Basic principles and ecological consequences of changing water regimes on nitrogen cycling in fluvial systems

Understanding the environmental consequences of changing water regimes is a daunting challenge for both resource managers and ecologists. Balancing human demands for fresh water with the needs of the environment for water in appropriate amounts and at the appropriate times are shaping the ways by which this natural resource will be used in the future. Based on past decisions that have rendered many freshwater resources unsuitable for use, we argue that river systems have a fundamental need for appropriate amounts and timing of water to maintain their biophysical integrity. Biophysical integrity is fundamental for the formulation of future sustainable management strategies. This article addresses three basic ecological principles driving the biogeochemical cycle of nitrogen in river systems. These are (1) how the mode of nitrogen delivery affects river ecosystem functioning, (2) how increasing contact between water and soil or sediment increases nitrogen retention and processing, and (3) the role of floods and droughts as important natural events that strongly influence pathways of nitrogen cycling in fluvial systems. New challenges related to the cumulative impact of water regime change, the scale of appraisal of these impacts, and the determination of the impacts due to natural and human changes are discussed. It is suggested that cost of long-term and long-distance cumulative impacts of hydrological changes should be evaluated against short-term economic benefits to determine the real environmental costs.     

论国际救灾法中的效率原则

在国际救灾过程中,抢救和保护生命、健康、财产、环境的紧迫需要使救援效率成为国际救灾中的首要追求。这一要求必须在救灾法中得到体现。效率原则就是要求重大灾害发生后,国际社会应当以最快的速度提供国际援助,而受灾国则应当尽快地作出救灾响应,在国际救灾人员的签证、工作许可,资金、物资、设备等的建立账户、通关、运输、储存、分发、等...     

Post-conflict health reconstruction: search for a policy

Despite increasing experience in health reconstruction in societies emerging from conflict, the policy basis for investing in the development of equitable and effective health systems in the wake of war remains unsettled. Consideration of post-conflict health reconstruction is almost entirely absent in donor policies on global health. Practically by default, health programmes are seen increasingly as an element of stabilisation and security interventions in the aftermath of armed conflict. That perspective, however, lacks an evidence base and can skew health programmes towards short-term security and stabilisation goals that have a marginal impact and violate the principles of equity, non-discrimination, and quality, which are central to sound health systems and public acceptance of them. A better approach is to ground policy in legitimacy, viewing health both as a core social institution and one that, if developed according to human rights principles, including equity, non-discrimination, participation and accountability, can advance the effectiveness and the quality of governance in the emerging state.     

管壳式循环水冷却器管束内漏的控制

管壳式换热器广泛应用于石油化工等装置,而管柬内漏的风险却一直困扰着装置的长周期运行。针对循环水冷却器管束内漏,结合制造与修理及相关文献的案例,从设计、制造及使用等控制环节对固定管板式、浮头式及u形管式等管柬的内漏进行了分析,为防止管束内漏的风险需要设计、制造及使用共同控制,并给出了合理的建议。     

铁路工程设计践行绿色发展的实践

设计是铁路工程绿色发展的关键环节之一,以某铁路工程为例,在阐述工程概况和主要问题的基础上,从线路纵断面、辅助坑道、隧道弃渣综合利用、弃土(渣)场数量及取土场数量等方面进行优化设计,并对优化效果进行分析。