Evaporite karst of Albania: main features and cases of environmental degradation     

Mario Parise  Perikli Qiriazi  Skender Sala 《Environmental Geology》2008,53(5):967-974

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A Consistent Soil Fatigue Framework Based on the Number of Equivalent Cycles   总被引：1，自引：0，他引：1  

Nii Allotey  M. Hesham El Naggar 《Geotechnical and Geological Engineering》2008,26(1):65-77

Cyclic soil degradation and hardening affects soil stiffness and strength, and is linked to an increase or decrease in the mean effective confining stress due to void ratio or pore pressure changes. This change of state can be explicitly modeled by using effective stress methods, or implicitly modeled using total stress methods. In the latter, this is achieved by using empirical functions based on the number of loading cycles that are derived from constant-amplitude stress or strain laboratory tests. To suite generalized loading conditions, these functions must be extrapolated to variable-amplitude loading. This falls under the general class of a fatigue-based problem. The main focus of this paper is to present a generalized consistent soil fatigue formulation for soils under cyclic loading. The paper then goes on to discuss the implementation of various cyclic soil degradation and hardening models reported in the literature, and highlights their important underlying assumptions, capabilities and limitations.  相似文献   

冀西北水晶屯金矿床剥蚀程度的判别方法   总被引：1，自引：0，他引：1  

魏俊浩  赵旭东 《矿产与地质》1995,(1)

从冀西北水晶屯金矿近矿围岩蚀变的空间组合、金的指示元素的空间特征、黄铁矿标型特征等多方面地质数据资料入手，来判别矿床的剥蚀程度，认为该金矿床剥蚀程度正处在矿体的中上部。  相似文献   

恢复生态学及其发展   总被引：54，自引：1，他引：54  

赵晓英  孙成权 《地球科学进展》1998,13(5):474-480

简述了国内外恢复生态学的发展概况,分析了我国在生态系统退化的原因、生态学过程以及退化生态系统恢复重建的方法和生态学机理等方面的研究进展。针对我国在恢复生态学研究和退化生态系统恢复实践中存在的问题,提出了加强我国恢复生态学研究的建议。  相似文献   

Evaluation of alkene degradation in the detailed tropospheric chemistry mechanism, MCM v3, using environmental chamber data   总被引：1，自引：0，他引：1  

P. G. Pinho  C. A. Pio  W. P. L. Carter  M. E. Jenkin 《Journal of Atmospheric Chemistry》2006,55(1):55-79

The representation of alkene degradation in version 3 of the Master Chemical Mechanism (MCM v3) has been evaluated, using environmental chamber data on the photo-oxidation of ethene, propene, 1-butene and 1-hexene in the presence of NO_x, from up to five chambers at the Statewide Air Pollution Research Center (SAPRC) at the University of California. As part of this evaluation, it was necessary to include a representation of the reactions of the alkenes with O(³P), which are significant under chamber conditions but generally insignificant under atmospheric conditions. The simulations for the ethene and propene systems, in particular, were found to be sensitive to the branching ratios assigned to molecular and free radical forming pathways of the O(³P) reactions, with the extent of radical formation required for proper fitting of the model to the chamber data being substantially lower than the reported consensus. With this constraint, the MCM v3 mechanisms for ethene and propene generally performed well. The sensitivity of the simulations to the parameters applied to a series of other radical sources and sink reactions (radical formation from the alkene ozonolysis reactions and product carbonyl photolysis; radical removal from the reaction of OH with NO₂ and β-hydroxynitrate formation) were also considered, and the implications of these results are discussed. Evaluation of the MCM v3 1-butene and 1-hexene degradation mechanisms, using a more limited dataset from only one chamber, was found to be inconclusive. The results of sensitivity studies demonstrate that it is impossible to reconcile the simulated and observed formation of ozone in these systems for ranges of parameter values which can currently be justified on the basis of the literature. As a result of this work, gaps and uncertainties in the kinetic, mechanistic and chamber database are identified and discussed, in relation to both tropospheric chemistry and chemistry important under chamber conditions which may compromise the evaluation procedure, and recommendations are made for future experimental studies. Throughout the study, the performance of the MCM v3 chemistry was also simultaneously compared with that of the corresponding chemistry in the SAPRC-99 mechanism, which was developed and optimized in conjunction with the chamber datasets.  相似文献   

