Effect Of Water Environment Research Articles

Water, iron, redox environment: effects on the wadsleyite–ringwoodite phase transition

The transition zone of the Earth's upper man- tle is characterized by three discontinuities in seismic wave velocity profiles. One of these at about a depth of 520 km is assigned to the transformation of wadsleyite (β-) to ring- woodite (γ-(Mg, Fe) 2 SiO 4 ) (e.g., Shearer in J Geophys Res 101:3053-3066, 1996). The exact location, width, and other properties of that discontinuity are affected by a mul- titude of parameters. The present study specifically focuses on the effect of water, iron content, and redox environment on the depth of the phase transition. We performed high- pressure experiments in a multi-anvil apparatus at 1200 °C with variation in Mg-Fe compositions (0.10 < xFe < 0.24), water contents (0 < xH2O < 2 wt%), and the redox envi- ronment (using different buffers: Fe/FeO (reducing), Re/ ReO 2 (oxidizing)). Run products were investigated using electron microprobe and Fourier transform infrared spec- troscopy to obtain the composition including the hydroxyl

Effects of sea water environment on glass fiber reinforced plastic materials used for marine civil engineering constructions

Glass fiber composites (GFRP) are common in civil engineering projects, but not in marine structures. One reason is that seawater effects degrade GFRP composites mechanical properties and interlaminar shear strength (ILSS). Here, influence of seawater environment is studied to determine the best composite materials for marine civil engineer applications, studying the influence of several factors in their mechanical properties. This is to determine safety factors to use in the design of structural calculations for marine applications. Glass/epoxy composites are the safest materials to use in marine civil structures as mechanical properties degradation becomes stabilized after moisture saturation level. UV and water cyclic analysis must be done to determine affection to transversal strength. Only vinylester GFRP has problems with biodegradation. GFRP fatigue performance is not influenced by seawater environment.

Effect of Soil Water Environment and Simulated Savanna Climate on Growth and Mineral Nutrition in Jatropha curcas L.

This study aimed to determine the optimal soil water conditions for J. curcas L. cultivation under the bi-annual rain seasons of the African Savannah climate. Changes in J. curcas L. seedling biomass and mineral nutrient uptake and movement patterns were examined under soil water matric potentials of -2.5, -2.9, -3.4 and -4.0kPa, and two rain seasons separated by a dry spell. The bi-annual savannah rain conditions were simulated using automated buried-type tensiometer system. During the first rain season (irrigation), -3.4kPa soil water matric potential showed the highest water-use efficiency (2.44 g dry weight L-) and biomass yield (57.14g). Seedlings were variously affected by the subsequent dry spell, including total defoliation and stunting. On re-irrigation, seedling recovery (biomass and water use efficiency) was less as compared to the first rain season. Among the nutrients monitored, N, P and K were the most predominantly uptaken, with N showing the closest correlation with seedling growth. Soil matric water potential of －3.4 kPa is the optimum soil water environment for J. curcas cultivation in the savannah conditions; additionally, irrigation during the dry season is essential for a stable harvest.

Effect of Hot Water Environment on Tensile Fracture Properties of Carbon Fiber Reinforced Polyoxamide Composites

Matrices for carbon fiber reinforced thermoplastics are appropriate to use comparatively cheaper resins such as polyamide. However polyamide 6 is highly hygroscopic and the mechanical properties of materials are reported to be degraded by water absorption. Polyoxamide (PX) has been developed as polyamide resins with low hygroscopicity. In this study, the effect of hot water environment on the tensile fracture properties of carbon fiber/polyoxamide composites has been clarified.

Strain Rate Calculation Approach in Environmental Fatigue Evaluations

Fatigue usage factor evaluations including the effects of reactor water environment have been performed in numerous nuclear plant license renewal efforts. A large number of these evaluations have used the environmental fatigue penalty factor, Fen, approach prescribed in various regulatory documents. The Fen equations require input of strain rate, but the prescribing documents do not provide methodology or criteria for the quantification of the strain rate to be input. As a result, numerous approaches have been offered and studied. This paper presents an approach used by Westinghouse to include strain rate in an automated calculation of Fen based on the modified rate approach (MRA) to integrated strain rate applications. The starting point of the approach is ASME Code Section III NB-3200 fatigue analysis. With environmental fatigue evaluations in new plant designs now emerging in ASME Code criteria, strain rate considerations remain part of the discussion. The intent of this paper is to provide further insight into this process.

