Streambed and lake sediment was studied in Sävjaån, a eutrophic mesoscale catchment (722 km²) in central Sweden. Triplicate sediment cores from five lakes and nine streams, ranging from headwater to fourth order, were sampled. The sediment was analyzed with a sequential extraction method, where six different phosphorus (P) fractions were measured. The results showed that streambed sediments store considerable amounts of P and in some cases have comparable P contents (g/kg DW) to lake sediment. Land use, soil type, and drainage area (location in the catchment) had a significant effect on the different P fractions found in surficial sediments. Sediment from lakes and forested headwater streams generally had high proportions of organic P and iron bound P. In larger streams located in agricultural areas on clay soils closer to the catchment outlet, with dense sediment and a relatively low proportion of organic matter, P was to a larger extent bound to calcium. Streambed sediment may be an important catchment scale P store and should be considered when modeling catchment P dynamics. The large stores of streambed legacy P should also be considered when performing ditch maintenance to avoid unnecessary mobilization of bioavailable P.

中文翻译：

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分馏河床沉积物对遗留磷的新见解

在富营养化的中尺度流域Sävjaån（722 km ²）在瑞典中部。对五个湖泊和九个溪流（从源头到第四阶）的一式三份沉积物核心进行了采样。沉积物采用顺序萃取法进行分析，其中测量了六个不同的磷（P）组分。结果表明，河床沉积物可存储大量的P，在某些情况下，P的含量（g / kg DW）可与湖泊沉积物相媲美。土地利用，土壤类型和流域（流域中的位置）对表层沉积物中不同的P含量具有显着影响。湖泊和森林源头溪流中的沉积物通常含有较高比例的有机磷和铁结合磷。在农业区较大的溪流中，靠近集水口的黏土上，沉积物密集，有机质含量相对较低，P在更大程度上与钙结合。河床沉积物可能是重要的流域规模P储量，在对流域P动力学进行建模时应考虑。在执行沟渠维护时，还应考虑大量存储的流式遗留P，以避免不必要地动员生物利用P。