Environmental Engineering Reference
In-Depth Information
6.2 Uses of Water Quality Data in Wetland Monitoring
One of the more common approaches to assess wetland water quality is to compare
measurements of current conditions with that of an ecologically similar but undis-
turbed or less-disturbed reference site (Norris et al.
2007
). Brinson (
1988
)usedthis
reference-based concept to help define “water quality”, stating that good water quality
represents the normal unaltered chemical condition with departures representing a
deterioration in quality. The biogeochemical assessment module for wetlands devel-
oped by the United States Environmental Protection Agency (USEPA
2008a
)isan
example of a reference-based application of water quality data for wetlandmonitoring.
A number of states in Australia have also incorporated various physical and chemical
water quality parameters as a component of the reference-based
Framework for
Assessing River and Wetland Health
(Norris et al.
2007
; Alluvium Consulting
2011
).
A second approach that uses chemical data to evaluate water quality is the compari-
son of specific chemical concentrations derived from site measurements with those
deemed to support designated uses of the water or habitat (Norris et al.
2007
; Chapelle
et al.
2009
). In the United States, this forms the basis for chemical-based wetland water
quality standards as mandated by Section 303 of the Clean Water Act (USEPA
1990
,
2008b
; ELI
2008
; Kusler
2011a
,
b
). As stated in USEPA (
1990
), the original objective
for US states was to have either narrative or chemical-based wetland water quality
standards in place by 1993. However, as of 2011, only 14 states had adopted standards
that were specific to wetlands (Kusler
2011a
;alsoseeELI(
2008
)forabroader
discussion of state-based wetland protection regulations in the US).
Physical and chemical data collected from wetlands may also provide important
ancillary information to help understand the distribution of organisms in both basic
and applied wetland studies. Water quality has a major influence on what organisms
occur in a wetland (e.g., Dunson et al.
1997
; Batzer et al.
2004
; Euliss et al.
2004
;
Longcore et al.
2006
; Ginocchio et al.
2008
; Chen et al.
2011
; Bojkova et al.
2011
),
with parameters such as salinity considered to be “keystone” variables that control
plant and animal assemblages and drive wetland structure (Mendelssohn and Batzer
2006
). Temperature, pH, dissolved oxygen, and alkalinity also dictate the extent
and rate of important wetland functional processes such as nutrient transformations
(Kadlec
1999
). Physicochemical data have also been used to modify classification
systems for wetlands (e.g., Cowardin et al.
1979
; Warner and Rubec
1997
).
6.3 What Makes Wetlands Different from Other Surface
Waters When Monitoring Water Quality?
Mitsch and Gosselink (
2007
) state that while no particular biogeochemical processes
are unique to wetlands, their flooding frequency (permanent or intermittent) can make
certain chemical processes more dominant in wetlands than in other types of aquatic
systems. In particular, the anaerobic conditions that prevail in wetland sediments can
lead to the reduction of chemicals that influences their ultimate fate in the system.
