Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310, United States; Resilient Infrastructure and Disaster Response Center, FAMU-FSU College of Engineering, Tallahassee, FL 32310, United States.
Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310, United States; Resilient Infrastructure and Disaster Response Center, FAMU-FSU College of Engineering, Tallahassee, FL 32310, United States.
Water Res. 2024 Oct 15;264:122238. doi: 10.1016/j.watres.2024.122238. Epub 2024 Aug 8.
Elongated periods of low flow conditions, which can be termed as streamflow droughts, influence the nutrient (e.g., nitrogen and phosphorus) balance in estuarine systems. Analyzing temporal trends of nutrient fluxes into such systems under different streamflow regimes can complement the understanding about the dynamic evolution of streamflow droughts and their impacts on nutrient levels. The objective of this paper was to evaluate how dynamic evolution of streamflow droughts (from low flow conditions) affects the inorganic nutrient flux in a tropical estuarine system. We analyzed a 20-year time series of streamflow data together with the concentrations of two nutrient parameters-dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN)-in the Lower Apalachicola River that drains into Apalachicola Bay in northeastern Gulf of Mexico, Florida. Our findings revealed that droughts affect the seasonal patterns and fluxes of both DIP and DIN. We also observed post-drought flushing patterns in DIP and contrasting changes in DIP and DIN fluxes in the long-term (20 years here) under different streamflow conditions. Dynamically changing correlations between the streamflow and the fluxes were found throughout different phases of droughts. In the long-term (from 2003 to 2021), the DIP flux in high flows increased by 35.3%, while the flux decreased by 15.7% in low flows. Conversely, DIN flux in high flows showed a decrease of <1.2%, but an increase of <23.7% in low flows after droughts end. The insights from this study highlighted the need for effective regulation plans such as proper nutrient management against streamflow droughts to mitigate negative ecological consequences in estuarine systems such as harmful algal blooms.
长时间的低流量条件，可被称为枯水期，会影响河口系统中的养分（如氮和磷）平衡。分析不同水流条件下这些系统中养分通量的时间趋势，可以补充对枯水期动态演变及其对养分水平影响的理解。本文的目的是评估枯水期（从低流量条件开始）的动态演变如何影响热带河口系统中的无机养分通量。我们分析了佛罗里达州墨西哥湾东北部阿巴拉契科拉湾入海口的下阿巴拉契科拉河 20 年的流量数据以及两种养分参数（溶解无机磷（DIP）和溶解无机氮（DIN））浓度的时间序列。我们的研究结果表明，枯水期会影响 DIP 和 DIN 的季节性模式和通量。我们还观察到枯水期后的 DIP 冲洗模式以及在不同水流条件下长期（这里为 20 年）中 DIP 和 DIN 通量的相反变化。在不同的枯水期阶段，我们发现流量与通量之间的动态相关关系发生了变化。在长期（2003 年至 2021 年）中，高流量时的 DIP 通量增加了 35.3%，而低流量时的通量减少了 15.7%。相反，枯水期结束后，高流量时的 DIN 通量减少了<1.2%，而低流量时的通量增加了<23.7%。本研究的结果强调了需要制定有效的调节计划，例如针对枯水期进行适当的养分管理，以减轻河口系统中有害藻类大量繁殖等负面生态后果。
