ImplementationofFloatingAquaticVegetativeTillingTechnologyintheCaloosahatcheeRiverWatershed
Task20Deliverable:FinalReport
Site1
Preparedfor:FloridaDepartmentofAgricultureandConsumerService
(FDACS)
Contract#021121
Preparedby:Water&SoilSolutions,LLC
Loxahatchee,FL
August18,2015
2
TableofContents
ListofFigures..............................................................................................3 ListofTables................................................................................................5 Executivesummary...................................................................................6 Introduction.................................................................................................9 FAVTSystemUnitProcesses.......................................................................................................................11
Optimization&MonitoringResults...................................................12 WaterChemistryintheFAVTsystem......................................................................................................12
Characterization of inflow and outflow water chemistry ..................................................... 15 TP and pH monitoring at cell inflows and outflows ............................................................. 21 Internal water chemistry monitoring of Cells 1 and 2 .......................................................... 28
FloatingandSubmergedAquaticVegetationSurveys.....................................................................30
3
ListofFiguresFigure 1. Project location within the watershed (Source – Caloosahatchee River Watershed
Protection Plan January 2009). ............................................................................................... 10
Figure 2. Internal water quality sampling locations in Cells 1 and 2 of the FAVT facility during June 2015. ............................................................................................................................... 14
Figure 3. TP concentrations in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. ................................................................................................................... 17
Figure 4. SRP concentrations in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. .................................................................................................. 17
Figure 5. DOP concentrations in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. .................................................................................................. 18
Figure 6. PP concentrations in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. ................................................................................................................... 18
Figure 7. TN concentrations in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. .................................................................................................. 19
Figure 8. Nitrate+nitrite (NOx) concentrations in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. ....................................................................... 19
Figure 9. Ammonia-N concentrations in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. ........................................................................................... 20
Figure 10. Alkalinity in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. ........................................................................................................................ 20
Figure 11. pH in the Caloosahatchee FAVT system inflow and outflow streams, for the POR 9/15/14 (initiation of system discharge) through 6/30/15. Monitoring was conducted on a weekly basis. ........................................................................................................................... 21
Figure 12. Surface water TP concentration and pH at the inflow and outflow of Cell 1 of the Caloosahatchee FAVT system. Monitoring was conducted on a weekly basis from November 2014 through June 2015. ......................................................................................................... 24
Figure 13. Surface water TP concentration and pH at the inflow and outflow of Cell 2 of the Caloosahatchee FAVT system. Monitoring was conducted on a weekly basis from November 2014 through June 2015. ......................................................................................................... 25
Figure 14. Surface water TP concentration and pH at the inflow and outflow of Cell 3 of the Caloosahatchee FAVT system. Monitoring was conducted on a weekly basis from November 2014 through June 2015. ......................................................................................................... 26
4
Figure 15. Mean surface water TP concentration (±1 standard deviation) at the system inflow (=Cell 1 inflow), Cell 1 outflow (=Cell 2 inflow), Cell 2 outflow (=Cell 3 inflow), and system outflow (=Cell 3 outflow) of the Caloosahatchee FAVT system. Values were calculated from data collected during 34 weekly monitoring events from November 2014 through June 2015. .................................................................................................................. 27
Figure 16. Mean surface water pH (±1 standard deviation) at the system inflow (=Cell 1 inflow), Cell 1 outflow (=Cell 2 inflow), Cell 2 outflow (=Cell 3 inflow), and system outflow (=Cell 3 outflow) of the Caloosahatchee FAVT system. Values were calculated from data collected during 34 weekly monitoring events from November 2014 through June 2015. ................... 27
Figure 17. Interpolated spatial TP profiles in Cells 1 and 2 (top), and individual data points for SRP (not interpolated) for Cells 1 and 2 (bottom), for the internal water quality monitoring event in Jun 2015. Note that most SRP values in Cells 1 and 2 were below the detection limit, so no interpolation of these data was performed. ................................................................... 29