城市景观格局演变的水环境效应研究综述

PDF HTML阅读 XML下载 导出引用 引用提醒 城市景观格局演变的水环境效应研究综述 DOI: 10.5846/stxb201306071391 作者: 作者单位: 中国科学院城市环境研究所;中国科学院大学,中国科学院城市环境研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（30800148）；厦门市科技计划项目（3502Z20122001） Research review on effects of urban landscape pattern changes on water environment Author: Affiliation: Institute of Urban Environment, Chinese Academy of Sciences,Institute of Urban Environment, Chinese Academy of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:人类活动导致的城市土地利用覆被变化在景观生态学上表现为城市景观类型的更替和城市景观格局的演变。我国城市景观格局中自然植被景观基质大幅被人工硬化地面所取代，自然景观斑块破碎化，城市道路和排水管网等人工廊道大量增加，造成“源”“汇”景观的比例失衡和格局失调，从而产生城市景观格局演变的水环境负效应，如非点源污染、水生生态系统失衡和城市内涝等，且水环境负效应存在时间尺度差异和空间尺度响应多样性。对城市景观类型及其格局演变产生的城市水环境效应相关研究进行总结，针对现有研究中存在的城市景观格局演变带来的生态过程变化研究较少、影响城市水环境的景观格局变化阈值不明确、研究结果推广难和重复性较差、人工廊道与城市水环境效应关系关注度较低和水环境负效应综合度研究欠缺等不足之处，提出未来研究的着力点，对实现可持续城市具有一定意义。 Abstract:Urban water environment is an important part of urban ecosystem including natural and man-made water, and the natural elements and urban landscape which are closely related to water at catchment scale. Healthy urban water environment could product positive ecological effects such as water retention and impoundment, environmental decontamination, material transportation, making energy flow smoothly and conserving biodiversity. However, the change of urban land cover induces the deterioration of urban water environment and leads to negative water environment effects, such as non-point pollution, imbalance of aquatic ecosystem and urban flooding. The replacement of urban landscape types and evolution of urban landscape pattern caused by human activities display at following aspects: widespread vegetation matrix is largely replaced by artificial hardened ground while natural landscape patches are fragmentized and manual corridors including urban roads and drainage network increase sharply, resulting in the disproportion of water pollution "source" and "sink" landscape types and landscape pattern. Through statistical analysis and model simulation, researchers at home and abroad find that: the cultivated land and urban construction land are the main sources of non-point pollution while natural vegetation landscape types contribute to the reduction of non-point source pollution. Urban surface hardening reduces the environmental capacity of urban water environment by influencing urban hydrological cycle, for instance, surface runoff, evaporation and infiltration and so on. Together with environmental capacity reduction, the eutrophication of urban water environment makes negative effects on the balance of aquatic ecosystem. Negative water environment effects responding to urban landscape pattern will change with spatial and temporal scales. This paper summarizes current researches about the effects of urban landscape types and pattern evolution on water environment and points out the deficiencies of recent researches, such as the lack of specific research coupling landscape pattern change and ecological process, the indeterminacy of the landscape pattern threshold influencing urban water environment, the difficulty in popularizing and repeating research results, neglecting the relationship between urban artificial corridor and water environment effects, and the lack of comprehensive research about negative water environment effects. At last, we put forward five key points of future researches: the lagging response of urban water environment to the change of urban landscape pattern; the differences of water environment effects with different types and distributions; the combined influences from the urban landscape pattern, including matrix, corridor and patch; development of new model which concentrates on urban water environmental effects; a set of related index for urban planning and urban water environmental effects. Our study will contribute to better understanding of urban sustainability. 参考文献 相似文献 引证文献

The significance of fatigue crack initiation for predictions of the fatigue limit of specimens and structures

The fatigue life of specimens and structures covers two periods: a crack initiation period and a crack growth period. Micro-crack nucleation and initial micro-crack growth are a surface phenomenon controlled by the local stress cycles at the material surface. The subsequent macro-crack growth is depending on the fatigue crack growth resistance of the material as a bulk property. The fatigue behaviour in both periods is qualitatively reasonably well understood. However, the quantitative analysis is problematic. Moreover the number of variables which can effect the fatigue behaviour of specimens and structures is large. The paper is focussed on realistic understanding of the prediction problem, especially on the prediction of the fatigue limit of notched specimens and structures. The effect of a salt water environment on the fatigue limit is discussed. As a special topic comments are presented on the notch effect of welded joints. Short comings of the so-called effective notch concept are indicated. Comments on the design recommendations of the International Institute of Welding are presented. The significance of realistic experiments and a profound FE-analysis are emphasized.

