The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK.
UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian EH26 0QB, UK.
Int J Environ Res Public Health. 2020 Jan 7;17(2):391. doi: 10.3390/ijerph17020391.
Phosphorus is one of the main causes of waterbodies in Scotland being at less than good ecological status (GES) in terms of the water framework directive (WFD). In Scotland, there are more than 8000 standing waters, defined as lakes and reservoirs that have a surface area of more than 0.5 km. Only about 330 of these are monitored routinely to assess compliance with the WFD. The export coefficient tool PLUS+ (phosphorus land use and slope) has been developed to estimate total phosphorus (TP) concentrations in the unmonitored sites; modelled values are then compared to WFD target concentrations for high, good, moderate, poor, and bad status to assess compliance. These type-specific or site-specific targets are set by the regulatory authority and form part of a suite of physical, chemical, and ecological targets that are used to assess GES, all of which must be met. During development, the PLUS+ tool was applied to 323 monitored catchments and 7471 unmonitored catchments. The efficacy of the tool was assessed against TP concentrations observed in 2014 and found to perform well in the rural catchments. 51% of standing waters had the same modelled and observed WFD class (i.e., High, Good, Moderate, Poor, Bad), and a further 40% of standing waters had a modelled WFD class that was within one class of observed water quality. The tool performed less well in catchments with larger inputs of TP from urban sources (e.g., sewage). The greatest deviations between measured and modelled classes were explained by the shortage of information on wastewater treatment works, fish farms, migratory birds, levels of uncertainty in TP measurements, and the amount of in-lake re-cycling of P. The limitations of the tool are assessed using data from six well documented case study sites and recommendations for improving the model performance are proposed.
磷是导致苏格兰水体在水质框架指令（WFD）方面生态状况不佳（GES）的主要原因之一。在苏格兰，有超过 8000 个静止水域，定义为表面积超过 0.5 公里的湖泊和水库。这些湖泊中只有约 330 个被常规监测，以评估其是否符合 WFD。PLUS+（磷土地利用和坡度）导出系数工具被开发用来估算未监测点的总磷（TP）浓度；然后将模拟值与 WFD 针对高、好、中、差和差状态的目标浓度进行比较，以评估合规性。这些特定类型或特定地点的目标是由监管机构设定的，是用于评估 GES 的一整套物理、化学和生态目标的一部分，所有这些目标都必须得到满足。在开发过程中，PLUS+工具应用于 323 个监测流域和 7471 个未监测流域。该工具的有效性是根据 2014 年观察到的 TP 浓度进行评估的，结果表明该工具在农村流域表现良好。51%的静止水域具有相同的模拟和观察到的 WFD 类别（即高、好、中、差、差），还有 40%的静止水域的模拟 WFD 类别与观察到的水质类别相差一个等级。该工具在 TP 输入量较大的流域（如污水）中的表现较差。测量和模拟类别之间最大的偏差是由污水处理厂、鱼类养殖场、候鸟、TP 测量不确定性水平以及湖中 P 的再循环量等信息的缺乏所解释的。该工具的局限性是使用来自六个记录良好的案例研究地点的数据进行评估的，并提出了改进模型性能的建议。
