Characteristics of vegetation and its relationship with landfill gas in closed landfill Chai Xiaoli a, *, Zhao Xin a , Lou Ziyang b , Takayuki Shimaoka c , Hirofumi Nakayama c , Cao Xianyan a , Zhao Youcai a a School of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China b School of Environmental and Engineering, Shanghai Jiaotong University, Shanghai, China c Institute of Environmental Systems, Graduate school of Engineering, Kyushu University, Fukuoka 812-8581, Japan article info Article history: Received 5 February 2010 Received in revised form 13 December 2010 Accepted 21 December 2010 Available online 14 January 2011 Keywords: Landfill Methane Carbon dioxide Vegetation condition Greenhouse gases abstract An investigation was carried out to elucidate landfill gas (LFG) and the vegetation char- acteristics in closed landfill. The results indicate that the stabilization process of the landfill is an important factor influencing the components of landfill gases. The coverage, height and species of vegetation increase with the closed time of landfill. Fourteen species were observed in the investigated cells, dominated by Phragmites australis, an invasive perennial plant. The concentrations of methane and carbon dioxide from vegetated cover soil were lower than those from non-vegetated cover soil. ª 2010 Elsevier Ltd. All rights reserved. 1. Introduction Although reduction, recycling, and reuse of municipal refuse are preferred practices solid waste disposal in landfills is still a common occurrence throughout the world. In fact, more than 90% of municipal solid wastes currently go into landfills in China. After being disposed in landfills, solid waste undergoes complex physicochemical and biological reactions. As a result, organic substances are degraded into leachable liquids or landfill gases (LFG). Under anaerobic conditions, the degrada- tion of organic substances generates a large amount of LFG comprised of methane and carbon dioxide, along with numerous trace gases, such as H 2 S, N 2 O and CO. CH 4 , CO 2 and N 2 O are anthropogenic greenhouse gases [1] that may signifi- cantly contribute to global warming. Although infrared spectrometer method can scan LFG emission all over a landfill surface, accurate measurement of LFG emissions from landfills has not been fully established due to the large area and heterogeneous nature of landfill sites. LFG emission is affected by the differences in refuse composition, the gas recovery system, and microbial CH 4 oxidation capacity [2e6]. Moreover, the characteristics of cover soil and vegetation conditions in landfills can affect the efficiency of CH 4 oxidation and bring about the alteration of the LFG components [7,8]. Cover soils with high porosity and large particle-size distribu- tion can retain CH 4 and oxygen longer in the pores, resulting in a higher oxidation rate of CH 4 [9]. Vegetation conditions can * Corresponding author. Tel.: þ86 21 65981831; fax: þ86 21 65980041. E-mail address: xlchai@tongji.edu.cn (C. Xiaoli). Available at www.sciencedirect.com http://www.elsevier.com/locate/biombioe biomass and bioenergy 35 (2011) 1295 e1301 0961-9534/$ e see front matter ª 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.biombioe.2010.12.051