The regulatory management of river water quality requires measurements of phosphorus that are operationally viable and meaningful in terms of insight into its effects. This need is a particular concern in globally rare and ecologically sensitive chalk streams. P data pertaining to rivers are commonly limited to soluble reactive P; other fractions of P may be of concern but are not routinely monitored. This study seeks to establish the nature and extent of non-regulated forms of P in UK chalk streams. Whilst soluble reactive P in two southern English chalk streams was found to comprise the majority of reactive P in surface waters in the majority of samples, 15–20% of the total reactive P was within other size fractions greater than 0.22 μm. The contribution of reactive P to the total P was highly variable. We conclude that, with some adjustments, the established method of regulatory monitoring of P in UK rivers is viable and valuable. In cases where the levels of reactive P are not consistent with ecological status and/or expected outcomes of programmes of measures, we recommend that targeted analysis of non-regulated forms of P is undertaken as a means to guide and focus management interventions.

河流水质的监管管理要求对磷进行测量，以了解其影响，这些磷在操作上是可行的和有意义的。在全球稀有且对生态敏感的白垩流中，这一需求尤其令人关注。与河流有关的磷数据通常仅限于可溶性反应性磷；P的其他部分可能值得关注，但不进行常规监控。本研究旨在确定英国白垩流中非受管制形式的P的性质和程度。虽然在大多数样品中发现了两条南部英国白垩流中的可溶性反应性P占地表水中的大多数反应性P，但总反应性P的15–20％在大于0.22μm的其他尺寸分数之内。反应性P对总P的贡献变化很大。我们得出的结论是，经过一些调整，在英国河流中对磷进行监管监测的既定方法是可行且有价值的。如果反应性P的水平与生态状况和/或措施计划的预期结果不一致，我们建议对非管制形式的P进行有针对性的分析，以此作为指导和集中管理干预措施的手段。