Formation and causes of NO x pollution on the east side of the Taihang Mountains in China

Abstract

Tropospheric column amounts of NO 2 from OMI/Aura products were applied to investigate the seasonal variation of NO x on the east side of the Taihang Mountains (ESTM) in China. The NO 2 concentration varied seasonally, with winter maxima and summer minima. To explore the causes of the heavy NO 2 pollution in this region, wind field simulations were conducted by using the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5). MM5 simulations showed that wind directions in the ESTM region were dominated by northeasterly and northwesterly winds throughout the year and to a lesser degree by southwesterlies. Elevated NO 2 concentrations (higher than 50×10 15 molec/cm 2 ) occurred in three meteorological situations: convergent wind fields (5 days), northeasterly winds (2 days), and calm days (1 day) in January. Although the local anthropogenic NO x emission strength was not so high as that in other developed areas, the calms and frequent occurrence of convergent wind fields, as well as unfavorable terrains for diffusion, resulted in the accumulation of atmospheric pollutants and hence heavy NO x pollution. Furthermore, long-distance NO x transportation from the Beijing-Tianjin-Tangshan region to the ESTM area could be seen when the wind was from a northeasterly direction, especially under high wind speeds.

Satellite remote sensing of changes in NO x emissions over China during 1996–2010

“…Recently developed space-borne remote sensing technology provides an alternative and effective approach to the quantification of air pollutants [7,8]. Among the various species amenable to satellite observation, NO 2 has been studied the most broadly [9][10][11][12][13]. This is because: (1) retrieval of NO 2 is less affected by the other strongly absorbing atmospheric species; and (2) NO 2 has a short atmospheric lifetime, which allows closer linking of the measured NO 2 columns to the surface emissions of NO x [10,14,15].…”

Nitrogen Oxides Emissions from Thermal Power Plants in China: Current Status and Future Predictions

“…Anthropogenic nitrogen oxides (NO x = NO + NO 2 ) emissions are associated with significant impacts on ecosystems and human health, including an increase in ground-level ozone, formation of fine particles, and regional acid deposition. − Local and regional photochemical smog and fine particulate (PM 10 /PM 2.5 ) formation, along with very high local NO x /NO 2 concentrations, are considered as severe environmental problems in China. − In addition, the variation of [SO 4 2– /NO 3 – ] ratio in precipitation composition reveals that acid deposition in many regions has been changing from a typical sulfate-controlled type to sulfate-and-nitrate-controlled type …”

“…During the past two decades, a series of studies on anthropogenic NO x emission inventories have been conducted, indicating that the power plants sector accounts for 21–44% of Chinese national NO x emissions. ,− Consequently, the power plant sector is regarded as the first priority for NO x emissions reduction in the Chinese national 12th five-year-plan (2011–2015). A rigorous goal of 29% NO x reduction compared with emissions in 2010 from thermal power plants for the target year 2015 has been set by the Chinese central government. , …”