Seasonal nutrient dynamics in a chalk stream: the River Frome, Dorset, UK
Seasonal nutrient dynamics in a chalk stream: the River Frome, Dorset, UK
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DOI：
10.1016/j.scitotenv.2004.05.026
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发表时间：
2005-01-05
影响因子：
9.8
通讯作者：
House, WA
中科院分区：
文献类型：
--
作者：
Bowes, MJ;Leach, DV;House, WA
白垩溪提供了独特的、对环境具有重要意义的生境，但特别容易受到人类活动的影响，例如在其肥沃的洪泛草地上进行取水、养鱼和密集的农业活动，从而导致养分浓度增加。每周磷，硝酸盐，溶解硅，氯化物和流量测量，在9个站点沿着32公里长的弗罗姆河及其支流，超过15个月的时间。延伸被分为两个部分（称为中游和下游）和质量平衡计算每个determinand合计从上游，支流，污水处理厂和地下水输入的估计，并减去从每个河段输出的负载输入。磷和硝酸盐保留在河道内，在夏季，由于生物积累到河流生物群和吸附的磷床沉积物。在秋季至春季期间，有一个净出口，归因于增加扩散输入从集水区在风暴期间，通道生物量的分解和从床沉积物中的磷的再活化。这种季节性的保留和再动员是较高的下游比中游，这是由于下游的土地利用和细泥沙的可用性变化。硅表现出少得多的季节性，但确实有一段时间的快速保留在春季，由于河道内的硅藻吸收，并随后从床沉积物在风暴事件释放。氯化物没有产生季节性模式，表明所观察到的磷和硝酸盐的季节性是扩散输入和内部河流过程的年度变化的产物，而不是采样，流量测量和分析误差的人工制品。(C)2004 Elsevier B.V.保留所有权利。
Chalk streams provide unique, environmentally important habitats, but are particularly susceptible to human activities, such as water abstraction, fish farming and intensive agricultural activity on their fertile flood-meadows, resulting in increased nutrient concentrations. Weekly phosphorus, nitrate, dissolved silicon, chloride and flow measurements were made at nine sites along a 32 km stretch of the River Frome and its tributaries, over a 15 month period. The stretch was divided into two sections (termed the middle and lower reach) and mass balances were calculated for each determinand by totalling the inputs from upstream, tributaries, sewage treatment works and an estimate of groundwater input, and subtracting this from the load exported from each reach. Phosphorus and nitrate were retained within the river channel during the summer months, due to bioaccumulation into river biota and adsorption of phosphorus to bed sediments. During the autumn to spring periods, there was a net export, attributed to increased diffuse inputs from the catchment during storms, decomposition of channel biomass and remobilisation of phosphorus from the bed sediment. This seasonality of retention and remobilisation was higher in the lower reach than the middle reach, which was attributed to downstream changes in land use and fine sediment availability. Silicon showed much less seasonality, but did have periods of rapid retention in spring, due to diatom uptake within the river channel, and a subsequent release from the bed sediments during storm events. Chloride did not produce a seasonal pattern, indicating that the observed phosphor-us and nitrate seasonality was a product of annual variation in diffuse inputs and internal riverine processes, rather than an artefact of sampling, flow gauging and analytical errors. (C) 2004 Elsevier B.V. All rights reserved.