Methane emissions from rice paddies natural wetlands, lakes in China: synthesis new estimate

Abstract

Sources of methane (CH 4 ) become highly variable for countries undergoing a heightened period of development due to both human activity and climate change. An urgent need therefore exists to budget key sources of CH 4 , such as wetlands (rice paddies and natural wetlands) and lakes (including reservoirs and ponds), which are sensitive to these changes. For this study, references in relation to CH 4 emissions from rice paddies, natural wetlands, and lakes in China were first reviewed and then reestimated based on the review itself. Total emissions from the three CH 4 sources were 11. ing reservoirs and ponds). Plentiful water and warm conditions, as well as its large rice paddy area make rice paddies in southeastern China the greatest overall source of CH 4 , accounting for approximately 55% of total paddy emissions. Natural wetland estimates were slightly higher than the other estimates owing to the higher CH 4 emissions recorded within Qinghai-Tibetan Plateau peatlands. Total CH 4 emissions from lakes were estimated for the first time by this study, with three quarters from the littoral zone and one quarter from lake surfaces. Rice paddies, natural wetlands, and lakes are not constant sources of CH 4 , but decreasing ones influenced by anthropogenic activity and climate change. A new progress-based model used in conjunction with more observations through model-data fusion approach could help obtain better estimates and insights with regard to CH 4 emissions deriving from wetlands and lakes in China.

The global methane budget 2000–2012

“…The decrease of CH 4 emissions from rice cultivation over the past decades is confirmed in most inventories, because of the decrease in rice cultivation area, the change in agricultural practices, and a northward shift of rice cultivation since 1970s (e.g. Chen et al, 2013). Furthermore, recent studies revealed that, together, high carbon dioxide concentrations and warmer temperatures predicted for the end of the twenty-first century will about double the amount of methane emitted per kilogramme of rice produced (van Groenigen et al, 2013).…”

“…The geographical distribution of the emissions is assessed by global (USEPA, 2006(USEPA, , 2012EDGARv4.2FT2010, 2013 and regional Chen et al, 2013;Chen and Prinn, 2006;Yan et al, 2009;Castelán-Ortega et al, 2014; inventories or by land surface models (Spahni et al, 2011;Zhang and Chen, 2014;Ren et al, 2011;Tian et al, 2010Tian et al, , 2011Li et al, 2005;Pathak et al, 2005). The emissions show a seasonal cycle, peaking in the summer months in the extratropics associated with the monsoon and land management.…”

“…The largest emissions are found in Asia (Hayashida et al, 2013), with China (5-11 Tg CH 4 yr −1 ; Chen et al, 2013;Zhang et al, 2016) and India (∼ 3-5 Tg CH 4 yr −1 ; Bhatia et al, 2013) accounting for 30 to 50 % of global emissions (Fig. 3).…”

Primary estimation of Chinese terrestrial carbon sequestration during 2001–2010

“…In a review of the CH 4 flux measurements from different types of natural wetlands and lakes in different regions of China determined by static chamber method, Chen et al [61] estimated that the total CH 4 emissions from natural wetlands and lakes (including reservoirs and ponds) in China were 2.02 TgC a -1 (ranging from 1.85 to 2.40 TgC a -1 ) and 0.35 TgC a -1 (ranging from 0.25 to 0.44 TgC a -1 ), respectively.…”

Microbial biomass in sediments affects greenhouse gas effluxes in Poyang Lake in China

“…, and from 0.012 to 0.21 nmol m ¡2 s ¡1 for CO 2 , CH 4 , and N 2 O, respectively (Wan et al 2010;Chen et al 2013;Liu et al 2013). In recent years, Poyang Lake has suffered severely from water pollution, lake dredging, and water level fluctuations due to human activities and climate change (Lake et al 2000;Fang et al 2006).…”