Sediment chemistry and nutrient influx in a hydrologically restored bottomland hardwood forest in Midwestern USA

Exchanges of total N and C between a river and its floodplain forest have been enhanced by sedimentation processes during flood pulses at a 5‐ha bottomland hardwood forest located at the Olentangy River Wetland Research Park in central Ohio. In the spring of 2000, the forest was hydrologically restored by notching an artificial levee that had separated the Olentangy River and its floodplain forest for 100 years. One‐hundred flat sediment traps (30 cm × 30 cm) were used to collect sediment samples during spring/summer flooding events from 2003 to 2005. Results showed that sediment deposition is determined by the landscape variability during flooding events, Net sediment deposit in the wettest area averaged 134 ± 12 g‐dry wt m^?2 in 2003, 127 ± 17 g‐dry wt m^?2 in 2004 and 149 ± 23 g‐dry wt m^?2 in 2005. Total N and C sedimentation ranged from 0.49 to 0.92 g‐N m^?2 and 5.2 to 19.9 g‐C m^?2. Fe dominates the sediment chemistry and results show the elemental abundance in the order of Al > Fe > Ca > K > Mg > S > P > Na > Mn > Zn > B > Cu > Mo. A hydrologic pulsing index (HPI) could be used as an indicator for mass changes of energies with hydrologic pulsing events. Restoration of seasonally flooded bottomland forests could stimulate potentially large nutrient and Fe releases, which would eventually lead to an enhanced forest productivity and biodiversity. Copyright © 2007 John Wiley & Sons, Ltd.     

EVALUATION OF SPAWNING SUBSTRATE ENHANCEMENT FOR WHITE STURGEON IN A REGULATED RIVER: EFFECTS ON LARVAL RETENTION AND DISPERSAL

Site‐specific habitat alterations have improved spawning success and early life stage survival of different fish species, including sturgeon, in regulated rivers. We modified the substrate within a section of river at the only known spawning site used by white sturgeon (Acipenser transmontanus) in the Mid Columbia River, Canada. Existing armoured riverbed conditions were modified using a mixture of larger and smaller angular rock with the assumption that the larger material would remain in place at higher discharges and help retain the smaller material. This increased substrate complexity and the amount of available interstitial spaces. We stocked 2‐day posthatch larvae over both the modified site and at an adjacent control site that represented existing substrate conditions. Our objectives were to determine (i) the extent that stocked larvae remained in both the modified and control sites immediately after release, (ii) the timing of subsequent dispersal of larvae from both sites and (iii) how total length of dispersing larvae changed over time and by site. Results from this work indicated that the modified section of riverbed retained significantly higher numbers of larvae after release compared with the control site. Larvae at the modified site were able to hide and remain within the substrate and initiated downstream drift 15 days after release. With the exception of the first day after release, dispersal from both sites occurred at night. There was a significant effect of time after release and site on the total length of dispersing larvae. The larger variation in total larval length observed at the control site compared with the modified site indicated greater difficulty in hiding within the control substrate. Larvae initiated dispersal from the modified site at a mean size of 17.5 mm, which may indicate an important growth threshold before drift. Results from this work are important for future mitigative efforts for sturgeon in regulated rivers where changes to spawning substrates have occurred. Copyright © 2012 John Wiley & Sons, Ltd.     

The worldwide urban water and wastewater infrastructure challenge

There are two parts to the challenge of providing the infrastructure necessary for universal access to water and sanitation. One challenge is the extension of existing infrastructure and new infrastructure to serve all in today's urban areas and to keep up with the expected rapid growth of cities; the other is the refurbishment of existing infrastructure to maintain access to water and sanitation. Meeting the second challenge is the more costly; it is also essential to meeting the first challenge. Infrastructure is the means, not the end, with a requirement for clear policies on objectives, priorities and service standards. Delivery will require effective planning, regulation, innovation, capacity building and training. Although the infrastructure costs will be high, the benefits will be greater.     

飞来峡大坝安全监测系统倒垂线修复

在修复断损垂线的过程中,必须解决钻机扫孔,清孔取出旧钢丝及锚块,安装新锚块,选择合适材料与直径的钢丝,保证测量数据衔接等技术问题,方可保证修复后的垂线能继续稳定有效的运行。介绍了在飞来峡断损垂线的修复过程中,技术人员的思路、方法、手段及效果,以期能够为对其他类似工程提供借鉴。     

河流生态修复的尺度格局和模型

通过分析水文过程与生态过程的耦合特征,论证了流域尺度是编制河流生态修复规划的适宜尺度。讨论了景观空间异质性与物种多样性的相关关系,提出了在流域和河流廊道两种尺度上改善景观格局配置的方法。特别指出了在河流廊道尺度下提高景观空间异质性的两个要点,一是增强地貌学意义上的空间异质性,二是改善生态水文学和生态水力学意义上的水文、水力学条件。本文还介绍了景观格局分析方法和景观格局-生态过程模型。     

河流生态修复技术和实践

河流生态修复的理念逐渐被人们所认知,一些符合生态修复理念的规划设计方法在工程建设中被逐步采用。在水利部科技创新项目和地方政府的支持下,一些河流生态修复示范工程取得了很好的建设效果并发挥了良好的示范效应。文中结合几个案例,介绍近几年在河流生态修复技术和实践方面所取得的部分进展。     

有关河流生态系统的恢复生态学研究综述

长久以来,人们忽略了河流的生态功能,破坏了河流的各种生态过程,导致河流污染严重、生态作用越来越小。在评述恢复生态学定义及有关认识的基础上,结合分析国内外河流生态恢复的研究现状和特点,提出在河流生态恢复中应注意的几个方面,从而达到人与自然的和谐。     

水土保持生态修复工程效益监测与评价

以山东省淄博市淄川区水土保持生态修复试点工程项目为例,在构建土石山区生态修复效益监测指标体系、划分生态修复措施类型的基础上,采用宏观遥感与微观实测耦合技术,对项目区内生态修复工程的生态效益、经济效益和社会效益进行了分类监测及系统评价。结果表明,生态修复区域林草覆盖度明显提高;植被生长状况明显改善,生物量显著提高;经济效益和社会效益显著。     

太湖五里湖生态恢复的理论与实践

在针对太湖五里湖水质严重污染和生态严重退化的情况,从分析浅水湖泊生态恢复的理论入手,提出生态恢复过程中控源减污、生境改善、生态重建、稳态调控的四个关键步骤,评价了西五里湖生态恢复示范工程的效果,计算了示范工程区水生植物覆盖度和生物多样性指数,指出达到景观要求的草型清水稳态湖泊还需要一个漫长的演替过程。     

重污染水体底泥环保疏浚与生态重建技术研究

全面介绍了国家“十五”“863”计划重大科技专项子课题之一“重污染水体底泥环保疏浚与生态重建技术”,阐述了示范工程实施地点太湖五里湖的水环境污染和生态退化的问题以及课题研究与五里湖治理的技术路线,总结了子课题研究所取得的技术方法创新与关键技术创新,评价了环保疏浚示范工程、退渔还湖示范工程、生态重建示范的实施效果以及太湖五里湖示范工程实施前后的水质变化。