Evaluating the longevity of in-stream phosphorus legacies: A downstream cascade of recovery following point source remediation
Evaluating the longevity of in-stream phosphorus legacies: A downstream cascade of recovery following point source remediation
复制标题
评估河内磷残留的寿命：点源修复后的下游级联恢复
DOI：
10.1016/j.scitotenv.2023.168711
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发表时间：
2023
影响因子：
9.8
通讯作者：
Kalcic, Margaret
中科院分区：
文献类型：
--
作者：
Wallington, Kevin;Cai, Ximing;Kalcic, Margaret
河流中磷(P)的残留造成上游修复和下游减负之间的滞后。然而，这些滞后的长度在很大程度上是未知的，特别是对于长距离的河流。因此，在大分水岭尺度上的滞后时间估计是抽象的，有时甚至是低估的。在这里，我们利用一个带有新改进的流内磷模拟的大面积流域模型(SWAT+P.R&R)来评估美国玉米带流域遗留磷再动员的规模、寿命和空间级联。我们的结果说明了假设性点源补救后P负荷的“螺旋式恢复”，其中下游位置需要更长的时间才能恢复到基线负荷水平。在流域出口，河流中遗留的磷贡献相当于修复后三年基线平均年磷负荷的30%。河流中的遗产在修复后至少9年才接近枯竭(95%被重新动员)。在从干旱年份开始的假设天气情景中，遗留贡献持续的时间更长。这些发现(1)表明，河流中的遗产可能会对大流域的磷负荷产生数年到数十年的影响，(2)支持在未来的河流中遗产的研究中明确考虑空间尺度，以及(3)对大流域水质恢复的影响。
In-stream phosphorus (P) legacies cause lags between upstream remediation and downstream load reductions. However, the length of these lags is largely unknown, especially for long stream distances. As a result, lag time estimates at the large-watershed scale have been abstract and sometimes understated. Here, we leverage a large area watershed model with newly improved in-stream P simulation (SWAT+P.R&R) to evaluate the magnitude, longevity, and spatial cascade of legacy P remobilization in a U.S. corn belt watershed. Our results illustrate the “spiraling recovery” of P loads after a hypothetical point source remediation, where locations further downstream take longer to recover to baseline load levels. At the watershed outlet, in-stream legacy P contributions are equivalent to 30% of the baseline average annual P loads for three years after remediation. In-stream legacies do not approach exhaustion (95% remobilized) until at least 9 years after remediation. In hypothetical weather scenarios beginning with dry years, legacy contributions persist even longer. These findings (1) suggest that in-stream legacies could impact P loads for years to decades in large river basins, (2) support explicit accounting for spatial scale in future studies of in-stream legacies, and (3) provide concerning implications for water quality recovery in large river basins.