WAMSI 2 - Dredging Node 3.2.2 - Plume Characterization – Lab Studies

The key objectives of Project 3.2:
(1) Characterize the physical/optical properties of sediment suspensions;
(2) Map the dredge-generated plume;
(3) Provide data to optimize and validate plume modelling;
(5) Assess the spatial and temporal variability (~10 years) of background suspended sediment loads using archived remote sensing data;
(6) To estimate the benthic light field with respect to TSS;

In this study we investigated various common turbidity sensors, including optical scattering and acoustic scattering instrumentation, and compared and contrasted their effectiveness in estimating particle load (TSS concentration), and/or Particle Size Distributions (PSDs). Studies were conducted in a controlled laboratory-based setting with a range of different sediment types primarily obtained from the Pilbara coast.

More specifically we:
• determined the particle size (PS) of sediment samples from Pilbara coastal waters using a sequoia scientific LISST 100X submersible particle size analyser and related PS to the particulate backscattering slope (γbp parameter) of HobiLabs HydroScat-6 and the particulate scattering slope (γb parameter) of WETLabs acs-176;
• Established the relationship between Turb and TSS concentration using the optical properties of particulate backscattering coefficient (bbp), scattering coefficient (bb) and total absorptions (a) from HydroScat-6 and acs-176; Wetlabs ECO NTU and Campbell Scientific OBS3+.

3.2项目的核心目标如下：
(1) 表征沉积物悬浮液的物理与光学特性；
(2) 绘制疏浚作业产生的悬浮羽流分布图；
(3) 提供数据以优化并验证羽流模型；
(5) 利用存档遥感数据，评估背景悬浮沉积物负荷的时空变化特征（观测时长约10年）；
(6) 估算针对总悬浮固体（Total Suspended Solids, TSS）的底栖光场。

本研究调研了多款常见浊度传感器，涵盖光学散射类与声学散射类仪器，并对比分析了它们在估算颗粒物负荷（即TSS浓度）以及/或粒径分布（Particle Size Distributions, PSDs）方面的应用效能。实验设置于受控实验室环境中，所用沉积物样本主要采集自皮尔巴拉（Pilbara）海岸海域。

更具体而言，本研究完成了以下工作：
• 采用Sequoia Scientific LISST 100X型水下粒径分析仪，测定皮尔巴拉沿海水域沉积物样本的粒径（PS），并将该粒径与HobiLabs HydroScat-6的颗粒物后向散射斜率（γbp参数）以及WETLabs acs-176的颗粒物散射斜率（γb参数）建立关联；
• 基于HydroScat-6与acs-176测得的颗粒物后向散射系数（bbp）、散射系数（bb）及总吸收系数（a），结合WETLabs ECO NTU与Campbell Scientific OBS3+的光学特性，建立浊度（Turb）与TSS浓度之间的定量关系。