Oxygen profiles were measured in the sediments of the Gulf of Aqaba (Red Sea), an oligotrophic marine system affected by episodic seasonal flash floods and intense aeolian dry deposition. Sediment cores were retrieved from shallow (15–45 m), intermediate (250–561 m) and deep (700 m) water sites of south–north and east–west transects. Dissolved oxygen concentrations were measured simultaneously by using microelectrodes and microoptodes immediately after sampling and after transportation. Oxygen penetration depths were found to increase from 2 to 5 mm at the shallow water sites with sandy permeable sediments to 10–21 mm at the deeper sites with cohesive muddy sediments. This increase corresponds to decrease in oxygen diffusive fluxes at the sediment–water interface and oxygen consumption rates with depth. Oxygen consumption rates exhibit local maxima at the oxic–anoxic sediment boundary, which may be attributed to oxygen reduction coupled to oxidation of dissolved Fe(II) and Mn(II) at deep and intermediate water sites and of hydrogen sulfide at shallow water sites. Microelectrodes and microoptodes measurements of cohesive sediments from deep and intermediate water sites yielded similar results. By comparison, the microoptodes displayed more robust measurements than microelectrodes in sandy near-shore sediments. This was attributed to their flexible fiber structure that is less likely to break or to abruptly displace sand particles. After transportation of sediment cores from Eilat to Beer Sheva followed by ≤ 24-h storage, no changes in oxygen fluxes and consumption rates were detected.

中文翻译：

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亚喀巴湾渗透性和粘性沉积物中的耗氧量

在亚喀巴湾（红海）的沉积物中测量了氧气剖面，亚喀巴湾是一个受季节暴发的季节性暴洪和强烈的风干沉积影响的贫营养海洋系统。沉积岩心取自南北断面和东西西断面的浅水位（15-45 m），中间水位（250-561 m）和深水位（700 m）。采样后和运输后立即使用微电极和微光电二极管同时测量溶解氧的浓度。氧气渗透深度在含砂质可渗透沉积物的浅水区域从2 mm增加到5 mm，而在具有粘性泥质沉积物的较深区域增加到10–21 mm。这种增加对应于沉积物-水界面处的氧气扩散通量的减少以及深度处的耗氧率。耗氧率在有氧-缺氧沉积物边界处表现出局部最大值，这可能归因于氧气的减少与在深水和中间水位处的溶解的Fe（II）和Mn（II）的氧化以及在浅水位的硫化氢的氧化有关。用微电极和微光电二极管对深部和中部水位的粘性沉积物的测量结果相似。相比之下，在沙质近岸沉积物中，微光电二极管的测量结果比微电极强。这归因于其柔软的纤维结构，该纤维结构不太可能破裂或突然移位砂粒。在将沉积物核芯从埃拉特运至比尔谢瓦之后，≤24小时储存，氧通量和消耗速率均未发现变化。这可能归因于氧气还原与深水和中间水位处溶解的Fe（II）和Mn（II）的氧化以及浅水位处的硫化氢的氧化有关。用微电极和微光电二极管对深部和中部水位的粘性沉积物的测量结果相似。相比之下，在沙质近岸沉积物中，微光电二极管的测量结果比微电极强。这归因于其柔软的纤维结构，该纤维结构不太可能破裂或突然移位砂粒。从埃拉特（Eilat）到比尔谢瓦（Beer Sheva）的沉积物芯运输之后，≤24小时储存，氧通量和消耗速率均未发现变化。这可能归因于氧气还原与深水和中间水位处溶解的Fe（II）和Mn（II）的氧化以及浅水位处的硫化氢的氧化有关。用微电极和微光电二极管对深部和中部水位的粘性沉积物的测量结果相似。相比之下，在沙质近岸沉积物中，微光电二极管的测量结果比微电极强。这归因于其柔软的纤维结构，该纤维结构不太可能破裂或突然移位砂粒。从埃拉特（Eilat）到比尔谢瓦（Beer Sheva）的沉积物芯运输之后，≤24小时储存，氧通量和消耗速率均未发现变化。