, China, are characterized on the basis of measurements in 2012 and 2013 using the 7-channel Aethalometer (model AE-31, Magee Scientific, USA). The AAC is estimated with direct and indirect corrections, which show 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 urban Nanjing, which is much lower than that in Pearl River Delta and as the same as that in rural areas (Lin'an) in Yangtze River Delta. The AAC in urban Nanjing shows strong seasonality (diurnal variations), high in cold seasons (at rush hours) and low in summer (in afternoon). It also show synoptic and quasi-two-week cycles in response to weather systems. Its frequency distribution follows a typical lognormal 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 pollutions. Air masses 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 compared to that from the Weingartner correction (Weingartner et al., 2003). Low AAEs mainly appear in summer in response to the relative humidity (RH). AAC increases with increasing AAE at a fixed aerosol loading. The RH-AAC relationship is more complex. Overall, AAC peaks around RH values of 40% (1.3 < AAE < 1.6), 65% (AAE < 1.3 and AAE > 1.6), and 80% (1.3 < AAE < 1.6).

The Impact on Athlete Health of Sulfate, Nitrate and Ammonium in Atmospheric Aerosol in the Urban Area of Yangtze River Delta, China

2011 ◽  
Vol 402 ◽  
pp. 860-863
Author(s):  
Bin Jiang
Keyword(s):  
Urban Area ◽  
Ion Chromatography ◽  
Atmospheric Aerosol ◽  
Yangtze River ◽  
Fine Particles ◽  
Yangtze River Delta ◽  
Residential Area ◽  
River Delta ◽  
The Impact

In this paper, aerosol samples were collected with Andersen cascade sampler on typical polluted days at residential area in Hangzhou, China. The concentrations of sulfate, nitrate and ammonium in aerosol were analyzed by the ion chromatography. Results showed the concentrations of SO42-, NO3- and NH4+ on polluted days were 21.4, 31.2 and 10.8µg m-3 in fine particles, respectively, and were 1.3-1.7 times higher than on unpolluted days. SO42-, NO3- and NH4+ in fine particles were the main threat of athlete health in the urban area of Yangtze River delta.

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.

scholarly journals Policies towards Migrants in the Yangtze River Delta Urban Region, China: Does Local Hukou Still Matter after the Hukou Reform?

2020 ◽  
Vol 12 (24) ◽  
pp. 10448
Author(s):  
Qian Zhang ◽  
Joris Hoekstra
Keyword(s):  
Yangtze River ◽  
Yangtze River Delta ◽  
River Delta ◽  
Urban Region ◽  
The Yangtze River ◽  
Access Policy ◽  
Hukou Reform ◽  
Access Policies ◽  
The Impact ◽  
The Yangtze River Delta

The 2014 hukou reform introduced by the Chinese central government was a turning point in China’s policies towards migration. Different from the previous hukou policies, which were largely exclusionary, the reformed policy encouraged migrants to permanently settle in their destination cities and make use of the public services available there. However, the actual results and consequences of this policy seem to vary between cities. This is due to the fact that Chinese municipal governments still have their own discretionary power when it comes to defining the criteria for accessing a local hukou. This raises the question of what the real impact of the hukou policy reform has been. This paper attempts to answer this question. It starts with a hukou access policy analysis of 20 different cities in the Yangtze River delta urban region. This analysis shows that the strictness of the local hukou access policy is related to city specific factors such as economic strength, share of migrant population, and population size. In the second part of the paper, we examine the impact of local hukou access policies on the intentions of migrants. Based on two logistic regression models, we find that the stricter the local hukou access policy is, the more willing migrants are to convert their current hukou into a local hukou. Furthermore, we observed that the settlement intention of migrants has a V-shaped rather than a linear relation with the strictness of local hukou access policies. Cities with relatively loose and cities with relatively strict hukou access policies are more desired as permanent settlement location than cities with moderately strict hukou access policies.

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