Phosphorus flux from lake sediments: Effect of epipelic algal oxygen production
Phosphorus flux from lake sediments: Effect of epipelic algal oxygen production
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DOI：
10.4319/lo.1988.33.4.0562
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发表时间：
1988-07
影响因子：
4.5
通讯作者：
R. Carlton;R. Wetzel
中科院分区：
文献类型：
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作者：
R. Carlton;R. Wetzel
以往的研究利用氧敏感的微电极已经证明，作为一个结果，epipelic藻类光合作用和微生物代谢，而不管上覆水的氧浓度，湖泊真光区内的沉积物经历显着的昼夜波动的氧气渗透的程度。本研究利用氧敏微电极、~（32）P_（0，3）-放射性示踪剂和一种新型的流通系统研究了表层藻类光合作用对沉积物氧动力学的影响以及伴随的湖泊沉积物磷释放模式。沉积物中的磷通过微氧化带的形成和分解释放到上覆水体中。在光照条件下，表层沉积物迅速氧化，从沉积物深层扩散的磷的释放受到抑制。在黑暗的微区成为缺氧，磷被释放到上覆水在加速的速度，产生显着的昼夜波动的流出率。所观察到的释放模式是一致的，最近的证据组成的沉积物微生物在各自的好氧或缺氧条件下快速吸收或rclcase溶解磷酸盐的机制。水生沉积物中的微生物代谢使无机磷酸盐再生，无机磷酸盐在间隙水中积累并形成浓度梯度。随后的扩散运输到上覆水可以通过一些过程，暂时或永久性地抑制磷酸盐的延迟。Mortimer（1941，1942）证明，沉积物表面存在氧化微区可抑制磷的释放，但在上覆水缺氧条件开始后，微区氧化还原电位降低，刺激Fe（III）还原，从而释放沉积物表面水合氧化物和凝胶中结合的磷酸盐。氧的这一关键作用已在各种湖泊和沉积物类型的大量研究中得到证实（Lamp-Nielsen 1974;帕特里克和Khalid 1974; Frevert 1980）。影响沉积物磷通量的因素还包括pH值、温度、pH值、温度
Previous studies utilizing oxygen-sensitive microelectrodes have demonstrated that as a result of epipelic algal photosynthesis and microbial metabolism, and regardless of the oxygen concentration of the overlying water, sediments within the euphotic zone of lakes undergo marked diel fluctuations in the extent of oxygen penetration. This investigation utilized oxygen-sensitive microelcctrodes, 32P0,3- radiotracer, and a novel flow-through system to examine the effect of epipelic algal photosynthesis on sediment oxygen dynamics and the concomitant pattern of phosphorus release from lake sediments. Epipelic algae mediated release of phosphorus from sediments to overlying water via daily formation and breakdown ofthe oxidized microzone. During illumination, surficial sediments rapidly became oxygenated, and release of phosphorus diffusing from deeper sediment layers was inhibited. During darkness the microzone became anoxic, and phosphorus was released to overlying water at an accelerated rate, producing marked diel fluctuation in efflux rate. Observed patterns of release are consistent with recent evidence for a mechanism consisting of rapid uptake or rclcase of dissolved phosphate by sediment microorganisms in response to respective oxic or anoxic conditions. Microbial metabolism in aquatic sediments regenerates inorganic phosphate that accumulates in interstitial water and forms concentration gradients. Subsequent diffusive transport to overlying water can be retarded by a number of processes that either temporarily or permanently immobilize phosphate. Mortimer (1941, 1942) demonstrated that the presence of an oxidized microzone at the sediment surface inhibited phosphorus release but that a decrease in redox potential of the microzone following the onset of anoxic conditions in the overlying water stimulated the reduction of Fe(III), thus releasing phosphate bound in hydrous oxides and gels at the sediment surface. This key role of oxygen has been substantiated in numerous studies in various lake and sediment types @Lamp-Nielsen 1974; Patrick and Khalid 1974; Frevert 1980). Also identified as factors affecting the rate of P flux from sediments are pH, tem