| China Xuanwei in Yunnan Province has been a region with a high incidence of lung cancer and mortality worldwide since the 1980 s.Researchers have conducted a large number of factors on the high incidence of lung cancer in Xuanwei from epidemiology,atmospheric science,and molecular biology.Research,in which indoor air pollution caused by the use of bituminous coal may be the reason for the high incidence of lung cancer in the Xuanwei area.Studies have suggested that the distribution of female lung cancer mortality in the Xuanwei-Fuyuan region is in good agreement with the distribution of the Late Permian coal seam.The main mineral form of bituminous coal produced in the region is chlorite,which is a silicate mineral with high iron content.Its high iron content catalyzes the emission of polycyclic aromatic hydrocarbons,resulting in a higher concentration of PAHs emitted from coal combustion in the Xuanwei area.At the same time,the aromatic compounds generated from the combustion of bituminous coal and the fine particulate matter are prone to produce environmental persistent free radicals(EPFRs).EPFRs,as a new type of environmental pollutants,can easily lead to oxidative stress reactions in the cells of living organisms,thereby creating health risks.Therefore,in addition to PAHs,we also examined the production of EPFRs and their combined effects with PAHs to measure possible health risks.This study selected coal-fired residents in high-incidence areas in Xuanwei as research subjects,and selected residents living in Liupanshui area as the control group.Experimental work can be summarized in two parts:1.Concern over the high iron content of bituminous coal used in the residents living in high-incidence areas in Xuanwei County and the potential health risks caused by the low iron content of free radicals in Liupanshui.The solutions produced relatively high concentrations of EPFRs.There was no significant correlation between free radical concentration and iron content in the coal of the two places.That is,freeradical data could not provide direct evidence for the high incidence of lung cancer in Xuanwei.However,high concentrations of free radicals may lead to an increase in PAH emissions,which we must consider.2.Pyrolysis of iron at 1:70 ratio in low iron content coal combustion,pyrolysis at different temperatures,and detection of pyrolysis results in free radicals and polycyclic aromatic hydrocarbons in coal combustion.The results show that the addition of elemental iron The coal produced a large number of carbon-based radicals at 350?.The higher levels of PAHs detected were PHE(3-ring),BKF(5-ring),Bap(5-ring),and Icdp(6-ring).DaA(5 rings)are all high-aromatic hydrocarbons,and the high-aromatic hydrocarbons are much more toxic than low-ring aromatics.At 350?,the free radical content of coal pyrolysis was detected to be higher than the free radical concentration at the time of pyrolysis at 500?,and the concentration of PAHs emitted from coal-fired pyrolysis at 350?was also higher than 500?.The concentration of pyrolytic PAHs emitted.The concentration of PAHs emitted at 350?was significantly different from that of PAHs emitted at 500?(p<0.05).Therefore,we conclude that at 350 ?,iron has a strong catalytic activity and can promote PAH emissions.And in the process of coal pyrolysis,the bridging bonds in the coal will break to generate free radicals,and the polymerization reaction between free radicals will form polycyclic aromatic hydrocarbons.Therefore,the generation of a large amount of free radicals during the pyrolysis of coal will also promote PAH emissions. |
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