Centre for Ecology and Hydrology, Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK.
Sci Total Environ. 2010 Sep 1;408(19):4239-50. doi: 10.1016/j.scitotenv.2010.05.016. Epub 2010 Jun 12.
Phosphorus (P) concentration and flow data gathered during the 1990s for a range of British rivers were used to determine the relative contributions of point and diffuse inputs to the total P load, using the Load Apportionment Model (LAM). Heavily urbanised catchments were dominated by sewage inputs, but the majority of the study catchments received most of their annual phosphorus load from diffuse sources. Despite this, almost 80% of the study sites were dominated by point source inputs for the majority of the year, particularly during summer periods when eutrophication risk is greatest. This highlights the need to reduce sewage P inputs to improve the ecological status of British rivers. These modelled source apportionment estimates were validated against land-use data and boron load (a chemical marker for sewage). The LAM was applied to river flow data in subsequent years, to give predicted P concentrations (assuming no change in P source inputs), and these estimates were compared with observed concentration data. This showed that there had been significant reductions in P concentration in the River Thames, Aire and Ouse in the period 1999 to 2002, which were attributable to the introduction of P stripping at sewage treatment works (STW). The model was then used to forecast P concentrations resulting from the introduction of P removal at STW to a 2 or 1mgl(-1) consent limit. For the urbanised rivers in this study, the introduction of phosphorus stripping to a 1mgl(-1) consent level at all STW in the catchment would not reduce P concentrations in the rivers to potentially limiting concentrations. Therefore, further sewage P stripping will be required to comply with the Water Framework Directive. Diffuse P inputs may also need to be reduced before some of the highly nutrient-enriched rivers achieve good ecological status.
利用负荷分配模型（LAM），对 20 世纪 90 年代英国一系列河流的磷（P）浓度和流量数据进行分析，以确定点源和非点源输入对总磷负荷的相对贡献。城市化程度较高的流域主要受到污水输入的影响，但大多数研究流域的大部分磷负荷来自非点源。尽管如此，在一年中的大部分时间里，近 80%的研究地点主要受到点源输入的影响，尤其是在富营养化风险最大的夏季。这突出表明需要减少污水磷的输入，以改善英国河流的生态状况。根据土地利用数据和硼负荷（污水的化学标记物）对这些模型源分配估计值进行了验证。随后，LAM 应用于后续年份的河流流量数据，以给出假定磷源输入没有变化时的预测磷浓度，并将这些估计值与观测到的浓度数据进行比较。这表明，自 1999 年至 2002 年，泰晤士河、艾尔河和乌斯河的磷浓度有显著下降，这归因于污水处理厂（STW）引入了磷去除工艺。然后，该模型被用于预测如果在 STW 引入磷去除工艺以达到 2 或 1mg/L 的许可限值，将会导致磷浓度的变化。对于本研究中城市化程度较高的河流，在流域内所有 STW 引入 1mg/L 的磷去除工艺，将无法使河流中的磷浓度降至潜在限制浓度。因此，需要进一步进行污水磷去除工艺，以符合《水框架指令》。在一些营养元素高度富集的河流达到良好的生态状况之前，可能还需要减少非点源磷的输入。
