Seasonal variation in concentration, size, and settling velocity of muddy marine flocs in the benthic boundary layer
Seasonal variation in concentration, size, and settling velocity of muddy marine flocs in the benthic boundary layer
复制标题
DOI：
10.1002/2014jc010644
复制
发表时间：
2015-08
影响因子：
--
通讯作者：
M. Fettweis;M. Baeye
中科院分区：
文献类型：
--
作者：
M. Fettweis;M. Baeye
在2006年至2013年的700多天里，对北海南部沿海浊度最大区域的水柱最低2 m处的悬浮颗粒物（SPM）浓度分布和河床以上2 m处的粒径分布进行了测量。本文根据潮汐差、滨岸剩余流方向和季节对SPM浓度、粒径和沉降速度的长期数据序列进行集合平均，探讨SPM的季节性动态及其与物理和生物过程的关系。数据表明，夏季SPM主要集中在近层，冬季SPM在整个水柱中混合较好。夏季水柱中SPM浓度的降低被较高的近层浓度所补偿，这表明夏季有很大一部分SPM仍留在该地区，而不是被平流排出。据我们所知，近床层和水柱之间的相反季节性尚未在文献中提出。诸如浪高、风气候或风暴等物理效应与观测到的季节性相关性较弱。支持微生物活动是季节性的主要驱动因素的论点在于观察到的絮体大小和沉降速度的变化。平均而言，夏季絮凝体较大，沉降速度高于冬季。
Suspended Particulate Matter (SPM) concentration profiles of the lowest 2 m of the water column and particle size distribution at 2 m above the bed were measured in a coastal turbidity maximum area (southern North Sea) during more than 700 days between 2006 and 2013. The long-term data series of SPM concentration, floc size, and settling velocity have been ensemble averaged according to tidal range, alongshore residual flow direction, and season, in order to investigate the seasonal SPM dynamics and its relation with physical and biological processes. The data show that the SPM is more concentrated in the near-bed layer in summer, whereas in winter, the SPM is better mixed throughout the water column. The decrease of the SPM concentration in the water column during summer is compensated by a higher near-bed concentration indicating that a significant part of the SPM remains in the area during summer rather than being advected out of it. The opposite seasonality between near-bed layer and water column has to our knowledge not yet been presented in literature. Physical effects such as wave heights, wind climate, or storms have a weak correlation with the observed seasonality. The argument to favor microbial activity as main driver of the seasonality lies in the observed variations in floc size and settling velocity. On average, the flocs are larger and thus settling velocities higher in summer than winter.