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Li Z.,Zhejiang Agriculture And forestry University | Song Z.,Zhejiang Agriculture And forestry University | Song Z.,Laboratory for Earth Surface Processes | Song Z.,Peking University | And 2 more authors.
Plant and Soil | Year: 2013

Aims: Carbon (C) bio-sequestration within the phytoliths of plants, a mechanism of long-term biogeochemical C sequestration, may play a major role in the global C cycle and climate change. In this study, we explored the potential of C bio-sequestration within phytoliths produced in cultivated rice (Oryza sativa), a well known silicon accumulator. Methods: The rice phytolith extraction was undertaken with microwave digestion procedures and the determination of occluded C in phytoliths was based on dissolution methods of phytolith-Si. Results: Chemical analysis indicates that the phytolith-occluded C (PhytOC) contents of the different organs (leaf, stem, sheath and grains) on a dry weight basis in 5 rice cultivars range from 0.4 mg g-1 to 2.8 mg g-1, and the C content of phytoliths from grains is much lower than that of leaf, stem and sheath. The data also show that the PhytOC content of rice depends on both the content of phytoliths and the efficiency of C occlusion within phytoliths during rice growth. The biogeochemical C sequestration flux of phytoliths in 5 rice cultivars is approximately 0.03-0.13 Mg of carbon dioxide (CO2) equivalents (Mg-e-CO2) ha-1 year-1. From 1950 to 2010, about 2.37 × 108 Mg of CO2 equivalents might have been sequestrated within the rice phytoliths in China. Assuming a maximum phytoliths C bio-sequestration flux of 0.13 Mg-e-CO2 ha-1 year-1, the global annual potential rate of CO2 sequestrated in rice phytoliths would approximately be 1.94 × 107 Mg. Conclusions: Therefore rice crops may play a significant role in long-term C sequestration through the formation of PhytOC. © 2013 Springer Science+Business Media Dordrecht. Source


Li Z.,Zhejiang Agriculture And forestry University | Song Z.,Zhejiang Agriculture And forestry University | Song Z.,Laboratory for Earth Surface Processes | Song Z.,Peking University | Li B.,Zhejiang Agriculture And forestry University
Applied Geochemistry | Year: 2013

Phytolith, the opal of amorphous silica formed in plant tissues, is present in most plants (mainly Poaceae, Cyperaceae and so on). The carbon bio-sequestration within the phytoliths of plants, one of the most promising approaches of long-term CO2 sequestration, is a significant mechanism of long-term biogeochemical carbon sequestration. This study analyzed the production and accumulation of phytolith-occluded-carbon (PhytOC) in Baiyangdian reed wetland of China. The plant phytolith extraction was undertaken with microwave digestion procedures and the soil phytolith extraction was based on the method of heavy liquid separation. The determination of the carbon content of phytoliths was based on phytolith-Si dissolution methods. The production flux of PhytOC for aboveground reed was 3.7-4.2gCO2m-2a-1 and the accumulation flux of PhytOC for soil layer (0-15cm) of soil deposition was 0.03gCO2m-2a-1. The results imply that PhytOC content in reed dry biomass mainly depends on the content of the silicon taken up by the plant and the occluded carbon content of phytoliths during the plant growth. In Baiyangdian reed ecosystems, the rate of PhytOC for aboveground reed is about 6.77-7.69×108geCO2a-1, and the accumulation rate of PhytOC for 0-15cm soil layer is around 5.49×106gCO2a-1. Assuming the plant-area (5.7×108ha) of global wetland with the similar maximum flux (0.054teCO2ha-1a-1) of reed PhytOC sequestration of atmospheric CO2, about 3.08 107 tone CO2 every year would be sequestrated by wetland ecosystem. The appropriate management of reed wetlands to maximize ANPP and select plant species with high-phytolith content or high-efficiency of phytolith occlusion of carbon has the potential to result in considerable production and accumulation quantities of PhytOC in reed wetland ecosystems. © 2013 Elsevier Ltd. Source


Chen Q.,Peking University | Chen Q.,Laboratory for Earth Surface Processes | Chen Q.,Qinghai Normal University | Cai Y.,Peking University | And 4 more authors.
Chinese Geographical Science | Year: 2013

China is experiencing a fast process of farmland conversion which is conducted mainly by local governments to fuel economic development. Social tension is aroused and policy makers take great concerns on coordinating interests among different stakeholders, especially for increasing farmers' interest. The purpose of this study is to get some insights related to land acquisition institution by exploring farmers' perception to farmland conversion. Participatory Rural Appraisal (PRA) was applied for the investigation in peri-urban area, of Xining City, Qinghai Province, China. The total of 519 householders from 15 villages completed valid questionnaire survey from July to November, 2012. The results indicate that farmland conversion has several impacts on farmers' life. Most farmers are gradually adapting to city life. Higher living expenses and more income are perceived by farmers with average score of 4.21 and 2.69, respectively. The average scores of 2.38 and 2.46 are for improvement of life security and more job opportunities. Farmers expect to get some stable ways of compensation in addition to lump-sum compensation in cash. Stable subsidies every year and obtaining same number of land received strong proposal. And these two options are cited by 49.6% and 43.9% of respondents. Farmland conversion brings about cleaner living condition and more amenities, but lower air visibility and drier air. Results reflect landless farmers' economic and life pressures and various demands. Local government should pay more attention to increase farmers' income and improve rural security system. © 2013 Science Press, Northeast Institute of Geography and Agricultural Ecology, CAS and Springer-Verlag Berlin Heidelberg. Source

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