Walking in Water and on Land After an Incomplete Spinal Cord Injury

Although no data are available on the effects of water environment on the gait of subjects with spinal cord injury (SCI), hydrotherapy is used in the rehabilitation protocols of SCI patients. The aim of this study was to characterize gait features of subjects with incomplete SCI walking in water and on land in comparison with healthy controls (CTRLs) to identify the specificity of water environment on influencing gait in SCI subjects. This is a matched case-control study. Kinematic gait parameters and range of motion of joint angles of 15 SCI subjects and 15 CTRLs were analyzed. Compared with gait on land, gait in water of the SCI patients was characterized by speed and stance phase reduction, gait cycle time increment, and invariance of stride length and range of motion values. Comparison with CTRL data remarked that walking in water reduces gait differences between the groups. Furthermore, in water, the SCI subjects presented a reduction in variability of the hip and knee joint angles, whereas in the CTRLs, a larger variability was observed. Gait in water of the SCI subjects is associated with kinematic parameters more similar to those of the CTRLs, particularly regarding speed, stride length, and stance phase, supporting the idea that walking in a water environment may be of rehabilitative significance for SCI subjects.

Agronomic Traits for High Productivity of Rice Grown in Aerobic Culture in Progeny of a Japonica Cultivar and a High-Yielding Indica Cultivar

Aerobic rice culture is a promising way to save water and achieve a high yield. The present study was conducted to identify the agronomic traits required for high rice productivity in aerobic culture using chromosomal segment substitution lines (CSSLs) obtained as progeny from the cross between Sasanishiki (japonica), as the recurrent parent and Habataki, a high-yielding indica cultivar with high spikelet production ability, grown under flooded and aerobic conditions in 2009 and 2011. Grain yields of the CSSLs in aerobic culture were similar to or higher than those in flooded culture in 2009, but were similar to or lower than those in flooded culture in 2011. There were significant effects of genotype and water environment on grain yield in both years. Most of the CSSLs had a higher grain yield than Sasanishiki in aerobic culture, whereas their average was close to that of Sasanishiki in flooded culture. Rice plants grown in aerobic culture had larger biomass production, which enabled most of the CSSLs to produce more spikelets per unit area and maintain single-grain weight, thereby producing a higher grain yield than Sasanishiki. These results suggest that high spikelet producing ability would promote high grain yield in aerobic culture.

Analyzing Ecological Environmental Effect of Coal Mine Closure

By means of reading literature, field survey, laboratory test and contrast study, the inevitability and seriousness of coal mine closure was summarized and the ecological environmental effects of coal mine closure especially of coal mine closure with underground mining were analyzed. Ecological environmental effects include water-environmental effects, atmospheric environmental effects, soil-environmental effects and the effects to land use and land cover changes.

A novel framework for analysis of cross-media environmental effects from agricultural conservation practices

Agricultural ecosystems are a source of greenhouse gas (GHGs) emissions and losses of nutrients to waterways. Several studies have recognized this and have documented the potential to reduce GHG fluxes and nutrient loss to waterways by using carbon offsets to fund the implementation of land retirement and afforestation. However, the ability to use land for both agricultural production and environmental conservation is also important. This study develops a novel analytical framework that is used to examine the cross-media (water and air) environmental effects of implementing offset-funded conservation practices in a working-lands setting. The framework is applied to a case study which examines the extent to which carbon pricing can affect practice implementation costs and the optimal distribution of these practices throughout an agricultural watershed. Results indicate that carbon offsets can reduce conservation practice implementation costs and have the potential to reduce greater amounts of nonpoint source pollution for a given cost of implementation. This conclusion has significant implications for policymaking, particularly with regard to using markets for GHG emissions to achieve water quality improvements where water quality trading or government conservation programs have historically been unsuccessful.

The effects of an explicit water environment on the interaction of a single wall carbon nanotube with amino acids: A theoretical study

Tight binding density functional theory was used to investigate the effects of a water environment on the interaction of amino-acids with a single wall carbon nanotube (SWCNT). We selected four amino acids (Gly, Ser, Arg, and Ile) according to their polarity and hydrophobicity indexes. The changes in the bond distances, in vacuum and water, are seen to be directly related to the amino acids hydrophobicities. The variations in binding energies are seen to be greater for non-polar amino acids. The interaction of the neutral and zwitterionic forms of Gly with the SWCNT in water were also analyzed and discussed.

