环境条件变化对海底沉积物实验室声速测量结果的影响

Effect of the Condition Changes on the Laboratory Acoustic Velocity Measurements of Seafloor Sediments

根据2009-06和2010-06两个航次的南黄海沉积声学调查数据,分析了用于实验室声速测量的沉积物样品相对于海底原位状态的变化,并探讨了对声速测量结果的影响。研究表明,沉积物取样后直接拿至船上实验室测量时,较原位状态最显著的改变是温度,其对声速测量值的影响符合Hamilton模型,可以通过温度校正来预测原位声速。然而,运至陆地实验室的样品,较原位状态基本物理性质发生了较大的改变,如温度、密度和含水率等,其对声速测量值的影响难以仅仅通过温度校正来消除。因此,当不具备对沉积物声速进行原位测量的条件时,建议取样后立即在船上实验室进行声速测量。

Based on the data obtained from the sediment acoustic surveys carried in the South Yellow Sea in 2009 and 2010, the physical property changes of the sediment samples used for measuring the acoustic ve- locity in the laboratory are analyzed relatively to their original state in the seafloor, and the effects of these changes on the acoustic velocity measurements are discussed. The results show that when the sediment samples are measured directly in the shipboard laboratory just after they are sampled, the foremost change in conditions is the temperature of sediment and such a change can be well corrected by Hamilton model. For the sediment samples transported to the onshore laboratory, however, not only their temperature, but also other properties such as their density and water content have also changed greatly, relatively to those of their original state. In such cases, the effect on the acoustic velocity measurements is hardly removed only by temperature correction. It is therefore suggested that for measuring the acoustic velocity of the seafloor sediments the shipboard method should be preferred if no in-situ measurement can be conducted.