Figure 18. Very dense mat of Eichhornia crassipes (water hyacinth) and Pistia stratiotes (water lettuce) in Cell 1 ...................................................................................................................... 32
Figure 19. Time-series for FAV species within Cells 1 and 2 depicting the percent of stations that was moderately dense or greater for each species. ................................................................. 33
Figure 20. Time-series for FAV species within Cells 1 and 2 depicting the percent of stations that each species present. ............................................................................................................... 34
Figure 21. Mixed species mat with Eichhornia crassipes (water hyacinth) and Pistia stratiotes (water lettuce) in Cell 1. .......................................................................................................... 35
Figure 22. Relative cover of the FAV species Eichhornia crassipes and Pistia stratiotes in Cells 1 and 2 of the Caloosahatchee wetland during October and December 2014 and February, April, and June 2015. The black dots represent the observation locations, and the six semi-quantitative density categories are shown in the legend. ........................................................ 36
Figure 23. Najas guadalupensis (southern naiad) growing near the outflow of Cell 3. ............... 38
Figure 24. Mixed SAV assemblage containing Utricularia sp. (bladderwort) and other species in Cell 3. ...................................................................................................................................... 39
Figure 25. Hydrilla verticillata, an invasive SAV species, at the Cell 2 culvert. ......................... 39
Figure 26. Time-series for SAV species within Cell 3 depicting the percent of stations that stations that was moderately dense or greater for each species. ............................................. 40
Figure 27. Time-series for SAV species within Cell 3 depicting the percent of stations that each species is present. .................................................................................................................... 41
Figure 28. Relative cover of Najas guadalupensis, Utricularia spp., and Hydrilla verticillata in Cell 3 of the Caloosahatchee wetland during October and December 2014, and February, April, and June 2015. The black dots represent the observation locations, and the six semi-quantitative density categories are shown in the legend. ........................................................ 42
5
ListofTables Table 1. Analytical methods used for laboratory analysis of surface water sampled for the
Caloosahatchee FAVT project. Method detection limits (MDL) are shown for each chemical parameter analyzed. ................................................................................................................ 14
6
ExecutivesummaryWater& Soil Solutions, LLC (WSSLLC) has deployed an approximately 523‐acre Floating
AquaticVegetativeTilling(FAVT)wetlandtreatmentfacilityintheHendry‐HilliardWater
ControlDistrict (HHWCD) in theEastCaloosahatcheeRiver Sub‐Watershed southwestof
LakeOkeechobee.Thepurposeoftheprojectistocosteffectivelyremovephosphorus(P)
and nitrogen (N) from regional canals, including surface waters of the HHWCD and the
Caloosahatchee River (C‐43 Canal), using the patented FAVT technology in aman‐made
flow‐throughtreatmentmarsh.
FAVTsystemsutilizeanovelapproachtoenhanceNandPremoval fromsurfacewaters.
Thetechnologyusesthedirectassimilationofnutrientsfromthewatercolumnthroughthe
use of floating plant roots (as compared to plants rooted in the soil) and, rather than
periodically harvesting the plants (which is costly and inefficient due to the highwater
contentof thevegetation),allof thebiomass israpidly incorporateddirectly intothesoil
via tilling during the dry season. FAVT systems therefore operate similarly to a
conventional treatmentwetland by storing P in the soil, but they accomplish P removal
moreefficientlyandatasignificantlyfasterrate. Atthissite,FAVspeciescommontothe
adjacentcanals,namelyEichhorniacrassipes (waterhyacinth)andPistiastratiotes (water
lettuce),areutilizedinthefronttwocells,whileNajasguadalupensis,Utriculariaspp.,and
otherspeciesofsubmergedaquaticvegetation(SAV)dominatethebackend(Cell3)asa
final,“polishing”,componentoftheFAVTsystem.
Thesystembecamefullyoperational inSeptember2014,receivingregionalsourcewater
anddischargingthroughtheoutflowculvertsbeginning9/15/14.Subsequentmonitoring
of system inflow and outflow water chemistry was conducted on a weekly basis.
Monitoring results through June2015showthat systemoutflowTPconcentrationswere
consistently lower than inflow TP concentrations, despite highly variable inflow TP
concentrationsrangingaslowas35µg/L,duringthedryseason,andashighas325µg/L,
during thewet season. Outflow TP concentrations ranged from 22 to 62 µg/L, with the
highest concentrations occurring during the first two months of system discharge
(September‐October 2014). During the remainder of the monitoring period outflow TP
7
concentrationsbecame increasinglystable,averaging29µg/Landranging from22to38
µg/L. OverallmeanTPconcentrationsintheinflowandoutflowstreamswere74and33
µg/L, respectively.Soluble reactiveP (SRP)concentrationswereconsiderably reduced in
theoutflowstream,fromanaverageof24µg/Lattheinflowto2µg/Lattheoutflow.On
average,SRPaccountedfor33percentofTPintheinflowstream,butonly7percentofTP
in the outflow stream. The reduction in SRP concentration is assumed to be largely
attributable to plant uptake. Dissolved organic P (DOP) and particulate P (PP)
concentrationswerealsoeffectivelyreducedbytheFAVTsystem.