Effects of Water Environment in Closed Water Body on Diffusion of High-Dissolved-Oxygen Water into Bottom Layer and Its Improvement of Water Quality

Effects of Water Environment in Closed Water Body on Diffusion of High-Dissolved-Oxygen Water into Bottom Layer and Its Improvement of Water Quality

Effect of water environment on jute/polypropylene composites

AbstractThis study investigates the effects of water immersion on tensile properties of jute fiber reinforced polypropylene (PP) composites. The long fiber type jute/PP pellet and neat PP pellet were used as materials and the jute/PP specimens with different fiber content were prepared by injection molding with dry-blending of jute/PP and neat PP pellets. All the specimens were aged in hot distilled water at 80°C, and after the fixed periods of immersion, the weight changes and the tensile properties were measured. The weight gain by water absorption was significantly affected by the fiber content. The specimens with the jute fiber content of 30 wt% more easily absorbed water and it reached more than 10%. In these specimens, significant material loss by immersion also occurred. The tensile strength after immersion decreased remarkably in the specimens with the jute fiber content of 30 wt% and more, and all the jute/PP composites showed lower strength than neat PP after immersion of 1000 h.

Effect of water flow velocity on growth and morphology of cultured Undaria pinnatifida sporophytes (Laminariales, Phaeophyceae) in Okirai Bay on the Sanriku coast, Northeast Japan

Undaria pinnatifida sporophytes, originating from the same strain, were cultured at the commercial cultivation site exposed to wave action and the uncultivated site protected from water action of Okirai Bay, Northeast Japan, from January to April 2007; simultaneously, water flow velocity, water temperature, salinity, NO3 + NO2, and chlorophyll a were monitored to investigate the effect of water environment on their growth and morphology. Water temperature and salinity fluctuated within the optimal range for their growth whereas water flow velocity at the cultivation site was greatly fast compared with that at the uncultivated site. Successive chlorophyll a increases synchronized with NO3 + NO2 decreases were observed only at the uncultivated site for over a month; indicating developments of phytoplankton blooms and their nutrient consumption under the low-flow condition. Meanwhile, blade growth rate of cultured sporophytes was higher at the cultivation site than at the uncultivated site. Their thallus size expressed by six morphological characters (blade length, stipe length, blade wet weight, stipe wet weight, blade width, and undivided blade width) at the cultivation site became large in comparison with that at the uncultivated site. Their three morphological correlations (correlations between blade length and thallus length; blade wet weight and thallus wet weight; and undivided blade width and blade width) differed between the sites. They produced a thick and flat blade at the cultivation site but formed a thin and wrinkled blade at the uncultivated site. These results show the significant impact of water flow velocity on their growth and morphology.

복합재료의 기계적 거동에 염수환경이 미치는 영향에 관한 연구

본 연구에서는 염수 침수 실험과 염수 분무 실험이라는 두 가지의 실험을 위그선의 구조재료로 사용될 3가지 다른 복합재료 시스템에 대해서 해수와의 접촉에 의한 물성저하를재현하기 위해 수행하였다. 140일간 염수환경하에서 노화시킨 후 탄소섬유 복합재료와유리섬유 복합재료의 인장, 압축, 전단 강성과 강도 및 층간 전단 강도를 측정하였다. 기본 물성파의 비교를 통해서 염수환경이 복합재료의 기계적 물성에 미치는 영향이 평가되었다. 실험을 통해 염수 분무환경과 침수 환경의 차이는 거의 영향을 미치지 않음을 확인하였다. 탄소섬유 복합재료의 경우 인장 물성에 적은 손실이 발생한 반면 유리섬유 복합재료에서는 인장물성의 저하률이 탄소섬유 복합재료에 비해서 큼을 확인하였다. 그리고 모재 지배적 물성들의 큰 물성저하가 관찰되었다. 이를 통해, 염수는 복합재료의 섬유와 모재 사이의 계면을 퇴화시키고, 또한 모재 자체 물성과 유리섬유의 물성을 저하시킬 수 있음을 확인하였다. In this paper, two different experiments, namely, salt water spray and salt water immersion, were performed to reproduce the contact of composites with the seawater for three kinds of woven fabric composite material systems which would be used for the WIG(wing in ground effect)craft. After aging 140 days in the salt water environment, material properties of carbon/epoxy and glass/epoxy composite such as tensile, compressive and shear stiffness and strength, and inter-laminar shear strength (ILSS) were measured. By comparing baseline material properties with degraded ones, the effects of the salt water environment on the composite mechanical properties were evaluated. From the experiments, it was confirmed that the difference in aging conditions had very small influence on composite properties. And it was found that tensile strength of carbon/epoxy composites showed little degradation, but much more degradation was observed in glass/epoxy composites. And large degradations on matrix dominant properties were observed. The salt water could damage the fiber-matrix interface, matrix properties and the glass fiber.

