Age of bed v, olduvai gorge, Tanzania

Various finds of hominid remains in the Olduvai Gorge, Tanzania, have focused interest upon the age of the deposits in the sequence of six beds. After bed I was dated by the potassium-argon decay method, an absolute date of 10,400 years has now been obtained with the radiocarbon method from a sample of mammalian bones for bed V.     

喀斯特峡谷区植被恢复过程中土壤性质变化

以典型喀斯特地区植被恢复过程中不同恢复阶段(退耕地阶段、草本阶段、灌木阶段、乔木阶段)为对象,研究了土壤养分、微生物量磷、碱性磷酸酶活性等土壤性质的变化及其相关性.结果表明,灌木地土壤有机质、全N、全P和水解性N均高于草地,但低于退耕地;乔木地除10-20cm有机质和0-10 cm速效K显著高于灌木地外,其它与灌木地元...     

加拿大不列颠哥伦比亚省的森林工业

本文分析了加拿大不列颠哥伦比亚省（Ｂ．Ｃ）的森林工业概况,林产品出口情况以及森林经营的原则和方法。并初步总结了Ｂ．Ｃ省值得我国借鉴的一些经验和做法。     

三江源区生物质资源沼气化利用潜力评价

分析和评价三江源区生物质能资源潜力,是建设庭院生态经济模式的基础。通过构建模型的方法,对三江源区的养殖业生产和牧区居民生活过程产生的畜禽粪便和人粪尿等生物质能源潜力进行了估算,分析结果表明,仅2011年,江河源区产生的牲畜粪便总量为5 819.31万t,人的粪便总量为135.92万t,合计5 955.23万t,如果进行沼气化利用,可产生沼气11.23～18.84亿m³,相当于7.97～13.38亿kg的标准煤,对三江源生态移民点和灾后恢复重建点发展能源型庭院生态经济模式具有重要作用。     

The columbia river basalts

Between 17 million and 6 million years ago, 200,000 square kilometers of the American Northwest were flooded by basaltic lava that erupted through fissures in the crust up to 150 kilometers long. Larger individual eruptions covered over a third of the Columbia Plateau in a few days. The lavas represent partial melts of the earth's mantle that were only slightly modified by near-surface, upper crustal processes. The abundant chemical and mineralogical data now available offer an opportunity to study mantle composition and the processes involved in the evolution of the earth's crust.