Groundwater density

The density of the leachate is a function of the temperature and the concentration of dissolved solids. Leachate with a total dissolved solid concentration of 2 X lO mgL is not uncommon (see Table 1) the density of such a leachate is >1% higher than the groundwater density. Density differences may significantly affect the vertical positioning of the plume just below the landfill. Field observations on the downward movement of the plume are often difficult to separate from the effect of local water table mounds (Christensen et al., 2001). A better understanding of the effects of higher leachate densities in field situations is needed. Density effects could be the major cause of vertical leachate spreading in aquifers since normal vertical dispersion is usually very small. 

In sedimentary basins, the gradient of groundwater density resulting from the change in solubility of minerals with temperature, is very small (Bj0rlykke... 

Because carbon dioxide is about 1.5 times as dense as air and 2.8 times as dense as methane, it tends to move toward the bottom of the landfill. As a result, the concentration of carbon dioxide in the lower portions of landfill may be high for years. Ultimately, because of its density, carbon dioxide will also move downward through the underlying formation until it reaches the groundwater. Because carbon dioxide is readily soluble in water, it usually lowers the pH, which in turn can increase the hardness and mineral content of the groundwater through the solubilization of calcium and magnesium carbonates. 

DAF is used to remove suspended solids by decreasing their apparent density they then rise and float on the water surface. DAF is also used to remove soluble iron, VOCs, oils, and surface active agents by oxidation, air stripping, and surface adsorption. The flotation technology is becoming one of the most important technologies for groundwater decontamination, industrial effluent treatment, and water purification.58-6170... 

The Belle Glade site, located southeast of Lake Okeechobee in south-central Florida, illustrates some of the problems that can develop with acidic-waste injection when carbonate rock is the confining layer. Contributing factors to the contamination of the aquifer above the confining zone were the dissolution of the carbonate rock and the difference in density between the injected wastes and the formation fluids. The injected waste was less dense than the groundwater because of its lower salinity and higher temperature.172... 

Frind, E.O., Simulation of long-term transient density-dependent transport in groundwater, Adv. Water... 

The global salt content was measured using a digital densimeter, and is expressed as the density difference of sample water relative to standard distilled water, at 25°C. It is noted as Ad and expressed in units of mg/l. Major solutes within the groundwater samples (Li, Na, K, Mg, Ca, and Sr) were analysed using absorption spectroscopy. 

The term passive interception is used to describe recovery systems that rely upon natural groundwater flow to deliver free-phase NAPLs to the collection facility without the addition of external energy (such as pumping). These systems often include linear interception-type systems such as trenches (or French drains), subsurface dams ( funnel-and-gate structures), combined hydraulic underflow with skimming, and density skimming units. 

Groundwater Chemicals Desk Reference Vapor density ... 

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