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Date: December 15, 2005 Report No. LOXA05-004
Enhanced Water Quality Program
Parameter Reduction Rationale
Report No. LOXA05-004
Prepared by:
Donatto Surratt, Ph.D.
A.R.M. Loxahatchee National Wildlife Refuge
December 2005
BACKGROUND
In 2004 Congress authorized funding for an Enhanced Water Q uality Monitoring
Program, which would aid in improving the scientific understanding of water quality
issues in the Arthur R. Marshall Loxahatchee National Wildlife Refuge (Refuge). The
1991 Federal Consent Decree established a set of analytical parameters based on previous
work carried out across the greater Everglades and 14 sampling location across the
Refuge. These stations are also part of a larger effort conducted by the South Florida
Water Management District to sample water quality in the Everglades Protection Area
(EVPA). The Enhanced Water Quality Monitoring Program (LOXA), initiated in June
2004, consists of an additional 39 sampling locations that are monitored for 23 of the
water quality parameters monitored at the 14-station Consent Decree network (Table 1).
The LOXA Work Plan (Brandt et al. 2004) states that, data will be reviewed
and the list of parameters reduced as appropriate (p. 12) with the objective to optimize
the marsh monitoring network. Further, the reduction of parameters has the potential to
reduce analytical cost and these reclaimed funds can be applied to extending the duration
of the LOXA monitoring effort. This document highlights the procedures and rationale
applied in selecting the analytical parameters for reduction in the Refuges Enhanced
Water Quality Monitoring Program. The analysis presented here are specific to the
Refuge and the objectives of our study. Parameter elimination recommendations
presented here may not be appropriate for other studies in the Everglades (e.g., EVPA).
PARAMETER REDUCTION PROCEDURES
In the effort to review and determine whether analytical parameters could be
eliminated from the LOXA program several approaches were involved: (1) collaboration
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Date: December 15, 2005 Report No. LOXA05-004
with members of the South Florida Water Management District (District) and experts in
the Department of Interior, (2) times-series characterization and correlation analysis, and
(3) consideration of rationale for parameter reduction by the District for the Storm Water
Treatment Areas (STA) in the non-ECP EFA Permit Modification Request of February
2005. Resource requirements for analyzing a particular constituent (e.g., field or
laboratory effort, cost to process) were not considered in this exercise, however the
recovered cost resulting from elimination of the selected parameters is presented in Table
2.
(1) Collaboration between the Refuge (Michael Waldon, Ph.D.; Matthew Harwell,
Ph.D. ; Laura Brandt, Ph.D. ; and Donatto Surratt, Ph.D. ), the District (Sue Newman,
Ph.D. and Scot Hagerthey, Ph.D.) and the United States Geological Survey (Paul
McCormick, Ph.D.) involved discussions of expert opinions on parameters that may be
less important from a management and scientific perspective, including those that
generally do not lead to increased understanding of water quality within the Refuge.
Eleven parameters identified as worth initial consideration for elimination were:
alkaline phosphatase (APA), color, dissolved organic carbon (DOC), hardness (HARD),
magnesium (Mg), sodium (Na), ammonium (NH4), nitrite (NO3), silica (SiO 2), total
dissolved solids (TDS), and turbidity (TURB).
(2) The next approach involved time-series characterization, spatial
characterization, and simple correlation analysis for all the parameters ove r the entire
sampling period (June 2004  May 2005). Time-series characterization of the data was
applied to explore, and validate where possible, some of the expert opinions when
selecting parameters to eliminate. Time-series characterization was an observation of
change in a parameter over the year that data was collected. The approach for
characterization was two fold in some cases including (1) an all marsh site analysis and
where necessary (particularly when observation of quantitative variability in the form of a
coefficient of variation was necessary) (2) an individual site analysis. If the parameter
had low variability over the year it generally did not yield quantitative information about
localized changes to the ecosystem, thus the parameter could be consider for elimination.
If the parameter demonstrated high variability then further analysis was necessary to
determine if it could be eliminated. There was no consistent pattern in variability for the
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Date: December 15, 2005 Report No. LOXA05-004
parameters in the marsh or in the canal. Another characterization approach was the
spatial analysis approach which was performed from canal to the interior of the marsh on
several parameters. In most cases this analysis was performed to determine if there was
an observable pattern for the parameter demonstrating some dependence on canal water
penetration into the interior of the Refuge. Simple correlation analysis was applied to
determine if there were parameters that produced redundant information. The analysis
included both canal and interior sites, which allowed the spectrum of rain-driven soft
water and hard canal water to be analyzed collectively. Correlation values, reported as r,
were used to assess how well parameters associated. Parameters with r greater than or
equal to 0.95 (Table 3) were considered well correlated and in some cases resulted in one
or more parameters being added to the list of parameters for elimination.
(3) The PRO ECP Non-ECP EFA Permit Modification Request of February 2005
drafted by the District and sent to the Florida Department of Environmental Protection
(FDEP) was reviewed for rationales for parameter reduction used by the District. This
letter provided rationale for eliminating seven parameters also monitored in LOXA:
ammonia, chloride, turbidity, total dis solved phosphorus, ortho-phosphate, total dissolved
nitrogen, and total dissolved solids. FDEP approved elimination from Non-ECP EFA
sampling of all except turbidity.
Personal emails between Dr. Surratt and David Struve, Ph.D. provided further
insight on the procedures for parameter reduction by the District. Dr. Struve was on the
review panel for parameter reduction for the PRO ECP Non-ECP EFA Permit
Modification Request of February 2005. Dr. Struve related some of the considerations
used to generate the modification request and some of these considerations were used to
address the parameter elimination issues in the present report. Two considerations
applied for our purposes were: (1) is there any significant variability in the given
parameters over time and (2) are there related parameters being measured that give the
same information (example: plot chloride vs. conductance and see if the data are a good
fit. If so, conductance values may be good enough to infer the chloride values). A final
consideration was the comparison of the parameter time-series data with the Class III
criteria defined in F.A.C. 62-302.530 and applied in the 2004 Everglades Consolidated
Report (SFWMD, 2004). If the data were observed to extend beyond the Class III
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criteria over the monitored period then it was determined that the parameter should
continue to be monitored. Some parameters only had narrative criteria associated with
them and the narrative criteria were not assessed in this study. Because of this limitation,
Class III criteria comparison was performed on only a portion of the analytes, particularly
alkalinity, dissolved oxygen, potassium, pH, and turbidity. Further, because of the short
time-series (12 months), less weight was given to the time-series  Class III criteria
comparison when determining whether or not to eliminate the parameter.
PARAMETER REDUCTION RATIONALE
There are 29 parameters used in the initial sample design. All the parameters
were reviewed for potential to eliminate them from the water quality analytical suite.
The following is a breakdown of all the parameters with rationales for elimination based
on the three approaches presented above. Correlation analysis with coefficients greater
than or equal to 0.95 is presented in Table 3. Because, in some case, we are eliminating
parameters based on the ability to reproduce that parameter from another analytical
parameter, it was necessary to choose an r cut-off limit that was high enough to show
exceptionally strong proportional relationships between the two parameters. Appendix A
presents the full correlation table for all parameters. Appendix B provides time-series
(June 2004  May 2005) graphs of the parameters for elimination and cross-plots of
correlated parameters identified in Table 3.
ALKA: Alkalinity correlated well with four parameters  calcium (r = 0.98), hardness (r
= 0.98), specific conductance (r = 0.96), and total dissolved solids (r = 0.95). The high
correlation between ALKA, calcium, and hardness is most likely an artifact of their
dependence on the concentration of CaCO3. Although each of these parameters share this
dependency they are still determined through unique analytical procedures and explain
different conditions of the analyzed water parcels and as such yield different values and
patterns through time, which is why they are not 100% correlated. Further, these
correlations allow the observer to quickly qualify data points as outliers (prior to a
rigorous quantitative assessment) with respect to specific conductance, which is
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Date: December 15, 2005 Report No. LOXA05-004
exceptionally important for tracking water movement from the canal to the interior
marsh.
Alkalinity has a Class III criterion of = 20 mg L-1. In October and November
2004 five sampled sites had values below the criteria. This criterion is inappropriate for
rainwater dominated wetlands where alkalinity is naturally below 20 mg L-1 (Weaver,
2005). A water quality goal of the Refuge is to maintain this low alkalinity condition.
Because ALKA provides the ability to quickly determine specific conductance outliers;
because there is an established numeric criterion pursuant to Section 62-302.530 F.A.C.;
and because ALKA is important to the ecology of softwater marshes, ALKA will not be
eliminated from the analytical suite. Alkalinity remains a monitored parameter.
APA: There were no strong correlations associated with alkaline phosphatase activity
(APA). APA can indicate phosphorus limitation in wetland ecosystems, as inducible
phosphatase enzymes are produced when the system becomes deplete in phosphorus
(Newman, et al., 2002). Spatial observation of APA for the marsh indicates that APA
values increase towards the interior of the marsh (>1.5 km interior of the canals), which
coincides with the reported phosphorus limitation for the Refuge (Vymazal, and
Richardson, 1995). APA has also been applied as an early warning indicator of wetland
eutrophication. The technique applied for analyzing APA for LOXA is not suitable for
using APA as an ecological warning indicator. We only measure standing water APA,
while the protocol requires the direct measurement of periphyton APA and the
subtraction of standing water APA to determine periphyton response to nutrient
enrichment (Newman et al., 2002). Because the only other applicable use of APA for the
marsh found in this research effort is the determination of phosphorus limitation, which
can be assessed with phosphorus and other parameters on the analytical list, APA can be
removed from the list of analytical parameters. APA is on the list of parameters to be
eliminated.