TPmonitoringattheinflowandoutflowofeachofCells1,2and3beginninginNovember
2014indicatedthatmostofthePremovalhasoccurredacrossCells1and2.Furthermore,
TPconcentrationsattheCell1and2outflowsdecreasedovertime,whileconcentrationsat
the Cell 3 outflow showed little or no overall change over time. This could be due to a
numberoffactors,includingreleaseofsoilPtotheoverlyingwaterinCell3,enhancedby
decreasing Cell 2 outflow concentrations, and a limited capacity for P removal via plant
uptakeduringestablishmentofrobustSAVcommunitiesinCell3.
Internal monitoring of TP and SRP at 15 sites within Cells 1 and 2 during June 2015
indicated that P removalwithin thewetland followed a predictable spatial pattern,with
gradualreductionsinTPconcentrationsoccurringinCell1asdistanceincreasedfromthe
inflowthroughthecell.TPlevelsinthebacktwo‐thirdsofCell2wereextremelylow,at15
µg/Lor less.Theobserved spatial trends inTP suggest thatmuchof thepumped inflow
waterpreferentiallypassesalongtheeasternsideofCell1.Thebioavailablephosphorous
(SRP) results,manyofwhichwerebelow thedetection limitof2µg/L, also support this
hypothesis,with highest SRP levels observed along the easternportion of the flowpath.
PlantcoveranddensityalsomayaffecttheobservedspatialpatternsinPremoval,andthis
willbeatopicoffutureassessmentatthisfacility.
Total N (TN) concentrations were not effectively reduced during the 2014‐2015
monitoring period. The overallmean outflow TN concentrationwas slightly higher than
meaninflowTN(1.48vs.1.39mg/L,respectively).NearlyalloftheTNloadtothesystem
was inorganic form, representingasubstantialpoolofN that isnot readilybioavailable.
8
Although some decomposition of organic N, and subsequent removal of inorganic N, is
likelyoccurring in thewater column, it is alsopossible that releaseofN from the soil is
serving to maintain elevated N concentrations in the overlying water during the early
stagesofoperationofthisrecently‐floodedsystem.Waterchemistrymonitoringduringthe
upcomingyearwill likelyprovideagreaterunderstandingof theshort‐and long‐termN
removalcapacityofthetreatmentsystem.
In order to evaluate vegetation growth and health, visual assessments of speciation and
areal coverage (i.e., relative abundance) of FAV (Cells 1 and 2) and SAV (Cell 3) were
performedonaroutinebasisatstations locatedonapre‐determinedgridpatternacross
Cells 1 (21 stations), 2 (33 stations) and 3 (53 stations). These surveyswere conducted
monthlyfromOctober2014throughJune2015.Resultsofthesurveysindicatedthatdense
growthofwaterhyacinthincreasedincoveragefrom56%to95%inCell1andfrom33%
to93%inCell2,withaslightdecreaseincoverageobservedattheendofthemonitoring
period.DensegrowthofPistiaoccurredat22%ofthestationsinCell1and13%ofstations
inCell2duringtheOctobersurvey,andreachedamaximumcoverageofonly30%inCell1
and19%inCell2, inFebruaryandMarch,respectively,beforedecreasingslightlyduring
theremainderoftheperiod.AmongeightSAVspeciesmonitoredinCell3,Utriculariaand
Najas (during later surveys) were by far the most commonly occurring. Utricularia
maintained a relatively dense growth across the majority of Cell 3 during the entire
monitoring period, whileNajas increased from sparse coverage in October to relatively
dense growth in 70% of Cell 3, mostly toward the inflow and outflow regions.Hydrilla
verticillataappearedinNovember,increasingincoverageslowlythroughearlyspring,and
morerapidlythereafter,andattaininganestimatedcoverageof45%ofthetotalareaofthe
Cell 3 during the June2015 survey. Continuedmonitoring of both SAV andFAVwill be
performedinFY2016,inordertoenhancesystemoperationsandmanagementpractices,
and to facilitate our understanding of spatial and temporal patterns in TP removal
performance.
