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71.
三峡水库调节典型时段对洞庭湖湿地水情特征的影响 总被引:3,自引:0,他引:3
洞庭湖与长江联系紧密,三峡工程运行将改变洞庭湖的水文过程,影响湖泊湿地生态系统。为了评估三峡工程运行对洞庭湖湿地的水文影响,选取水文情势变化大且可能对植被生长产生重大影响的汛末蓄水和汛前腾空两个时段,运用反映江湖水动力交互的水动力学方法计算了三峡水库不同调节流量下湖泊水位与流量的变化特征,并结合湖泊高程和面积关系曲线,分析了不同增减下泄流量对洲滩湿地淹没出露的影响。结果表明,洞庭湖吞吐长江,复杂的江湖水动力交互作用使得湿地水文过程变化有明显的非线性。在恒定流条件下,汛末蓄水减泄4 000 m3/s流量可使城陵矶水位降低1 m。同样抬高1 m水位,汛前腾空约需增泄3 500 m3/s。在空间分布上,三峡水库调节对洞庭湖水情影响具有明显的异质性,受江湖关系和湖盆地形的影响,与长江水力联系紧密的东洞庭湖、南洞庭湖东部和西洞庭湖北部受三峡水库调节影响大,而西洞庭湖南部影响较小 相似文献
72.
Introduction: Despite the rich tradition of research on predictors of workplace injury, most studies rely on cross-sectional, between-person designs. Furthermore, prior research has often overlooked the possibility that factors outside the work domain can influence the occurrence of actual injuries at work. To address these limitations, the current study examined the effects of work and family demands on the occurrence of workplace injury. Drawing on the intuition of the work-home resources model (W-HR), we investigated how within-person level changes in demands and resources from both domains influence work injuries over a 12-year period. Method: We used 12 years of longitudinal data (N = 7,820) to study the long-term within-person changes in work and family domains and to capture the event of low frequency incidence such as workplace injury. Specifically, we conducted multilevel analyses to study the links between within-person change in time and energy resources both in work and family domains and within-person change in the likelihood of experiencing a workplace injury. Results and conclusion: The findings showed that within-person changes in work hours, spousal work hours, income and number of children, were significantly associated with changes in the likelihood of experiencing a workplace injury. We conclude with a discussion of implications for theory and future research of workplace injuries. Practical application: The research provided useful insights on the intimate association between work and family domains in the context of safety management. 相似文献
73.
Junhong Yang Xuyang Cui Yuanzheng Feng Guangning Jing Ligai Kang Mengyuan Luo 《International Journal of Green Energy》2017,14(15):1269-1276
Microalgae have been identified as a superior feedstock for biodiesel production and varied tubular photobioreactors are developed for high efficient and scale-up microalgae cultivation. This article presented a novel concentric double tubes using aeration through radial pores along the length direction of inner tube. Experiments on microalgae cultivation were carried out in the novel photobioreactor, and two control groups including concentric double tubes with axial aeration at both ends and common tubular. The biomass productivity of novel photobioreactor increased by 43.6% and 107.4%, respectively, compared with concentric double tubes with axial aeration at both ends and common tubular without aeration. The values of pH shifted from 7.5 to 9.0 for novel photobioreactor, but 7.5 to 8.8 for common tubular, and 7.5 to 9.6 for concentric double tubes with axial aeration. The dissolved oxygen concentration fluctuated between 6.0 and 7.0 mg·L?1 for novel photobioreactor, but rose from 6.6 to 10.2 mg·L?1 for the common tubular, and 6.9 to 8.1 mg·L?1 for the concentric with axial aeration. Results show that the aeration style of novel photobioreactor can make efficient local mixing and maintain smaller range of pH and lower level of dissolved oxygen in case of higher biomass concentration. Moreover, compared with the two control groups, the novel concentric double tubes have advantages on the light/dark cycle frequency, which may be benefit for microalgae cultivation. The novel concentric double tubes presented in this work can give some inspiration for high efficiency microalgae cultivation. 相似文献
74.
Revealing the Diversity of Natural Hydrologic Regimes in California with Relevance for Environmental Flows Applications 下载免费PDF全文
Belize A. Lane Helen E. Dahlke Gregory B. Pasternack Samuel Sandoval‐Solis 《Journal of the American Water Resources Association》2017,53(2):411-430
Alterations to flow regimes for water management objectives have degraded river ecosystems worldwide. These alterations are particularly profound in Mediterranean climate regions such as California with strong climatic variability and riverine species highly adapted to the resulting flooding and drought disturbances. However, defining environmental flow targets for Mediterranean rivers is complicated by extreme hydrologic variability and often intensive water management legacies. Improved understanding of the diversity of natural streamflow patterns and their spatial arrangement across Mediterranean regions is needed to support the future development of effective flow targets at appropriate scales for management applications with minimal resource and data requirements. Our study addresses this need through the development of a spatially explicit reach‐scale hydrologic classification for California. Dominant hydrologic regimes and their physio‐climatic controls are revealed, using available unimpaired and naturalized streamflow time‐series and generally publicly available geospatial datasets. This methodology identifies eight natural flow classes representing distinct flow sources, hydrologic characteristics, and catchment controls over rainfall‐runoff response. The study provides a broad‐scale hydrologic framework upon which flow‐ecology relationships could subsequently be established towards reach‐scale environmental flows applications in a complex, highly altered Mediterranean region. 相似文献
75.
