Advective transport and decomposition of chain-forming planktonic diatoms in permeable sediments
Advective transport and decomposition of chain-forming planktonic diatoms in permeable sediments
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DOI：
10.1016/j.seares.2004.01.004
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发表时间：
2004-09-01
影响因子：
2
通讯作者：
Huettel, M
中科院分区：
文献类型：
--
作者：
Ehrenhauss, S;Huettel, M
在实验室室内实验中，我们证明，暴露在边界流中的可渗透沉积物(bbb7 × 10（-12) m(2)）会过滤水柱中形成链的海岸藻华硅藻（costatum和Thalassiosira rotula），导致新鲜有机颗粒物质在72小时内快速转移到5厘米深的沉积层中。硅藻的渗透深度取决于床的渗透性和链的长度。长链不像短链或单细胞那样深入沉积物。在高能海岸环境中，浮游植物细胞向沙质沉积物的快速平流转移可能是促进有机质吸收和防止沉积有机质再悬浮的重要过程。相对于溶质交换以扩散为主的沉积物，中粒和粗粒沙质沉积物的高平流冲刷速率增强了被困硅藻的矿化(2300至3200 μ mol C m(-2) d(-1))，刺激了底栖生物的氧气消耗(2300至3000 μ mol O-2 m(-2) d(-1))，以及硝化作用(高达20 μ mol NO3- m（-2) d(-1)）。随渗透率增加而增加的顺流溶质交换率阻止了Si(OH)(4)在溶解结块附近和孔隙水中的积累，从而导致溶解的二氧化硅在水柱(95至101 μ mol Si(OH)(4) m（-2) d(-1)）中有效地循环到生产过程中。这个过程也可能通过保持比细粒沉积物更高的欠饱和程度来提高沉积在粗粒砂中的蛋白石的溶解速率。我们的研究结果表明，浮游硅藻对可渗透沉积物的平流过滤增加了高能陆架区Si(OH)(4)和有机质的矿化和再循环。(C) 2004 Elsevier B.V.版权所有
In laboratory chamber experiments we demonstrate that permeable sediments (>7 x 10(-12) m(2)) exposed to boundary flows filter chain-forming coastal bloom diatoms (Skeletonema costatum and Thalassiosira rotula) from the water column, causing rapid transfer of fresh organic particulate matter into sediment layers as deep as 5 cm within 72 h. The penetration depth of the diatoms depends on the permeability of the bed and the length of the chains. Long chains were not transported as deep into the sediment as short chains or single cells. The fast advective transfer of phytoplankton cells into sandy sediments may be an important process facilitating organic matter uptake and preventing resuspension of deposited organic material in high-energy coastal environments. High advective flushing rates in medium- and coarse-grained sandy sediments enhanced the mineralisation of the trapped diatoms (2300 to 3200 mumol C m(-2) d(-1)), stimulated benthic oxygen consumption (2300 to 3000 mumol O-2 m(-2) d(-1)), as well as nitrification (up to 20 mumol NO3- m(-2) d(-1)), relative to sediment where diffusion dominated the solute exchange. Advective solute exchange rates that increase with increasing permeability prevent the accumulation of Si(OH)(4) near the dissolving frustules and in the pore water, leading to an effective recycling of dissolved silica to the production process in the water column (95 to 101 mumol Si(OH)(4) m(-2) d(-1)). This process may also enhance dissolution rates of the deposited opal in coarse-grained sands by maintaining higher degrees of undersaturation than in fine-grained sediments. Our results suggest that advective filtration of planktonic diatoms into permeable sediments increases mineralisation and recycling of Si(OH)(4) and organic matter in high energetic shelf areas. (C) 2004 Elsevier B.V. All rights reserved.