Environmental Engineering Reference
In-Depth Information
Table 6.1 (continued)
Potential sources of variability to consider when monitoring
wetlands
Parameter
General notes/reasons for measuring the parameter
Total dissolved solids
Total dissolved solids (TDS) is a measure of those solids in water
that pass through a 2.0
μ
m filter and include ions such as sodium,
chloride, and calcium
Hydrology
:
Water source is the major source of between-wetland variability in
TDS. For example, groundwater sources often have higher
TDS levels due to contact with geologic material while
wetlands that fill mostly via precipitation usually have lower
TDS levels than those receiving groundwater or other surface
input
While effects of elevated TDS on water quality are mostly related to
impacts on domestic or industrial use, there could be physio-
logical implications for freshwater organisms if levels become
sufficiently elevated
TDS and salinity are often used interchangeably and conversion
factors are available to estimate one value from the other (see
salinity)
Temporal/seasonal variation in TDS could result from dilution
effects due to precipitation events or evapoconcentration
associated with water drawdown at the end of the hydroperiod
(Charkhabi and Sakizadeh
2006
)
Spatial differences in TDS could occur within a wetland due to
differences in water quality of tributaries flowing into the
system.
Salinity
The sum of all dissolved ions in water determines the 'salinity', with
the salinity of most inland waters dominated by Ca
+2
,Mg
+2
,
Na
+
,K
+
,CO
3
2
, HCO
3
,SO
4
2
, and Cl
Hydrology
:
See influences for TDS
Salinity has been identified as a “keystone” chemical parameter
because it differentiates freshwater from brackish and
marine systems and so significantly influences plant
and animal assemblages and wetland structure and
function
Salinity has been used as a water quality modifier in wetland
classification systems (see Cowardin et al.
1979
), although
moderate variation in salinity common in most inland wetlands
may not represent a significant influence on wetland organisms
(see Mendelssohn and Batzer
2006
)