9
IntroductionWater&SoilSolutions,LLC(WSSLLC)hascompletedthefirst fullyearofoperationofan
approximately 523‐acre Floating Aquatic Vegetative Tilling (FAVT) wetland treatment
facilityintheHendry‐HilliardWaterControlDistrict(HHWCD)intheEastCaloosahatchee
River Sub‐Watershed southwest of Lake Okeechobee. The watershed is located in the
NorthernEvergladeswestofLakeOkeechobee.Theprojectsiteispartofalargeparcelof
privateland(Sections18&19/Township44South/Range32East)onthesouthernside
of the Caloosahatchee River (Figure 1). The purpose of the project is to cost effectively
removephosphorus(P)andnitrogen(N)fromregionalcanals,includingsurfacewatersof
the HHWCD and the Caloosahatchee River (C‐43 Canal), using the patented FAVT
technology in aman‐made flow‐through treatmentmarsh. This document encompasses
theFinalReportfortheprojectperiodJuly1,2014throughJune30,2015.
10
ProjectSite
Figure1.Projectlocationwithinthewatershed(Source–CaloosahatcheeRiverWatershedProtectionPlanJanuary2009).
11
FAVTSystemUnitProcesses
FAVTsystemsutilizeanovelapproachtoenhanceNandPremoval fromsurfacewaters.
ManyspeciesofFAV,suchaswaterhyacinth,areknowntorapidlyassimilateNandP,but
their high nutrient uptake rate can only be sustained if the plants aremaintained at an
optimaldensity.The ideal coverage is usually achievedbyperiodicharvesting; however,
since FAV are predominantly water, mechanical removal of the biomass is costly and
inefficient.FAVTovercomestheseconstraintsbyusingthefollowingoperationalapproach:
(1)theFAVwetlandisoperatedforaninitialgrowingseason,duringwhichtimetheFAV
assimilatenutrientsandgrowtoahighdensity;(2)thewetlandisdrainedduringthedry
season,therebystrandingtheFAVonthesoil;(3)afteranaturaldryingprocess,theplant
material is tilled into the soil togetherwith its associated nutrients; (4) thewetland is
reflooded;and(5)FAVthatarestoredindeeperzonesareusedtorepopulatethewetland
for the subsequent growth period. During this post‐tilling process, water is held in the
wetlandwithoutdischargeforseveralweekstoprovidetimeforthevegetationandwater
columnnutrient levels to equilibrate. It is anticipated that tillingwill beperformedon a
yearlybasis(approximately)attheProjectsite.
FAVTsystemsthereforeoperatesimilarlytoaconventionaltreatmentwetlandbystoringP
inthesoil,buttheyaccomplishPremovalmoreefficientlyandatasignificantlyfasterrate.
Thetechnologyusesthedirectassimilationofnutrientsfromthewatercolumnthroughthe
useoffloatingplantroots(ascomparedtoplantsrootedinthesoil),andallofthebiomass
israpidlyincorporateddirectlyintothesoilthroughtilling.Theprocesstherebyresultsina
reductionofup to80%of landneeded for treatmentascomparedto traditionalwetland
treatment systems. It isexpected that theFAVTsystemswillprovideP reductions in the
rangeof3to15gP/m2‐yr,dependingonthegrowthrateoftheFAV,whichwillbelinkedto
factorssuchas theP loadingrate,speciationofP inthe inflowwaters,andavailabilityof
inorganic N and other macro‐ and micro‐nutrients in the inflow waters. Similarly, N
removalcanbeextremelyhighinFAVsystems(upto250gN/m2‐yr)whenthesupplyof
inorganicNishighintheinflowwaters.AnefforttoestimatetotalPandNmassremoval
bytheEastCaloosahatcheeRiverProjecthasnotyetbeenmadeduetouncertaintiesofkey
underlyingvariables,suchaswateravailabilityandnutrientlevels.
12
At this site, FAV species common to the adjacent canals are being utilized, for example,
Eichhornia crassipes (water hyacinth). Maximum growth (and P uptake) rates of this
species occur in the summer, which coincides with the periods of highest runoff flows
availablefortreatment.
Asnotedabove,soilsaretheultimatestoragereservoirforPwithinalltreatmentwetlands.
In conventional, emergent plant based wetlands such as the front‐end cells of the
Everglades Stormwater Treatment Areas (STAs), most of the soil P is associated with
organicmatterwith lesseramounts associatedwithminerals suchas calcium, aluminum
andiron.AnimportantaspectoftheFAVTtillingapproachisthatitacceleratestherateof
transferringnotonlyP,butalsoorganicmatterand inorganicP‐sorbingcompounds into
permanentstorage.
