The influence of water column density shifts on vertical transport of dissolved chemicals: applications to problems of monitoring and predicting water resource quality
V. Kushnir et al., The influence of water column density shifts on vertical transport of dissolved chemicals: applications to problems of monitoring and predicting water resource quality, WATER SCI T, 42(1-2), 2000, pp. 341-346
A steep gradient density layer (density shift) in a water column often form
s due to intense summer heating of the surface and wind mixing the upper la
yer. It influences the vertical transport of chemicals and pollutants, due
to the significant power generated, overcoming Archimedes forces. The mecha
nism of Vertical transport of dissolved chemicals through the density shift
is connected with the stochastic formation of local turbulent structures -
"turbulence flares", which arise because of shifts of current speed in int
ernal waves and eddy-wave formation of the "billows" type. Analyses of data
from the Black Sea and Lake Kinneret indicate the universal character for
conditions of the dimensionless dependence of logRi = f(Z/Zm) and logRi = f
(2logN/Nm), where Ri = the Richardson number, Z = depth, Zm = the depth of
the Brunt-Vaisala frequency N(Z) maximum (Nm). A high positive correlation
(R = 0.75) between logRi and 2 logN/Nm values allows the use of vertical de
nsity profile data (water temperature) for estimating the vertical fluxes o
f chemical elements and pollutants. The simplicity of measurement and avail
ability of data on density structure of water basins provide means for effe
ctive monitoring of vertical transport of chemical elements and pollutants
under various conditions.