76.
R. PAL P. DAS K. CHAKRABARTI A. CHAKRABORTY A. CHOWDHURY 《Journal of environmental science and health. Part. B》2013,48(7):1103-1113
The degradative characteristics of butachlor (N-Butoxymethyl-2-chloro-2′,6′-diethyla- cetanilide) were studied under controlled laboratory conditions in clay loam alluvial (AL) soil (Typic udifluvent) and coastal saline (CS) soil (Typic endoaquept) from rice cultivated fields. The application rates included field rate (FR), 2-times FR (2FR) and 10-times FR (10FR). The incubation study was carried out at 30°C with and without decomposed cow manure (DCM) at 60% of maximum water holding capacity (WHC) and waterlogged soil condition. The half-life values depended on the soil types and initial concentrations of butachlor. Butachlor degraded faster in AL soil and in soil amended with DCM under waterlogged condition. Microbial degradation is the major avenue of butachlor degradation from soils. 相似文献
77.
Many “natural” areas are exposed to military or recreational off-road vehicles. The interactive effects of different types
of vehicular disturbance on vegetation have rarely been examined, and it has been proposed that some vegetation types are
less susceptible to vehicular disturbance than others. At Fort Riley, Kansas, we experimentally tested how different plant
community types changed after disturbance from an M1A1 Abrams tank driven at different speeds and turning angles during different
seasons. The greatest vegetation change was observed because of driving in the spring in wet soils and the interaction of
turning while driving fast (vegetation change was measured with Bray-Curtis dissimilarity). We found that less vegetation
change occurred in communities with high amounts of native prairie vegetation than in communities with high amounts of introduced
C3 grasses, which is the first experimental evidence we are aware of that suggests plant communities dominated by introduced
C3 grasses changed more because of vehicular disturbance than communities dominated by native prairie grasses. We also found
that vegetation changed linearly with vehicular disturbance intensity, suggesting that at least initially there was no catastrophic
shift in vegetation beyond a certain disturbance intensity threshold. Overall, the intensity of vehicular disturbance appeared
to play the greatest role in vegetation change, but the plant community type also played a strong role and this should be
considered in land use planning. The reasons for greater vegetation change in introduced C3 grass dominated areas deserve further study. 相似文献
78.
Effect of Rainfall Regime and Slope on Runoff in a Gullied Loess Region on the Loess Plateau in China 总被引:4,自引:0,他引:4
Runoff was measured from seven plots with different slopes nested in Tuanshangou catchment on the Loess Plateau to study effect of slopes on runoff in relation to rainfall regimes. Based on nine years of field observation and K-mean clusters, 84 rainfall events were grouped into three rainfall regimes. Rainfall regime A is the group of events with strong rainfall intensity, high frequency, and short duration. Rainfall regime C consists of events with low intensity, long duration, and infrequent occurrence. Rainfall regime B is the aggregation of events of medium intensity and medium duration, and less frequent occurrence. The following results were found: (1) Different from traditional studies, runoff coefficient neither decreased nor increased, but presented peak value on the slope surfaces; (2) For individual plot, runoff coefficients induced by rainfall regime A were the highest, and those induced by rainfall regime C were the lowest; Downslope, the runoff coefficients induced by three rainfall regimes presented the same changing trend, although the peak value induced by regime A occurred on a shorter slope length compared to those by regime B and C; (3) Scale effect on runoff induced by rainfall regime A was the least, and that induced by rainfall regime C was the largest. These results can be explained by the interactions of crusting, soil moisture content, slope length and gradient, and erosion units, etc., in the context of different rainfall regimes. 相似文献
79.
国际环境制度对能源安全战略的重大影响 总被引:1,自引:0,他引:1
刘东民 《中国人口.资源与环境》2003,13(3):44-47
能源安全一直是国际政治和经济领域的重大问题。在追求可持续发展和全球化不断推进的2l世纪,国际环境制度的逐步形成为能源安全赋予了新的涵义,生态安全已经成为能源安全的重要组成部分。以保障能源供应为主要出发点的传统能源安全观逐渐向着涵盖能源供应、经济竞争力和环境质量三大要素的“综合能源安全观”的方向发展。 相似文献
80.
殷世林 《防灾减灾工程学报》1997,(2)
根据对南黄海6.1级地震前,苏州地区1995年9月~1996年10月以地下水动态、地下水化学为主的前兆异常的分析,预报了这次地震,并对其进行了检验及原因分析 相似文献