가압기 밀림관 환경피로평가를 위한 피로보정계수 적용에 관한 연구

Nuclear power plants applying for the continued operation over design life are required to address the effects of reactor water environment in fatigue design requirement of the ASME Code. Reactor water environmental effects are generally evaluated by calculating fatigue correction factors on fatigue usage. This paper describes the application for pressurizer surge line of environmental fatigue correction factors and the strain rate impact in the application. From this paper, the environmental fatigue correction factors resulted from the assumption of a step change in temperature are especially compared with those calculated from the data measured during plant startup. As a conclusion of this paper, the design transient conditions applied to the fatigue design may be conservative in case of the environmental fatigue evaluation.

Effects of water environment on tribological properties of DLC rubbed against brass

The effects of the water environment, such as temperature, dissolved ions, and dissolved oxygen, on the tribological properties of diamond-like carbon (DLC) against brass were studied as part of the development of water-lubricated hydraulics, valves and cylinders based on metals (Fe alloys, Cu alloys, etc.). A ball-on-disk type tribotester was used to examine the above various factors. DLC was deposited on stainless steel disks using an unbalanced magnetron sputtering system. Pure water and quasi-tap water, which imitate typical tap water sampled in Tokyo, were used to study the effects of dissolved ions. The water temperature was elevated from 20°C to 80°C. The results show that temperature as well as the dissolved ions has a major impact on friction and wear. More specifically, the coefficient of friction was increased at elevated temperatures. Also, in pure water, abrasive wear of DLC was observed due to aluminum condensation on the brass surface, whereas it was prevented in quasi-tap water since aluminum was removed from the contact region due to the dissolved ions. EPMA, XPS and AES indicated that the tribo-layer on the metal surfaces, which consists of carbon and the base metal as well as some elements from water, plays an important role.

Effects of different water availability at post-anthesis stage on grain nutrition and quality in strong-gluten winter wheat

Wheat ( Triticum aestivum L.) is one of the most important agricultural crops worldwide. However, water is the most important limiting factor for wheat production. This study was initiated to test water stress environmental effects on grain quality and nutritional value of wheat by using single different water conditions at post-anthesis stage. Further analyses were conducted to examine variations in concentrations and compositions of the bioactive compounds and nutritions in strong-gluten winter wheat subjected to different levels of water deficit during grain filling. For the experiment on the response to different soil water conditions during post-anthesis stage, effects of soil water environment on protein content and composition in the grains were significant. Soil water conditions in this study greatly affected mineral contents in the grains of winter wheat, particularly with regard to the major minerals (P, K, Ca and Mg). Water deficit during grain filling can result in a decrease in lipid contents in wheat grains, which agrees well with experimental findings elsewhere. Concomitantly, a mild water deficit during grain filling would be beneficial to the grain filling and starch compositions, significantly improved bread-making quality. Therefore, it was concluded that good management of wheat field water at post-anthesis stage was helpful to improving grain quality and nutritions relevant to processing and human nutrition. To cite this article: C.-X. Zhao et al., C. R. Biologies 332 (2009).

Advances in research on the effect of rural landscape pattern on water environment

Due to serious pollution of rural water environments in China,it is very crucial that our knowledge on water environmental pollution control theory and technique are augmented.In this paper,the impact of rural landscape pattern on water quality and landscape-optimizing methods are reviewed.At present,much studies focus on the static effect of single landscape on water environment on small-to medium-scale rather than a dynamic landscape effect at multi-componential large-scale.And most domestic researches stagnate on parameter adaptation for existing models and simple re-coupling.Prediction scenarios of water environment effects of different landscape patterns also require augmentation.Studies should be directed in the following areas: interaction mechanism between rural landscape patterns and ecological processes,models of water environment effects based on watershed landscapes and uncertainty analyses,optimization methods of landscape patterns and their research applications for decision-making and management in China.