Abstract Variation in the timing and quantity of diffuse versus point-source inputs of phosphorus (P) to streams can be evaluated by examining P concentration-flow relationships. Diffuse load inputs usually increase with stream flow (due to increased delivery caused by precipitation); whereas, point-source concentrations decrease with rising river flow (due to increased dilution). This study tested the suitability of a load apportionment model (LAM), a power-law function of flow, to estimate contributions of diffuse and point inputs to P loads for eight sub-watersheds in the Red River Valley, a cold-climate rural region of Manitoba, Canada. For all but two sub-watersheds, annual and seasonal (snowmelt and summer) models of P concentration versus flow best fit a strictly diffuse source contribution. The models identified significant point-source inputs (in addition to diffuse sources) in two sub-watersheds, during summer in both watersheds (consistent with the fact that wastewater from sewage lagoons is discharged to upstream reaches between June and September) and during snowmelt for one watershed. Application of a LAM proved to be a simple and rapid method for nutrient source apportionment as well as detection of unknown sources for cold-climate, rural sub-watersheds. Such information is critical for developing the most effective mitigation strategies to reduce P concentrations and eutrophication risk.

中文翻译：

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使用负荷分配模型评估寒冷气候地区河流中的扩散和点源磷输入

摘要 磷 (P) 向河流的扩散与点源输入的时间和数量的变化可以通过检查 P 浓度-流量关系来评估。扩散载荷输入通常随河流流量增加（由于降水引起的输送增加）；而点源浓度随着河流流量的增加而降低（由于稀释增加）。本研究测试了负载分配模型 (LAM) 的适用性，该模型是流量的幂律函数，用于估计在寒冷气候农村地区红河谷的八个子流域的扩散和点输入对 P 负载的贡献加拿大曼尼托巴省。对于除两个子流域外的所有子流域，P 浓度与流量的年度和季节性（融雪和夏季）模型最适合严格的扩散源贡献。这些模型确定了两个子流域的重要点源输入（除了扩散源），在两个流域的夏季（与污水泻湖的废水在 6 月和 9 月之间排放到上游河段的事实一致）和融雪期间一个分水岭。事实证明，LAM 的应用是一种简单快速的方法，可用于营养源分配以及检测寒冷气候农村子流域的未知来源。这些信息对于制定最有效的缓解策略以降低 P 浓度和富营养化风险至关重要。在两个流域的夏季（与污水泻湖的废水在 6 月和 9 月之间排放到上游河段这一事实一致）和一个流域的融雪期间。事实证明，LAM 的应用是一种简单快速的方法，可用于营养源分配以及检测寒冷气候农村子流域的未知来源。这些信息对于制定最有效的缓解策略以降低 P 浓度和富营养化风险至关重要。在两个流域的夏季（与污水泻湖的废水在 6 月至 9 月之间排放到上游河段这一事实一致）和一个流域的融雪期间。事实证明，LAM 的应用是一种简单快速的方法，可用于营养源分配以及检测寒冷气候农村子流域的未知来源。这些信息对于制定最有效的缓解策略以降低 P 浓度和富营养化风险至关重要。