Departamento de Biología Animal, Biología Vegetal y Ecología, Campus de Las Lagunillas, s/n, University of Jaén, Jaén E-23071, Spain.
Sci Total Environ. 2014 Jan 1;466-467:965-75. doi: 10.1016/j.scitotenv.2013.07.123. Epub 2013 Aug 28.
Sediment desiccation is expected to drastically affect nutrient cycling in Mediterranean wetlands as global climate change models predict that many areas will become significantly drier than they currently are. In this study, we selected two Mediterranean wetlands that clearly differ in their water chemical composition (Honda and Hituelo wetlands) in order to determine the impact of sediment desiccation on phosphate (PO₄(3-)) adsorption and desorption properties. A decrease in PO₄(3-) sorption properties was observed in transects from the littoral zone to dry land in both lakes concomitantly with a reduction in organic matter content, revealing a critical role of organic matter for sequestering P in the lake sediment. Our experiments designed to determine if drying events would lead to an enhanced P release upon re-wetting have shown that, simulating natural conditions of re-flooding (that is without adding sodium azide), PO₄(3-) concentrations were notably higher in the overlying water than those initially measured in the lake water. These results highlight the impact of drying sediment and the subsequent re-wetting on increasing P concentrations in lake water and accordingly, affecting to lake trophic state. Finally, we aimed on determining the overall effect of biotic versus abiotic activity on P release patterns observed upon re-wetting. Our results have evidenced that while in Honda, biotic processes upon re-wetting are crucial for increasing P retention in the sediment; P exchange across sediment and water upon dry sediment re-wetting is basically mediated by abiotic processes in Hituelo.
沉积物干燥预计将极大地影响地中海湿地的养分循环，因为全球气候变化模型预测，许多地区将变得比现在干燥得多。在这项研究中，我们选择了两个湿地，它们在水化学组成上明显不同（本田和希图洛湿地），以确定沉积物干燥对磷酸盐（PO₄(3-)）吸附和解吸特性的影响。在两个湖泊的从滨岸区到旱地的剖面上，随着有机质含量的减少，观察到 PO₄(3-)吸附性能下降，表明有机质在湖泊沉积物中固定 P 具有重要作用。我们设计的实验旨在确定干燥事件是否会导致再润湿时 P 的释放增强，结果表明，模拟自然的再淹没条件（即不添加叠氮化钠），上层水中的 PO₄(3-)浓度明显高于初始测量的湖水浓度。这些结果突出了干燥沉积物的影响，以及随后的再润湿对增加湖水 P 浓度的影响，从而影响湖泊的营养状态。最后，我们旨在确定生物和非生物活性对再润湿时观察到的 P 释放模式的综合影响。我们的结果表明，在本田，再润湿时的生物过程对于增加沉积物中 P 的保留至关重要；而在希图洛，干燥沉积物再润湿时，沉积物与水之间的 P 交换主要由非生物过程介导。
