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首页> 外文期刊>Freshwater science >Variation in water-mediated connectivity influences patch distributions of total N, total P, and TN:TP ratios in the Upper Mississippi River, USA
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Variation in water-mediated connectivity influences patch distributions of total N, total P, and TN:TP ratios in the Upper Mississippi River, USA

机译：水介导的连通性的变化会影响美国密西西比河上游的总氮，总磷和总氮和总磷比率的斑块分布

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Floodplain rivers have been conceptualized as patchwork mosaics of hydrogeomorphic zones that differ in hydrological, physiochemical, and ecological conditions. However, few investigators have empirically examined the extent to which basic ecological properties of large rivers, such as nutrient concentrations, are patchily distributed or the relationship between such distributions and water-mediated connectivity. We used global and local measures of spatial autocorrelation in 5 reaches of the Upper Mississippi River from 1994-2008 in spring (higher discharge) and summer(lower discharge)to examine distributions of total N(TN), total P(TP), and TN:TP for evidence of patchiness. TN was distributed as discrete patches regardless of season, but the patches of TP and TN:TP were more distinct during summer low-flow than spring high-flow conditions. The occurrence of patches of low TN, high TP, and low TN:TP was highly predictable, generally occurring in backwater, low-velocity(0.1 m/s)environments. Patches of high TN, low TP, and high TN:TP were less common and less predictable, but were more likely to occur in channels with high current velocities(>0.1 m/s)or in impounded areas with low current velocity, but adjacent to channel environments. These patch distributions are consistent with our current understanding of dominant mechanisms of riverine nutrient cycling and were generally consistent across 5 river reaches that spanned nearly the entire length of a large floodplain river. Watershed characteristics ultimately determine nutrient inputs to river systems, but our results support the idea that local geomorphic and hydraulic conditions influence spatial patterns of nutrient delivery and biochemical transformation and create a patchwork mosaic of nutrient distributions within large floodplain rivers.
机译：洪泛区河流已被概念化为水文地貌区的拼凑而成的马赛克，水文，理化和生态条件各不相同。但是，很少有研究者凭经验检查大型河流的基本生态特征（如养分浓度）的分布是分散的程度，还是这种分布与水介导的连通性之间的关系。我们在1994-2008年春季（高流量）和夏季（低流量）的密西西比河上游5个河段使用了全球和局部空间自相关度量，以检验总N（TN），总P（TP）和TN：TP证明有斑点。 TN无论季节如何都以离散斑块的形式分布，但是在夏季低流量条件下，TP和TN：TP的斑块比春季高流量条件下的特征更为明显。低TN，高TP和低TN：TP斑块的发生是高度可预测的，通常发生在回水，低速（0.1 m / s）环境中。高TN，低TP和高TN：TP的斑块较不常见且难以预测，但更可能出现在高流速（> 0.1 m / s）的通道中或在低流速但邻近区域的蓄水区中引导环境。这些斑块分布与我们目前对河流养分循环的主要机制的理解是一致的，并且在横跨大泛滥平原河几乎整个长度的5条河段中总体上是一致的。流域的特征最终决定了河流系统的养分输入，但是我们的结果支持以下观点：当地的地貌和水力条件影响养分输送和生化转化的空间格局，并在洪泛区河流中形成养分分布的拼凑而成的马赛克。

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