Fertilizer, landscape features and climate regulate phosphorus retention and river export in diverse Midwestern watersheds
Fertilizer, landscape features and climate regulate phosphorus retention and river export in diverse Midwestern watersheds
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DOI：
10.1007/s10533-019-00623-z
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发表时间：
2019-11-30
期刊：
影响因子：
4
通讯作者：
Finlay, Jacques C.
中科院分区：
文献类型：
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作者：
Boardman, Evelyn;Danesh-Yazdi, Mohammad;Finlay, Jacques C.
磷的非点源污染是导致水体富营养化的主要原因之一，由于流域尺度上磷的迁移和转化过程是动态的，人们对其了解甚少，因此非点源污染给流域管理带来了挑战。我们研究了磷的输入，保留，并在62个不同的流域，包括广泛的土地覆盖和使用（最小干扰人类为主）和人类P输入在美国明尼苏达州的河流损失。中耕作物种植的肥料投入是农业流域磷的主要来源。绝大多数磷输入被保留在流域土壤中或在农产品中被去除。然而，肥料投入是最重要的因素与平均每年的河流运输的总，溶解，颗粒磷（PP）。年平均径流量增加了总磷和溶解磷的产量，减少了磷的保留。溶解磷组成了一个显着的一部分，每年的河流负荷在网站与高利率的P输入和河流TP的出口，溶解PP出口的比例增加与作物覆盖和化肥投入。PP出口增加，河道附近的侵蚀崖程度更大。悬崖仅占流域面积的一小部分，但由于其靠近河道，对泥沙负荷的贡献不成比例地高，而河道越来越受人类和气候驱动的河流水文变化的影响。总之，我们的研究结果表明，由于气候变化和农业集约化加上高速率的P输入的排放量和流量的变化将保持到未来的河流P出口升高。如果不减少磷的投入，不减少可溶性磷的损失和河岸侵蚀，就很难逆转水质退化。
Non-point source pollution of phosphorus (P) is a primary cause of eutrophication of aquatic ecosystems, and poses a persistent management challenge due to the dynamic and poorly understood processes controlling the transport and transformation of P at the watershed scale. We examined phosphorus inputs, retention, and riverine losses in 62 diverse watersheds that included a wide range of land cover and use (minimally disturbed to human dominated) and human P inputs in Minnesota, USA. Fertilizer inputs from row crop cultivation were the dominant source of P to agricultural watersheds. A large majority of P inputs was retained in watershed soils or removed in agricultural products. However, fertilizer input was the most important factor associated with average annual river transport of total, dissolved, and particulate phosphorus (PP). Mean annual runoff increased total and dissolved P yields and decreased P retention. Dissolved P made up a significant portion of annual river loads at sites with high rates of P inputs and river TP export, with the ratio of dissolved to PP export increasing with crop cover and fertilizer inputs. PP export rose with larger extents of eroding bluffs near channels. Bluffs constitute only a small proportion of watershed area, but make a disproportionately high contribution to sediment loads due to their close proximity to river channels that are increasingly affected by human and climate-driven changes to river hydrology. Together, our results suggest that rising discharge and flow variability due to climate change and agricultural intensification coupled with high rates of P inputs will maintain elevated fluvial P export into the future. Without reductions in P inputs and reductions in both soluble P losses and stream bank erosion, reversal of water quality degradation will be difficult to achieve.