Traffic Density-Related Black Carbon Distribution: Impact of Wind in a Basin Town

Black carbon is one of the riskiest particle matter pollutants that is harmful to human health. Although it has been increasingly investigated, factors that depend on black carbon distribution and concentration are still insufficiently researched. Variables, such as traffic density, wind speeds, and ground levels can lead to substantial variations of black carbon concentrations and potential exposure, which is even riskier for people living in less-airy sites. Therefore, this paper “fills the gaps” by studying black carbon distribution variations, concentrations, and oscillations, with special emphasis on traffic density and road segments, at multiple locations, in a small city located in a basin, with frequent temperature inversions and infrequent low wind speeds. As wind speed has a significant impact on black carbon concentration trends, it is critical to present how low wind speeds influence black carbon dispersion in a basin city, and how black carbon is dependent on traffic density. Our results revealed that when the wind reached speeds of 1 ms−1, black carbon concentrations actually increased. In lengthy wind periods, when wind speeds reached 2 or 3 ms−1, black carbon concentrations decreased during rush hour and in the time of severe winter biomass burning. By observing the results, it could be concluded that black carbon persists longer in higher altitudes than near ground level. Black carbon concentration oscillations were also seen as more pronounced on main roads with higher traffic density. The more the traffic decreases and becomes steady, the more black carbon concentrations oscillate.

Submicron Aerosol and Black Carbon in the Troposphere of Southwestern Siberia (1997–2018)

Based on the multiyear measurements in the surface atmospheric layer (from five stations) and regular flights of aircraft laboratory over the background region of Southwestern Siberia, the compositions of mass concentrations of submicron aerosol and absorbing substances (soot and black carbon) are analyzed. The annual average concentrations of submicron aerosol and black carbon were found to be maximal in 1997, 2012, and 2016, when the largest numbers of wildfires occurred across the entire territory of Siberia. No significant, unidirectional trend of interannual variations in the concentration of submicron particles was observed, while the concentration of absorbing substance reliably decreased by 1.5% each year. To estimate the effect of urban pollutants, mass concentrations of aerosol and absorbing substance in the surface layer at the Aerosol Station (in the suburban region of Tomsk) were compared to those at the Fonovaya Observatory (in the background region). It was shown that the largest contribution of anthropogenic sources in the suburban region was observed in the winter season, while minimal difference was observed in the warm period of the year. The seasonal behavior of the concentrations of elemental carbon at three stations in Novosibirsk Oblast almost completely matched the dynamics of the variations in the black carbon concentration in the atmosphere of Tomsk Oblast. Data of aircraft sensing in the troposphere of the background region of Southwestern Siberia (2000–2018) were used to determine the average values of the vertical distribution of the submicron aerosol and black carbon concentrations in the altitude range of 0.5–7 km for each season. It was found that at altitudes of 0.5–7 km, there were no unidirectional trends in submicron aerosol; however, there was an increase of black carbon concentration at all altitudes with a positive trend of 5.3 ± 2.2% per year at an altitude of 1.5 km, significant at a p-value = 0.05.

Comparing Seasonal Diffences of Black Carbon in Tibetan Plateau transported from South Asia using WRF-Chem

<p>The melting of glaciers and snow on the Qinghai-Tibet Plateau, known as the Earth’s “Third Pole” and “World Water Tower”, is source of fresh water for hundreds of millions of people in South Asia, Southeast Asia, and East Asia, but it is now suffering from an unprecedented crisis. The black carbon deposited on the surface of the glacier will reduce the snow albedo and absorb more solar radiation, leading to accelerated melting of ice and snow.Previous studies have shown that black carbon from South Asia is one of the main sources of the Qinghai-Tibet Plateau, and the transportation of black carbon to the Qinghai-Tibet Plateau presents obviously seasonal differences.However, the transport of black carbon from South Asia to the Qinghai-Tibet Plateau in different seasons shows a completely opposite trend to wind field conditions.This study uses the WRF-Chem model to study the transmission mechanism of South Asian black carbon to the Tibetan Plateau in April (pre-monsoon), July (summer monsoon) and December (winter monsoon).MIX emission inventory and Peking University's global black carbon emission inventory (PKU-BC) were involved to analyze the seasonal distribution of black carbon concentration, dry and wet deposition in the Qinghai-Tibet Plateau and South Asia, and the distribution of BC concentration and wind field at different altitudes.Combined with the vertical distribution of BC concentration across the Himalayas, the transport mechanism of black carbon in South Asia to Qinghai-Tibet Plateau in different seasons is studied.In the selected three months, December had the highest surface black carbon concentration in South Asia and the Qinghai-Tibet Plateau, while July had the lowest black carbon concentration; Mainly because of the large amount of wet deposition of black carbon brought about by the heavy precipitation in South Asia in July;According to the vertical distribution of black carbon,black carbon can climb up the hillside and eventually reach the southern slope of the Qinghai-Tibet Plateau in April. In July, black carbon is mainly distributed below 3km. In December, black carbon can be uplifted to 4-5km, and finally transported into Qinghai-Tibet Plateau.</p>