云南宣威地区燃煤排放颗粒物中石英矿物的特征

云南宣威地区是我国人群肺癌死亡率最高的地区之一,过往研究表明,该区的高肺癌死亡率可能与居民室内燃煤排放颗粒物中的多环芳烃(PAHs)有关,而最近研究发现,其中的nm级石英可能是导致肺癌发生的原因, 但鲜见该区燃煤排放颗粒物中细粒石英矿物的研究. 为探究燃煤排放细粒矿物的分布特征,采集了肺癌高发区宣威市来宾镇及周边5个乡镇煤矿中的15个煤样,使用光学显微镜、X射线衍射仪(XRD)、带能谱的扫描电镜(SEM/EDS)分析了煤样的煤岩组分及矿物组成. 结果表明:宣威煤以中挥发分、较高镜质组烟煤为主,煤中主要矿物为石英、鲕绿泥石、高岭石和方解石；不同煤样中,矿物质的结晶程度有所差异；单颗粒统计结果显示,在所统计的775个矿物颗粒中,石英颗粒占37.9%,并且粒径多分布在1~2μm之间; 石英矿物颗粒的形状不规则且以微粒的形式填充在煤缝隙中. 石英与鲕绿泥石共存的现象显示,宣威煤中石英来源于富含Fe和Al的硅质热液流,而非岩石碎屑沉积；此外,在肺癌高发区(来宾镇),其煤中Si+Fe质矿物颗粒含量较Si质矿物高. 今后将重点研究石英颗粒在Fe参与下的生物活性. 

Characteristics of the Fine Quartz Particles from the Local Coal Combustion in Xuanwei, Yunnan Province

Previous studies showed that the high mortality rate of lung cancer was associated with exposure to indoor smoky coal emission, which contains high concentrations of polycyclic aromatic hydrocarbons (PAHs). More recent studies demonstrated that the lung cancer risk was associated with nanoquartz embedded in the soot emissions from coal combustion. However, there were few reports related to mineralogy of the fine quartz particles from the local coal samples. In order to investigate mineralogical characterization of quartz particles in the Permian coal deposited in Xuanwei City, 15coal samples were collected from Laibin Town (higher lung incidence area) and its adjacent areas. Mineral composition in the samples was determined by optical microscope, X-ray diffraction (XRD) and scanning electronic microscopy coupled with energy dispersive spectroscopy (SEM/EDS). Results showed that the coal in Xuanwei is bituminous which contained volatile and vitrinite. Minerals in the coal are mainly consisted with quartz, chamosite, calcite and kaolinite. Crystalline degrees of minerals are different among coal samples. Statistical analysis results of individual mineral particles showed that the percentage of quartz particles was 37.9% among the measured 775particles. Diameters of quartz grains mostly ranged from 1-2μm in the coal. The irregular fine quartz particles coexisting with chamosite could be found in the fractions of coal samples. This result demonstrated that the quartz in Xuanwei coal was deposited from a siliceous hydrothermal fluid which contained a large amount of iron and aluminum, and not originated from deposition of clastic rock. In addition, the percentage of minerals containing rich silicon and iron could be found in the coal samples collected in the areas with high risk of lung cancer such as Laibin Town. With these data, we will further focus on the biological activity of quartz grains with the participation of iron, and try to produce new valuable data for the research on lung cancer in Xuanwei City.