Ca: Calcium correlated well with hardness (r = 0.99), specific conductance (r = 0.95),
and total dissolved solids (r = 0.95). Temporal observation of Ca can indicate shifts
between minerotrophic (flow [stream, canal, groundwater] driven) and ombortrophic
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(precipitation driven) wetland systems (Kadlec and Knight, 1996). Further, alterations to
Ca levels impacts plant growth rates, which can alter community structures and reduce
biodiversity. Calcium remains a monitored parameter.
Cl: Chloride had strong correlations with sodium (r = 0.99) and specific conductance (r =
0.95). Elevated Cl has been associated with fertilizers and other contaminants that may
reach the Refuge from Everglades Agricultural Area (EAA) operations during by-passes
of untreated water (McPherson and Halley, 1996; Orem, 2004). Chloride concentrations
can be used as a tracer of flow rates in wetland systems because of it low biological
demand. Chloride remains a monitored parameter.
COLOR: There were no strong correlations associated with color. Color was initially
considered for elimination because it was expected to have a small range of values over
time, ultimately providing little information about water quality. Based on a station by
station time-series characterization the coefficient of variation for color was ~ 24%.
Color is often used in assessing raw drinking water sources for treatability. It is often
found to be correlated with the presence of organic materials including lignin and tanic
acids. Color is a semi-qualitative parameter and did peak strongly when there were
heavy precipitation events (i.e., hurricanes) in September and October 2004. Regardless
of this observation color is being eliminated as a monitored parameter, because of its
qualitative nature and the fact that there are other parameters that provide more
quantitative information about hurricane and other events (i.e., SO4, TPO4, TDPO4, SiO 2,
etc.). Color is on the list of parameters to be eliminated.
DO: There were no strong correlations observed between dissolved oxygen and other
analytes. Dissolved oxygen (DO) has an alternative Class III criterion called the site-
specific alternative criteria (SSAC). The SSAC is a sinusoidal diel cycling algorithm
(Weaver et al., 2001). The algorithm was adjusted, finalized, and presented in the
Everglades Marsh Dissolved Oxygen Site Specific Alternative Criterion Technical
Support Document (Weaver, 2004). Between June 2004 and May 2005 approximately
79% of the marsh samples were below the modeled criterion, 42% of the canal samples
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were below the criterion, and 72% of all the samples from the Refuge were below the
determined criterion. DO in marsh systems gives a measure of oxidation potentials in the
water column. When DO drops below 2 mg L-1 plant mortality significantly increases
-
(Kadlec and Knight, 1996). None of the calculated SSAC values were below the 2 mg L1, 43% of marsh samples, 18% of canal samples, and 39% of all the Refuge samples were
below the 2 mg L-1. DO remains a monitored parameter.
DOC: Dissolved organic carbon has been linked to microbial respiration and fulvic acid
regulated mercury methylation in the southern Everglades (Reddy and Aiken, 2001).
One of the experts in preliminary lab experiments revealed microbial respiration to be
strongly carbon limited instead of phosphorus or nitrogen limited as for most system.
Additional influxes of labile carbon can affect marsh soil processes. Reddy and Aiken
(2001) demonstrate strong correlations between Hg bioaccumulation and DOC
concentrations. Correlation analysis for DOC did not reveal significant correlation with
other parameters. Because neither Hg nor microbial respiration are monitored in the
Refuge ; because of the potential of DOC concentration changes to cause Hg
bioaccumulation rates to change; and because no other parameters can serve as surrogates
of DOC, monitoring DOC is recommended. DOC remains a monitored parameter.
HARD: Hardness is measured as an equivalent concentration of calcium carbonate
(CaCO3) and was expected to correlate well with alkalinity (which is also measured as an
equivale nt concentration of CaCO3). Hardness correlated well with ALKA (r = 0.98), Ca
(r = 0.99), magnesium (r = 0.97), specific conductance (r = 0.97), and TDS (r = 0.97).
Although these strong correlations are observed the Florida Class III water quality criteria
for various metals (Cd, Cr, Cu, Pb, Ni, Zn) require hardness in order to calculate the
metal criterion (Bechtel, 2000). These metals have never been measured as a part of the
LOXA project and where discontinued from the EVPA project in 2000. From the
perspective of tracking softwater movement interior of the canals ALKA and specific
conductance appears to provide the necessary information, thus the elimination of the
hardness appears to be warranted. Hardness is on the list of parameters to eliminate.
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Date: December 15, 2005 Report No. LOXA05-004
K: Potassium did not correlate well with any other parameters and does not have a
specific Class III criterion. Although there were no strong correlations associated with K,
a station by station time-series characterization (not including August and September of
2004) showed low variability with a coefficient of variation of 19% and the pattern for
the entire data set matched well with the TDS pattern. K in the interior of the Refuge did
not drop below 0.64 mg L-1 and averaged 4.22.8 mg L-1, which is above the reported 2
mg L-1 K water column limitation value (Demaneche et al., 2001; Spijkerman and
Coesel, 1998; Palmen et al., 1994). Based on the low variability in the K data set, the
matching patterns between K and TDS, and because the K concentration was above the
limitation concentration, K will be eliminated as a monitored water quality parameter.
Potassium is on the list of parameters to be eliminated.
Mg: Magnesium is expected to contribute to hardness. Mg had a strong correlation with
hardness (r = 0.97), specific conductance (r = 0.97), and TDS (r = 0.97), thus specific
conductance and TDS can serve as a proxy for Mg in future analysis. Because hardness
was dropped and there was no other indication that Mg contributed to an increased
understanding of water quality magnesium was added to the elimination list. Magnesium
is on the list of parameters to be eliminated.
Na: Sodium is expected to contribute to observed alkalinity values. Na had a strong
correlation with specific conductanc e (r = 0.96) and TDS (r = 0.95), thus specific
conductance and TDS can serve as a proxy for Na in future analysis. Na can serve as a
conservative tracer for calculating dilution and concentration and for tracking
groundwater discharges from wetlands (Kadlec and Knight, 1996). Based on the analysis
Na provides redundant information with respect to water quality and SPCOND or TDS
may be applied to replace sodium as a tracer. Sodium is on the list of parameters to be
eliminated.
NH4: There were no strong correlations associated with ammonia-nitrogen. Ammonium
is on the list of parameters to be dropped although it may provide useful information
about the seasonal processes of plant growth and decomposition in marsh systems
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(Kadlec and Knight, 1996). NH4 is a plant nutrient contributing to total Kjeldahl
nitrogen. It may impact dissolved oxygen through oxidation to nitrate and may also
cause aquatic toxicity. NH4 is generally quite low in Everglades Protection Area (EPA)
waters and generally constitutes only a small fraction of EPA total nitrogen. The
rationale for eliminating NH4 is that total nitrogen encompasses NH4 and because
nitrogen is not considered a limiting nutrient in Refuge wetlands (Vymazal, and
Richardson, 1995), the specific details of alteration to NH4 are of little consequence.
Ammonium is on the list of parameters to be eliminated.
NO3: There were no strong correlations associated with nitrate. Nitrate is generally a
significant portion of nitrate-nitrite (NOX) measurement and in combination with the
other components of total nitrogen provides information about nutrient lability. Because
NO2 is generally only a small fraction of the NOX, it was expected that NOX values can
be used to estimate the NO3 concentration. This rationale holds true for station LZ40 in
Lake Okeechobee such that NO2 was ~11% and NO3 was ~90% of the NOX
concentration. However, this pattern was not observed in the Refuge marsh. Observation
of the data showed NO2 at ~43% and NO3 at ~58% of the NOX concentrations. Thirty-
one percent of the NO3 values for the Refuge was below detection limits, which may
have complicated this assessment and potentially confound any trend analysis attempted
for the Refuge. Independently, NO3 is not particularly useful and the va lue is maintained
in NOX. Nitrate is on the list of parameters to be eliminated.
NO2: There were no strong correlations associated with nitrite. Nitrite is on the
elimination list because it was thought to be short lived and represent only a small
fraction of the nitrogen pool due to its rapid conversion to nitrate. Generally, NO2 found
in wetlands above detection limits is indicative of an anthropogenic source of nitrogen
(Kadlec and Knight, 1996). Inspection of Refuge data demonstrates that NO2 can
contribute up to 43% of the inorganic nitrogen pool, which does not support the
assumption that NO2 is a small portion of NOX. Again this assessment may be skewed as
~25% of the NO2 values were below detectable limits (0.004 mg L-1). Conversely, the
observed imbalance between NO2 and NO3 with respect to NOX may reflect loading of
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anthropogenically generated nutrients in the Refuge. Regardless, nitrite will be
incorporated in the analysis of nitrate-nitrite. Nitrite is on the list of parameters to be
eliminated.
NOX: There were no strong correlations associated with nitrate-nitrite. NOx is the sum
of NO2 and NO3. NOX is a fraction of the inorganic nitrogen pool and in a balanced
wetland can serve as a proxy for the essential plant nutrient, NO3. The sum of NOX and
total Kjeldahl nitrogen approximates total nitrogen. Total nitrogen can be employed to
determine the lability of food sources for marsh plant communities (Thomann, 1972).
