林区可循环生态功能区建设存在的问题及建议

探讨了大兴安岭林区可循环生态功能区建设存在的森林资源数量减少、森林结构失调、森林防护效能减弱等问题,提出了树立新的资源使用观念、调整经营布局、实施5大工程、建设5大基地等发展循环生态功能区建设的措施。     

Subduction and slab detachment in the Mediterranean-Carpathian region

Seismic tomography models of the three-dimensional upper mantle velocity structure of the Mediterranean-Carpathian region provide a better understanding of the lithospheric processes governing its geodynamical evolution. Slab detachment, in particular lateral migration of this process along the plate boundary, is a key element in the lithospheric dynamics of the region during the last 20 to 30 million years. It strongly affects arc and trench migration, and causes along-strike variations in vertical motions, stress fields, and magmatism. In a terminal-stage subduction zone, involving collision and suturing, slab detachment is the natural last stage in the gravitational settling of subducted lithosphere.     

Osmium isotope evidence for an s-process carrier in primitive chondrites

Osmium extracted from unequilibrated bulk chondrites has isotope anomalies consistent with an insoluble s-process carrier, termed Os(i) here. Osmium from metamorphosed bulk chondrites does not have isotope anomalies, implying that the Os(i) carrier was destroyed by metamorphism. The isotopic homogeneity of metamorphosed bulk chondrites is consistent with extremely effective mixing of presolar grains from varied sources in the nebula. Osmium in the Os(i) carrier is likely from nucleosynthetic sites with a neutron density about two to four times as high as that of the average solar s-process Os.     

Osmium isotope heterogeneity in the constituent phases of mid-ocean ridge basalts

Radiogenic isotope variations in mid-ocean ridge basalts (MORB) are commonly attributed to compositional variations in Earth's upper mantle. For the rheniumosmium isotope system, constituent MORB phases are shown to possess exceptionally high Re/Os (parent/daughter) ratios, consequently radiogenic 187Os is produced from the decay of 187Re over short periods of time. Thus, in the absence of precise age constraints, Os isotope variations cannot be unambiguously attributed to their source, although Re-Os isotope data for constituent minerals can yield crystallization ages, details of equilibration, and initial Os isotope values that relate directly to the mantle source.     

山东省农菌资源循环利用模式现状与研究进展

农菌循环利用是当前现代农业与低碳经济领域结合发展的热点。山东是食用菌生产大省,在产业发展过程中,已发展形成集农业秸秆等废弃物资源循环利用和食用菌高效种植产业化于一体的循环农业模式,如小尺度和中尺度循环模式等。本文就不同农菌模式产业近年进展的各自特点和适用性、及其运行保障体系的结构功能、经济效益和存在问题等方面进行了综述,并对发展趋势进行展望。     

Subduction and recycling of nitrogen along the Central American margin

We report N and He isotopic and relative abundance characteristics of volatiles emitted from two segments of the Central American volcanic arc. In Guatemala, delta15N values are positive (i.e., greater than air) and N2/He ratios are high (up to 25,000). In contrast, Costa Rican N2/He ratios are low (maximum 1483) and delta15N values are negative (minimum -3.0 per mil). The results identify shallow hemipelagic sediments, subducted into the Guatemalan mantle, as the transport medium for the heavy N. Mass balance arguments indicate that the subducted N is efficiently cycled to the atmosphere by arc volcanism. Therefore, the subduction zone acts as a "barrier" to input of sedimentary N to the deeper mantle.     

玉米秸秆预处理技术及资源化研究进展

为缓解当前能源危机,寻求农业秸秆的有效利用途径,本文介绍了我国玉米秸秆的处理现状及存在问题。利用农业秸秆产生还原糖、生产乙醇、生成腐殖酸、制氢等方面对玉米秸秆资源化应用进行了综述,并分析了资源化过程中存在的问题,就其发展前景进行了展望。     

新疆干旱地区杨树的灌溉造林

干旱地区杨树灌溉造林可以防风护田、生物排水、提供木材和其他林副产品、改善人类的生态环境,具有重要的意义。干旱地区水分不足,通过灌溉可以发展杨树,但必须开源节流,合理用水,做到水土平衡。沿渠带状造林省水省地省工,林木生长好,效益高,应作为主攻方向,水土条件好的地方可以发展杨树片林,此外,胡杨的引洪灌溉造林和盐碱地造林也很有发展前途。当前干旱地区杨树灌溉造林的水平不高,生长量低,还有相当大的潜力,除管好现有林木,促进生长,提高质量外,今后发展中必须注意克服以往造林中选地和造林技术不当、树种单纯、造林过密、管理粗放、灌水不足、牲畜及病虫危害等问题。本文在调查研究和田间试验的基础上,结合有关资料,对干旱地区杨树灌溉造林中的一些问题进行初步的探讨。     

污水资源化研究

以污水为水培液,通过水培植物净化污水中氮磷等营养物质,实现污水资源化的污水水培净化系统。结果表明,该污水水培净化系统对污水中氮磷等营养物质具有很好的净化效果;黑麦草、酸模、生菜3种植物在水培系统中生长正常,水培系统具有较好的生产性能。     

养殖废弃物循环处理利用对策

就当前我国畜禽废弃物的排放现状及存在问题进行了综合分析,并提出了相应的解决对策。     

农牧交错带农村土地流转分析

以河北省洁源县为例,对坝上地区农村土地流转进行调研,分析了当前农牧交错带农村土地承包经营权流转的基本现状和主要问题,并给出了相应的对策。     

特区农业产业化发展的认识与对策

经济特区作为中国改革开放的“窗口”和“试验场”,应当承担起探索农业产业化发展道路的历史重任。本文强调对特区农业地位进行再认识,并在分析特区农业产业化特区发展的意义的基础上,提出了特区农业产业化发展的一般对策 。     

上海市开发区土地集约利用评价研究

在定性研究的基础上,建立评价指标体系、构建评价模型,对上海31个国家级和市级开发区土地集约利用水平进行定量化评价,根据评价结果提出进一步提升上海开发区土地集约利用水平的政策建议.     

我国开发区土地集约利用的评价

为提高土地资源持续保障能力,缓解土地供需矛盾,开发区必须认真落实科学发展观和建设节约型社会的要求,建立集约高效的开发区用地模式。综述了开发区概况、土地集约利用原理、评估的重要性、土地集约利用途径、评价体系、土地集约利用现状和存在的问题,并提出了合理的对策。     

开发区域的累积环境影响及实例分析

在探讨开发区域的累积效应行为与类别的前提下,深入分析区域活动累积环境影响的响应方式,建立相对应的4种累积环境影响的理论计算模型。最后,以海南省某一开发区作为实例,运用全幕景分析方法,结合区域景观结构分析、海域水动力模型等背景技术,在累积环境影响识别的基础上,通过开发区域的土地利用变异、全幕景变化,对开发区域的陆生生态、近岸海域生态进行累积环境影响分析。