A biogeochemical model, Denitrification‐Decomposition (DNDC), was modified to enhance its capacity of predicting greenhouse gas (GHG) emissions from paddy rice ecosystems. The major modifications ...focused on simulations of anaerobic biogeochemistry and rice growth as well as parameterization of paddy rice management. The new model was tested for its sensitivities to management alternatives and variations in natural conditions including weather and soil properties. The test results indicated that (1) varying management practices could substantially affect carbon dioxide (CO2), methane (CH4), or nitrous oxide (N2O) emissions from rice paddies; (2) soil properties affected the impacts of management alternatives on GHG emissions; and (3) the most sensitive management practices or soil factors varied for different GHGs. For estimating GHG emissions under certain management conditions at regional scale, the spatial heterogeneity of soil properties (e.g., texture, SOC content, pH) are the major source of uncertainty. An approach, the most sensitive factor (MSF) method, was developed for DNDC to bring the uncertainty under control. According to the approach, DNDC was run twice for each grid cell with the maximum and minimum values of the most sensitive soil factors commonly observed in the grid cell. The simulated two fluxes formed a range, which was wide enough to include the “real” flux from the grid cell with a high probability. This approach was verified against a traditional statistical approach, the Monte Carlo analysis, for three selected counties or provinces in China, Thailand, and United States. Comparison between the results from the two methods indicated that 61‐99% of the Monte Carlo‐produced GHG fluxes were located within the MSA‐produced flux ranges. The result implies that the MSF method is feasible and reliable to quantify the uncertainties produced in the upscaling processes. Equipped with the MSF method, DNDC modeled emissions of CO2, CH4, and N2O from all of the rice paddies in China with two different water management practices, i.e., continuous flooding and midseason drainage, which were the dominant practices before 1980 and in 2000, respectively. The modeled results indicated that total CH4 flux from the simulated 30 million ha of Chinese rice fields ranged from 6.4 to 12.0 Tg CH4‐C per year under the continuous flooding conditions. With the midseason drainage scenario, the national CH4 flux from rice agriculture reduced to 1.7–7.9 Tg CH4‐C. It implied that the water management change in China reduced CH4 fluxes by 4.2–4.7 Tg CH4‐C per year. Shifting the water management from continuous flooding to midseason drainage increased N2O fluxes by 0.13–0.20 Tg N2O‐N/yr, although CO2 fluxes were only slightly altered. Since N2O possesses a radiative forcing more than 10 times higher than CH4, the increase in N2O offset about 65% of the benefit gained by the decrease in CH4 emissions.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Validations of the DeNitrification‐DeComposition (DNDC) model against field data sets of trace gases (CH4, N2O, and NO) emitted from cropping systems in Japan, China, and Thailand were conducted. The ...model‐simulated results were in agreement with seasonal N2O emissions from a lowland soil in Japan from 1995 to 2000 and seasonal CH4 emissions from rice fields in China, but failed to simulate N2O and NO emissions from an Andisol in Japan as well as NO emissions from the lowland soil. Seasonal CH4 emissions from rice cropping systems in Thailand were poorly simulated because of site‐specific soil conditions and rice variety. For all of the simulated cases, the model satisfactorily simulated annual variations of greenhouse gas emissions from cropping systems and effects of land management. However, discrepancies existed between the modeled and observed seasonal patterns of CH4 and N2O emissions. By incorporating modifications based on the local soil properties and management, DNDC model could become a powerful tool for estimating greenhouse gas emissions from terrestrial ecosystems.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In this paper, we present recent field studies conducted by NASA's SMART-COMMIT (and ACHIEVE, to be operated in 2013) mobile laboratories, jointly with distributed ground-based networks (e.g., ...AERONET, http://aeronet.gsfc.nasa.gov/ and MPLNET, http://mplnet.gsfc.nasa.gov/) and other contributing instruments over northern Southeast Asia. These three mobile laboratories, collectively called SMARTLabs (cf. http://smartlabs.gsfc.nasa.gov/, Surface-based Mobile Atmospheric Research &Testbed Laboratories) comprise a suite of surface remote sensing and in-situ instruments that are pivotal in providing high spectral and temporal measurements, complementing the collocated spatial observations from various Earth Observing System (EOS) satellites. A satellite-surface perspective and scientific findings, drawn from the BASE-ASIA (2006) field deployment as well as a series of ongoing 7-SEAS (2010–13) field activities over northern Southeast Asia are summarized, concerning (i) regional properties of aerosols from satellite and in-situ measurements, (ii) cloud properties from remote sensing and surface observations, (iii) vertical distribution of aerosols and clouds, and (iv) regional aerosol radiative effects and impact assessment. The aerosol burden over Southeast Asia in boreal spring, attributed to biomass burning, exhibits highly consistent spatial and temporal distribution patterns, with major variability arising from changes in the magnitude of the aerosol loading mediated by processes ranging from large-scale climate factors to diurnal meteorological events. Downwind from the source regions, the tightly coupled-aerosol–cloud system provides a unique, natural laboratory for further exploring the micro- and macro-scale relationships of the complex interactions. The climatic significance is presented through large-scale anti-correlations between aerosol and precipitation anomalies, showing spatial and seasonal variability, but their precise cause-and-effect relationships remain an open-ended question. To facilitate an improved understanding of the regional aerosol radiative effects, which continue to be one of the largest uncertainties in climate forcing, a joint international effort is required and anticipated to commence in springtime 2013 in northern Southeast Asia.
