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| 1 | Regional Δ~14C patterns and fossil fuel derived CO_2 distribution in the Beijing area using annual plants显示文摘The level of atmosphericΔ14C and the fossil fuel derived CO 2 concentration in the Beijing area from May to September,2009, were systematically analyzed based on radiocarbon(14C)measurements of annual plants by accelerator mass spectrometry(AMS). The results show that the maximumΔ14C in Beijing was 29.6‰±2.2‰,and the minimum was–28.2‰±2.5‰,with a trend of decreasingΔ14C from the outer suburbs to inner suburbs to the urban center.This trend correlates well with increases in fossil fuel derived CO2 caused by human activities such as population density,industrial emissions and traffic,with lower values of atmosphericΔ14C associated with more intensive human activities.The fossil fuel derived CO 2 concentrations from May to September, 2009,ranged from 3.9±1.0 ppm to 25.4±1.0 ppm.It was calculated that each additional 1 ppm of CO2 from fossil fuels depleted the atmosphericΔ14C by approximately 2.70‰.This study suggests that 14C measurements of annual plants by AMS provide an effective method to rapidly trace fossil fuel derived CO2. | XI XianTing DING XingFang FU DongPo ZHOU LiPing LIU KeXin | 2011 | Chinese Science Bulletin2011，56，16： | 7 |
| 2 | Carbon isotopic composition and its implications on paleoclimate of the underground ancient forest ecosystem in Sihui,Guangdong显示文摘We present the carbon isotopic composition of the total organic carbon(TOC) and fine roots in the sedimentary profile from the underground ancient forest in Sihui to study the climatic and environmental changes from 4.5 ka BP to 0.6 ka BP.Results show that C3 plant was the main vegetation from 4.5 ka BP to 0.6 ka BP in this region.The ancient forest began to develop in the wetland at around 4 ka BP and disappeared together with the wetland at about 3.0 ka BP,implying that the climate had changed greatly at around 3.0 ka BP.As indicated by the simulation results,the content of atmospheric CO2 increased slightly during 3.5 ka BP and 3.0 ka BP,implying climate warming during that period.The interval of radiocarbon age between 3.0 ka BP and 1.2 ka BP was possibly caused by the strong erosion when the block was lifted in the neotectonic movement.From 1.2 ka BP to 0.6 ka BP,the region remained in terrestrial sedimentary environment,and the surface plant biomass declined gradually.Drought caused by the climate change was the likely cause for the disappearance of the ancient forest.South transition of Intertropical Convergence Zone(ITCZ) was probably the main mechanism for the climate change. | Ping Ding ChengDe Shen Ning Wang WeiXi Yi KeXin Liu XingFang Ding DongPo Fu | 2009 | Science China Earth Sciences2009，52，5： | 4 |
| 3 | Carbon isotopic composition,turnover and origins of soil CO_2 in a monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir,South China显示文摘Carbon isotopic compositions of soil CO2 in rainy season (July) from two natural soil profiles (DHLS & DHS) in the monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir (DBR),South China,are presented.Turnover and origins of soil CO2 are preliminarily discussed in this paper.Results show that the content of soil CO2 varies between 6120 and 18718 ppmv,and increases with increasing depth until 75 cm,and then it declines.In DHLS,soil CO2 δ 13C ranges from -24.71‰ to -24.03‰,showing a significant inverse correlation (R2=0.91) with the soil CO2 content in the same layer.According to a model related to soil CO2 δ 13C,the soil CO2 is mainly derived from the root respiration (>80%) in DHLS.While in DHS,where soil CO2 δ 13C ranges from -25.19‰ to -22.82‰,soil CO2 is primarily originated from the decomposition of organic matter (51%–94%),excluding the surface layer (20 cm,90%).Radiocarbon data suggest that the carbon in soil CO2 is modern carbon in both DHLS and DHS.Differences in 14C ages between the 'oldest' and 'youngest' soil CO2 in DHLS and DHS are 8 months and 14 months,respectively,indicating that soil CO2 in DHLS has a faster turnover rate than that in DHS.The Δ14C values of soil CO2,which range between 100.0‰ and 107.2‰ and between 102.5‰ and 112.1‰ in DHLS and DHS,respectively,are obviously higher than those of current atmospheric CO2 and SOC in the same layer,suggesting that soil CO2 is likely an important reservoir for Bomb-14C in the atmosphere. | DING Ping SHEN ChengDe WANG Ning YI WeiXi DING XingFang FU DongPo LIU KeXin ZHAO Ping | 2010 | Chinese Science Bulletin2010，55，23： | 4 |
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