Degradation of Microbes for the Crude Oil Contaminants     

LIU Xiao-yan  SHI Peng-fei  SUN De-zhi 《地球科学进展》2004,(Z1)

Production and storage-transportation of crude oil can not only give rise to soil pollution but also destroy ecological environment. Degradation of microbes for oily soil was studied with the instnunent, Geofina Hydrocarbon Meter (GHM), by experimental analysis qualitatively and quantitatively in the paper. Analytical result showed that the crude oil could be considerably degraded by eating-oil microbes in oily soil and the number of eating-oil microbes increased while the working hours of oil-well rising. As a result, contaminated oil could be degraded more quickly by a lot of eating-oil microbes in the soil. At the same time, the degradation rate of contaminated oil increased gradually as the time went on. In addition, amount of gaseous component in the oily soil samples increased with degraded time and the microbes could selectively consume contaminated oil strongly, so biedegradation might alleviate the degree of contamination and destruction to the soil and environment in the process of oil product  相似文献   

西藏湿地资源价值损失评估   总被引：5，自引：0，他引：5  

李忠魁  洛桑桑旦 《湿地科学与管理》2008,4(3):24-29

西藏高原独特的自然环境和气候条件,造就了特有的、世界独—无二的高原湿地资源。应用环境经济学的理论与方法,计算了西藏湿地的全部生态环境价值为4023.8068×10^8元/a,以5%的贴现率计算,湿地价值的现值为44261.8748×108元,相当于73.72×10^4元/hm^2。从湿地生态服务功能的价值构成来看,直接使用价值（提供产品和文化功能）约占总价值的24.40%,而间接价值（调蓄洪水、疏通河道、水资源蓄积、土壤持留、净化环境、固定碳和支持功能）则占75.6%,西藏高原湿地退化面积为60.4272×10^4hm^2,相当于年退化面积2.0143×10^4hm^2。已退化湿地损失价值4454.69×10^8元,年损失价值148.49×10^8元。  相似文献   

Impacts of recreational motorboats on fishes: A review     

A.K. Whitfield  A. Becker 《Marine pollution bulletin》2014

A considerable amount of research has been conducted on the impacts of recreational boating activities on fishes but little or no synthesis of the information has been undertaken. This review shows that motor boats impact on the biology and ecology of fishes but the effects vary according to the species and even particular size classes. Direct hits on fishes by propellers are an obvious impact but this aspect has been poorly documented. Alterations in the wave climate and water turbidity may also influence fishes and their habitats, especially submerged and emergent plant beds. Sound generated by boat motors can also influence the communication and behaviour of certain species. Pollution arising from fuel spillages, exhaust emissions and antifouling paints all have detrimental effects on fishes. Finally, the use of recreational boats as vectors of aquatic invasive organisms is very real and has created major problems to the ecology of aquatic systems.  相似文献   

Electrochemical Treatment of Reactive Blue 52 Using Zirconium,Palladium and Graphite Electrode          下载免费PDF全文

Milica Jović  Dragan Manojlović  Dalibor Stanković  Marijana Marković  Ivan Anđelković  Jelena Papan  Goran Roglić 《洁净——土壤、空气、水》2014,42(6):804-808

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Electrochemical Degradation of Triclosan at a Ti/SnO2‐Sb/Ce‐PbO2 Anode          下载免费PDF全文

Dusmant Maharana  Junfeng Niu  Neti Nageswara Rao  Zesheng Xu  Jianghong Shi 《洁净——土壤、空气、水》2015,43(6):958-966

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