中文摘要：

对贵阳市区到农村地区4个方向的石生苔藓碳氮含量和同位素组成进行了分析.苔藓碳含量（34.47%～52.76%）从市区到农村随距离逐渐降低,并与氮含量（0.85%～2.97%）存在较好的正相关关系,表明大气氮沉降对苔藓的碳吸收能力具有促进作用,市区较高的大气氮输入或铵沉降增强了苔藓的光合作用和固碳能力,同时使碳同化过程发生较大的13C分馏.苔藓δ^13C值（-30.69‰～-26.96‰）从市区往外逐渐升高,还与城市人为CO2排放有关,主要机制在于人为成因的CO2源本身富含12C并可能增加市区大气CO2的浓度,从而导致市区苔藓δ^13C值偏负.此外,根据苔藓碳含量和δ^13C随距离的变化关系判断,贵阳城市人为来源的CO2对植物的影响主要集中在20 km范围内.本研究重点探讨了控制苔藓碳含量和δ^13C变化的因素及其与氮素的相互关系,揭示了苔藓碳和δ^13C响应城市CO2排放和大气氮沉降变化的规律,为城市大气污染的防治和周边生态系统的保护提供了新的地球化学证据.

英文摘要：

We investigated the carbon （C） and nitrogen （N） concentrations and isotopic signatures （δ ^13C and δ ^15N） in epilithic mosses collected from urban sites to rural sites along four directions at Guiyang area. Mosses C （34.47 %-52.76% ） decreased significantly with distance from urban to rural area and strongly correlated with tissue N （0.85 %-2.97 % ）, showing atmospheric N deposition has positive effect on C assimilation of epilithic mosses, higher atmospheric N/NHx deposition at urban area has improved the photosynthesis and C fixation of mosses near urban, which also caused greater ^13 C discrimination for urban mosses. Mosses δ ^13C signatures （ - 30.69‰- - 26.96‰） got less negative With distance from urban to rural area, which was also related to the anthropogenic CO2 emissions in the city, and these ^12C-enriehed CO2 sources would lead to more negative mosses δ ^13C through enhancing the atmospheric CO2 concentration in urban area. Moreover, according to the characteristics of mosses C and δ ^13C variations with distance, it is estimated that the influences of urban anthropogenic CO2 sources on plants was mainly within 20 km from city center. This study mainly focused on the factors regulating tissue C and δ ^13C of mosses in city area and the interaction between C and N in mosses, the responses of mosses C and δ ^13C to urban CO2 emission and atmospheric N deposition have been revealed, which could provide new geochemical evidences for the control of city atmospheric pollution and the protection of ecosystems around city.