We assessed the prevalence and causes of sediment phosphorus (P) release within urban stormwater ponds, a process that may reduce P removal by sedimentation. Data collected from surface water of 98 urban stormwater ponds in Minnesota showed that nearly 40% had median summer total P concentrations in excess of average stormwater runoff (0.38 mg L⁻¹), implying effects of internal loading. We sampled seven ponds more intensively and found four were strongly stratified with persistent hypolimnetic anoxia, despite mean depths <2 m. Sediment core incubations revealed that, unlike in most lakes, both labile organic P (NaOH minus persulfate extractions) and redox‐sensitive P (NH₄Cl and Na₂S₂O₄ extractions) contribute to P release. Together, these analyses suggest P accumulated in stormwater ponds is highly susceptible to internal release and potentially contributes to downstream eutrophication. Understanding how frequently these conditions occur and how they affect different P forms is vital to improving pond design and management.

中文翻译：

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雨水池塘的内部负荷作为下游水的磷源

我们评估了城市雨水塘中沉积物磷（P）释放的发生率和原因，该过程可能会减少沉积物对磷的去除。从明尼苏达州98个城市雨水池塘的地表水收集的数据显示，近40％的夏季总P浓度中值超过平均雨水径流（0.38 mg L ^-1），这意味着内部负荷的影响。我们对7个池塘进行了更密集的采样，发现其中4个池层均分层强烈，并伴有持续的低铁性缺氧，尽管平均深度<2 m。沉积物核心温育表明，与大多数湖泊不同，不稳定的有机磷（NaOH减去过硫酸盐萃取物）和对氧化还原敏感的磷（NH ₄ Cl和Na ₂ S ₂ O _4）提取物）有助于磷的释放。综合起来，这些分析表明，雨水塘中积累的磷对内部释放高度敏感，并可能导致下游富营养化。了解这些情况的发生频率以及它们如何影响不同的磷形态对改善池塘设计和管理至关重要。