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| 1 | N_2O emissions from agricultural soils in the North China Plain: the effect of chemical nitrogen fertilizer and organic manure显示文摘An enclosed chamber technique was used to measure N 2O emissions from intensively agricultural soils of the North China Plain during the periods of 1995—1996 and 1997—1998, to reflect distinct components of winter wheat and summer maize growing seasons. The results showed that the continuous application of fertilizer in agricultural soils increased N\-2O emissions by a factor of 24.1—28.1, the calculated annual chemical N fertilizer\|transformed N\-2O\|N emissions was 0.67%. Our results indicated that the application of organic manure also had a significant influence on soil N 2O emissions, which combined with the use of chemical N increased about 20% in a year. It was calculated that there were about 0.11% N of organic manure transformed as N 2O N. Annual mean N 2O emission from our study area of fertilized soils was estimated to be 57.1 μgN 2O/(m 2·h). A weak correlation was also found between N 2O emissions and soil available nitrogen content NH + 4. | DONG Yun\|she 1,2,3 , Dieter Scharffe 2, Manfred Domroes 3, QI Yu chun 1, ZHANG Shen 1 (1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China E\|mail: dongys@dls.iog.ac.cn 2. M | 2000 | Journal of Environmental Sciences2000，12，4： | 6 |
| 2 | Effects of Preheating Temperature, Moisture and Sodium Metabisulfite Content on Property of Maize Flour Dough显示文摘Processing temperature, maze flour particle size, and level of water and sodium metabisulfite were varied during the preparation of maize noodles. Preheated to 90—95 ℃ a mixture of maize flour or meal, water(43%—45% moisture) and salt enabled the preparation of noodles using a pasta extruder. Maize flour with smaller particle size yielded better noodles than did maize meal. The addition of sodium metabisulfite enabled the production of noodles at lower processing temperatures; however, cooking losses increased. Processing maize flour with higher water absorption yielded noodles that required longer cooking time but with decreased losses. The functionalities of starch and protein in raw ingredients and in products were determined. Starch gelatinized and retorgraded during processing maize noodles, as indicated by changes in pasting viscosity curves. Maize proteins contributed to the increased viscosity of dough above 40 ℃. The increased integrity of cooked maize noodles, however, corresponded to the increased amounts of gelatinized and retrograded starch. | TONG Yi 1, Waniska Ralph D. 2 and LI Wei 1** (1. College of Life Science, Jilin University, Changchun, 130023 2. Cereal Quality Laboratory, Department of Soil & Crop Sciences, Texas A & M University, College Station, Texas, 77843 24474) | 2000 | Chemical Research in Chinese Universities2000，16，3： | 2 |
| 3 | SOURCE RADIATION AND RESPONSES OF WAVE PROPAGATION显示文摘Recordings of seismic waves propagating from earthquake source to a station at the earth’s surface are a system response function. The convolution operator in time domain can be simplified as a multiplication operator in frequency domain. We discuss in frequency domain the separation of source, path and site effects for global scaling of earthquake source radiation. Also discussed are source scaling model, faulting mechanism, and the H/V inversion problems with crustal and near surface structures. Gross features of apparent source spectra appear to be not much region dependent although there may be difference between tectonic styles within a region of tectonic mixture for which we need further study as data accumulate. Vertical spectra may be a better approach to approximate source radiation, as it has less crustal amplification effects than horizontal spectra. The H/V ratio is evidently a comprehensive indicator of amplification effects from near surface to deep structure. This gives it potential as an inversion tool to deduce site crustal structure. | CHEN Sheng zao 1 and Gail M Atkinson 2 (1. Geomatrix Consultants, Inc., 2101 Webster St., 12 th Floor, Oakland, CA 94612, USA, formerly at Dept. Earth Sciences & Ottawa Carleton Geoscience Center, Carleton University, Ottawa, Canada 2. Dept. Ea | 2001 | Geotectonica et Metallogenia2001，25，1： | 2 |
| 4 | Water status in winter wheat grown under salt stress显示文摘Properties of the soil surface layer, the temporal pattern of the microclimate variables as well as crop condition were combined to analyze the characteristics of the evapotranspiration from winter wheat fields in a saline soil area. In order to accomplish this analysis, evapotranspiration was divided into evaporation from the soil and transpiration from wheat. Moreover, the effect of soil salinity on evapotranspiration was evaluated through the relationship between actual evapotranspiration and potential evapotranspiration (Ea/Eo) and the total soil water potential () was divided into two components: matric potential (M) and osmotic potential (o). Two sites with different salinity levels were chosen for this study, located in Hebei Province, China. Measurements were conducted in April-May 1997 and May 1998. The Bowen ratio method was used to estimate the actual evapotranspiration (Ea), whereas potential evapotranspiration (Eo) was estimated using Penman’s equation. Measurements of soil evaporation (Es) were obtained with micro-lysimeters, and transpiration was calculated from the difference between Ea and Es. The results show that transpiration comprised on average almost 80 % of total evapotranspiration. Evaporation from the soil differed slightly between years, but this variation was dominated by the leaf area index (LAI), which ranged from 4 to 5 during the study period of 1997 and 1998. Soil electric conductivity (EC), which is directly related to osmotic potential, ranged from 1.9 to 3.5 mS cm-1 in 1997 and was negligible in 1998. Our results indicate that lower osmotic potential decreases the total soil water potential, thus affecting plant transpiration. Hence, it is possible to say that soil salinity actually decreases evapotranspiration from winter wheat fields. | M Larry Lopez C~1, WANG Rong~2, MAO Xue-sen~2, Takahashi Hidenori~1 (1. Hokkaido University, Graduate School of Environmental Earth Science, Sapporo, 060-0810 Japan 2. Shijiazhuang Institute of Agricultural Modernization, CAS, Shijiazhuang 050021, | 2001 | Journal of Geographical Sciences2001，11，2： | 0 |
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