Optimization&MonitoringResultsThegoalofthisoptimizationandmonitoringeffortistocollect,analyzeandreportwater
quality, water flow, vegetation and soil data to facilitate optimization of the East
CaloosahatcheeFAVTsysteminanenvironmentallysoundmannerandinaccordancewith
establishedprotocols.
WaterChemistryintheFAVTsystem
Thesystembecamefullyoperational inSeptember2014,receivingregionalsourcewater
anddischargingthroughtheoutflowculverts,beginning9/15/14.Subsequentmonitoring
ofsysteminflowandoutflowwaterchemistrywasconductedonaweeklybasis.Resultsof
ongoingwaterqualitymonitoringarepresentedfortheperiod9/15/14–6/30/15.
Water samples collected during each event were analyzed for the parameters listed in
Table1,usingstandardmethodsofanalysis.DissolvedorganicP(DOP)andparticulateP
(PP)werecalculatedfromTP,SRPandTSP(DOP=TSP‐SRPandPP=TP‐TSP);totalN(TN)
was calculated as the sum of TKN and NOx‐N. pH was measured on site during each
samplingevent.
13
Additionalweeklymonitoring,forTPandpHonly,wasconductedattheoutflowsofCells1
and2(equivalenttotheinflowsofCells2and3,respectively),startinginNovember2014.
The objective of this supplemental monitoring is to evaluate water chemistry changes
withineachofthethreesystemcells.Forthispurpose,thesysteminflowandoutflowdata
representtheCell1inflowandCell3outflow,respectively.
During June 2015, internal monitoring of selected water quality constituents (e.g., total
phosphorus[TP],solublereactiveP[SRP])wasperformedtobettercharacterizethespatial
watertreatmentpatternswithinthefloatingaquaticvegetation(FAV)dominatedportions
ofthewetland(i.e.,Cells1and2).TheinternalwatersamplinggridisshowninFigure2.
14
Table1.AnalyticalmethodsusedforlaboratoryanalysisofsurfacewatersampledfortheCaloosahatcheeFAVTproject.Methoddetectionlimits(MDL)areshownforeachchemicalparameteranalyzed.
Figure2.InternalwaterqualitysamplinglocationsinCells1and2oftheFAVTfacilityduringJune2015.
Parameter Method MDL
Total Phosphorus (TP) SM4500‐P F 3 µg/L
Soluble reactive P (SRP) SM4500‐P F/DBE SOP OPO4 2 µg/L
Total Soluble Phosphorus (TSP) SM4500‐P F 3 µg/L
Alkalinity EPA 310.1 3 mg CaCO3/L
Nitrate + nitrite (NOx‐N) EPA/353.2/SM4500 NO3‐F 0.003 mg/L
Total ammonia (NH3+NH4) EPA 350.11 0.020 mg/L
Total Kjeldahl Nitrogen (TKN) EPA 351.2 0.08 mg/L
15
Characterizationofinflowandoutflowwaterchemistry
During the September 2014 – June 2015 monitoring period, system outflow TP
concentrationswere consistently lower than inflowTP concentrations (Figure3). Inflow
TPconcentrationswerehighlyvariable,rangingaslowas35µg/L,duringthedryseason
(February 2015), and as high as 325 µg/L, during the wet season. Outflow TP
concentrations ranged from 22 to 62 µg/L, with the highest concentrations occurring
during the first twomonths of system discharge (September‐October 2014). During the
remainderofthemonitoringperiodoutflowTPconcentrationsbecameincreasinglystable,
averaging29µg/Landrangingfrom22to38µg/L.OverallmeanTPconcentrationsinthe
inflowandoutflowstreamswere74and33µg/L,respectively.
SolublereactivePconcentrationwasconsiderablyreducedintheoutflowstream,relative
to inflow concentration (Figure 4). Inflow SRP concentrations averaged 24 µg/L, but
rangedwidely,from6to171µg/L,duringthemonitoringperiod.Incontrast,outflowSRP
concentrationswereconsistentlybelow10µg/L,rangingfromnon‐detectable(<2µg/L)to
7µg/Landaveraging2µg/L.Onaverage,SRPaccountedfor33percentofTPintheinflow
stream,butonly7percentofTPintheoutflowstream.ThereductioninSRPconcentration
isassumedtobelargelyattributabletoplantuptake.
