Liu Mengwei, Park Junghee, Santamarina J Carlos
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
Department of Civil and Environmental Engineering, Incheon National University, 119 Academy-Ro, Yeonsu-Gu, Incheon, 22012, South Korea.
Sci Rep. 2024 May 20;14(1):11453. doi: 10.1038/s41598-024-62035-w.
Stratified water columns are often found in lakes and oceans. Stratifications result from differences in density due to salt concentration, temperature, solid content and oxygenation. The stability of stratifications affects bioactivity, sedimentation, contaminant transport and environmental remediation. This study investigates the evolution of 6 stratified water columns created by differences in salinity, suspended minerals and the presence of a bottom heat source. We use acoustic wave reflection, photography, and both electrical conductivity and temperature profiles to track changes in stratification. Results show that multiple concurrent processes emerge across layers in otherwise quiescent water bodies. Dissimilar chemo-thermo conditions give rise to chemical and thermal diffusion, convection, and double-diffusion convection. When stratification involves suspended particles, interlayer processes include diffusiophoresis, flocculation/aggregation, sedimentation, osmosis, and chemo-consolidation; in this case, the specific surface and surface charge of suspended particles, and the salt concentration in contiguous layers determine aggregation-sedimentation-consolidation patterns. The interlayer transition zone acts as a high-pass filter that preferentially reflects low-frequency long-wavelength P-waves; invasive thermal and electrical conductivity probes provide complementary information and may identify stratification even when it is undetected by acoustic signals.
分层水柱常见于湖泊和海洋中。分层现象是由盐浓度、温度、固体含量和氧合作用导致的密度差异引起的。分层的稳定性会影响生物活性、沉积作用、污染物迁移和环境修复。本研究调查了由盐度差异、悬浮矿物质和底部热源的存在所形成的6个分层水柱的演变情况。我们利用声波反射、摄影以及电导率和温度剖面来追踪分层的变化。结果表明，在原本静止的水体中，各层会出现多个并发过程。不同的化学-热条件会引发化学和热扩散、对流以及双扩散对流。当分层涉及悬浮颗粒时，层间过程包括扩散泳、絮凝/聚集、沉积、渗透和化学固结；在这种情况下，悬浮颗粒的比表面积和表面电荷以及相邻层中的盐浓度决定了聚集-沉积-固结模式。层间过渡带起到高通滤波器的作用，优先反射低频长波长P波；侵入式热导率和电导率探头可提供补充信息，即使在声学信号未检测到分层的情况下，也可能识别出分层。
