Surface sealing as influenced by slope angle and position of simulated stones in the top layer of loose sediments

The influence of five different slope angles and two different positions of simulated stones in the top layer of a sandy and a silty sediment on surface sealing intensity is examined in the laboratory. Sealing intensity is assessed by studying changes of percolation rate through a sediment layer with simulated rainfall duration and by measuring cohesion of the 5 mm thick upper sediment layer, a measure of seal strength, by means of a torvane. Slope has a negative influence on sealing intensity. For a constant per cent of simulated stone cover, sealing intensity is lowest in the case of stones placed on the sediment surface compared to the case of stones pushed into the surface layer. Explanations for these findings are given and some implications are further discussed.     

博大精深的琅琊文化

对琅琊台、琅琊港、琅琊郡、琅琊刻石、越王勾践徒都琅琊、秦始皇三次巡视琅琊台和徐福东渡上进行了现场调查和历史考证,提出了“琅琊文化”学说,就琅琊文化的形成及其发展作了阐述。     

谈山东观赏石资源现状及分类

山东观赏石资源十分丰富,种类多,造型美,品相佳。自古山东为观赏石大省,具有深邃的齐鲁石文化积淀。文中对山东观赏石分类,并着重论述了泰山石奇石、琅砑石、临朐石等30多种观赏石的机理及特征。对观赏石的研究与开发,领先的奇石文化市场,必然对山东经济发展具添砖增瓦意义,山东石文化将在发展中谱写出新的篇章。     

临朐奇石鉴赏特征及其成因简述

对临朐奇石进行了分类 ,介绍了临朐奇石各色品种的鉴赏特征。简述了临朐奇石的成因 ,认为除个别品种外 ,皆与寒武—奥陶纪地层关系密切     

谈山东观赏石资源现状及分类

山东观赏石资源十分丰富,种类多,造型美,品相佳。自古山东为观赏石大省,具有深邃的齐鲁石文化积淀。文中对山东观赏石分类,并着重论述了泰山石奇石、琅砑石、临朐石等30多种观赏石的机理及特征。对观赏石的研究与开发,领先的奇石文化市场,必然对山东经济发展具添砖增瓦意义,山东石文化将在发展中谱写出新的篇章。     

Can the substrate influence the distribution and composition of benthic macroinvertebrates in streams in northeastern Brazil?

We sampled different substrates (sand, gravel, leaf litter and stones) in the rainy and dry season to study the distribution and composition of benthic macroinvertebrates in tropical streams (northeastern Brazil). Benthic macroinvertebrates were distributed according to the substrates, with stones showing a higher richness and abundance of species and abundance of collector-gatherers and filter-collectors. The results of the PCoA showed a separation of stones from the other substrates and similarities between sand and gravel.