Slide 1

Report
Mark Campbell
Brief Intro of Wetlands
Turkey Creek Wetland
A restored floodplain wetland at a private farm in rural McLean
County, Illinois
Characteristics of Wetlands
 Wetlands are transitional areas between land and
water
 Main Characteristic present of surface or near-surface
water, at least periodically
 The hydrology of wetlands is generally one of slow
flows and either shallow waters or saturated substrates
 Also forms an Anaerobic environment
Benefits
 Provides the removal of




contaminants: Nitrates,
Phosphorous, metalloids
Allows for sedimentation to
occur
Low Cost Removal as
opposed to Ion-Exchange
Control of Flooding
Ecosystem for wildlife
Costs
 Loss of Land use $$$$
 Aesthetic Value
Soil Profile
Differences between Soils in
Constructed and Natural Wetlands
20 cm Depth
5 cm Depth
Variable
CW
Reference
CW
Reference
Organic (%)
4.8
11.5
2.8
7.2
Sand
Content (%)
52.1
23.7
54.3
21.9
Clay (%)
22.0
30.0
30.1
31.4
Silt (%)
20.0
45.2
15.0
39.5
Campbell et al (2002)
Comparison
 It was also found that the diversity of plant
communities were higher in reference sites
 Even in long-term CW’s the organic matter did not
reach levels of reference sites
 This has shown to be an indicator of removal of nitrogen
(Reddy and D’Angelo 1997).
Another comparative study
O’Geen et al (2007)
What is the chemistry that goes on
that in hydric soils that helps with
denitification?
Factors that affect
Denitrification rates
 Temperature

With season, can not control, lower temp. lower rate
 pH

pH in natural waters is in the between 6 to 8, optimal pH for
denitrifying bacteria
 Redox Potential

Organic Carbon and Dissolved Oxygen
 Retention time/Flow Rate
Biochemistry
 Organic Material is oxidized by aerobic respiration use
Oxygen as the electron receptor, while anaerobic
conditions use Nitrogen as receptor (Metcalf and Eddy
2003).
 Corganic + 4 NO3- + 4H+ = 2N2 + 5CO2 + 2H2O
 Pseudomonas
 Thiobacillus
Constructed wetlands have found to remove ≈40% of NO3- ther is
a high degree of variability there have been reports of up to 75%
and low of 15% (Kovacic et al. 2000)
Effects of DO and TN Removal
H. C. Kim et al. (2010)
Flow Rate and Retention Time
 During pulse flows, in the case of storm events the
amount of denitrification is greatly reduced (Kovaic
2006).
 Still wetlands need slow flow, to have some mixing in
the water. Need to create anaerobic environment.

The average retention time 6-8 days for optimal conditions
(Zedler 2003).
 Horizontal substrate is more important, while increase
in depth lowers efficiency(Garcia et al 2010).
Substrate soils for CW
Since high levels of nutrients
Sand and Gravel- cheap
Soils with high clay content- good at retaining
phosphorous
Organic Substrate- sawdust, compost, or hay.
USDA-NRCS Handbook for constructed wetlands

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