Supplementary Material

An Assessment of Iron and Calcium Amendments for Managing Phosphorus Release from Impacted Everglades Soils

Forrest E. Dierberg†, Thomas A. DeBusk†, Scott D. Jackson†, Michelle D. Kharbanda†, Stacey C. Galloway†, Patrick D. Owens†, and Delia B. Ivanoff††

Wetlands Ecology and Management

†DB Environmental, Inc.

365 Gus Hipp Boulevard

Rockledge, FL 32955, USA

Ph: (321) 631-0610

Fax: (321) 631-3196

E-mail:

††Delia Ivanoff

Applied Sciences Bureau

South Florida Water Management District

3301 Gun Club Road

West Palm Beach, FL 33406, USA

Mesocosm Preparation Timeline

On December 17, 2006, all mesocosms were flooded with pre-treated (PT) water from Stormwater Treatment Area (STA)-1W. Twenty-nine days later, all mesocosms were drained to 5 – 10 cm standing water and then sprayed with the herbicide glyphosate. Subsequent heavy rains necessitated a second application of herbicide four days after the initial application. The fallen dead cattail biomass resulting from herbicide treatment was not removed from the mesocosms (Fig. A1; in Electronic supplementary material). The mesocosms were refilled with PT water 30 days after initial herbicide application, in preparation for a batch-sampling event. Soil amendments (limerock and FeCl3) were applied March 14, 2007, after removing the overlying water, and flow-through operation of the mesocosms was restarted on March 19, 2007.

Schedule of Porewater Sampling Using “Sippers”

The first “sipper” porewater sampling date was on February 20, 2007, which occurred after the herbicide application but prior to the chemical amendments and under batch conditions. After 50 weeks of flow-through operation, the porewaters were sampled again (March 13, 2008) immediately before the planned dry down. Another porewater sampling on August 28, 2008 occurred 3.5 months after the resumption of flow-through following the seven-week dry down. The last porewater samples were collected on January 13, 2009, just prior to termination of the demonstration project.

Dry Down and Reflood

The Control and Fe from Site N exhibited a higher response in TP concentration to dry down-reflood than the corresponding mesocosms from Site C. For example, mean TP concentrations in the Site N Control and Fe mesocosms were 185 and 161 mg L-1, compared to their respective TP concentrations of 95 and 80 µg L-1 in the Site C mesocosms. This corresponded to an increased P flux for the Site N soils (mean = 6.4 mg P m-2 d-1), but only slightly higher flux rates for the Site C soils (mean = 3.2 mg P m-2 d-1), during the post-dry down initial two-week “flush” of P in the Control mesocosms compared to the mean pre-dry down rate. With the exception of the Fe mesocosms from both sites, which had the highest overall water column P during the study, TP outflow concentrations returned to pre-dry down levels within two weeks (~ two HRTs) of reflooding for soils from both sites.

Following the two-week post-dry down reflood period, mean P flux in the Site N and Site C Ca mesocosms decreased slightly relative to mean pre-dry down levels. Flux rates did not change substantially over the course of the study in the Site C Fe mesocosm, but rates were lower (4.5 mg P m-2 d-1) during the post-dry down period relative to the pre-dry down period (7.3 mg P m-2 d-1) in the Site N Fe mesocosms. Mean post-dry down P flux in the Control was lower than mean pre-dry down flux, for both Site C and Site N soils.

We consistently observed phytoplankton blooms in Fe mesocosms before and after the seven-week dry down, but there were also other mesocosms that exhibited blooms, although not as consistent or pervasive as in the Fe mesocosms (Table A1; in Electronic supplementary material). Uncorrected chlorophyll a concentrations measured according to Standard Methods 10200 H (APHA AWWA WEF 1992) on August 22, 2007 (before dry down) were consistently higher in the Fe mesocosms from Site N (58, 70 and 107 mg m-3 in the three replicate mesocosms), while concentrations greater than 40 mg m-3 were measured in one of three replicate mesocosms in the Ca (42.1 mg m-3) and Control (273 mg m-3) treatments for Site N only. Chlorophyll a concentrations for Site C on the same date were generally less than for Site N, except for the 65 mg m-3 measured on one of each of the three replicate mesocosms receiving Fe and Ca treatments.

It is interesting to note the increase in PP concentration in the Fe treatments immediately following reflooding was coincident with the decrease in SRP, both of which were especially pronounced in the Site N mesocosms (Fig. A4; in Electronic supplementary material). This presumably reflects uptake of SRP by phytoplankton following the initial flush of SRP from the soil. The proliferation of phytoplankton, especially in the Fe mesocosms, suggests that SRP flux from mesocosm soils was of a significantly greater magnitude than indicated by water column measurement of only SRP concentrations.