► Multi-year, international efforts for studying aerosol and climate impacts across Southeast Asia. ► Aerosol and cloud properties measured from both ground- and satellite-based platforms. ► Investigation of aerosol–cloud interactions and planning for future experiments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Soft lining material is a soft elastic and resilient material which helps alleviate stresses from the denture bases to the underlying supporting tissues in the pa-tients. The purpose of this study ...was to develop the new soft lining material from natural rubber to replace commercial soft lining materials which have several disadvantages and limitations. In this study, the high-ammonium natural rubber latex was vulcanized and grafted with ethyl methacrylate by γ-irradiation to improve its quality. The grafted natural rubber latex, socalled grafted copolymer, was then studied for its ultrastructure and prepared for evaluation of its bonding ability to the denture base material and cytotoxicity by using light and electron microscopies and human gingival fibroblast co-culture method. The results from electron microscopic study showed a complete junction between the grafted copolymer and the denture base material. Microscopic investigations in cell culture, the human gingival fibroblasts demonstrated well proliferation and well attachment around and on the surface of the grafted copolymer. In conclusion, the grafted copolymer has a good bonding to the denture base material and a good cellular biocompatibility. Therefore, it would be worth to modify the grafted copolymer for using as denture soft lining materials.
Measurements of gaseous SO
2, NH
3, and O
3 using IVL passive sampler technology were obtained during a pilot measurement program initiated as a key component of the newly established WMO/GAW Urban ...Research Meteorology and Environment (GURME) project. Monthly measurements were obtained at 50 stations in Asia, Africa, South America, and Europe. The median SO
2 concentrations vary from a high of 13
ppb at Linan, China, to <0.03
ppb at four stations. At 30 of 50 regional stations, the observed median concentrations are <1
ppb. Median ammonia concentrations range from 20
ppb at Dhangadi, India, to <1
ppb at nine stations. At 27 of regional stations, the ambient ammonia levels exceed 1
ppb. The median ozone concentrations vary from a maximum of 45
ppb at Waliguan Mountain, China, to 8
ppb in Petit Saut, French Guiana. In general, the highest ozone values are found in the mid-latitudes, with the Northern hemisphere mid-latitude values exceeding the Southern hemisphere mid-latitude levels, and the lowest values are typically found in the tropical regions.
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The serum fraction of latex from
Hevea brasiliensis, the para rubber tree, is known to contain an
endo-chitinolytic enzyme, hevamine. Herein the activity of the rubber serum towards ...β-chitin is investigated. The serum contained 6
mg/mL of protein and a chitinolytic activity of 18
mU per
mg of protein. The optimum ratio of enzyme to chitin was 0.22
mU/mg, and the optimum substrate concentration was 60
mg/mL. The optimum pH range was pH
2–4, and the optimum temperature was 45
°C. At these conditions both (GlcNAc)
2 and GlcNAc were produced in a molar ratio of approximately 2:1. The hydrolysis of 300
mg of chitin with 64
mU of the rubber serum for 8
days under the optimum conditions gave 39
mg of GlcNAc and 108
mg of (GlcNAc)
2 as determined by HPLC. Mixing the rubber serum preparation with an
Aspergillus niger pectinase preparation containing β-
N-acetylhexosaminidase can be used to produce almost exclusively the GlcNAc monomer in about 50% yield.
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