福建省主要乔木树种森林可燃物元素含量与燃烧释放PM_(2.5)中元素含量相关性分析

Correlation analysis of element contents between forest fuel and PM_(2.5)released by combustion of main tree species in Fujian Province

探究森林可燃物与燃烧产生的细小颗粒物(PM_(2.5))中的元素含量及其相关性,以揭示林火过程中各元素迁移轨迹,为理解森林火灾对环境化学元素含量和生态系统物质循环的影响提供重要依据。以马尾松(Pinus massoniana)、杉木(Cunninghamia lanceolata)、大叶桉(Eucalyptus robusta)和香樟(Cinnamomum camphora)的树枝、树叶以及树皮3个不同部位器官为研究对象,采用自主设计的模拟燃烧装置进行室内阴、明燃两种不同燃烧状态模拟燃烧,测算5种常量元素Mg、Al、P、K、Ca及7种微量元素Na、Cr、Mn、Fe、Ni、Cu、Zn的含量,同时比较阴、明燃情况下排放PM2.5中元素含量的差异,并分析森林可燃物自身元素含量与各元素排放因子的相关性。结果表明:森林可燃物中常量元素Mg、K、Ca和微量元素Zn含量高,森林可燃物元素含量针叶树高于阔叶树,不同器官元素含量差异显著;燃烧释放PM2.5中Mg、K、Ca、Zn排放因子较高,Cu次之,Cr最少,常量元素高于微量元素;不同燃烧状态下对排放因子也存在一定的影响,普遍表现为明燃大于阴燃;不同燃烧状态下,各器官释放PM_(2.5)与自身元素含量的比值中,Cu元素最高,其他元素占比范围在0~0.09%;森林可燃物与PM_(2.5)的元素间相关性较大,相关水平达0.700~0.999。不同森林可燃物器官燃烧释放烟气及PM_(2.5)存在差异,且森林可燃物自身与燃烧释放颗粒物PM_(2.5)具有较强的相关性。

Exploring the element contents and their correlation between forest fuel and fine particulate matter(PM_(2.5))emitted during combustion and revealing the migration trajectory of each element during forest fire provide an important basis for understanding the impacts of forest fire on environmental chemical element content and ecosystem material cycle.The branches,leaves and bark of four tree species(Pinus massoniana,Cunninghamia lanceolata,Eucalyptus robusta and Cinnamomum camphora)were burnt under smoldering and flaming states using self-designed combustion simulation device to measure the contents of five major elements(Mg,Al,P,K,Ca)and seven trace elements(Na,Cr,Mn,Fe,Ni,Cu,Zn).We analyzed the differences of element contents in PM_(2.5)emitted between different burning states,and the correlation between the element contents of fuels and the emission factors of each element in emitted PM_(2.5).The results showed that the contents of Mg,K,Ca and Zn in forest fuel were higher.The element contents in conifers were generally higher than those in broadleaved species,and the element contents in different organs of same tree species were significantly different.The emission factors of Mg,K,Ca and Zn in PM_(2.5)released during combustion were highest,followed by Cu and Cr,with a pattern of higher for the major elements than for the trace elements.Combustion states influenced emission factors of elements,generally showing that flaming was greater than smoldering.Under different combustion states,the ratio of Cu content in PM2.5 released during combustion of each organ to its own element content was the highest,and the ratios of other elements ranged from 0 to 0.09%.The correlations of element contents between forest fuels and PM_(2.5)were relatively high(0.700-0.999).In conclusion,there were differences in emissions of flue gas and PM_(2.5)released by the combustion among different tree organs,and there was a strong correlation between fuel itself and PM_(2.5)released by fuel combustion.