Total nitrogen is also a concern for water downstream of the Refuge. NOx remains a
monitored parameter.
OPO4: Ortho-phosphate had a strong correlation (r = 0.99) with total dissolved
phosphate and appears to provide redundant information, thus OPO4 is on the list for
parameter elimination. Although OPO4 is on the parameter elimination list it was argued
that the presence of OPO4 was a good indicator of phosphorus enrichment in Water
Conservation Area 2 (WCA2), and may play a similar role within the Refuge. Also,
eleven percent of the reported OPO4 values were below detection limits (0.004 mg L-1).
At greater than 1 km interior of the canals surrounding the Refuge, OPO4 values do not
exceed 0.03 mg L-1, which suggest that OPO4 does not provide useful information about
Refuge water quality dynamics. Ortho-phosphate is on the list of parameters to be
eliminated.
pH: There were no strong correlations associated with pH. pH has a Class III criterion
that suggests the pH should remain between 6 and 8.5. The maximum limit of this
criterion was not exceeded during the stud y period. In November 2004 the sample values
fail below a pH of 6 in the northeastern region of the Refuge. pH remains a monitored
parameter.
SiO2: There were no strong correlations associated with silica. Silica shows a seasonal
pattern for the interior sites of the Refuge. Silica is higher in the wet-warm season (late
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April  early November) and lower during the dry-cool season (November to early
April). Independent research has demonstrated that silica concentrations decrease during
the cooler season when algae populations (dominated by diatoms) are dying off and
increase during the warmer season when these populations grow in again. Changes in
these patterns can serve as a good indication of eutrophication and even biota shifts
(Biggs, 1990). These assertions are generally for flowing waters (i.e., rivers) and
historically appear to be of less import for the Refuge wetland ecosystem which ha s a low
diatom abundance associated with the periphyton population dominating as the primary
producer of the Refuge (Kadlec and Knight, 1996). However, with STA-1E becoming
operational in September 2005, there will be larger volumes of higher mineral content
water discharge into the L-40 Canal. Canal water penetration into the marsh has been
documented (Harwell et al., 2005). The introduction of higher mineral content water into
a soft-water ecosystem is expected to impact the biotic community. The combination of
temperature, nitrogen to phosphorus, and silica to phosphorus ratios has been shown to
relate to algae species distributions (Adamus et al., 2001). This suite of indicators can
theoretically be applied as an indicator of changes in periphyton community dynamics as
the high mineral content water impacts the Refuge. Presently, WCA-2 has a higher
diatom abundance associated with the periphyton communities (relative to the Refuge)
and the Refuge perimeter canals are major sources of water for WCA-2. Because of the
potential of silica concentration change to cause biotic shifts, and because the canals of
the Refuge provide water to other areas of the Everglades, silica is not on the elimination
list. Silica remains a monitored parameter.
SO4: There were no strong correlations associated with sulfate. Sulfate mediates methyl
mercury production (Axelrad et al., 2005). Mercury contamination has been a concern
for areas of the Everglades. As sulfate increases sulfide formation increases, which
increases the potential for methyl mercury formation. At toxic levels sulfate can induce
plant mortality, because of the reduction of sulfate to hydrogen sulfide (Armstrong et al.,
1996). Increasing sulfate loads to the marsh can alter biogeochemical cycling (e.g., Fe
and P) and result in decreased biodiversity for the ecosystem. Because of the significant
role sulfate plays in the biogeochemical cycling and the generation of toxic forms of
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mercury sulfate is not being considered for elimination from the monitoring program.
Sulfate remains a monitored parameter.
SPCOND: Specific conductance is a conservative parameter that can be used to track
canal water penetration into the marsh. SPCOND can also be employed to develop
hydrological and chemical budgets for the Refuge. SPCOND had strong correlations
with ALKA (r = 0.96), Ca (r = 0.95), Cl (r = 0.95), HARD (r = 0.97), Mg (r = 0.97), Na (r
= 0.96), and TDS (r = 0.98). The Class III criterion of = 1250 S/cm for SPCOND is
well in excess of values experienced in the marsh and as such the criterion is meaningless
when compared to values observed in the marsh. Specific conductance remains a
monitored parameter.
TDKN: There were no strong correlations associated with total dissolved Kjeldahl
nitrogen (TDKN). TDKN is the fraction of the total Kjeldahl nitrogen (TKN) that passes
through a 0.45 micron filter. The sum of organic nitrogen (in the trinegative oxidation
state) and ammonia make up Kjeldahl Nitrogen (Clesceri et al., 1998). Sources of
Kjeldahl nitrogen include the decay of organic material and urban and industrial organic
waste. Large amounts of ammonia and organic nitrogen are applied to cropland as
fertilizer. Both ammonia and organic nitrogen are relatively immobile in soils and
ground water because of adsorption on soil surfaces and particulate filtering. These
nitrogen constituents are susceptible to nitrification under aerobic conditions (Kadlec and
Knight, 1996). The coefficient of variations for TDKN in the Refuge interior and canals
were ~21% and ~20%, respectively. TDKN had a range of 0.65 and 2.57 mg L-1. At
greater than 3 km interior of the canals impounding the Refuge (with the exception of 2
outliers in August and September 2004) TDKN values drop below 1.3 mg L-1, which
suggest marsh TDKN maybe pulse driven by canal water penetration. TKN shows a
similar pattern with a range of 0.63 to 4.11 mg L-1 (not including outliers) and dropping
below 2 mg L-1 at greater than 3 km interior of the marsh canals. SPCOND serves as a
more sensitive tracer of canal water penetration as the variable shows a finer gradient
than TDKN. Because of the relatively low variability and because TKN will continue to
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Date: December 15, 2005 Report No. LOXA05-004
be monitored TDKN can be removed from the suite of analytical water quality
parameters. TDKN is on the list of parameters to be eliminated.
TDPO4: Total dissolved phosphorus (not phosphate) had a strong correlation with OPO4
(0.99). TDPO4 provides a quick estimation of biologically available phosphorus. TDPO4
is subtracted from total phosphorus to yield total particulate phosphorus. The total
particulate phosphorus value provides a good estimate of total phosphorus that is
unavailable for biological uptake at the time of the measurement as well how much may
become biologically available in the future. Total dissolve phosphate remains a
monitored parameter.
TDS: Total dissolved solids was suggested as a parameter to be eliminated. TDS and
conductance are highly correlated (r = 0.98). TDS, as well as ALKA, are used to
determine if outliers or invalid measurement values exist in SPCOND data. Further the
ratio between Cl and TDS is expected to indicate sources of water (i.e., canal, marsh,
rain, groundwater, etc.) for the Refuge (Waldon, 2005). Because of these applications,
the conservative nature of TDS, and the observed variability in the time-series data for
TDS it was suggested that the parameter not be dropped. Total dissolved solids remains
a monitored parameter.
TEMP: There were no strong correlations associated with temperature. Temperature is
an integral parameter that changes seasonally. It is used to adjust conductance, dissolved
oxygen measurements, determine DO saturation, and the DO-SSAC. There were no
strong correlations associated with temperature. Temperature remains a monitored
parameter.
TKN: There were no strong correlations associated with total Kjeldahl nitrogen. TKN
combined with NOX provides a value for total nitrogen, which is important in understand
water quality and is of particular concern downstream of the Refuge. There were no
strong correlations associated with TKN. TKN remains a monitored parameter.
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TOC: There were no strong correlations associated with TOC. From the time-series
characterization TOC demonstrated a consistent range and did not appear to indicate any
anthropogenic or natural events that may have impacted the marsh. One caveat for TOC
was presented by a recent USGS study that demonstrated problems in obtaining
consistent TOC results (Aiken et al. 2001). The difference between TOC and DOC
yields particulate organic carbon (POC). POC has been linked to mercury methylation in
WCA2 (Reddy and Aiken, 2001). Because TOC is necessary for determining POC and
because there are no surrogates for TOC, TOC will remain a monitored parameter. TOC
remains a monitored parameter.
TPO4: Total phosphorus (not total phosphate). Phosphorus is a nutrient required for
plant growth and in most freshwater systems phosphorus is considered a limiting nutrient.
Historic phosphorus loads for the Everglades were generally low and derived from
atmospheric deposition. Recent (last half century) increases in phosphorus loading are
associated, in part, with run-off from agricultural sources upstream of the Everglades in
the EAA. Regardless of this relatively new source of nutrients for the Everglades, total
phosphorus has been identified as the key limiting nutrient (McCormick et al., 2002).
With the development of agricultural in regions north of the Refuge, nutrient run-off
towards the Refuge has been an increasing concern. The Consent Decree issued in 1991
mandates the monitoring of phosphorus in the Refuge. Total phosphate remains a
monitored parameter.
