Phosphorus supplies (concentrations and fluxes) are essential drivers for biological activities in rivers and should be controlled to prevent eutrophication that usually results from urbanization and agricultural expansion. In this paper, data from 26 sub-catchments in the Mississippi Basin, the United States, were compiled for the period from 2013 to 2017 to identify how catchment area, precipitation, and land cover affect discharge and total phosphorus (TP), and how TP yield diverges from a generalized local response mode. Results revealed that area-weighted discharge (Qarea ) is controlled by precipitation and land cover (i.e., increases with precipitation and with both urban and forest land covers, and decreases with both shrub/scrub and pasture/grassland covers). TP concentration increases with agricultural land cover and decreases with both forest and water/wetland covers. TP yield (product of Qarea and concentration) is mainly governed by Qarea as the latter changes by a higher order of magnitude compared to concentration in the current study. Hence TP yield is following the same trends that Qarea exhibits with precipitation and land cover. In all catchments, TP yield varied significantly (p < 0.05) and positively with instantaneous discharge. However, the rate of yield variations with discharge exhibited a significant (p < 0.0001) strong negative (r2 = -0.74) correlation with catchment area. This study provided a robust model that can predict the TP concentration and yield across different catchment scales in the Mississippi Basin by means of discharge readings. This article is protected by copyright. All rights reserved.

中文翻译：

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密西西比流域子集水区土地覆盖、降水和集水区对排放和磷的综合影响

磷供应（浓度和通量）是河流生物活动的重要驱动因素，应加以控制以防止通常由城市化和农业扩张引起的富营养化。在本文中，2013 年至 2017 年期间美国密西西比盆地 26 个子流域的数据被汇编，以确定流域面积、降水和土地覆盖如何影响排放和总磷 (TP)，以及如何TP 产量与广义局部响应模式不同。结果表明，面积加权排放量 (Qarea ) 受降水和土地覆盖控制（即，随着降水以及城市和森林土地覆盖而增加，而随着灌木/灌木和牧场/草地覆盖而减少）。TP 浓度随农业用地覆盖而增加，随森林和水/湿地覆盖而减少。TP 产量（Qarea 和浓度的乘积）主要受 Qarea 控制，因为与当前研究中的浓度相比，后者的变化幅度更高。因此，TP 产量遵循 Qarea 在降水和土地覆盖方面表现出的相同趋势。在所有流域中，TP 产量变化显着（p < 0.05），并且与瞬时排放呈正相关。然而，产量随流量的变化率与流域面积呈显着（p < 0.0001）强负相关（r2 = -0.74）。这项研究提供了一个强大的模型，可以通过排放读数预测密西西比盆地不同流域规模的 TP 浓度和产量。本文受版权保护。版权所有。