Anthropogenic emissions of carbon dioxide (C02),one of the most important greenhouse gases,have been the primary driver of recent global warming (IPCC,2013;NRC,2010).About half of anthropogenic carbon emitted to the atmosphere has accumulated in the atmosphere,which leads to 40% increase of carbon dioxide concentrations in the atmosphere since pre-industrial times (IPCC 2013).The annual emission rate is increasing in some developing countries,such as China (Gregg et al.,2008;Olivier et al.,2012).