TSS: There were no strong correlations associated with total suspended solids. Total
suspended solids are generally a concern for potable waters. There are conditions when
water is pumped out of the Refuge as water supply for neighboring residential areas (e.g.,
Lake Worth Drainage District) and TSS serves as an indicator water clarity and hence the
suitability of using the water for drinking and hygienic purposes. Further, high TSS has
been associated with marsh disturbance and can help indicate sample sites that may have
been agitated during sample collection. TSS remains a monitored parameter
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TURB: There were no strong correlations associated with turbidity. Turbidity has a
Class III criteria of less than or equal to 29 NTU above natural background. Natural
background was defined for the STAs and cannot be applied for the marshes. Regardless,
turbidity was suggested as a parameter to be dropped because it was expected to be
correlated to TSS. Inversely, the coefficient of determination (r = 0.55) was less than
expected. A station by station time-series varia tion analysis shows that turbidity had a
coefficient of variation of ~65% compared to the even higher TSS coefficient of variation
of ~128%. The observed high variability in turbidity suggest that the parameter is
sensitive to small scale changes to water conditions and further analysis of the parameter
may lead to increased understanding of temporal and spatial hydrologic dynamics.
Turbidit y is a proxy for the condition and productivity of natural bodies of water as it
rela ys information about the clarity of the water parcel. Turbidity is a measure of light
scatter and absorbance and can reveal a level of detail about light penetration to the
marsh peat and algal communities (Clesceri et al., 1998). Also, high turbidity has been
associated with marsh disturbance and can help indicate sample sites that may have been
agitated during sample collection. Turbidity remains a monitored parameter.
FINAL LIST OF PARAMETERS FOR ELIMINATION
As a result of this exercise 11 monitoring parameters are being proposed for elimination:
 Alkaline phosphatase,
 Ammonium,
 Color,
 Hardness,
 Magnesium,
 Nitrate,
 Nitrite,
 Ortho-phosphate.
 Potassium,
 Sodium,
 Total dissolved Kjeldahl nitrogen, and
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
The work presented in this document was an important exercise for the LOXA program.
Part of the recognition that these parameters may be acceptable to eliminate is that they
are presently monitored at EVPA sites. Therefore, parameter reduction recommendations
for the LOXA program may not be appropriate for the EVPA program, or other water
quality studies in the Everglades.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
REFERENCES
Adamus, P., Danielson, T.J., Gonyaw, A., 2001. Indicators for Monitoring Biological
Integrity of Inland, Freshwater Wetlands A Survey of North American
Technical Literature (1990-2000). Environmental Protection Agency, EPA843-
R-01.
Aiken, G., Kaplan, L.A., Weishaarc, J., 2001. Assessment of relative accuracy in the
determination of organic matter concentrations in aquatic systems. Journal of
Environmental Monitoring v4, p7074.
Armstrong, J., F. Afreen-Zobayed, and W. Armstrong. 1996. Phragmites die-back:
Sulphide and acetic acid-induced bud and root death, lignifications, and blockages
within aeration and vascular systems. New Phytologist, v134, p601-614.
Axelrad, D., Atkeson, T., Pollman, C., Lange, T., 2005. Chapter 2B: Mercury monitoring
research and environmental assessment in South Florida. G. Redfield, ed. In: 2005
South Florida Environmental Report. West Palm Beach, FL.
Bechtel, T., Hill, S., Iricanin, N., Mo, C., Van Horn, S., 2000. Chapter 4: Status of water
quality criteria compliance in the Everglades Protection Area and at Non-ECP
Structures. G. Redfield, ed. In: 2000 Everglades Consolidated Report. West
Palm Beach, FL.
Biggs, B. J., 1990. Periphyton communities and their environments in New Zealand
Rivers. New Zealand Journal of Marine and Freshwater Research, v24, p367386.
Brandt, L.A., Harwell, M., Waldon, M. 2004. Work Plan: Water Quality Monitoring and
Modeling for the A.R.M. Loxahatchee National Wildlife Refuge: 2004-2006.
Prepared for the A.R.M. Loxahatchee National Wildlife Refuge. April, 2004. 33
pp. http://sofia.usgs.gov/lox_monitor_model/workplans/2004-
2006_workplan.html
Clesceri, L.S., Greenberg, A.E., Eaton, A.D., 1998. Standard Methods for the
Examination of Water and Wastewater, 20th edition. Published by: American
Public Health Association, American Water Works Association, and Water
Environment Federation.
Demaneche, S., Kay, E., Gourbiere, F., and Simonet, P., 2001. Natural transformation of
Pseudomonas fluorescens and Agrobacterium tumefaciens in soil. Applied
Environmental Microbiology, v67, i6, p2617-2621.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Harwell, M, Surratt, D, Waldon, M, Walker, B, Laura, B. 2005. A.R.M Loxahatchee
National Wildlife Refuge Enhanced Water Quality Monitoring and Modeling
Interim Report
Kadlec, R. H., Knight, R. L., 1996. Treatment of Wetlands. Lewis Publishers, CRC
Press LLC.
McCormick, P.V., Newman, S., Miao, S., Gawlik, D.E., Marley, D., Reddy, K.R.,
Fontaine, T.D., 2002. Effects of anthropogenic phosphorus inputs on the
Everglades. J.W. Porter and K.G. Porter, ed. In: The Everglades, Florida Bay,
and Coral Reefs of the Florida Keys  An ecosystem sourcebook. CRC Press
LLC.
McPherson, B., Halley, R., 1996. The South Florida Environment: a region under stress.
USGS, Circular no.1134. United States Government Printing Office.
Newman, S., McCormick, P.V., Backus, J.G., 2002. Phosphatase activity as an early
waring indicator of wetland eutrophication: problems and prospects. Journal of
Applied Phycology v15,i1, p45-59.
Non-ECP PM, 2005. Non-ECP EFA Permit Modification Request, February 2005
Orem, W., 2004. Impacts of sulfate contamination on the Florida Everglades. USGS,
Fact Sheet, FS 109-03.
Palmen, R., Buijsman, P., Hellingwerf, K.J., 1994. Physiological regulation of
competence induction for natural transformation in Acinetobacter calcoaceticus.
Archives of Microbiology, v162, p344351.
Reddy, M.M., Aiken, G.R., 2001. Fulvic acid-sulfide ion competition for mercury ion
binding in the Florida Everglades. Water, Air, and Soil Pollution, v132, p89-104.
SFWMD, 2004. Everglades Consolidated Report 2004. South Florid a Water
Management District, West Palm Beach, Florida.
Spijkerman, E., Coesel, P.F.M., 1998. Different response mechanisms of two planktonic
desmid species (Chlorophyceae) to a single, saturating addition of phosphate.
Journal of Phycology v34, p 438-445.
Thomann, RV, 1972. System analysis and water quality measurement. Environmental
Research and Application, Inc., New York.
Vymazal, J., Richardson, C.J., 1995. Species composition, biomass, and nutrient content
of periphyton in the Florida Everglades. Journal of Phycology v31, p343-354.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Waldon, M., 2005. Verbal communication on September 19. Environmental Program
Team, ARM Loxahatchee Wildlife Refuge..
Weaver, K., Bennett, T., Payne, G., Germain, G., Hill, S., Iricanin, N., 2001. Chapter 4:
Status of Water Quality Criteria Compliance in the Everglades Protection Area.
G. Redfield ed. In: 2001 Everglades Consolidate Report. South Florida Water
Management District.
Weaver, K., 2004. Everglades Marsh Dissolved Oxygen Site Specific Alternative
Criterion Technical Support Document. Water Quality Standards and Special
Projects Program Division of Water Resource Management Florida Department
of Environmental Protection Tallahassee, FL.
http://www.dep.state.fl.us/water/wqssp/everglades/dossac.htm
Weaver, K., Payne, G., 2005. Chapter 2A: Status of Water Quality in the Everglades
Protection Area. G. Redfield, ed. In: 2005 South Florida Environmental Report.
South Florida Water Management District, West Palm Beach, FL.
EXPERTS CONSULTED
A.R.M. Loxahatchee National Wildlife Refuge
Michael Waldon, Ph.D., Senior Hydrologist
Matthew Harwell, Ph.D., Senior Ecologist
Laura Brandt, Ph.D., Senior Wildlife Biologist
South Florida Water Management District
Sue Newman, Ph.D., Senior Supervising Environmental Scientist
Scot Hagerthey, Ph.D., Senior Environmental Scientist
David Struve, Ph.D., Water Quality Division Director
United States Geological Survey
Paul McCormick, Ph.D., Ecologist
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Table 1. Analytical water quality monitoring parameters for the A.R.M. Loxahatchee
National Wildlife Refuge - Enhanced Water Quality Project. Parameter descriptions and
IDs are as listed in the SFWMD DBHYDRO database.
PARAMETER ID UNITS
ALKALINITY TOTAL as CaCO3 ALKA mg L-1
COLOR COLOR PCU
TURBIDITY TURB NTU
ALKALINE PHOSPATASE APA nM/minmL
CALCIUM Ca mg L-1
CHLORIDE Cl mg L-1
DISSOLVED OXYGEN DO mg L-1
DISSOLVED ORGANIC CARBON DOC mg L-1
HARDNESS as CaCO3 HARD mg L-1
POTASSIUM K mg L-1
MAGNESIUM Mg mg L-1
SODIUM Na mg L-1
AMMONIUM NH4 mg L-1
NITRATE NO3 mg L-1
NITRITE NO2 mg L-1
NITRATES and NITRITES as N NOX mg L-1
PHOSPHATE, ORTHO as P OPO4 mg L-1
pH pH mg L-1
SILICA SiO2 mg L-1
SULFATE SO4 mg L-1
SP CONDUCTANCE SpCOND uS/cm
KJELDAHL NITROGEN, DISSOLVED TDKN mg L-1
PHOSPHATE, DISSOLVED as P TDPO4 mg L-1
TOTAL DISSOLVED SOLIDS TDS mg L-1
TEMPERATURE TEMP Deg. C
KJELDAHL NITROGEN, TOTAL TKN mg L-1
CARBON, TOTAL ORGANIC TOC mg L-1
PHOSPHATE, TOTAL as P TPO4 mg L-1
TOTAL SUSPENDED SOLIDS TSS mg L-1
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Table 2. Cost recovery resulting from parameter elimination. The reported cost of
analysis from SFWMD for the second quarter of 2004 was projected over all four
quarters of year 2 for the before parameter elimination cost assessment and only in the
first quarter of year 2 for the after parameter elimination cost assessment.