References- Supplementary Material

APHA, AWWA, WEF (1992) Standard Methods for the Examination of Water and Wastewater, 18th edn. American Public Health Association, American Water Works Association, Water Environment Federation, Washington, DC

Table A1 Field notes on vegetation observed in each mesocosm before (January 12, 2007 to March 14, 2008) and after (May 16, 2008 to November 19, 2008)) dry down (March 13, 2008 to May 13, 2008). CT = herbicide applied to eliminate cattail (control); Ca = herbicide followed by limerock (LR) amendment; Fe = herbicide followed by FeCl3 amendment

Location / Mesocosm ID / Period / Description /
North / CT-1 / Before / Phytoplankton blooms, but clear water by the end of the period
After / Phytoplankton blooms; alligator weed and aquatic plants
North / CT-2 / Before / Very dense Chara
After / Very dense Chara
North / CT-3 / Before / Phytoplankton bloom
After / Large, thick algal mat
North / Ca-1 / Before / Phytoplankton blooms; large algal mats
After / Algal mats; aquatic plants, cattail (2-3’ tall), alligator weed
North / Ca-2 / Before / Very dense Chara
After / Very dense Chara
North / Ca-3 / Before / Very dense Najas
After / Very dense Chara/trace Najas
North / Fe-1 / Before / Phytoplankton; tadpoles
After / Very dense Chara by the end of the period
North / Fe-2 / Before / Phytoplankton
After / Phytoplankton blooms; some alligator weed present at the end of the period
North / Fe-3 / Before / Clear water, but some phytoplankton blooms
After / Phytoplankton blooms; aquatic plants and alligator weed
Central / CT-1 / Before / Phytoplankton blooms
After / Clear water; Chara present and very dense at the end of the period
Central / CT-2 / Before / Phytoplankton blooms
After / Moderate Chara noted once; aquatic plants and alligator weed noted towards the end of the period
Central / CT-3 / Before / Mostly clear water
After / Went from sparse to very dense Chara during the period
Central / Ca-1 / Before / Phytoplankton blooms
After / Dense algae mat
Central / Ca-2 / Before / Very dense Chara
After / Very dense Chara
Central / Ca-3 / Before / Filamentous algae; tadpoles
After / Benthic periphyton; moderate Chara at the end of the period
Central / Fe-1 / Before / Tadpoles; few algal blooms
After / Phytoplankton blooms, mesocosm discontinued in June 2008
Central / Fe-2 / Before / Algal and phytoplankton blooms
After / Went from sparse to very dense Chara during the period
Central / Fe-3 / Before / Algal and phytoplankton blooms; tadpoles
After / Algal and phytoplankton blooms; tadpoles; one observation of trace Najas

Table A2 The molar ratios of dissolved iron to soluble reactive phosphorus in the porewaters of each replicate iron-amended (Fe) mesocosm from Sites N and C. The mesocosm for Site C, Rep 1 was discontinued in June 2008

Site N / Site C
Sample Date / Rep 1 / Rep 2 / Rep 3 / Rep 1 / Rep 2 / Rep 3
March 13, 2008 / 1.5 / 0.6 / 0.5 / 10.5 / 3.6 / 1.1
August 28, 2008 / 5.2 / 1.1 / 0.3 / ns / 2.0 / 0.4
January 13, 2009 / 0.5 / 2.8 / 9.5 / ns / 0.8 / 0.8

Fig. A1 Photos and schematic of the ex situ flow-through intact mesocosms at the South Advanced Technology Treatment Site (SATTS) of Stormwater Treatment Area (STA)-1W. Photos were taken on February 2, 2007 (top), 14 days after herbicide treatment for some of the cores, and again on February 20, 2007 (bottom), 32 days after herbicide treatment. The cores with the live cattail leaves in the foreground did not receive herbicide. Note the transition of the standing dead leaves in the cores that received herbicide in the top photo to fallen leaves in the bottom photo. Inset map shows location of the SATTS at the outflow of STA-1W

Source: DBHydro downloaded on 9/23/14

Fig. A2 Annual mean TP concentrations for inflow structure S10-C (n=5-16) to WCA-2A. The shaded area indicates the study period. The first of the Stormwater Treatment Areas (STA-1W) came on-line in 2000; it was mostly off-line during 2004-2007 due to rehabilitation

Fig. A3 Comparisons between the analyzed and calculated (soil TP – Σ extracted P pools) residual phosphorus (P) in the 0-10 and 10-30 cm depth intervals in soils at Sites N and C for the treated control (CT = herbicide applied to eliminate cattail); Ca treatment = herbicide followed by LR amendment; Fe treatment = herbicide followed by FeCl3 amendment. Error bars represent ± 1 S.E.

Fig. A4 Mean ±1 S.E. (n=3) soluble reactive phosphorus (SRP), dissolved organic phosphorus (DOP), and particulate phosphorus (PP) concentrations in the outflows of the mesocosms containing soil from the N (left panels) and C (right panels) field sites. CT = herbicide applied to eliminate cattail (control); Ca = herbicide followed by LR amendment; Fe = herbicide followed by FeCl3 amendment

Fig. A5 Mean ± 1 S.E. pH in the inflow (n=1) and outflows (n=3) of mesocosms containing soil from the N and C field sites that received herbicide applied to eliminate cattail followed by FeCl3 amendment (Fe treatment)

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Fig. A6 Mean ± 1 S.E. dissolved iron (Fe) concentrations in the inflow (n=1) and outflows (n=3) of mesocosms containing soil from the N and C field sites that received herbicide applied to eliminate cattail followed by FeCl3 amendment (Fe treatment)

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