ConcentrationofDOP,whichisnotreadilyavailableforplantuptake,wasslightlylowerin
theoutflowstreamthanintheinflowstreamduringmostofthemonitoringperiod(Figure
5). The overallmean inflowDOP concentrationwas 23µg/L, comparedwith an outflow
mean concentration of 15 µg/L. Inflow DOP concentrations were considerably more
variable,rangingfrom10to66µg/L,relativetooutflowDOPconcentrations,whichranged
from 8 to 25 µg/L. On average, the proportion of DOP as a fraction of total P increased
betweenthesysteminflowandoutflow,from32to46percentofTP,reflectingthelower
bioavailabilityofDOPversusSRP.
ParticulatePconcentrationsdecreasedbetweenthesysteminflowandoutflowduringthe
majorityof themonitoringperiod (Figure6),with inflowandoutflowPP concentrations
averaging 26 and 16 µg/L, respectively. Inflow PP concentrationswere somewhatmore
variable,rangingfrom8to172µg/L,whileoutflowPPconcentrationsrangedfrom2to40
16
µg/L. The stability in outflow PP concentration relative to inflow PP is indicative of
effectivesettlingofparticulatesoverawiderangeofinflowPconcentrations.
DuringtheSeptember‐Junemonitoringperiod,TNconcentrationsintheinflowandoutflow
streamsweresimilar(Figure7),reflectinglittleornonetremovalofNduringthisperiod.
InflowTNconcentrationsrangedfrom1.02to2.19mg/L,whileoutflowTNconcentrations
weremorevariable,rangingfrom0.93to2.30mg/L.TheoverallmeanTNconcentrationin
the outflow streamwas slightly higher than themean inflowTN concentration (1.48 vs.
1.39 mg/L, respectively). Only a small fraction of the TN load to the system was in
inorganicform,eitherasNOx‐Norammonia‐N(Figure8andFigure9).Thelargefractionof
organic N in the system inflow represents a substantial pool of N that is not readily
bioavailable. Although mineralization of this organic N (decomposition of organic N to
ammonia‐N)islikelyoccurringwithinthewetland,itisalsopossiblethataneteffluxofsoil
organicN(includingsoilorganicmatteroriginatingfrommanure)isoccurringduringthe
early stages of operation of this recently‐flooded system. Within the much smaller
inorganic N pool in the system inflow, there is evidence of depletion of NOx‐N either
throughplantuptakeordenitrification, andammonia‐Nviaplantuptakeornitrification.
Thus,itislikelythatnetremovalofTNfromthecombinedsoil‐watersystemhasoccurred,
butthatsurfacewaterTNconcentrationshaveremainedelevatedduetocontinuedsoilN
efflux.Waterchemistrymonitoringduringtheupcomingyearwilllikelyprovideagreater
understandingoftheshort‐andlong‐termNremovalcapacityofthetreatmentsystem.
Alkalinitylevelsintheinflowwateraveraged146mg(asCaCO3)/Landrangedfrom114to
188mg/L, with no obvious seasonal trend observed over the course of themonitoring
period(Figure10). Outflowalkalinityrangedfrom112to165mg/L,andwasalternately
greaterthanorlessthaninflowalkalinity,thoughtheoverallmeanvalue(141mg/L)was
similar to mean inflow alkalinity. Outflow pH was consistently higher than inflow pH
(Figure 11), likely due in part to the consumption of dissolved CO2 by submerged
vegetation(SAV) inCell3of thetreatmentsystem. InflowpHrangedfrom6.8to8.1and
averaged7.3,whileoutflowpHrangedfrom7.2to8.3andaveraged7.7.
17
Figure3.TPconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams,for the POR 9/15/14 (initiation of system discharge) through 6/30/15.Monitoring wasconductedonaweeklybasis.
Figure 4. SRP concentrations in the Caloosahatchee FAVT system inflow and outflowstreams,forthePOR9/15/14(initiationofsystemdischarge)through6/30/15.Monitoringwasconductedonaweeklybasis.
18
Figure 5. DOP concentrations in the Caloosahatchee FAVT system inflow and outflowstreams,forthePOR9/15/14(initiationofsystemdischarge)through6/30/15.Monitoringwasconductedonaweeklybasis.
Figure6.PPconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams,for the POR 9/15/14 (initiation of system discharge) through 6/30/15.Monitoring wasconductedonaweeklybasis.
