西安市雨水花园蓄渗雨水径流的试验研究

雨水花园是结合城市景观,以滞留和净化雨水径流为主要功能的生物滞留处理系统,能够在一定程度上减轻城市化进程对城市水文和水质的负面影响。根据在西安市雨水花园蓄渗屋面雨水径流的现场试验,确定在各种暴雨条件下,花园设计及土壤入渗能力不同时,雨水花园拦蓄雨水径流的能力以及花园溢流的时间和溢流量。结果显示,黄土具有良好的入渗能力,达到2.346m/d;在较为湿润的2011年基本没有发生溢流,汇集的雨水径流全部入渗补给了地下水。对于某一重现期的暴雨,雨水花园溢流总量受到降雨强度和历时二者叠加效果的影响。     

二维地表漫流模型在农田水淹损害因果关系中的应用

目前,人工构筑物修建与农田水淹损害因果关系鉴定实践需求多,现有判定方法精度低、可信性弱。二维地表漫流模型可以实现农业环境因果关系模拟计算,提高因果关系判定的精确性。本文通过模拟分析人工构筑物修建前后受淹农田的淹没范围、淹没水深、淹没流速以及淹没时长,确定降雨与农田水淹损害之间的因果关系,揭示水淹损害与排涝条件受损之间的关联,并通过时空关联及历史实测数据进行方法验证。结果表明：二维地表漫流模型在农田水淹损害鉴定因果关系分析中具有很好的应用价值,为农田水淹因果关系分析提供了新视角和新方法,具有很好的推广前景。     

Response to drought and salt stress of lemon ‘Fino 49’ under field conditions: Water relations,osmotic adjustment and gas exchange

Drought and salinity are two of the most important factors limiting the lemon yield in south-eastern Spain. The effects of drought and salt stress, applied independently, on water relations, osmotic adjustment and gas exchange in the highest evapotranspiration period were studied to compare the tolerance and adaptive mechanisms of 13-year-old ‘Fino 49’ lemon trees, in immature and mature leaves. The study was carried out in an experimental orchard located in Torre Pacheco (Murcia). Three treatments were applied: Control, well-irrigated; drought-stress (DS), non-irrigated from 15th May to 7th July and salinity, irrigated with 30 mM NaCl from 1st March to 7th July. At the end of the experiment, only DS trees showed a decreased leaf stem water potential (Ψ_md). Under DS conditions, both types of leaf lost turgor and did not show any osmotic or elastic mechanism to maintain leaf turgor. Osmotic adjustment was the main tolerance mechanism for maintenance of turgor under salt stress, and was achieved by the uptake of Cl⁻ ions. Gas-exchange parameters were reduced by DS but not by salinity, stomatal closure being the main adaptive mechanism for avoidance of water loss and maintenance of leaf turgor. Salinity gave rise to greater Cl⁻ accumulation in mature than in immature leaves. The increase of proline in immature leaves due to DS indicates greater damage than in mature leaves.     

Circulation of the eastern North Atlantic and north-west European continental shelf – a hydrodynamic modelling study

As part of the interdisciplinary investigation of Calanus finmarchicus migrations between oceanic and shelf areas off north-west Europe (the ICOS project), a three-dimensional, prognostic baroclinic circulation model system, consisting of a coarse and a nested fine scale model, was constructed. The aim was to simulate the flow fields around Iceland, the Faroe Islands and the north-west European continental shelf and slope, including the northern North Sea. The coarse scale model covered the northern North Atlantic and provided the far field flow to the finer scale model. The latter was initialized and forced with climatological seasonal (winter and spring) means of temperature, salinity, river run-off, and other parameters necessary for the calculation of heat fluxes. Seasonal average simulations of flow and hydrographic conditions were performed, together with simulations of specific scenarios of uniform wind forcing from different directions. A feature common to all the results was a topographically guided northwards flow along the continental shelf edge, with a southwards counter-flow in the vicinity of the Faroe–Shetland Channel. The extent and strength of the shelf edge current, of its counter flow, and of the re-circulation cell in the northern North Sea, were dependent on the prevailing wind direction. The modelling results were consistent with the accepted circulation patterns in the area, and a comparison with field measurements in the Faroe–Shetland Channel showed that the main characteristics of the flow were well replicated, although the estimated strength of the slope current was somewhat less than in the field observations.     

Root restriction-induced limitation to photosynthesis in tomato (Lycopersicon esculentum Mill.) leaves

Root restriction often depresses photosynthetic capacity and the mechanism for this reduction, however, remains unclear. To identify the mechanism by which root restriction affects the photosynthetic characteristics, tomato (Lycopersicon esculentum Mill.) seedlings were subjected to root restriction stress with or without supplemental aeration to the nutrient solution. With the development of the root restriction stress, CO₂ assimilation rate was decreased only in confined plants without supplemental aeration. There were also significant decreases in leaf water potential, stomatal conductance (g_s), intercellular CO₂ concentration (C_i), and increases in the stomatal limitation (l) and the xylem sap ABA concentration. Meanwhile, the maximum carboxylation rate of Rubisco (V_cmax) and the capacity for ribulose-1,5-bisphosphate regeneration (J_max) also decreased, followed by substantial reductions in the quantum yield of PSII electron transport (Φ_PSII). Additionally, root restriction resulted in accumulation of carbohydrates in various plant tissues irrespective of aeration conditions. It is likely that root restriction-induced depression of photosynthesis was mimicked by water stress.     

