Contamination Characteristics And Pollution Control Methods Of Atmospheric Nitro-polycyclic Aromatic Hydrocarbons In Ningdong Energy And Chemical Industry Base

Nitro-aromatic polycyclic hydrocarbons(NPAHs)are characterized by low polarity,semi-volatile,high fat-soluble and hard-to-decompose properties.Carcinogenicity and mutagenicity are 100 to 100,000 times higher than that of maternal PAHs,which is extremely harmful to the human body.As the part of the Energy Golden Triangle,Ningdong Energy and Chemical Industry Base(NECIB)is located in the east of Ningxia Province,the southeast of Yinchuan City.The NECIB is a large-scale national coal production and chemical industry base and one of largest coal to liquid industries in the world.However,the development of NECIB also results in air pollution in this industrial base and surroundings.There are still large knowledge gaps in the emission and spatial-temporal distribution of toxic chemicals such as aromatic polycyclic aromatic hydrocarbons(PAHs)and nitro-PAHs in the NECIB which are often released from fossil fuel burning.This study aimed to fill this knowledge gap and enhance our understanding of sources and intensities of PAHs pollution in the NECIB.The results could provide scientific support to relevant industries and government agents to develop appropriate measures and policies in control and mitigation of air pollution.To assess temporal and spatial distribution,seasonal differences,and sources for atmospheric NPAHs and dry deposition flux of NECIB,gas phase and dry deposition for NPAHs were collected using passive air samplers(PAS-PUF)and dry deposition samplers(PAS-DD).The results show that:(1)The seasonal mean concentration levels of 12 NPAHs are higher than many countries,but that are similar to that measured in China domestic atmospheric concentration.The concentrations and dry deposition fluxes of NPAHs during heating season are higher than those during non-heating season.(2)The ratios of 2-NF/ 1-NP and NPAHs/ p PAHs suggested that the main source of atmospheric NPAHs sampled in the NECIB was from incomplete combustion in coal and chemical industries during heating season and was from photochemical reactions during non-heating season.Among measured NPAHs,6-NC and 2-NFL were predominate congeners inthe both seasons,while 9-NPhe and 2-NF are not significant.(3)Among the 11 sampling sites,the Baofeng Energy Industrial Base exhibited the highest level of NPAHs.NPAH concentrations at other sampling sites were,to some extent,identical.(4)Based on the results of this sampling study,following control and mitigation measures should be taken into consideration to reduce NPAH emissions: 1.to adopt state-of-art technologies to improve the fuel composition and combustion process;2.to improve the production process and waste recycling;3.to implement desulfurization and denitrification technology to reduce direct emissions;and 4.to follow national standards for air pollution emissions and eliminate illegal discharge.