Abstract Understanding riverine phosphorus (P) dynamics, its transport, and transformation mechanisms from sources in the watersheds to receiving water bodies are essential for the development of effective strategies to decrease excess P loading and reduce eutrophication. Karst watersheds are thought to be especially vulnerable to P pollution due to their geomorphological features. In this study, we investigated the dynamics of particulate P (PP) chemical phases in two karst watersheds from a Great Lakes Area of Concern in southern Ontario (Bay of Quinte, Canada). Suspended solids were collected during different hydrological regimes representing storm events with low and high discharge, and particulate P binding forms were measured using extraction techniques. Our results show that in these karst watersheds, particulate P is dominated by chemical species that are likely to be highly bioavailable and contribute 62–75% to total PP. Concentrations of these bioavailable P binding forms in suspended solids increase two- to three-fold on dry mass basis during periods of high river flow. Electron microprobe and energy dispersive X-ray spectroscopy suggest that the primary carriers of particulate P are aggregates of Fe oxyhydroxides and Al-silicates. Our results underscore the influence of particulate P sources on the ongoing eutrophication in the Bay of Quinte Area of Concern.

中文翻译：

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降雨期间安大略南部森林覆盖的喀斯特流域中颗粒磷的形态和生物利用度

摘要 了解河流磷 (P) 动态、其运输以及从流域源到接收水体的转化机制对于制定减少过量磷负荷和减少富营养化的有效策略至关重要。由于其地貌特征，喀斯特流域被认为特别容易受到 P 污染。在这项研究中，我们调查了安大略省南部（加拿大昆特湾）大湖区的两个喀斯特流域中颗粒 P (PP) 化学相的动力学。在代表具有低排放和高排放的风暴事件的不同水文情况下收集悬浮固体，并使用提取技术测量颗粒 P 结合形式。我们的结果表明，在这些喀斯特流域中，颗粒磷主要由可能具有高生物利用度的化学物种主导，占总磷的 62-75%。在高河流流量期间，这些生物可利用的磷结合形式在悬浮固体中的浓度以干重为基础增加了两到三倍。电子微探针和能量色散 X 射线光谱表明颗粒 P 的主要载体是 Fe 羟基氧化物和铝硅酸盐的聚集体。我们的结果强调了颗粒磷源对昆特湾关注区持续富营养化的影响。电子微探针和能量色散 X 射线光谱表明颗粒 P 的主要载体是 Fe 羟基氧化物和铝硅酸盐的聚集体。我们的结果强调了颗粒磷源对昆特湾关注区持续富营养化的影响。电子微探针和能量色散 X 射线光谱表明颗粒 P 的主要载体是 Fe 羟基氧化物和铝硅酸盐的聚集体。我们的结果强调了颗粒磷源对昆特湾关注区持续富营养化的影响。