U形渠道量水槽的筛选研究

U形渠道抛物线形无喉段量水槽、直壁式量水槽、圆底形量水槽具有与U形渠道自然衔接,不抬高底坎,过泥沙能力较强,工程量较小,量水精度较高的优点,是U形渠道量水的优化选择,对这3种量水槽在不同尺寸、底坡和糙率条件下的U形渠道的适应性、壅水高度、工程量及其量水精度等技术性能进行系统分析,表明抛物线形无喉段量水槽的适用面广、工程量小、壅水高度较低,量水精度与其它两种量水槽的量水精度相当,是一种高性能的多泥沙U形渠道量水装置。     

过水堆石围堰铅丝笼护面失稳破坏临界条件试验研究

从过水堆石围堰护面失稳破坏的工程实践出发,探讨了铅丝笼护面失稳破坏的成因,在模型试验的基础上,分析了影响铅丝笼护面稳定的主要因素及失稳破坏的临界水力条件。并应用水流能量方程和边界层理论,研究了围堰过水时的水流能量转换关系,得到了失稳临界条件的指标和经验判别式。通过模型试验的对比与分析计算,验证了失稳临界条件经验判别式的正确性。     

新疆三工河流域渔尔沟水源地地下水开发利用浅析

渔尔沟水源地开发利用地下水已有40多年的历史,为下游冲洪积平原222团灌区提供了稳定、可靠的水源.通过对其地下水动态资料的分析得出,渔尔沟水源地在开采地下水由小到大的过程中,其地下水埋深稳定在13 m上下;通过回归分析,得出水源地年单位地下水开采量为597.3×104 m3/(m·a),开采能力较大.在对222团灌区现状及流域未来节水战略的实施等因素分析后,得出流域水资源的高效合理利用会缓解对地下水的开发,在三工河潜水溢出带的渔尔沟水源地开发利用地下水是高效和可持续的.     

Photosynthetic characteristics and protective mechanisms against photooxidation during high temperature stress in two citrus species

Exposure of Satsuma mandarin (Citrus unshiu Marc.) and Navel orange (Citrus sinensis Osbeck) plants to high temperature (38 °C) led to reductions of the net photosynthetic rate (Pn), the photorespiration rate (Pr), the quantum efficiency CO₂ assimilation (ΦCO₂${\Phi }_{\text{C}{\text{O}}_2}$), the maximal photochemical efficiency of PS2 (Fv/Fm), the photochemical quenching (qP) and the quantum efficiency of PS2 photochemistry (Φ_PS2), whereas the minimal fluorescence yield (Fo) and the non-photochemical quenching (qN) increased. Increase in the value of Pr/Pn and ΦPS₂/ΦCO₂${\Phi }_{\text{PS}2}/{\Phi }_{\text{C}{\text{O}}_2}$ was attributed to the greater decrease in Pn and ΦCO₂${\Phi }_{\text{C}{\text{O}}_2}$ than Pr and Φ_PS2. In addition, the superoxide radical (O₂⁻) production, the H₂O₂ concentration and the activities of antioxidant enzymes such as the superoxide dismutase (SOD, EC 1.15.1.1), the ascorbate peroxidase (APX, EC 1.11.1.11), the dehydroascorbate reductase (DHAR, EC 1.8.5.1) and the catalase (CAT, EC 1.11.1.6) were raised. On the other hand, the chlorophyll concentration in leaves decreased during high temperature stress. These results suggest that decline in Pn related to inactivation of PS2 reaction centers may be due to the enhanced number of active oxygen species in the citrus leaves. The water–water cycle may play a role in limiting the degree of photodamage caused by high temperature. Lower O₂⁻ production rate, the H₂O₂ concentration and the antioxidant enzymes activity were observed in high temperature tolerant species of citrus. The exogenous active oxygen scavenger ascorbic acid (Asc) enhanced the ability to clear the O₂⁻ in citrus plants, and quicken the recovery of photosynthetic apparatus.     

Evaluation of Juvenile salmon passage and survival through a fish weir and other routes at Foster Dam,Oregon, USA

Downstream passage for juvenile Chinook salmon Oncorhynchus tshawytscha (Walbaum) and steelhead Oncorhynchus mykiss (Walbaum) through the fish weir at Foster Dam, Oregon, was evaluated to assess the weir's efficacy as a long-term passage solution. Radio telemetry was used to estimate survival, passage and effectiveness for the fish weir, spillway and turbines. Survival of Chinook salmon through the fish weir varied by season and reservoir elevation (66%–87%), and passage proportions were low (8%–20%). Fish weir effectiveness was low to moderate (0.39–2.09). Steelhead survival was lower (57%–77%) but passed the fish weir in higher proportions (77%), and weir effectiveness was consistently high (2.96–5.49). The results indicate the existing fish weir will not be a suitable long-term passage solution for all species. However, because of the high passage proportions and effectiveness observed for steelhead, further development of the surface-flow concept appears to be promising for safely passing downstream-migrating fishes.