YR2 TOTAL
ESTIMATED COST BEFORE
PARAMETER
ELIMINATION
YR2 TOTAL
ESTIMATED COST AFTER
PARAMETER
ELIMINATION
COST
DIFFERENCE
TEST
CODE PRICE COUNT COST COUNT COST COST
ALKA $6.53 488 $3,186.64 488 $3,186.64 $0.00
APA $17.21 488 $8,398.48 122 $2,099.62 $6,298.86
CA $8.13 488 $3,967.44 488 $3,967.44 $0.00
CL $8.07 512 $4,131.84 512 $4,131.84 $0.00
COLOR $6.30 488 $3,074.40 122 $768.60 $2,305.80
DOC $12.20 488 $5,953.60 122 $5,953.60 $0.00
K $8.13 488 $3,967.44 122 $991.86 $2,975.58
MG $8.13 488 $3,967.44 122 $991.86 $2,975.58
NA $8.13 488 $3,967.44 122 $991.86 $2,975.58
NH4 $6.53 492 $3,212.76 123 $803.19 $2,409.57
NO2 $6.53 488 $3,186.64 122 $796.66 $2,389.98
NOX $6.53 504 $3,291.12 504 $3,291.12 $0.00
OPO4 $6.53 492 $3,212.76 123 $803.19 $2,409.57
SIO2 $8.25 488 $4,026.00 488 $4,026.00 $0.00
SO4 $8.07 512 $4,131.84 512 $4,131.84 $0.00
TDKN $12.26 496 $6,080.96 124 $1,520.24 $4,560.72
TDPO4 $11.42 496 $5,664.32 496 $5,664.32 $0.00
TDS $12.20 488 $5,953.60 488 $5,953.60 $0.00
TKN $12.26 492 $6,031.92 492 $6,031.92 $0.00
TOC $12.20 492 $6,002.40 123 $6,002.40 $0.00
TPO4 $9.14 520 $4,752.80 520 $4,752.80 $0.00
TSS $7.77 488 $3,791.76 488 $3,791.76 $0.00
TURB $6.53 488 $3,186.64 488 $3,186.64 $0.00
TOTAL 11352 $103,140.24 7311 $64,872.00 $38,268.24
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Table 3. Correlation parameter with correlation coefficient (r) greater than or equal to
0.95.
CORRELATED PARAMETERS r VALUE
ALKA Ca 0.98
ALKA HARD 0.98
ALKA SPCOND 0.96
ALKA TDS 0.95
Ca HARD 0.99
Ca SPCOND 0.95
Ca TDS 0.95
Cl Na 0.997
Cl SPCOND 0.95
HARD Mg 0.97
HARD SPCOND 0.97
HARD TDS 0.97
Mg Na 0.95
Mg SPCOND 0.97
Mg TDS 0.97
Na SPCOND 0.96
Na TDS 0.95
OPO4 TDPO4 0.997
SPCOND TDS 0.98
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Table 4. Finalized list of water quality parameters to be eliminated from the Enhanced
Water Quality Monitoring Program.
Parameter Primary Justification for Elimination
APA Non-stand alone parameter requiring further data to be useful
COLOR Low value with respect to water quality in the marsh
HARD Redundant to alkalinity
K Redundant to TDS; low value as WQ indicator for the marsh
Mg Redundant to hardness and thus alkalinity
Na Redundant to alkalinity
NH4 Encompassed in total nitrogen measurement
NO3 Captured in NOX measurement
NO2 Short lived and captured in NOX measurement
OPO4 Redundant to TDPO4
TDKN Captured in total nitrogen measurement
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Appendix A
Table A.1. Pearson product moment correlation analysis for the suite of 29 parameters considered for elimination from the A.R.M. Loxahatchee
National Wildlife Refuge - Enhanced Water Quality Monitoring Program.
ALKA APA CA CL COLOR DEPTH DISS_O2 DOC HARD K MG NA NH4 NO2 NOX OPO4 PH_FIELD SIO2 SO4 SpCond TDKN TDPO4 TDS TEMP TKN TOC TPO4 TSS TURB TN TPP
ALKA 1.000
APA -0.622 1.000
CA 0.981 -0.615 1.000
CL 0.883 -0.528 0.857 1.000
COLOR 0.385 -0.292 0.419 0.199 1.000
DEPTH 0.536 -0.359 0.561 0.556 -0.072 1.000
DISS_O2 -0.022 0.095 -0.030 0.131 -0.463 0.331 1.000
DOC 0.705 -0.391 0.683 0.772 0.594 0.137 -0.106 1.000
HARD 0.984 -0.610 0.993 0.897 0.395 0.553 -0.012 0.720 1.000
K 0.916 -0.597 0.916 0.860 0.515 0.473 -0.081 0.776 0.929 1.000
MG 0.943 -0.570 0.931 0.937 0.324 0.511 0.027 0.762 0.968 0.911 1.000
NA 0.894 -0.539 0.868 0.997 0.217 0.553 0.110 0.770 0.909 0.867 0.950 1.000
NH4 0.387 -0.224 0.414 0.320 0.251 0.505 -0.087 0.249 0.389 0.393 0.320 0.326 1.000
NO2 0.429 -0.242 0.450 0.392 0.264 0.498 0.089 0.318 0.445 0.434 0.415 0.396 0.491 1.000
NOX 0.382 -0.202 0.386 0.365 -0.024 0.536 0.297 0.158 0.390 0.341 0.381 0.367 0.339 0.775 1.000
OPO4 0.258 -0.219 0.322 0.100 0.370 0.323 -0.164 0.062 0.264 0.362 0.131 0.103 0.514 0.286 0.161 1.000
PH_FIELD 0.774 -0.556 0.770 0.797 0.061 0.683 0.327 0.484 0.786 0.743 0.783 0.793 0.320 0.415 0.431 0.209 1.000
SIO2 0.641 -0.403 0.620 0.613 0.521 0.191 -0.295 0.609 0.659 0.690 0.709 0.632 0.114 0.215 0.065 0.033 0.354 1.000
SO4 0.842 -0.482 0.865 0.835 0.344 0.524 -0.003 0.656 0.902 0.847 0.937 0.854 0.343 0.427 0.368 0.217 0.731 0.676 1.000
SpCond 0.958 -0.590 0.950 0.954 0.330 0.552 0.022 0.759 0.972 0.917 0.972 0.962 0.403 0.429 0.381 0.199 0.796 0.659 0.895 1.000
TDKN 0.741 -0.371 0.752 0.753 0.602 0.283 -0.098 0.907 0.769 0.815 0.769 0.752 0.432 0.420 0.255 0.269 0.560 0.548 0.728 0.782 1.000
TDPO4 0.294 -0.241 0.358 0.136 0.365 0.361 -0.145 0.078 0.301 0.395 0.165 0.138 0.526 0.301 0.182 0.997 0.249 0.040 0.248 0.236 0.290 1.000
TDS 0.953 -0.574 0.950 0.941 0.415 0.525 -0.020 0.794 0.972 0.938 0.974 0.949 0.377 0.430 0.342 0.214 0.765 0.721 0.910 0.979 0.816 0.247 1.000
TEMP 0.218 -0.119 0.233 0.203 0.218 0.215 -0.170 0.090 0.244 0.293 0.255 0.215 0.189 0.134 -0.039 0.222 0.236 0.412 0.381 0.260 0.189 0.226 0.289 1.000
TKN -0.021 0.138 -0.015 0.032 0.285 -0.073 -0.054 0.227 -0.011 0.045 -0.001 0.021 0.018 0.048 -0.014 0.002 -0.050 0.089 -0.006 0.010 0.232 -0.003 0.037 -0.332 1.000
TOC 0.675 -0.425 0.666 0.673 0.491 0.144 -0.134 0.811 0.690 0.727 0.708 0.679 0.287 0.258 0.117 0.117 0.463 0.557 0.635 0.700 0.769 0.137 0.730 0.305 -0.280 1.000
TPO4 0.023 0.157 0.049 0.008 0.254 0.042 -0.081 0.109 0.033 0.087 -0.002 0.002 0.138 0.106 0.038 0.275 -0.015 0.020 0.029 0.024 0.133 0.274 0.044 -0.276 0.728 -0.227 1.000
TSS 0.021 0.010 0.027 0.059 -0.211 0.038 0.157 -0.001 0.030 -0.023 0.035 0.047 0.114 0.024 0.054 0.002 0.127 -0.124 0.017 0.035 0.078 0.009 0.015 0.024 0.139 0.017 0.056 1.000
TURB 0.431 -0.218 0.445 0.490 -0.188 0.587 0.341 0.149 0.452 0.363 0.446 0.478 0.321 0.384 0.489 0.150 0.584 0.076 0.443 0.467 0.268 0.184 0.427 0.130 0.053 0.124 0.107 0.547 1.000
TN -0.015 0.135 -0.009 0.038 0.284 -0.065 -0.050 0.230 -0.005 0.050 0.005 0.027 0.023 0.060 0.002 0.004 -0.043 0.090 0.000 0.016 0.236 0.000 0.042 -0.333 1.000 -0.279 0.729 0.140 0.061 1.000
TPP -0.061 0.232 -0.053 -0.034 0.163 -0.062 -0.045 0.091 -0.053 -0.021 -0.051 -0.040 -0.007 0.028 -0.012 0.004 -0.090 0.010 -0.041 -0.045 0.053 0.003 -0.026 -0.354 0.751 -0.274 0.962 0.017 0.044 0.751 1.000
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Appendix B
Temporal graphs of parameters considered for elimination by the expert scientists.
