1
Introduction
1.1 Groundwater Quality
The chemical and biological constituents contained in groundwater depend
on two factors: the natural environment of groundwater storage and movement, and human activities. Precipitation infiltration and surface water percolation are the natural sources of groundwater. The total dissolved solids
(TOS) of precipitation is generally very low, but its chemical components will
be changed when infiltrated through soil beds by aseries of actions, such as
solution, oxidation, reduction, ion exchange, and so on. The infiltration and
percolation water will be involved in groundwater movement in both the
vertical and the lateral directions in the aquifer. Ouring this process, the TOS
of groundwater will continually increase as rocks and minerals are dissolved
into the water. Human activities may change the natural process and cause
groundwater to contain organisms, hydrocarbons, heavy metals and other
harmful matter. Groundwater, therefore, should be looked upon as a multicomponent fluid. The content of each component in groundwater can be
expressed by its concentration, i.e., a mass of certain component contained in
unit volume of water (M/L 3). If the concentration of component a is written
as C", then the standard of water quality for a certain use can be written in the
following common form:
C".min < C" < C".max'
(1.1.1)
(0( = 1,2, ... ,n)
where C".min and C".max are the given lower and upper limits, respectively, of
the concentration of component 0(, and n is the total number of components
considered. According to the actual situation, the components may refer to
either single ions or multi-ion compositions.
If the groundwater quality (inciuding its physical, chemical, and biological
properties) has been changed so that it is no longer suited to the previous
uses, then the groundwater is said to be polluted.
Since groundwater is buried under the land surface, it is not as easily
polluted as the surface water. Because of its low flow rate, the pollutants
1
Introduction
1.1 Groundwater Quality
The chemical and biological constituents contained in groundwater depend
on two factors: the natural environment of groundwater storage and movement, and human activities. Precipitation infiltration and surface water percolation are the natural sources of groundwater. The total dissolved solids
(TOS) of precipitation is generally very low, but its chemical components will
be changed when infiltrated through soil beds by aseries of actions, such as
solution, oxidation, reduction, ion exchange, and so on. The infiltration and
percolation water will be involved in groundwater movement in both the
vertical and the lateral directions in the aquifer. Ouring this process, the TOS
of groundwater will continually increase as rocks and minerals are dissolved
into the water. Human activities may change the natural process and cause
groundwater to contain organisms, hydrocarbons, heavy metals and other
harmful matter. Groundwater, therefore, should be looked upon as a multicomponent fluid. The content of each component in groundwater can be
expressed by its concentration, i.e., a mass of certain component contained in
unit volume of water (M/L 3). If the concentration of component a is written
as C", then the standard of water quality for a certain use can be written in the
following common form:
C".min < C" < C".max'
(1.1.1)
(0( = 1,2, ... ,n)
where C".min and C".max are the given lower and upper limits, respectively, of
the concentration of component 0(, and n is the total number of components
considered. According to the actual situation, the components may refer to
either single ions or multi-ion compositions.
If the groundwater quality (inciuding its physical, chemical, and biological
properties) has been changed so that it is no longer suited to the previous
uses, then the groundwater is said to be polluted.
Since groundwater is buried under the land surface, it is not as easily
polluted as the surface water. Because of its low flow rate, the pollutants
1