石灰岩质高陡边坡覆绿生态地质指标阈值研究

为探索高陡边坡植被重建所需的地下生境条件,依托生态地质学理论,以山东、河南地区石灰岩质高陡边坡为研究对象,通过对边坡上有植物生长的裂缝生境条件进行调查,测量壁面体裂隙率、裂隙的温湿度、隙缝中土壤肥分,并运用样地法统计石灰岩山坡植物根群圈的特征,归纳总结生态地质指标阈值。结果表明华北石灰岩质高陡边坡覆绿生态地质指标阈值包括:(1)岩体体裂隙率适应值范围为1.2‰~5%;(2)小乔木与灌木的根群圈深度为20~40 cm,此范围温湿度适应值分别为0~26℃,90%~100%,20~40 cm也即物种的地境稳定层;(3)土壤也需满足一定的肥分指标。连通性良好的裂隙网络、适宜并相对稳定的温湿度、一定的土壤肥分是石灰岩质边坡植被重建过程中的重要条件,保障了植物生长所需的稳定地境。

云南民居建筑的空间取向

从人文地理学和建筑学的观点出发 ,分析和阐述了云南民居建筑的地景条件、空间形式及其特征 ,认为在现代建筑大量涌现的今天 ,云南传统民居建筑和乡村聚落的多样性更加珍贵 。

Research on Full Space Transient Electro-magnetism Technique for Detecting Aqueous Structures in Coal Mines

Based on the transmitting theory of "smoke ring effect", the transient electromagnetism technique was used in coal mines to detect abnormal areas of aquiferous structures in both roofs and floors of coal seams and in front of excavated roadways. Survey devices, working methods and techniques as well as data processing and interpretation are discussed systematically. In addition, the direction of mini-wireframe emission electromagnetic wave of the full space transient electromagnetism technique was verified by an underground borehole for water detection and drainage. The result indicates that this technique can detect both horizontal and vertical development rules of abnormal water bodies to a certain depth below the floor of coal seams and can also detect the abnormal, low resistance water bodies within a certain distance of roofs. Furthermore, it can detect such abnormal bodies in ahead of the excavated roadway front. Limited by the underground environment, the full space transient electromagnetism technique can detect to a depth of only 120 m or so.

Developing a risk assessment system for gas tunnel disasters in China

Gas disasters always restrict the tunnel constructions in mountain area, which becomes a major geological barrier against the development of underground engineering. China is rich in coal resources and has a large amount of gas with a wide range of distribution. However, China experienced not only adverse effects on coal mining but also gas disasters in underground engineering construction, such as tunnels and chambers. With the increased number of tunnels passing through coal-bearing strata, the incidence of gas accidents is also rising. Therefore, the significance of preventing and mitigating gas disasters should be emphasized, and an effective risk assessment method for gas disasters should be established. On the basis of research on over 100 gas tunnels in China, a relatively ideal gas disaster risk assessment method and system for tunnels are established through the following measures. Firstly, geo-environmental conditions and gas situations were analyzed during construction. Secondly, qualitative analysis was combined with quantitative analysis. Finally, the influencing factors of gas disasters, including geological conditions, gas,and human factors, were investigated. The gas tunnel risk assessment system includes three levels:(1) the grading assessment of a gas tunnel during the planning stage,(2) the risk assessment of gas tunnel construction during the design and construction stages,(3) the gas tunnel outburst risk assessment during the coal uncovering stage. This system was applied to the dynamic assessment of gas disaster during the construction of the Zipingpu tunnel of Dujiangyan–Wenchuan Highway(in Sichuan, Southwest China). The assessment results were consistent with the actual excavation, which verified the rationality and feasibility of the system. The developed system was believed to be back-up and applied for risk assessment of gas disaster in the underground engineering construction.

Introduction of Pinus radiata for afforestation:a review with reference to Aba, China

Pinus radiata D. Don, native to a Californian coastal environment, has been introduced to many parts of the world as an exotic species for afforestation. It is now a major plantation species in the Southern Hemisphere. In 1990, it was introduced to the heavily degraded, dry Min river valley area in Aba prefecture of Sichuan Province, P. R. China. Survival and growth of young trees planted at several sites appear to be reasonable. This review is to serve as an introduction to the large body of literature on P. radiata for forest scientists in China. It covers the following aspects: P. radiata in its native environment and in ex situ plantations, provenance and genetic variations, environmental limitations and climate niche, diseases and pests, lessons from unsuccessful introductions, and the use of P. radiata for ecological restoration. The early growth of P. radiata planted in the dry river valley area is briefly described. Potential problems associated with the introduction of P. radiata in Aba and future research needs are also identified.

