Aquatic Ecology Laboratory, Department of Evolution, Ecology, and Organismal Behavior, The Ohio State University, 230 Research Center, 1314 Kinnear Road, Columbus, OH 43212, USA.
Aquatic Ecology Laboratory, Department of Evolution, Ecology, and Organismal Behavior, The Ohio State University, 230 Research Center, 1314 Kinnear Road, Columbus, OH 43212, USA; Translational Data Analytics Institute, The Ohio State University, Columbus, OH, USA.
Water Res. 2022 Aug 15;222:118845. doi: 10.1016/j.watres.2022.118845. Epub 2022 Jul 12.
Cyanobacterial harmful blooms have been increasing worldwide, due in part to excessive phosphorus (P) losses from agriculture-dominated watersheds. Unfortunately, cyanobacteria bloom management is often complicated by uncertainty associated with river P cycling. River P cycling mediates P exports during low flow but has been assumed to be unimportant during high flows. Thus, we examined interactions between dissolved reactive phosphorus (DRP) and suspended sediment P during high flows in the Maumee River network, focusing on March-June Maumee River DRP exports, which fuel recurring cyanobacteria blooms in Lake Erie. We estimate that during 2003-2019 March to June high flow events, P sorption reduced DRP exports by an average of 13-27%, depending upon the colloidal-P:DRP ratio, decreasing the bioavailability of P exports, and potentially constraining cyanobacteria blooms by 13-40%. Phosphorus sorption was likely lower during 2003-2019 than 1975-2002 due to reductions in suspended sediment loads, associated with soil-erosion-minimizing agricultural practices. This unintended outcome of erosion management has likely decreased P sorption, increased DRP exports to Lake Erie, and subsequent cyanobacteria blooms. In other watersheds, DRP-sediment P interactions during high flow could have a positive or negative effect on DRP exports; therefore, P management should consider riverine P cycles, particularly during high flow events, to avoid undermining expensive P mitigation efforts.
蓝藻有害藻华在全球范围内不断增加，部分原因是农业为主的流域中过量的磷（P）流失。不幸的是，蓝藻水华的管理通常因与河流 P 循环相关的不确定性而变得复杂。河流 P 循环在低流量期间调节 P 输出，但在高流量期间被认为不重要。因此，我们在 Maumee 河流网络中高流量期间研究了溶解反应性磷（DRP）和悬浮泥沙 P 之间的相互作用，重点关注 Maumee 河 3 月至 6 月的 DRP 输出，这些输出为伊利湖反复出现的蓝藻水华提供了燃料。我们估计，在 2003 年至 2019 年期间，3 月至 6 月的高流量事件中，磷吸附平均减少了 DRP 输出的 13%-27%，具体取决于胶体-P:DRP 比值，降低了 P 输出的生物可利用性，并通过 13%-40%来限制蓝藻水华。由于与土壤侵蚀最小化农业实践相关的悬浮泥沙负荷减少，与 1975 年至 2002 年相比，2003 年至 2019 年期间的磷吸附可能较低。侵蚀管理的这种意外结果可能降低了磷吸附，增加了 DRP 向伊利湖的输出，并随后导致蓝藻水华。在其他流域，高流量期间的 DRP-泥沙 P 相互作用可能对 DRP 输出产生积极或消极影响；因此，磷管理应考虑河流 P 循环，特别是在高流量事件期间，以避免破坏昂贵的 P 缓解工作。
