Bukaveckas Paul A
Center for Environmental Studies, Department of Biology, Virginia Commonwealth University, Richmond, Virginia 23111, USA.
Environ Sci Technol. 2007 Mar 1;41(5):1570-6. doi: 10.1021/es061618x.
Channel design is an important component of stream restoration, but little is known of the interplay between hydrogeomorphic features and ecosystem processes within designed channels. Water velocity, transient storage, and nutrient uptake were measured in channelized (prerestoration) and naturalized (postrestoration) reaches of a 1-km segment of Wilson Creek (KY) to assess the effects of restoration on mechanisms of nutrient retention. Stream restoration decreased flow velocity and reduced the downstream transport of nutrients. Median travel time was 50% greater in the restored channel due to lower reach-scale water velocity and the longer length of the meandering channel. Transient storage and the influence of transient storage on travel time were largely unaffected except in segments where backwater areas were created. First-order uptake rate coefficients for N and P were 30- and 3-fold higher (respectively) within the restored channel relative to its channelized state. Changes in uptake velocities were comparatively small, suggesting that restoration had little effect on biochemical demand. Results from this study suggest that channel naturalization enhances nutrient uptake by slowing water velocity. Solute injection experiments revealed differences in the functional properties of channelized, restored, and reference streams and provided a means for quantifying benefits associated with restoration of ecosystem services.
河道设计是河流修复的一个重要组成部分，但对于设计河道内水文地貌特征与生态系统过程之间的相互作用却知之甚少。在肯塔基州威尔逊溪1公里河段的渠化（修复前）和自然化（修复后）河段测量了水流速度、暂态存储和养分吸收，以评估修复对养分截留机制的影响。河流修复降低了流速，减少了养分的下游输送。由于河段尺度的水流速度较低以及蜿蜒河道的长度较长，修复后的河道中位旅行时间长了50%。暂态存储及其对旅行时间的影响在很大程度上未受影响，除非在形成回水区域的河段。与渠化状态相比，修复后的河道内氮和磷的一级吸收速率系数分别高出30倍和3倍。吸收速度的变化相对较小，表明修复对生化需氧量影响不大。本研究结果表明，河道自然化通过减缓水流速度增强了养分吸收。溶质注入实验揭示了渠化、修复和参照溪流功能特性的差异，并提供了一种量化与生态系统服务恢复相关效益的方法。