Research on the relationship between stand productivity and site condition of Larix kaempferi

In this research, five plots are Selected based on stand storage and productivity of planted forest of Larix kaempferi （Japanese larch） as well as their relationship with factors suCh as forest age, site condition and stand density. Through standard plot investigation and method of trunk analysis, systematic research is conducted on storage and productivity of the planted forest and their relationship with site condition. As shown in the research, productivity of planted forest of Larix kaempferi in low latitude area is higher than that in high latitude area while stand productivity is higher in slight acid soil. Contents of potassium element in the soil have Considerable influence on productivity of the Larix kaempferi forest.

Environmental Issues and Management for Hydropower Peaking Operations

Many hydropower plants are operated as peak generators or frequency controllers, because they can change their output quickly to follow the fluctuating power demand. When meeting peak load requirements, a power station is turned on at a particular time during the day, generates power at a constant load for a certain number of hours, and is then turned off or set to a different load for another time period, resulting in a high variability inflow discharges. Where reservoir hydro schemes are operated primarily to provide peak load services, there are particular environmental risks that should be considered in any environmental impact assessment. At a minimum these should focus on water quality, fluvial geomorphology, riparian vegetation, macro-invertebrate and fish communities underpinned by a sound hydrological analysis. Frequent temperature changes may occur downstream of a peaking power station; increased seepage-induced erosion of riverbanks due to frequent water level drawdowns; and impacts to macro-invertebrate and fish communities due to rapid and frequent in channel habitat conditions. With a sound understanding of the potential environmental issues, there are strategies that can be employed at the siting and design stage to minimize or mitigate these risks, including but not limited to minimum environmental flows, ramping rules, utilization of a re-regulation storage and localized treatment works.

Genetic analysis of land subsidence in Anshan

Land subsidence is a complex geological phenomenon which is concerned by the researchers at home and abroad. In this paper,the observation data from Anshan Second Order Leveling during 1987-[KG-*7]-1994,combined with the area of environmental engineering geology and geological conditions analysis shows that land subsidence in Anshan City is closely related to active tectonics,Quaternary strata and groundwater exploitation.

Advances in GDGT research in Chinese Marginal Seas: A review

Archaeal and bacterial glycerol dialkyl glycerol tetraethers(GDGTs) play a unique role in discerning the biogeochemical processes and climate change in terrestrial(e.g. soil, peat, stalagmites, lakes, rivers, hot springs) and marine environments. Organic proxies based on GDGTs(e.g. TEX_(86), MBT/CBT and BIT) have made impressive applications in the open ocean and terrestrial environments. However, the applicability of these proxies in marginal seas has not been thoroughly evaluated, which is necessary given the complexity and dynamics of these systems, such as organic matter(OM) flux, hydrodynamic conditions, and human impact. This review aims to summarize recent studies of GDGTs and GDGT-based proxies in the Chinese marginal seas(CMS), which are characterized by diverse gradient in terrigenous supplies and ocean productivity and hold rich information on climate and sea level changes, ocean current dynamics, sedimentary evolution and biogeochemical processes.

Climatic and Topographical Factors Affecting the Vegetative Carbon Stock of Rangelands in Arid and Semiarid Regions of China

Rangeland systems play an important role in ecological stabilization and the terrestrial carbon cycle in arid and semiarid regions. However, little is known about the vegetative carbon dynamics and climatic and topog- raphical factors that affect vegetative carbon stock in these rangelands. Our goal was to assess vegetative carbon stock by examining meteorological data in conjunction with NDVI （normalized difference vegetation index） time se- ries datasets from 2001-2012. An improved CASA （Carnegie Ames Stanford Approach） model was then applied to simulate the spatiotemporal dynamic variation of vegetative carbon stock, and analyze its response to climatic and topographical factors. We estimated the vegetative carbon stock of rangeland in Gansu province, China to be 4.4×10^14 gC, increasing linearly at an annual rate of 9.8×10^11 gC. The mean vegetative carbon density of the whole rangeland was 136.5 gC m-2. Vegetative carbon density and total carbon varied temporally and spatially and were highly associated with temperature, precipitation and solar radiation. Vegetative carbon density reached the maximal value on elevation at 2500-3500 m, a slope of 〉30°and easterly aspect. The effect of precipitation, tem- perature and solar radiation on the vegetative carbon density of five rangeland types （desert and salinized meadow, steppe, alpine meadow, shrub and tussock, and marginal grassland in the forest） depends on the acquired quantity of water and heat for rangeland plants at all spatial scales. The results of this study provide new evidence for ex- plaining spatiotemporal heterogeneity in vegetative carbon dynamics and responses to global change for rangeland vegetative carbon stock, and offer a theoretical and practical basis for grassland agriculture management in arid and semiarid regions.