Phosphorus Mitigation to Control River Eutrophication: Murky Waters, Inconvenient Truths, and "Postnormal" Science
Phosphorus Mitigation to Control River Eutrophication: Murky Waters, Inconvenient Truths, and "Postnormal" Science
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DOI：
10.2134/jeq2012.0085
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发表时间：
2013-03-01
影响因子：
2.4
通讯作者：
Neal, Colin
中科院分区：
文献类型：
--
作者：
Jarvie, Helen P.;Sharpley, Andrew N.;Neal, Colin
这篇评论探讨了一个“难以忽视的真相”，即长期以来被视为富营养化管理关键工具的磷(P)营养缓解，在许多情况下尚未产生预期的水质降低和河流及其相关下游生态系统中有害藻类生长的效果。我们研究了为什么水质和水生生态没有恢复，在某些情况下，经过20年或更长时间的磷输入减少，包括(i)过去土地利用管理的遗产，（ii）在富营养化受损的河流中，藻类生长对河流磷负荷的响应解耦；（iii）恢复轨迹，可能是非线性的，具有阈值和可选稳定状态的特征。有可能基线已经改变，一些受干扰的河流环境可能永远不会恢复到干扰前的状态，或者可能需要将磷降低到最初引发生态退化的水平以下。本文以美国红河流域为例，讨论了设定磷基营养标准对保护和改善河流水质和生态的实际意义。我们的结论是，营养管理和富营养化控制面临的挑战具有“后常态”科学的特征，其中不确定性很大，迫切需要管理干预，决策风险很高。我们提出了一种更全面的富营养化管理方法，包括更复杂的基于制度的营养标准，并考虑其他营养物质和污染物控制以及河流恢复（例如，物理栖息地和功能性食物网的相互作用），以促进更有弹性的水质和生态系统功能。
This commentary examines an "inconvenient truth" that phosphorus (P)-based nutrient mitigation, long regarded as the key tool in eutrophication management, in many cases has not yet yielded the desired reductions in water quality and nuisance algal growth in rivers and their associated downstream ecosystems. We examine why the water quality and aquatic ecology have not recovered, in some case aft er two decades or more of reduced P inputs, including (i) legacies of past land-use management, (ii) decoupling of algal growth responses to river P loading in eutrophically impaired rivers; and (iii) recovery trajectories, which may be nonlinear and characterized by thresholds and alternative stable states. It is possible that baselines have shifted and that some disturbed river environments may never return to predisturbance conditions or may require P reductions below those that originally triggered ecological degradation. We discuss the practical implications of setting P-based nutrient criteria to protect and improve river water quality and ecology, drawing on a case study from the Red River Basin in the United States. We conclude that the challenges facing nutrient management and eutrophication control bear the hallmarks of "postnormal" science, where uncertainties are large, management intervention is urgently required, and decision stakes are high. We argue a case for a more holistic approach to eutrophication management that includes more sophisticated regime-based nutrient criteria and considers other nutrient and pollutant controls and river restoration (e.g., physical habitat and functional food web interactions) to promote more resilient water quality and ecosystem functioning along the land-freshwater continuum.