PDF(Pubmed)
Abstract：
Despite over two decades since the EU Water Framework Directive have passed, achieving the desired water quality in German surface waters remains challenging, regardless of efforts to reduce phosphorus inputs and associated environmental impacts. This study aims at analyzing the characteristics governing the concentrations of four key water quality parameters (total phosphorus, orthophosphate, particulate phosphate, and suspended solids) in two lowland catchments: the 50 km2 catchment of the Kielstau, Germany, and its 7 km2 tributary, the Moorau, which are dominated by agricultural land use. To this end, different sampling methods, particularly high-resolution precipitation event-based sampling and daily mixed samples, are conducted and evaluated, and their effectiveness is compared. The identification of sources and characteristics that affect phosphorus and suspended sediment dynamics, both in general and specifically during heavy precipitation events, is one focus of the study. Over a 15-year period, increasing concentrations of these parameters were observed in daily mixed samples, exhibiting distinct seasonal patterns-higher in summer and lower in winter-consistent with lowland catchment behavior. Particularly during heavy precipitation events, the smaller catchment exhibits a more complex and less predictable response to chemical concentrations compared with the dilution effect observed in the larger catchment. The results underline the complexity of phosphorus dynamics in small catchments and emphasize the importance of event-based sampling for capturing short-term concentration peaks for all four parameters, particularly beneficial regarding measuring suspended solids. While daily mixed samples capture average phosphorus concentrations, event-based sampling is crucial for detecting short-term spikes, providing a more comprehensive understanding of phosphorus dynamics.
摘要：
尽管欧盟水框架指令已经通过了二十多年，在德国地表水中实现所需的水质仍然具有挑战性，无论努力减少磷的投入和相关的环境影响。本研究旨在分析控制四个关键水质参数(总磷，正磷酸盐,颗粒磷酸盐，和悬浮固体）在两个低地集水区：Kielstau的50平方公里集水区，德国,和它的7平方公里支流，Moorau,以农业用地为主。为此,不同的抽样方法，特别是基于高分辨率降水事件的采样和每日混合样本，进行和评估，并对其有效性进行了比较。确定影响磷和悬浮沉积物动力学的来源和特征，无论是在一般情况下，特别是在强降水事件期间，是研究的重点之一。在15年的时间里，在每日混合样品中观察到这些参数的浓度增加，表现出明显的季节模式-夏季较高，冬季较低-与低地集水行为一致。特别是在强降水事件期间，与在较大集水区观察到的稀释效应相比,较小的集水区对化学浓度表现出更复杂和更不可预测的反应。结果强调了小流域磷动态的复杂性，并强调了基于事件的采样对于捕获所有四个参数的短期浓度峰的重要性。特别有利于测量悬浮固体。而每日混合样品捕获平均磷浓度，基于事件的采样对于检测短期尖峰至关重要，对磷动力学有更全面的了解。
