川中丘陵区城墙岩群和蓬莱镇组紫色岩上土壤性质研究

采用野外调查、取样和室内实验分析相结合的方法,研究了川中丘陵区白垩系城墙岩群(K1cg)和侏罗系蓬莱镇组(J3p)两种紫色母岩上土壤理化性质特征和差异,结果表明:两种紫色岩母质发育的土壤粘粒含量低,而砂粒含量高;土壤有机质和氮素含量低,而矿质养分含量丰富;在相同的地形部位上,J3p发育的土壤粘粒、全钾、速效钾和速效磷含量高于K1cg发育的土壤,而K1cg发育的土壤pH和土壤全磷均高于J3p发育的土壤,两种紫色岩母质形成的土壤有机质和氮素差异不明显。从丘顶到丘脚,土层逐渐增厚,土壤粘粒含量逐渐递增,砂粒含量逐渐递减;土壤有机质及各种矿质养分含量均呈递增趋势。     

An analysis of wet deposition of sulfate using a trajectory model for East Asia

A long-range transport model for East Asia was developed to estimate the wet deposition of sulfate. The model is a trajectory type which is appropriate for long-term analysis. Trajectories of air masses are calculated by tracing the wind field which changes spatially and temporally. The processes of reactions, rainout removal, intake of sulfate in cloud water into rain water, and dry and wet depositions are considered. It is possible to calculate the concentration of sulfate in precipitation at a receptor by performing material balance in a grid box containing the receptor.The results obtained by the long-range transport model were evaluated through comparison with observation data of acidic deposition. The observation was conducted at 21 stations throughout Japan for one year. The calculated amount of wet deposition of sulfate in Japan was 0.22Tg/y in S equivalent, while the observed amount was 0.29Tg/y. The long-range transport model can predict almost 80% of observed wet deposition. The contributions of domestic anthropogenic sources and volcanic eruption to wet deposition of sulfate in Japan were estimated using the longrange transport model. The ratio of the deposition of sulfate due to Japanese anthropogenic sources to that due to the Asian continental sources was about 1 to 2. Since air stream from the direction of the Asian continent dominates during winter, the contribution of Japan to wet deposition in the region which faces the Sea of Japan amounted to less than 15%. The contribution of the sulfur oxides from volcanoes was about 20%.     

Folk experiments

Folk experiments in agriculture are often inspired by new ideas blended with old ones, motivated by economic and environmental change. They tend to save labor or capital. These notions are illustrated with nine short case studies from Nicaragua and El Salvador. The new ideas that catalyze folk experiments may be provided by development agencies, but paradoxically, the folk experiments are so common that the agencies that inspire them usually pay little attention to them. Some folk experiments are original, but others simply copy innovations that farmers have seen somewhere else. Unlike formal scientific research, in which results are consistently written, folk experiments are rarely “inscribed,” because the results are for use by individual farmers and need not be shared with an audience.     

东南亚猪的遗传育种

简要地回顾了东南亚猪近50年来的猪品种改良历程,重点阐述了泰国正大集团在猪育种上的发展过程,分析了现行的猪繁育体系结构.对猪育种的基本原则、性状遗传相关的影响、杂种优势的利用、育种与环境的关系、市场需求导向等进行了讨论.在总结作者从事养猪生产50余年经验的基础上,对目前东南亚猪的育种提出了有参考价值的建议.     

基于NOAA卫星数据的中亚地区盐渍化动态监测研究

以1989、1999、2009年3期NOAA遥感影像数据为基础,采用ICA-T-SVM分类和目视解译结合的方法,对中亚地区中度以上级别的土壤盐渍化进行监测研究分析.结果显示,中亚地区的盐渍化主要集中在土库曼斯坦、哈萨克斯坦以及乌兹别克斯坦的西部地区;从数量上看,盐渍化程度在逐年加重,特别是乌兹别克斯坦变动程度较大.结合当地情况,从自然环境因子和社会经济因子2方面分析了盐渍化成因,提出建立完善的灌溉系统,建立现代化排水系统,种植耐盐碱植物,增施农家肥等防治措施.     

Importance of reservoirs for the conservation of freshwater molluscs in a tropical urban landscape

Freshwater species and ecosystems are gravely imperiled, particularly within urban landscapes of tropical Asia. In one of the region’s most urbanized landscapes (i.e., Singapore), we determined: (1) the importance of six different habitats (i.e., catchment reservoirs, estuarine reservoirs, forest streams, rural streams, ponds and monsoon canals) for conserving the diversity of freshwater molluscs; (2) key environmental factors (e.g., pH) affecting molluscan distribution; (3) important biogeographical determinants (e.g., area) of molluscan richness within each habitat; and (4) the habitat affinities of introduced species. High sampling saturation was achieved at most study habitats with minimal sampling effort, suggesting that the utilization of molluscs as bioindicators can expedite freshwater conservation initiatives. Estuarine reservoirs (6.0 ± 2.0) had the highest molluscan richness, vis-à-vis catchment reservoirs, forest streams, rural streams, ponds and monsoon canals (3.0 ± 1.5; 0; 3.3 ± 2.0; 1.8 ± 0.5 and 3.5 ± 0.5 respectively). Both reservoir types possessed species compositions distinct from other habitats and contained majority (76%) of the sampled species. Reservoirs therefore serve to conserve the bulk of local freshwater malacofauna, especially if they are maintained at near-neutral pH levels (i.e., ∼7.3) and contain large substrates (i.e., rocks). Area was the best predictor of molluscan richness across all habitats, implying that larger freshwater habitats require higher conservation priorities than smaller ones. Introduced (non-native) species (e.g., Pomacea canaliculata) had high affinities for reservoirs, which are in need of monitoring to curb population expansions. The interminable growth of human settlements urgently requires a reconciliatory approach, which includes the ecologically-sound design and management of modified habitats to complement reserves in sustaining native freshwater species.     

青藏高原中部土壤水中稳定同位素变化

根据 1 998年夏季测得的青藏高原中部那曲地区降水和土壤水中稳定同位素 ,分析了不同层位土壤剖面中稳定同位素的变化规律及与水分迁移的关系。研究结果发现 ,土壤表层水中δ1 8O受降水中δ1 8O的直接影响 ,并且与降水中δ1 8O有相同的变化趋势 ,而地下水中δ1 8O受降水中δ1 8O的直接影响不明显 ,变化幅度很小 ,表明地下水并非直接来源于当年夏季的降水 ,可能代表了多年降水的平均状态。不同土壤剖面水中δ1 8O的变化反映了降水向地下逐渐渗浸的过程。表层土壤水中δ1 8O受降水的影响最为明显 ,而向下土壤水中δ1 8O受地下水δ1 8O的影响增强 ,显示出地下水在土壤水分活动中起着活跃的作用。