光纤荧光法对吸附于红树叶片表面上荧蒽的测定

利用光纤荧光法实现了吸附于白骨壤（Am）、海漆（Ea）、秋茄（Kc）、桐花树（Ac）和老鼠筋（Ai）叶片表面上荧蒽（Fla）的定量测定。所建方法测定吸附于Am、Ea、Kc、Ac和Ai叶片表面上Fla的线性范围分别为2．5～500、2．0—600、4．5～1100、15～600、3．5～450ng/spot，相应的检出限分别为0．91、0．63、1．12、3．52、1．40ng／spot，方法的相对标准偏差小于7．8％（n=15），加标回收率分别为97％～108％、78％～95％、77％～90％、84％～108％和78％-102％。利用所建方法考察了5种红树叶片正反面吸附不同量Fla的信号强度随时间的变化情况。结果表明：在200min内，叶片正反面上Fla的信号均发生不同程度的衰减，且反面的信号衰减率大于正面；5种红树叶片正反面对Fla的吸附特性均不同；吸附于叶片正面的Fla多残留在叶片表面，而吸附于叶片反面的Fla易向叶片内部迁移。

激光诱导纳秒时间分辨荧光法原位测定吸附于红树叶片表面的菲

实现吸附于植物叶片表面多环芳烃（Polycyclicaromatichydrocarbons，PAHs）的现场原位测定，是该研究领域的发展方向之一。本实验利用激光诱导纳秒时间分辨荧光（Laser—inducednanosecondtime—resolvedfluorescence，LITRF）系统，建立了原位测定吸附于秋茄（Kandeliaobovata，Ko）、木榄（Bruguieragymnorhiza，融）和桐花树（Aegicerascorniculatum，Ac）3种红树叶片表面菲（Phenanthrene，Phe）的新方法。本方法测定吸附于K0、Bg和4c叶片表面Phe的线性范围分别为2—1400ng/spot，1—1000ng/spot和4～2000rig／spot，检测限分别为0．20，0．14和0．42ng／spot，加标回收率为89．6％～108．1％，78．2％～92．4％和93．2％～112．9％．且方法的相对标准偏差小于6．0％（n=9）。将方法用于实验室暴露样品的原位测定，并与光纤荧光法对比，其灵敏度、线性范围改善显著，更有利于实现植物叶片上PAHs的现场原位测定。

固体表面荧光法测定吸附于白骨壤和木榄叶片上的蒽

以新鲜白骨壤和木榄叶片为基质，建立了直接测定吸附于叶片表面蒽（An）的固体表面荧光分析法（SSF）。考察了白骨壤和木榄叶片上An的吸附量随An暴露浓度、暴露时间等因素的变化情况。方法测定吸附于白骨壤叶片上An的线性范围为0．92～8．71μg/g，检出限为5．77ng/g，加标回收率为79．2％～85．9％；测定吸附于木榄叶片上An的线性范围为89．5～698．2ng／g，检出限为1．79ng/g，加标回收率为75．1％～102．3％；对于两种叶片，方法的相对标准偏差都小于10％。

Effect of water stress on N_2O emission rate of 5 tree species

The N2O emission rates, photosynthesis, respiration and stomatal conductance of the dominant tree species from broadleaf/Korean pine forest in Changbai Mountain were measured by simulated water stress with the closed bag-gas chromatography. A total of five species seedlings were involved in this study, i.e.,Pinus koraiensis Sieb. et Zucc,Fraxinus mandshurica Rupr,Juglans mandshurica Maxim,Tilia amurensis Rupr, andQuercus mongolica Fisch. ex Turcz.. The results showed that the stomatal conductance, net photosynthetic rate and N2O emission of leaves were significantly reduced under the water stress. The stoma in the leaves of trees is the main pathway of N2O emission. N2O emission in the trees mainly occurred during daytime. N2O emission rates were different in various tree specie seedlings at the same water status. In the same tree species, N2O emission rates decreased as the reduction of soil water contents. At different soil water contents (MW, LW) the N2O emission rates ofPinus koraiensis decreased by 34.43% and 100.6% of those in normal water condition, respectively. In broadleaf arbor decreased by 31.93% and 86.35%, respectively. Under different water stresses N2O emission rates in five tree species such asPinus koraiensis, Fraxinus mandshurica, Juglans mandshurica, Tilia amurensis, andQuercus mongolica were 38.22, 14.44, 33.02, 16.48 and 32.33 ngN2O·g?1DW·h?1, respectively. Keywords Trees - N2O emission rate - Soil water stress - broadleaf/Korean pine forest - Changbai Mountain CLC number S718.55 Document code A Foundation item: This project was supported by the National Natural Science Foundation of China (No. 30271068), the grant of the Knowledge Innovation Program of Chinese Academy of Sciences (KZ-CX-SW-01-01B-10), and the Special Funds for Major State Basic Research Program of China (No. G1999043407)Biography: Wang Miao (1964-), male, associate professor in Institute of Applied Ecology, Chinese Academy of Science, Shenyang 110016, P. R. China.Responsible editor: Song Funan