19
Figure7.TNconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams,for the POR 9/15/14 (initiation of system discharge) through 6/30/15.Monitoring wasconductedonaweeklybasis.
Figure 8.Nitrate+nitrite (NOx) concentrations in the Caloosahatchee FAVT system inflowandoutflowstreams,forthePOR9/15/14(initiationofsystemdischarge)through6/30/15.Monitoringwasconductedonaweeklybasis.
20
Figure9.Ammonia‐NconcentrationsintheCaloosahatcheeFAVTsysteminflowandoutflowstreams,forthePOR9/15/14(initiationofsystemdischarge)through6/30/15.Monitoringwasconductedonaweeklybasis.
Figure10.AlkalinityintheCaloosahatcheeFAVTsysteminflowandoutflowstreams,forthePOR9/15/14(initiationofsystemdischarge)through6/30/15.Monitoringwasconductedonaweeklybasis.
21
Figure11.pH intheCaloosahatcheeFAVTsystem inflowandoutflowstreams, forthePOR9/15/14(initiationofsystemdischarge)through6/30/15.Monitoringwasconductedonaweeklybasis.
TPandpHmonitoringatcellinflowsandoutflows
Water chemistry monitoring at the inflow and outflow of Cells 1 – 3 during November
through June revealed somewhat different temporal trends in TP concentrations among
cells.TPconcentrationintheCell1outflowwassimilarto,orslightlylowerthan,TPinthe
Cell1inflow(systeminflow)duringmuchoftheperiodfromNovembertomid‐February
(Figure12).During the remainderof themonitoringperiod,Cell 1outflowTP showeda
slightoveralldecrease,evenas inflowTPtendedto increase,suggestiveofanincreasein
plantuptakeofPduringthe2015growingseason.ThelowestTPconcentrationsintheCell
1 outflow stream were measured at the end of the reporting period during June 2015,
whenconcentrationsaveraged21µg/Landrangedfrom17to27µg/L.
Cell 2 outflow TP concentration decreased as Cell 2 inflow (same as Cell 1 outflow) TP
concentrationtrendeddownward,withlowerTPlevelsmeasuredintheoutflowduringthe
majorityofthemonitoringperiod(Figure13)reflectingadditionalPremovalinCell2.As
observedfortheCell1outflow,thelowestTPconcentrationsintheCell2outflowoccurred
duringthelatterpartofthemonitoringperiod,inMayandJune.Duringthosemonths,Cell
2outflowTPaveraged14µg/Landrangedfrom12to18µg/L.
22
In contrast to Cells 1 and 2, TP concentrations in the Cell 3 outflow (system outflow)
showedno overall trendduring theNovember – Juneperiod, as indicated earlier in this
report,despitethedecreasingtrendinTPconcentrationintheCell2outflow/Cell3inflow
(Figure14).Thiscouldbeduetoanumberoffactors,includingdiffusivefluxofsoilPtothe
overlying water, enhanced by decreasing Cell 2 outflow concentrations, and a limited
capacityforPremovalviaplantuptakeduringestablishmentofrobustSAVcommunitiesin
Cell3.
Monitoringofcell inflowsandoutflowsalsoshowsaminimalchange inpHacrossCell1
(from inflow to outflow), although during June the Cell 1 outflow pH decreased to
approximately0.3unitslowerthaninflowpH(Figure12).Conversely,pHincreasedacross
Cell 2, especially during the 2015 growing season, while both inflow and outflow pH
trendeddownwardovertime(Figure13).AfurtherincreaseinpHwasobservedbetween
theinflowandoutflowofSAV‐dominatedCell3throughoutmostofthemonitoringperiod,
contributing to the overall net increase in pH between the system inflow and outflow
(Figure14).UnlikeCells1and2,theCell3outflowpHdidnotexhibitadetectabletemporal
trendduringtheNovember‐Junemonitoringperiod.