Graphs with stars (*) in the upper left corner are also on the final list of parameters
to be dropped.
Figure 1. *Alkaline Phosphatase for the period June 2004 to May 2004.
Figure 2. *Color for the period June 2004 to May 2004.
Figure 3. Dissolved organic carbon for the period June 2004 to May 2004.
Figure 4. *Hardness for the period June 2004 to May 2004.
Figure 5. *Potassium for the period June 2004 to May 2004.
Figure 6. *Magnesium for the period June 2004 to May 2004.
Figure 7. Total organic carbon for the period June 2004 to May 2004.
Figure 8. *Sodium for the period June 2004 to May 2004.
Figure 9. *Ammonium for the period June 2004 to May 2004.
Figure 10. *Nitrite for the period June 2004 to May 2004.
Figure 11. *Total dissolved Kjeldahl nitrogen for the period June 2004 to May 2004.
Figure 12. *Ortho-phosphate for the period June 2004 to May 2004.
Figure 13. Silica for the period June 2004 to May 2004.
Figure 14. Total dissolved solids for the period June 2004 to May 2004.
Figure 15. Turbidity for the period June 2004 to May 2004.
Figure 16. Total organic carbon for the period June 2004 to May 2004.
Correlation graphs for parameters with R values greater than or equal to 0.95.
Figure 17. Correlation graphs for (a) Alkalinity verses Calcium, (b) Alkalinity verses
Hardness, (c) Alkalinity verses Specific conductance, and (d) Alkalinity
verses Total dissolved solids.
Figure 18. Correlation graphs for (a) Calcium verses Hardness, (b) Calcium verses
Specific conductance, (c) Calcium verses Total dissolved solids, and (d)
Chloride verses Sodium.
Figure 19. Correlation graphs for (a) Chloride verses Specific Conductance, (b)
Magnesium verses Specific Conductance, (c) Hardness verses Specific
Conductance, and (d) Hardness verses Total dissolved solids.
Figure 20. Correlation graphs for (a) Alkalinity Magnesium verses Specific
Conductance, (b) Magnesium verses Total Dissolved Solids, (c) Sodium
verses Specific Conductance, and (d) Sodium verses Total Dissolved Solids.
Figure 21. Correlation graphs for (a) Ortho-phosphate verses Total Dissolved
Phosphorus and (b) Specific Conductance verses Total Dissolved Solids.
Status: Final 26
Date: December 15, 2005 Report No. LOXA05-004
Figure 1. Alkaline Phosphatase for the period June 2004 to May 2004.
*
COLOR
* LOXA
200
300
180
160
250
200
150
100
50
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05
COLOR_COLOR_DATE
Figure 2. Color for the period June 2004 to May 2004.
COLOR (PCU)
Status: Final 27
Date: December 15, 2005 Report No. LOXA05-004
DISSOLVED ORGANIC CARBON
LOXA
50
45
40
35
30
25
20
15
10
5
DOC_INTERIOR
DOC_CANAL
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
DATE
Figure 3. Dissolved organic carbon for the period June 2004 to May 2004.
DOC (mg/L)
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
HARD (mg/L)
* HARDNESS as CaCO3
350
300
250
200
150
100
50
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
LOXA HARD_INTERIOR
HARD_CANAL
DATE
Figure 4. Hardness for the period June 2004 to May 2004.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
K (mg/L)
POTASSIUM
*
LOXA
14
12
10
8
6
4
2
0
K_INTERIOR
K_CANAL
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
DATE
Figure 5. Potassium for the period June 2004 to May 2004.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
MG (mg/L)
MAGNESIUM
* ALL LOXA
30
25
20
15
10
5
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
MG_INTERIOR
MG_CANAL
DATE
Figure 6. Magnesium for the period June 2004 to May 2004.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
TOTAL ORGANIC CARBON
LOXA
60
TOC_INTERIOR
TOC_CANAL
50
40
30
20
10
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
DATE
Figure 7. Total organic carbon for the period June 2004 to May 2004.
TOC (mg/L)
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
NA (mg/L)
* SODIUM
LOXA
140
120
100
80
60
40
20
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
NA_INTERIOR
NA_CANAL
DATE
Figure 8. Sodium for the period June 2004 to May 2004.
Status: Final 33
Date: December 15, 2005 Report No. LOXA05-004
* AMMONIUM
LOXA
NH4 (mg/L)
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
23-Apr-04 12-Jun-04 1-Aug-04 20-Sep-04 9-Nov-04 29-Dec-04 17-Feb-05 8-Apr-05 28-May-05 17-Jul-05
NH4_INTERIOR
NH4_CANAL
DATE
Figure 9. Ammonium for the period June 2004 to May 2004.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
NO2 (mg/L)
* NITRITE
LOXA
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
NO2_INTERIOR
NO2_CANAL
DATE
Figure 10. Nitrite for the period June 2004 to May 2004.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
TDKN (mg/L)
TOTAL DISSOLVE KJELDAHL NITROGEN
*
LOXA
3
2.5
2
1.5
1
0.5
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
DATE
TDKN_INTERIOR
TDKN_CANAL
Figure 11. Total dissolved Kjeldahl nitrogen for the period June 2004 to May 2004.
Status: Final 36
Date: December 15, 2005 Report No. LOXA05-004
ORTHO PHOSPHATE
* LOXA
OPO4 (mg/L)
0.6
0.5
0.4
0.3
0.2
0.1
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
OPO4_INTERIOR
OPO4_CANAL
DATE
Figure 12. Ortho-phosphate for the period June 2004 to May 2004.
Status: Final 37
Date: December 15, 2005 Report No. LOXA05-004
SILICA
LOXA
SIO2 (mg/L)
45
40
35
30
25
20
15
10
5
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
SIO2_INTERIOR
SIO2_CANAL
DATE
Figure 13. Silica for the period June 2004 to May 2004.
Status: Final 38
Date: December 15, 2005 Report No. LOXA05-004
TOTAL DISSOLVED SOLIDS
LOXA
TDS (mg/L)
800
700
600
500
400
300
200
100
0
TDS_INTERIOR
TDS_CANAL
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
DATE
Figure 14. Total dissolved solids for the period June 2004 to May 2004.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
TURBIDITY
LOXA
25
TURB_INTERIOR
TURB_CANAL
20
15
10
5
0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
DATE
Figure 15. Turbidity for the period June 2004 to May 2004.
TURB (NTU)
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
TOC (mg/L)
TOTAL ORGANIC CARBON
* LOXA
60
50
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0
23-Apr-04 22-Jun-04 21-Aug-04 20-Oct-04 19-Dec-04 17-Feb-05 18-Apr-05 17-Jun-05
TOC_INTERIOR
TOC_CANAL
DATE
Figure 16. Total organic carbon for the period June 2004 to May 2004.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
a
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ALKALINITY (mg/L) ALKALINITY AS CaCO3 (mg/L)
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TOTAL DISSOLVED SOLIDS (mg/L) HARDNESS AS CaCO3 (mg/L)
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SPECIFIC CONDUCTIVITY (mS/cm) CALCIUM (mg/L)
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ALKALINITY AS CaCO3 (mg/L) ALKALINITY AS CaCO3 (mg/L)
Figure 17. Correlation graphs for (a) Alkalinity verses Calcium, (b) Alkalinity verses Hardness, (c) Alkalinity verses Specific
conductance, and (d) Alkalinity verses Total dissolved solids.
600
500
400
300
200
Status: Final 42
Date: December 15, 2005 Report No. LOXA05-004
350
a 1200
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TOTAL DISSOLVED SOLIDS (mg/L) HARDNESS AS CaCO3 (mg/L)
SODIUM (mg/L) SPECIFIC CONDUCTIVITY ( mS/cm)
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0102030405060708090100 0102030405060708090100
CALCIUM (mg/L) CALCIUM (mg/L)
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CALCIUM (mg/L) CHLORIDE (mg/L)
80
60
Figure 18. Correlation graphs for (a) Calcium verses Hardness, (b) Calcium verses Specific conductance, (c) Calcium verses
Total dissolved solids, and (d) Chloride verses Sodium.
Status: Final 43
Date: December 15, 2005 Report No. LOXA05-004
1400
a 1200
b
1200
1000
TOTAL DISSOLVED SOLIDS (mg/L) SPECIFIC CONDUCTIIVITY (mS/cm)
SPECIFIC CONDUCTIVITY ( mS/cm) SPECIFIC CONDUCTIVITY mS/cm
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CHLORIDE (mg/L) MAGNESIUM (mg/L)
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800
c
d
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0
0
0 50 100 150 200 250 300 350 0 50 100 150 200 250 300 350
HARDNESS (mg/L) HARDNESS (mg/L)
Figure 19. Correlation graphs for (a) Chloride verses Specific Conductance, (b) Magnesium verses Specific Conductance, (c)
Hardness verses Specific Conductance, and (d) Hardness verses Total dissolved solids .
