The right answer is Deposition.
This is the case, for example, with chlorinated solvents.
Chlorinated solvents, or chlorinated aliphatic hydrocarbons, are used as solvents for the cleaning as well as for the extraction and the separation of certain products, they are also used as refrigerants (chlorofluorocarbon or CFC). They are widespread. Their presence in landfills of all types constitutes a risk of groundwater pollution because they are not retained by the clays. After percolation into the ground, groundwater near urban or industrial areas (industrial discharges) can be contaminated by these highly volatile pollutants. They are not degradable and tend to settle in the lower part of the water table.
