Density-driven interstitial water motion in sediments

Sediment depth distributions and fluxes of dissolved chemical substances have been interpreted as being a result of reaction, diffusion, bioturbation and irrigation1,2. However, several studies suggest that density-driven convection3 can alter the depth distribution and increase the fluxes of dissolved substances when density decreases below the sediment surface 4-7. We present here temperature-time series measurements for a freshwater lake undergoing autumn cooling. These are the first in situ observations of heat transport due to motion of interstitial waters over periods of less than 1 hour. Density, calculated from temperature, decreases with depth at the time and place that this motion occurs. © 1982 Nature Publishing Group