600
500
400
300
200
Status: Final 44
Date: December 15, 2005 Report No. LOXA05-004
1200
a 800
b
700
SPECIFIC CONDUCTIVITY ( mS/cm) SPECIFIC CONDUCTIIVITY (mS/cm)
TOTAL DISSOLVED SOLIDS (mg/L) TOTAL DISSOLVED SOLIDS (mg/L)
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0 5 1015202530 0 5 10 15 2025 30
MAGNESIUM (mg/L) MAGNESIUM (mg/L)
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c 900
d
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1400
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0 20 40 60 80 100120140 0 20 40 60 80 100120140
SODIUM (mg/L) SODIUM (mg/L)
Figure 20. Correlation graphs for (a) Alkalinity Magnesium verses Specific Conductance, (b) Magnesium verses Total
Dissolved Solids , (c) Sodium verses Specific Conductance, and (d) Sodium verses Total Dissolved Solids .
700
600
500
400
300
200
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
800
700
b
TOTAL DISSOLVED PHOSPHORUS (mg/L)
a
0.1
100
0
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0 200 400 600 800 1000 1200
ORTHO-PHOSPHATE (mg/L) SPECIFIC CONDUCTIVITY ( mS/cm)
TOTAL DISSOLVED SOLIDS (mg/L)
600
500
400
300
200
Figure 21. Correlation graphs for (a) Ortho-phosphate verses Total Dissolved Phosphorus and (b) Specific Conductance
verses Total Dissolved Solids .
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
10216 Lee Road, Boynton Beach, Florida 33437-4796
APPENDIX C
Phone (561) 732-3684 Fax (561) 369-7190
January 17, 2006
To: TOC and interested parties
From: Donatto Surratt, Ph.D.
Matt Harwell, Ph.D.
Subject: Response to written comments on the November 7, 2005 draft A.R.M. Loxahatchee
National Wildlife Refuge Enhanced Water Quality Program  Parameter Reduction
Rationale
We appreciate the continued interest in our water quality monitoring program and the careful and
detailed review that outside interested parties gave our draft report, Enhanced Water Quality
Program Parameter Reduction Rationale. Report No. LOXA05-004 by Surratt, D. This exercise
to reduce unnecessary parameters from our monitoring program benefited from the constructive
technical comments we received. Below we provide a written response to the comments we
received, as well as identify how the final version of the report (available at:
http://www.sofia.usgs.gov/lox_monitor_model) was modified.
SFWMD Comments
First bullet: The objective for reducing parameters, as stated in the second paragraph on the
first page, was to reduce analytical costs and reclaim funds to extend the duration of the LOXA
monitoring effort. The rationale for selecting parameters to meet this objective did not appear to
be consistently applied across parameters
Response  As stated in the cover memo when the draft report was circulated for review and
comment, the primary aim of the exercise was to eliminate redundant parameters and those not
providing valuable information. Cost savings was intentionally not a driving factor in the
analysis. To clarify this point we added, The LOXA Work Plan (Brandt et al. 2004) states that,
data will be reviewed and the list of parameters reduced as appropriate (p. 12) with the
objective to optimize the marsh monitoring network.
Second bullet:  It is important to undertake an initial data analysis to assess whether some
sites can be eliminated for optimizing the expanded network .
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Response  As stated in the cover memo when the draft report was circulated for review and
comment, we are currently undertaking a site optimization exercise.
Responses to more detailed technical comments from SFWMD.
Page 3, Line 2 (missing text and need for editing?)
Response  The revised text now reads: Another characterization approach was the spatial
analysis approach which was performed from canal to the interior of the marsh on several
parameters.
Alkalinity: Calcium, alkalinity and hardness correlated well because two of the parameters are
reported in units as CaCO3. It seems that the correlation analysis of this parameter was
unnecessary. The reason to keep ALKA is not because of its correlation with calcium or
hardness. It was kept because it had a numeric criterion pursuant to Section 62-302.530 F.A.C.
and is important to the basic ecology of a softwater marsh.
Response  The revised text now reads: Alkalinity correlated well with four parameters 
calcium (r = 0.98), hardness (r = 0.98), specific conductance (r = 0.96), and total dissolved solids
(r = 0.95). The high correlation between ALKA, calcium, and hardness is most likely an artifact
of their dependence on the concentration of CaCO3. Although each of these parameters share
this dependency, they are still determined through unique analytical procedures and explain
different conditions of the analyzed water parcels and as such yield different values and patterns
through time, which is why they are not 100% correlated. Further, these correlations allow the
observer to quickly qualify data points as outliers (prior to a rigorous quantitative assessment)
with respect to specific conductance, which is exceptionally important for tracking water
movement from the canal to the interior marsh.
Alkalinity has a Class III criterion of = 20 mg L-1. In October and November 2004, five
sampled sit es had values below the criterion. This criterion is inappropriate for rainwater-
dominated wetlands where alkalinity is naturally below 20 mg L-1 (Weaver, 2005). A water
quality goal of the Refuge is to maintain this low alkalinity condition. Because ALKA provides
the ability to quickly determine specific conductance outliers; because there is an established
numeric criterion pursuant to Section 62-302.530 F.A.C.; and because ALKA is important to the
ecology of softwater marshes, ALKA will not be eliminated from the analytical suite. Alkalinity
remains a monitored parameter.
Chloride: Chloride is strongly correlated with sodium and specific conductance (and strongly
correlated with TDS). If it has a strong correlation with specific conductivity and cost needs to
be reduced, specific conductivity might be an acceptable surrogate and chloride could be
reduced. If justification is needed, why isnt mass balance modeling mentioned?
Response  We decided to keep chloride as it provides a check for specific conductance. We
have found a number of occasions when specific conductance has been entered incorrectly in
DBHYDRO. Further, these two parameters are the only parameters that act as true biologically
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
and chemically conservative parameters out of the monitored suite of parameters and as such we
are maintaining both of them to ensure we will be able to track canal water penetration in the
future.
Dissolved Organic Carbon (DOC): DOC is very important to the biogeochemical cycling in the
marsh. It may not be appropriate to eliminate DOC as a monitoring parameter.
Response  We have revisited DOC and agree with the conclusion to continue monitoring DOC.
The revised text now reads: Dissolved organic carbon has been linked to microbial respiration
and fulvic acid regulated mercury methylation in the southern Everglades (Reddy and Aiken,
2001). One of the experts in preliminary lab experiments revealed microbial respiration to be
strongly carbon limited instead of phosphorus or nitrogen limited as for most system. Additional
influxes of labile carbon can affect marsh soil processes. Reddy and Aiken (2001) demonstrate
strong correlations between Hg bioaccumulation and DOC concentrations. Correlation analysis
for DOC did not reveal significant correlation with other parameters. Because neither Hg nor
microbial respiration are monitored in the Refuge, because of the potential of DOC concentration
changes to cause Hg bioaccumulation rates to change, and because no other parameters can serve
as surrogates of DOC, continued monitoring DOC is recommended. DOC remains a monitored
parameter.
Dissolved Oxygen (DO): Since DO follows a diel cycle influenced by light and temperature,
the usefulness of DO grab samples is highly debatable. As described in the Refuges draft paper
current legal mandates were adjusted by a Site Specific Alternative Criteria (SSAC). The value
of grab sample monitoring of DO at an expanded list of stations is questionable. A more
practical approach would be deployments at selected stations for several days.
Response  Along the central transect in the marsh we do monitor DO for several consecutive
days during the wet season. However, this does not replace the entire monitoring network. Grab
sample monitoring for DO will continue.
Hardness: Hardness is calculated from calcium and magnesium: Hardness=2.497 (Ca, mg/L)
+ 4.118 (Mg, mg/L). If magnesium is eliminated from the parameter list, hardness can not be
calculated. The argument presented for keeping hardness stems from the f act that it is used to
calculate criteria for a variety of trace metals. However, since trace metals are not monitored in
the LOXA program, is there another reason for keeping this parameter? From the viewpoint of
tracking the softwater aspects of the marsh, alkalinity should provide all necessary information.
A reconsideration of the value of hardness appears worthwhile.
Response  We have revisited hardness based on the above suggestion and concur with the
recommendation to remove hardness from the monitored parameters. The revised text for
hardness is:
HARD: Hardness is measured as an equivalent concentration of calcium carbonate (CaCO3)
and was expected to correlate well with alkalinity (which is also measured as an equivalent
concentration of CaCO3). Hardness correlated well with ALKA (r = 0.98), Ca (r = 0.99),
magnesium (r = 0.97), specific conductance (r = 0.97), and TDS (r = 0.97). Although these
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
strong correlations are observed, the Florida Class III water quality criteria for various metals
(Cd, Cr, Cu, Pb, Ni, Zn) require hardness in order to calculate the metal criterion (Bechtel,
2000). These metals have never been measured as a part of the LOXA project and were
discontinued from the EVPA project in 2000. From the perspective of tracking softwater
movement interior of the canals, ALKA and specific conductance appear to provide the
necessary information, thus the elimination of the hardness appears to be warranted. Hardness is
on the list of parameters to eliminate.
