Environmental Engineering Reference
In-Depth Information
Specific conductance
(Conductivity)
Conductivity is a measure of the electrical resistance in an aqueous
solution and depends on the total concentration of dissolved
electrolytes
Hydrology
:
See influences for TDS
Internal and other processes
:
Seasonal variation in conductivity has been associated with
increased biological activity and chemical reactions that result
from changing oxidation/reduction characteristics (Eser and
Rosen
1999
; Stratford et al.
2004
)
Increased biological activity may also lead to spatial differences
within the wetland (although this is not extensively reported in
the literature)
Conductivity can serve as a general indicator of productivity of
freshwater systems (with highly productive systems usually
having higher conductivity than less productive systems) and
water source
Conductivity has been used as a surrogate for total dissolved solids
(Trebitz et al.
2007
) and factors for converting between the two
parameters are available. (e.g., Conductivity
0.67 ~ total
dissolved solids (mg/L) (Dickerson and Vinyard
1999
). More
complex equations are available to estimate salinity from con-
ductivity (APHA, AWWA and WEF
2005
)
Total Hardness
Total hardness is a measure of divalent cations in water, primarily
calcium and magnesium.
Hydrology
:
Water source and associated basin and catchment geochemistry
represent the dominant source of between-wetland variation in
water hardness
Also see influences for TDS
Total hardness is not often evaluated in wetland monitoring studies
although may be a useful modifier for some wetland classifica-
tion schemes (e.g., Warner and Rubec
1997
) or to establish
wetland water quality criteria for metal contaminants (Gordon
et al.
1997
; Nimmo et al.
2006
)
Total suspended solids
Total suspended solids (TSS) is a measure of those solids in water
that are retained on a 2.0
μ
m filter and include both organic and
inorganic and living and dead material
Hydrology
:
Water source can influence TSS levels due to the import of partic-
ulate matter associated with overland flow and tributaries
entering the wetland
Elevated levels of suspended material in the water column can
reduce light availability and lead to elevated water temperatures
due to increased absorbance of thermal radiation. Light avail-
ability and temperature affect bacterial, algal, and zooplankton
physiology, as well as the feeding and movements of
macroinvertebrates and fish.
Temporal/seasonal variation in TSS could result from dilution
effects due to precipitation events or evapoconcentration
associated with water drawdown at the end of the hydroperiod
(Boeckman and Bidwell
2007
)
Internal and other processes
:
Blooms of phyto and zooplankton can lead to increased levels of
suspended solids and result in spatial differences in TSS within a
wetland
Wetlands may reduce TSS of through-flowing water by facilitating
settling of particulate material (Evans et al.
1996
)
When coupled with other chemical indicators such as levels of
