| Xuan Wei, Yunnan Province, is famous for the highest lung cancer mortality rates in China.Previous research results showed that the high lung cancer mortality rate was associated withexposure to indoor smoky coal emission pollutants which contained high levels of polycyclicaromatic hydrocarbons (PAHs).However, more recent study demonstrated that nanoquartzembedded in the soot emissions from coal combustion was found to be associated with the lungcancer risk. Therefore, the mechanism of the high lung incidence is still unclear. In this study,15coal samples which were produced in Laibin town (higher lung incidence area) and its aroundtowns were collected and mineral composition in the samples were investigated.Physicochemicalcharacterization and biological activity of raw coals and coal emission particles was studied, andtried to provide new scientific date for the occurrence of lung cancer in Xuan Wei.The results showed that:(1) Xuan Wei coal is bituminous coal containing volatile, highvitrinite. Major minerals in Xuan Wei coals are quartz, chamosite, calcite, andkaolinite.Crystallization of minerals in different coal samples are different in. Diameter of quartzgrains mostly distributed in the size range of1~2μm, and even some of quartz grains with thediameter less than1μm could be found in the coal. The irregular fine quartz particles could befound in the crack of coal, coexisting with chamosite. This phenomenon implied that the quartz inXuan Wei coal was deposited from a siliceous hydrothermal fluid which contained a significantamount of Fe and Al, rather thant from clastic rock deposition. Additionally, individualparticlesstatistical results showed that minerals in the coal which collected in Laibin, containedmuch more “Si+Fe” particles compared than that in other coal samples.(2) Most of particles from coal combustion were in the size1~10μm. Particles from the coalcombustion could be identified as soot particles (C, S); regular mineral particles (with mainchemical elements, Si, O, Fe, Zn), smooth or not smooth spherical particles(C、O、Si、Al),irregular (deformed) bulk material（C、O、Cl）, biological particles（C、O），regular mineralparticles(Si, O, Fe, Zn）and other unknown particles. Soots and fly ashes were the main particletypes and could easily been found in the coarse particles (about10μm in size), while the mineralparticles and quatz were always been found in the small particles with diameter less than1μm;STEM results further confirmed the main mineral component of single particle are silicates, sulfates and Fe-containing minerals.(3) The ICP-AES results show the elements are divided into two categories based on theirmass concentration in different components: the main elements (Al, Ca, Fe, Mg, Mn, K)and thetrace elements(As, Cd, Co, Cr, Cu, Ni, Pb, Se, V, Zn). The mass concentration distribution modelof the chemical elements was: ash>bottom ash>coal. The relative content of main elements Al andCa were all high in raw coal and inbottom ash fly ash.The percent of Fe in raw coal and bottomash were3.24%~37.73%and3.09%~40.83%respectively,while it in fly ash isonly1.05%~6.27%. The percentage of K in raw coal and bottom are only0.66%~1,78%,exceptZiquan C2coal, while in PM10-1and PM1, they were26.83%~58.43%and28.87%~36.33%respectly.The relative content of trace elements As, Co, Cr, Cu, Ni, V, Zn in raw coal and bottomash were higher than Cr, Pb and Se, in which the concentration of Se was rarely; while in fly ash,the highest percentage was Cr32.30%~72.27%,then Zn0.03%~37.76%， and then As9.43%~29.27%；the relative percentage of Se was0.00%~14.43%, higher than it in raw coal andbottom ash.(4)The results of MTT showed that: A549cell activity induced by different samples (rawcoal, PM10-1and PM1) was different. The higher the exposure dose, the lower the cell viability;water-soluble fractions of PM10-1and PM1had higher ability to cause the A549cells deathcompared with that caused by other components. Cell viability caused by Guangming B2, TianbaK1+K2and Ziquan C2coal sample were25.5%,52.9%and71.2%respectively. Our MTT resultsalso demonstrated that significant differences exist between any two different components(different coal samples, different fractions); This significance mainly existed in water-solublefraction and whole sample of PM10-1and PM1.(5)DTT is a method to assess oxidative ability of particulate matters. Our results show that:the rate of consumption DTT induced by water-soluble fractions is higher than that of wholesamples, and the rate of consumption DTT caused by PM10-1and PM1was higher than that ofraw coal and bottom ash; the significant differences tests show that the significant differencesexisted among the water-soluble fractions of PM1, the whole sample of raw coals and thewater-soluble fractions of bottom ash; Zi quan C2coal has significant difference compared to theother coals, as well as Guangming B2coal.The relevance of the result between DTT and MTT have been compared in the exposure dose of40μg/mL, the results show that: the results of the different components in Guangming B2coaland Ziquan C2coal show a positive correlation between MTT and DTT methods, the correlationcoefficients R2were0.8147and0.9799respectively. The results of the whole samples in TianbaK1+K2coal show a positive correlation between MTT and DTT methods, while the results of thewater-soluble fractions in Tianba K1+K2coal show a negative correlation between MTT and DTTmethods. In the whole, the results show a positive correlation between MTT and DTT methods,indicating that the smaller the particle size, the more likely to cause cells to produce reactiveoxygen species, the stronger to inhibit the growth activity of cells.Correlation coefficients R2between the main heavy metals (Fe、Zn、Cr、As) and the rate ofconsumption DTT in Guangming B2coal were0.4441、0.6985、0.6907and0.6952respectively;while the correlation coefficients R2between the elements(Fe、Zn、Cr、As) and the rate ofconsumption DTT in Zhaojiachong B3coal were0.8692、0.8775、0.8637and0.8797respectively.The results demonstrated that heavy metals in the coal emission PM contributing to the ratio ofDTT consumption. |
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