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Acid Release from an Acid Sulfate Soil Sample Under Successive Extractions with Different Extractants

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Pedosphere 2000年第3期10卷 221-228页

作者： C.LIN M.M.ISLAM 等 CentreforAcidSulfateSoilResearch SouthernCrossUniversityNSW2480Australia schoolofgeography TheUniversityofNewSouthWalesSydneyNSW2052Australia

An acid sulfate soil sample was successively extracted with deionized water, 1 mol L-1 KCl and 0.000 5 mol L-l Ca(OH)2 solutions. The results showed that only very small amounts of acidity were extracted by deionized water, possibly through slow jarosite hydrolysis. Acid release through jarosite hydrolysis was greatly enhanced by Ca(OH)2 extraction at the expense of the added OH- being neutralized by the acid released. Successive extraction of the sample with KCl removed the largest amounts of acidity from the sample. However, it is likely that the major form of acidity released by KCl extraction was exchangeable acidity. The results also show the occurrence of low or non charged Al and Fe species in water and Ca(OH)2 extracts after first a few extractions. It appears that such a phenomenon was related to a decreasing EC value with increasing number of extractions.

关键词： acid release acid sulfate soil successive extractio`

China＇s geographical regionalization in Chinese secondary school curriculum （1902-2012）

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Journal of Geographical Sciences 2013年第2期23卷 370-383页

作者： HE Yaqiong WANG Min schoolofgeography BeijingNormalUniversityBeijing100875China

AS geographic literacy training is an education, national geographical education is essential content for Chinese citizens＇ literacy one of the indispensable key aspects of that training. Because of China＇s vast land area and the significance of the regional differences, it is difficult for students to receive a solid education regarding China＇s geography. In 1902, the government established the geography curriculum and began to incorporate the concept of geographical regionalization to facilitate the teaching of China＇s geography by publishing the first syllabi, which was modified later and put into use in 1904. Since 1904, numerous geog raphy textbooks have attempted to find an appropriate way to present China＇s geographical regionalization, as it is important for secondary students to have a clear understanding and appreciation for the different regional characteristics. Accordingly, the geographical region alization content is divided into four main phases： 1902 to 1927; 1928 to 1948; 1949 to 1986; and 1986 to the present. During these phases, the content related to China＇s geographical regionalization in secondary middle school geography textbooks has been gradually simplified and has adopted a more scientific foundation, thus leading to the present time where there are now four geographical regional areas. From this historical study, we find that while China＇s geographical regionalization has gradually matured, there are still some problems. For example, dividing the study into four regions to describe the panorama of China is too simplified, and the learning therefore becomes too scattered and haphazard, particularly qiven the new curriculum reform.

关键词： geographical regionalization secondary school geography curriculum geography textbook historicalstudy

Inversion of Biochemical Parameters by Selection of Proper Vegetation Index in Winter Wheat

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Agricultural Sciences in China 2004年第3期3卷 178-185页

作者： HUANGWen-jiang WANGJi-hua LIULiang-yun ZHAOChun-jiang WANGZhi-jie WANGJin-di ResearchCenterforRemoteSensingandGIS SchoolofGeographyBeijingNormalUniversityBeijing100875P.R.China NationalEngineeringResearchCenterforInformationTechnologyinAgriculture Beijing100089P.R.China

Recent studies have demonstrated the application of vegetation indices from canopy reflectedspectrum for inversion of chlorophyll concentration. Some indices are both response tovariations of vegetation and environmental factors. Canopy chlorophyll concentration, anindicator of photosynthesis activity, is related to nitrogen concentration in green vegetationand serves as an indicator of the crop response to soil nitrogen fertilizer application. Thecombination of normalized difference vegetation index (NDVI) and photochemical reflectanceindex (PRI) can reduce the effect of leaf area index (LAI) and soil background. The canopychlorophyll inversion index (CCII) was proved to be sensitive to chlorophyll concentration andvery resistant to the other variations. This paper introduced the ratio of TCARI/OSAVI to makeaccurate predictions of winter wheat chlorophyll concentration under different cultivars. Itindicated that canopy chlorophyll concentration could be evaluated by some combined vegetationindices.

关键词： Winter wheat,Canopy reflected spectrum,Structure Insensitive Vegetation Index Chlorophyll concentration

Modeling Soil Erosion with the Aid of GIS

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Journal of Northeast Agricultural University(English Edition) 2005年第1期12卷 42-47页

作者： WUPing-li schoolofgeography LeedsUniversityLeedsLS29JTUK／／CollegeofEnvironmentandResourcesFuzhouUniversityFuzhouFujian350002PRC

Soil erosion caused by water is an increasing global problem. In order to relieve this problem, several erosion models have been developed to measure the rate of erosion for soil conservation planning. This study takes Lee County, South Carolina, USA as an example to map soil erosion within ArcGIS environment by using the RUSLE with erosion indexes retrieved from DEM. This study proves that the integration of soil erosion models with GIS is a very simple but efficient tool for soil conservation.

关键词： mapping erosion RUSLE GIS DEM

Cultivar,Nitrogen and Irrigation Influence on Grain Quality and Its Forecasting Methods by In situ Reflected Spectrum of Winter Wheat

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Agricultural Sciences in China 2004年第11期3卷 831-841页

作者： HUANGWen-jiang WANGJi-hua LIULiang-yun WANGZhi-jie TANChang-wei SONGXiao-yu WANGJing-di NationalEngineeringResearchCenterforInformationTechnologyinAgriculture P.O.Box2449-26Beijing100089P.R.China ResearchCenterforRemoteSensingandGIS SchoolofGeographyBeijingNormalUniversityBeijing100875P.R.China

Field experiments were conducted to examine the influence factors of cultivar, nitrogen application and irrigation on grain protein content, gluten content and grain hardness in three winter wheat cultivars under four levels of nitrogen and irrigation treatments. Firstly, the influence of cultivars and environment factors on grain quality were studied, the effective factors were cultivars, irrigation, fertilization, etc. Secondly, total nitrogen content around winter wheat anthesis stage was proved to be significantly correlative with grain protein content, and spectral vegetation index significantly correlated to total nitrogen content around anthesis stage were the potential indicators for grain protein content. Accumulation of total nitrogen content and its transfer to grain is the physical link to produce the final grain protein, and total nitrogen content at anthesis stage was proved to be an indicator of final grain protein content. The selected normalized photochemical reflectance index (NPRI) was proved to be able to predict grain protein content on the close correlation between the ratio of total carotenoid to chlorophyll a and total nitrogen content. The method contributes towards developing optimal procedures for predicting wheat grain quality through analysis of their canopy reflected spectrum at anthesis stage. Regression equations were established to forecast grain protein and dry gluten content by total nitrogen content at anthesis stage, so it is feasible for forecasting grain quality by establishing correlation equations between biochemical constitutes and canopy reflected spectrum.

关键词： Winter wheat Canopy reflected spectrum Normalized photochemical reflectance index (NPRI) Grain quality indicators Forecasting