High resolution measurements of sediment resuspension above an accumulation bottom in a stratified lake
High resolution measurements of sediment resuspension above an accumulation bottom in a stratified lake
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分层湖堆积底部上方沉积物再悬浮的高分辨率测量
DOI：
10.1007/bf00005730
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发表时间：
1994
期刊：
影响因子：
2.6
通讯作者：
G. Weyhenmeyer
中科院分区：
文献类型：
--
作者：
D. Pierson;G. Weyhenmeyer
使用 Sea Tech 透射计在瑞典中部中等深度（平均深度 9 m，最大深度 21 m）的二重相湖 Erken 湖主盆地进行频繁（间隔 30 分钟）波束衰减测量，获得了堆积底部上方 1.5 m 和地表下方 13.5 m 的底栖边界层 (BBL) 中悬浮颗粒物 (SPM) 浓度的详细记录。 SPM 浓度 (g m−3) 与光束衰减系数 (c, [m−1]) 的相关性不如无机 SPM 部分的浓度。显然，这是由大的不具有光学活性的有机颗粒引起的，这些颗粒显着影响了SPM的测量，但对光的衰减影响不大。当水柱热分层时，BBL中的SPM浓度呈现季节性增加，这与温跃层深度的增加有关。随着水层加深，SPM 浓度快速且大幅变化的发生率也显着增加。失去分层后，SPM 的量及其浓度的时间变异性降低。由于表面波不能影响测量深度的沉积物再悬浮，这些数据显示了内波在沉积物堆积区域促进沉积物再悬浮的重要性。每年夏季相对较短的时期，当温跃层达到足够的深度以允许在积累底部上重新悬浮时，可能对湖泊沉积物的重新分布和磷的内部负荷产生重要影响。
A detailed record of suspended particulate matter (SPM) concentrations in the benthic boundary layer (BBL) 1.5 m above an accumulation bottom and 13.5 m below the surface was obtained from frequent (30 min interval) beam attenuation measurements made with a Sea Tech transmissometer in the main basin of Lake Erken, a moderately deep (mean depth 9 m, maximum depth 21 m) dimictic lake in central Sweden. Concentrations of SPM (g m−3) were not as strongly correlated to the beam attenuation coefficient (c, [m−1]), as were concentrations of the inorganic SPM fraction. Apparently, this was caused by large optically inactive organic particles which significantly affected the measurements of SPM, but had little effect on the attenuation of light.When the water column was thermally stratified, SPM concentrations in the BBL showed a seasonal increase which was related to an increase in the thermocline depth. As the epilimnion deepened, there was also a marked increase in the occurrence of rapid and large changes in SPM concentration. After the loss of stratification, the amount of SPM and the temporal variability in its concentration was reduced. Since surface waves could not influence sediment resuspension at the depth of measurement, these data show the importance of internal waves in promoting sediment resuspension in areas of sediment accumulation. The relatively short period in each summer, when the thermocline reaches a sufficient depth to allow for resuspension over accumulation bottoms, can have important consequences for both the redistribution of lake sediments and the internal loading of phosphorus.