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2003年6月14日-22日, 利用现场激光粒度仪LISST-100在不扰动颗粒物的情况下, 于长江口徐六泾定点连续观测了洪季大、小潮表层粘性悬浮细颗粒泥沙絮凝体的实有粒径、体积浓度, 配合OBS-3A现场测量的悬沙浓度计算了现场絮凝体的有效密度和静水沉速.观测结果显示, 徐六泾大、小潮表层絮凝体体积浓度、粒径、有效密度和静水沉速的平均值分别为98.0 μl/L、39.8 μm、1173 kg/m^3、1.14 mm/s和70.8 μl/L、64.4 μm、919 kg/m^3、2.32 mm/s.研究表明： ①长江口徐六泾表层絮凝体体积浓度主要受水流流速影响, 再悬浮现象明显, 体积浓度过程线滞后流速过程线, 落潮期间滞后10-30 min, 涨潮则滞后30-50 min; ②小于一定流速时絮凝体平均粒径随流速增大而增大, 大于一定流速时絮凝体平均粒径则随流速增大而减小, 徐六泾大、小潮表层絮凝体在50 cm/s的垂线平均流速时出现平均粒径与垂线平均流速关系的转折; ③徐六泾大、小潮表层絮凝体平均粒径在体积浓度75 μl/L时出现平均粒径与体积浓度关系的转折, 体积浓度小于75 μl/L时粒径随体积浓度增加而增大, 超过75 μl/L时粒径随体积浓度的增加变化不明显; ④絮凝体有效密度由粒径大小控制, 粒径大, 有效密度小, 反之亦然, 粒径和有效密度共同决定絮凝体静水沉速, 有效密度和沉速与平均粒径之间均存在良好的幂指数关系. 相似文献
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根据2012年夏季和2016年冬季在南黄海中部利用原位激光粒度仪(laser in situ scattering and transmissometry,LISST)进行调查获得的实测数据,对两种平均粒径计算方法的结果进行比较研究,并对产生差别的原因进行分析。结果表明:无论在夏季和冬季,在温度跃层以上粒度分布以粗颗粒为主,两种计算方法差值较小,可以相互替代。在温盐跃层以下层位,细颗粒组分增加,导致二者计算差值变大。端元分析表明较高的平均粒径值倾向于造成平均粒径差值增大。矩值法强调了粗颗粒组分的贡献,而平均粒级法对细颗粒组分的贡献更加敏感,后者是更适用于将LISST观测数据应用于陆架海区现代沉积环境研究的粒径参数计算方法。本文为使用LISST在陆架海区进行现代沉积过程研究提供了参考。 相似文献
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Alexander Bartholomä Adam Kubicki Thomas H. Badewien Burghard W. Flemming 《Ocean Dynamics》2009,59(2):213-225
The German Wadden Sea (southern North Sea) sediments are composed of both cohesive and non-cohesive deposits. The spatial
distribution patterns are mainly driven by wind-induced waves and tidal currents. Transport intensity and duration depend
on the hydrodynamic conditions, which vary over time. In this paper, the transport of suspended sediment was investigated
on seasonal, tidal and hourly time scales in the back-barrier system of Spiekeroog Island. Long- and short-term data of fair
weather periods and two storm events were investigated based on stationary and mobile measurements of currents and waves by
Acoustic Doppler Current Profiler (ADCP), in situ particle size and suspended sediment concentration (SSC) measurements by
laser in situ scattering and transmissometry (LISST) as well as wind records. The ADCP backscatter intensities were calibrated
by means of LISST volume concentration data in order to quantify longer term SSCs and fluxes in the back-barrier system. Values
up to 120 mg l−1 were recorded, but concentrations more commonly were below 60 mg l−1. The long-term results confirm former observations of a balanced budget during low-energy (fair weather) conditions in the
study area. In general, SSCs were higher during spring tides than during neap tides. The data also clearly show the remobilisation
of sediment by tidal current entrainment. The records include two severe storm events, “Britta” (1st November 2006) and “Kyrill”
(18th January 2007). The data reveal very complex temporal flow and transport patterns. During both storm events, the export
of material was mainly controlled by the interaction of wind, waves and tidal phase. The typical ebb-dominance occurring during
fair-weather conditions was temporarily neutralised and even reversed to a flood-dominated situation. During “Kyrill”, the
wind and high-waves setup in conjunction with the tidal phase was even able to compress the duration of two successive ebb
cycles by over 70%. Although SSCs increased during both storms and higher turbulence lifted particle clouds upwards, an export
of suspended matter towards the North Sea was only observed under the conditions taking place during “Britta”. Such fluxes,
however, are currently still difficult to quantify because the backscatter intensity during high energy events includes a
substantial amount of noise produced by the high turbulence, especially near the water surface. 相似文献
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