Measurement and interpretation of solute concentration gradients in the benthic boundary layer
Measurement and interpretation of solute concentration gradients in the benthic boundary layer
复制标题
DOI：
10.4319/lom.2011.9.1
复制
发表时间：
2011-01-01
影响因子：
2.7
通讯作者：
Bruchert, Volker
中科院分区：
文献类型：
--
作者：
Holtappels, Moritz;Kuypers, Marcel M. M.;Bruchert, Volker
沿海海洋的特点是沉积物和水柱之间有机物、氧气和营养物质的交换率很高。在沉积物和上覆水柱之间交换的溶质通过湍流扩散的方式穿过底栖边界层（BBL）。因此，在BBL中的溶质浓度梯度包含有价值的信息，有关各自的通量。在这项研究中，我们提出的仪器和采样策略来测量氧气和营养浓度梯度的BBL。我们提供的理论背景和计算程序，从这些浓度梯度的养分和氧通量的比率。在波罗的海西部的两个采样点，营养盐和氧气浓度梯度高达5和30亩M m（-1），分别说明了非侵入性的方法，进行了测量。营养盐和氧通量比被用来建立沉积物和水柱之间的氮通量平衡，表明20%和50%的矿化氮以N-2的形式离开沉积物（站A和B，分别）。完整的沉积物芯的沉积物培养实验，测量反硝化速率，和氧的吸收的结果是支持的。所提出的通量比的方法是适用的，没有知识的BBL中的湍流扩散系数，因此，不受非稳态电流速度和扩散系数。
The coastal ocean is characterized by high exchange rates of organic matter, oxygen, and nutrients between the sediment and the water column. The solutes that are exchanged between the sediment and the overlying water column are transported across the benthic boundary layer (BBL) by means of turbulent diffusion. Thus, solute concentration gradients in the BBL contain valuable information about the respective fluxes. In this study, we present the instrumentation and sampling strategies to measure oxygen and nutrient concentration gradients in the BBL. We provide the theoretical background and the calculation procedure to derive ratios of nutrient and oxygen fluxes from these concentration gradients. The noninvasive approach is illustrated at two sampling sites in the western Baltic Sea where nutrient and oxygen concentration gradients of up to 5 and 30 mu M m(-1), respectively, were measured. Nutrient and oxygen flux ratios were used to establish a nitrogen flux balance between sediment and water column indicating that 20% and 50% of the mineralized nitrogen left the sediment in form of N-2 (station A and B, respectively). The results are supported by sediment incubation experiments of intact sediment cores, measuring denitrification rates, and oxygen uptake. The presented flux ratio approach is applicable without knowledge of turbulent diffusivities in the BBL and is, therefore, unaffected by non-steady-state current velocities and diffusivities.