NH4 (ammonium): The EPA in the context of south Florida refers to the Everglades
Protection Area not the Environmental Protection Agency. It is worthwhile to note also that
NH4 is rapidly recycled and instantaneous concentrations are not usually helpful in
understanding N availability in a functioning marsh with relatively high levels of nitrogen.
However, NH4 is the inorganic portion of the TKN value and it provides (through subtraction)
an estimate of the organic nitrogen content. By dropping this parameter, it will not be known if
that make-up shifts in the future.
Response  We corrected the editorial mistake. NH4 is low in the Refuge marsh and TKN is
comprised mostly of organic material. As such we do not find it necessary to continue the
monitoring of this parameter.
Nitrate, nitrite, and NOx: The only reason that should be given for keeping NOx is that it is
necessary to calculate total nitrogen. The rationales for eliminating NO3 and NO2 do not flow
logically and some of the facts presented could argue to keeping them. It could be noted in these
sections that NO2 and NO3 are not particularly useful as individual parameter and their value is
maintained by measuring NOx.
Response  The revised text now reads: There were no strong correlations associated with
nitrate. Nitrate is generally a significant portion of nitrate-nitrite (NOX) measurement and in
combination with the other components of total nitrogen provides information about nutrient
lability. Because NO2 is generally only a small fraction of the NOX, it was expected that NOX
values can be used to estimate the NO3 concentration. This rationale holds true for station LZ40
in Lake Okeechobee such that NO2 was ~11% and NO3 was ~90% of the NOX concentration.
However, this pattern was not observed in the Refuge marsh. Observation of the data showed
NO2 at ~43% and NO3 at ~58% of the NOX concentrations. Thirty-one percent of the NO3
values for the Refuge were below detection limits, which may have complicated this assessment
and potentially confound any trend analysis attempted for the Refuge. Independently, NO3 is not
particularly useful and the value of this nitrogen fraction is maintained in measurements of NOX.
Nitrate is on the list of parameters to be eliminated.
OPO4 (Orthophosphate) and TDP: OPO4 is the bio-available fraction of P. It is the P fraction
that can be compared to Si or inorganic N to look at nutrient availability and potential
limitation. Since it may have a strong correlation to TDP and cost less to analyze, there is no
compelling reason to eliminate it and keep TDP. TDP could be eliminated because it costs more
and it does not provide a quick estimate of the biologically available P. Since OPO4 is extremely
strongly correlated to TDP (r=0.99), then particulate P could be estimated by subtracting OPO4
from TP. Reconsideration of these parameters would seem appropriate.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Response  The argument presented here is very strong, but the only issue is the number of times
OPO4 is below the detection limit. TDP and OPO4 are already not analyzed when the water
depth is below 20 cm. But even when OPO4 is below detection limit, TDP values generally are
measurable. If we eliminate TDP to keep OPO4, we will have even larger data gaps. As such,
we decided to estimate OPO4 from TDP and eliminate OPO4.
pH: Point measurements for pH can hint at interesting processes but cannot resolve the
actual issue. This parameter is better suited for diel deployments combined with research to
understand the processes that drive pH below 6.
Response  Presently, we monitor pH for several consecutive days during the wet season along
the central transect through marsh. We do not have a research portion of this program dedicated
to understanding what drives pH below 6. Our water is poorly buffered and even monthly snap
shots help us understand the marsh and when conditions may be changing, particularly if pH
deviates from the normal pH values we have observed.
Silica (SiO2): The reference below is incorrect as written:
 There is no mention of hard water altering ecosystem structure, only biotic communities. Has
the author noticed the changes in Si:P ratios in the Refuge or are these changes associated with
diatoms anticipated in the near future? The argument is not easily followed as written and not
very compelling.
Response  The citation has been referenced appropriately in the revised text. There were no
strong correlatio ns associated with silica. Silica shows a seasonal pattern for the interior sites of
the Refuge. Silica is higher in the wet-warm season (late April  early November) and lower
during the dry-cool season (November to early April). Independent research has demonstrated
that silica concentrations decrease during the cooler season when algae populations (dominated
by diatoms) are dying off and increase during the warmer season when these populations grow in
again. Changes in these patterns can serve as a good indication of eutrophication and even biota
shifts (Biggs, 1990). These assertions are generally for flowing waters (i.e., rivers) and
historically appear to be of less importance for the Refuge wetland ecosystem which has a low
diatom abundance associated with the periphyton population dominating as the primary producer
of the Refuge (Kadlec and Knight, 1996). However, with STA-1E becoming operational in
September 2005, there will be larger volumes of higher mineral content water discharge into the
L-40 Canal. Canal water penetration into the marsh has been documented (Harwell et al., 2005).
The introduction of higher mineral content water into a soft-water ecosystem is expected to
impact the biotic community. The combination of temperature, nitrogen to phosphorus, and
silica to phosphorus ratios has been shown to relate to algae species distributions (Adamus et al.,
2001). This suite of indicators can theoretically be applied as an indicator of changes in
periphyton community dynamics as the high mineral content water impact the Refuge.
Presently, WCA-2 has a higher diatom abundance associated with the periphyton communities
(relative to the Refuge) and the Refuge perimeter canals are major sources of water for WCA-2.
Because of the potential of silica concentration change to cause biotic shifts, and because the
canals of the Refuge provide water to other areas of the Everglades, silica is not on the
elimination list. Silica remains a monitored parameter.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
Total Dissolve Solids (TDS): With the ability to measure specific conductivity, this parameter
is unnecessary. Chloride (rather than TDS) could be used to verify that specific conductivity is
measured correctly
Response  As we have historically used TDS to identify outliers and erroneous data, we have
decided to keep TDS.
Temperature: The reasoning for keeping TEMP is intriguing. All multi-parameter sonde units
automatically correct specific conductance whether temperature is recorded or not. Just
because it is used to adjust conductance is not a compelling reason to keep temperature. There
are costs associated with data entry, data review, equipment calibration, etc., even if there are
not analytical costs for temperature. If data are entered into the database, it should have value;
point measurements for temperature have limited value.
Response  There were no strong correlations associated with temperature. Temperature is an
integral parameter that changes seasonally. It is used to adjust conductance, dissolved oxygen
measurements, determine DO saturation, and the DO-SSAC. As noted above, cost savings was
not the primary factor in this exercise, and the minor cost savings alone does not provide enough
justification to eliminate this parameter. Temperature remains a monitored parameter.
Corps Comments
1. Most of the parameters that were eliminated, the logic is compelling. A few of them you may
wish to reconsider. These are NH4 and DOC. You may wish to include these for the following
reasons:
2. Relative to NH3- NH4, : certainly You can identify TN with TKN and
NOx but you may not fully understand any future transformations or changes to the Refuge due
to ECP modifications and CERP. Consider the following:
a. NH3- NH4: Ammonium is a product of soil organic matter and NO-3 consumption
per the simplified formula :
(CH2O) 106 (NH3) 16 (H3PO4) + 84.8NO3- ?106 CO2 + 16 NH3 + H3PO4+148.4 H2O
b. Increases in this may be increases in these patterns. (Davidson2000)
c. This may contribute to substantial TN losses for poorly buffered waters in high
photosynthetic areas (due to associated changes in pH),(DeBusk ).
d. This is of particular interest to the down stream of the Refuge and will contribute to
understanding the TN changes taking place in the refuge.
3. Relative to DOC:
a. Hg interaction with DOC may be important in regulating ecosystem mercury
methylation patterns (Reddy and Aiken 2001).
b. Certainly, sulfate serves as the electron donor for bacteriamediated methylation of mercury
c. but fulvic acid competes with the inorganic sulfide ion for mercury binding.
d. Fulvate is a substantial fraction of the DOC.
e. In my estimation, you really need both parameters to effectively track this.
f. I am attaching some the pictorial plates from REMAP as a file.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
g. Note TOC (I couldn't find anything for DOC) corresponds to some of the methylation
patterns.
Response to the NH4 comment Though we recognize the potential value of the information lost
when we eliminate NH4, NH4 is relatively low in the Refuge compared to most marsh systems.
NH4 is also a very small component of TKN, which is mostly organic and is a parameter we
continue to monitor. The rationale for eliminating NH4 is that total nitrogen encompasses the
NH4 fraction and because nitrogen is not considered a limiting nutrient in the Refuge. The small
NH4 fraction of total nitrogen provides limited ecologically meaningful information. As a result,
NH4 is being eliminated from this monitoring network.
Response to the DOC comment  Please see comments for DOC above.
ENP Comments
Parameter reduction can also be achieved through application of "Principle Component or
Factor Analysis" which are more robust statistical tools for such applications. Other rationale
still can be applied to bring in or throw out parameters after that. Some links below can be
referred to check whether these procedures would apply or not for your report.
Response  We agree that PCA techniques can be valuable for general data exploration and
analysis. For the purposes of our exercise, we chose to stick with the presented degree of
analysis which allowed us to look at variables from both individua l and multivariate approaches.
In our more robust analysis of the data sets (independent of the presented parameter reduction
report) we do employ PCA and other similar techniques to include canonical correspondence
analysis and multidimensional scaling approaches to assessing the datasets.
Status: Final
Date: December 15, 2005 Report No. LOXA05-004
APPENDIX D
Comments from reviewers