Figure15summarizestheoverall lineartrend inTPconcentrationalongthesystemflow
path during the November 2014 – June 2015 period, for which inflow‐outflow TP was
monitoredsimultaneouslyforCells1,2and3.ThemeansysteminflowTPconcentrationof
65µg/Lduringthatperioddecreasedtoameanvalueof38µg/LattheCell1outflowand
furtherdecreasedto27µg/LattheCell2outflow.Thesimultaneousdecreaseovertimein
Cell 2 outflow TP concentration and lack of change in Cell 3 outflow TP concentration
(Figure 14) is reflected in Figure 15 as a slight increase in the overallmean outflowTP
concentration (29 µg/L) as compared tomeanCell 2 outflowTP. Standard deviations of
meanTPconcentrationsatthecellinflowandoutflowpointsreflectasubstantialdecrease
intemporalvariabilityinTPconcentrationsalongthesystemflowpath,andareindicative
ofsubstantialattenuationwithinthesystemofhighlyfluctuatinginflowTPconcentrations
observedduringthemonitoringperiod.
23
Changes in pH across sequential treatment cells are summarized in Figure 16.Mean pH
valuesfortheNovember‐JuneperiodindicatethesmalldecreaseinpHobservedbetween
thesysteminflowandCell1outflow,andsubsequentincreasesinpHacrossCells2and3.
ThemeanpHof7.34at thesysteminflowdecreasedslightly toameanpHof7.31atthe
Cell1outflow,whilethemeanpHvaluesfortheCell2andCell3outflowswere7.53and
7.74,respectively.
24
Figure12.SurfacewaterTPconcentrationandpHattheinflowandoutflowofCell1oftheCaloosahatcheeFAVTsystem.MonitoringwasconductedonaweeklybasisfromNovember2014throughJune2015.
25
Figure13.SurfacewaterTPconcentrationandpHattheinflowandoutflowofCell2oftheCaloosahatcheeFAVTsystem.MonitoringwasconductedonaweeklybasisfromNovember2014throughJune2015.
26
Figure14.SurfacewaterTPconcentrationandpHattheinflowandoutflowofCell3oftheCaloosahatcheeFAVTsystem.MonitoringwasconductedonaweeklybasisfromNovember2014throughJune2015.
27
Figure 15. Mean surface water TP concentration (±1 standard deviation) at the systeminflow (=Cell1 inflow),Cell1outflow (=Cell2 inflow),Cell2outflow (=Cell3 inflow),andsystemoutflow(=Cell3outflow)oftheCaloosahatcheeFAVTsystem.Valueswerecalculatedfromdatacollectedduring34weeklymonitoringeventsfromNovember2014throughJune2015.
Figure 16.Mean surfacewater pH (±1 standard deviation) at the system inflow (=Cell 1inflow),Cell1outflow (=Cell2 inflow),Cell2outflow(=Cell3 inflow),andsystemoutflow(=Cell 3 outflow) of the Caloosahatchee FAVT system. Valueswere calculated from datacollectedduring34weeklymonitoringeventsfromNovember2014throughJune2015.
28
InternalwaterchemistrymonitoringofCells1and2
ResultsofinternalmonitoringofTPandSRPindicatedthatPremovalwithinthewetland
followed a predictable spatial pattern, with gradual reductions in TP concentrations
occurringinCell1asdistanceincreasedfromtheinflowthroughthecell.TPlevelsinthe
backtwo‐thirdsofCell2wereextremelylow,at15µg/Lorless(Figure17).Theobserved
spatial trends inTP suggest thatmuchof thepumped inflowwaterpreferentiallypasses
alongtheeasternsideofCell1.Thebioavailablephosphorous(SRP)results,manyofwhich
werebelow thedetection limit of2µg/L, also support thishypothesis,withhighest SRP
levels observed along the eastern portion of the flow path (Figure 17). Plant cover and
densityalsomayaffecttheobservedspatialpatternsinPremoval,andthiswillbeatopic
offutureassessmentatthisfacility.
29
Figure17.InterpolatedspatialTPprofilesinCells1and2(top),andindividualdatapointsforSRP(notinterpolated)forCells1and2(bottom),fortheinternalwaterqualitymonitoringeventinJun2015.NotethatmostSRPvaluesinCells1and2werebelowthedetectionlimit,sonointerpolationofthesedatawasperformed.
30
FloatingandSubmergedAquaticVegetationSurveys
Visualassessmentofspeciationandarealcoverage(i.e.,relativeabundance)ofFAV(Cells1
and 2) and SAV (Cell 3)was performed on a routine basis at stations located on a pre‐
determinedgridpattern acrossCells 1 (21 stations), 2 (33 stations) and3 (53 stations).
These surveys were conducted monthly from October 2014 through June 2015. Survey
dates were 10/28/14, 11/30/14, 12/30/14, 1/30/15, 2/24/15, 3/30/15, 4/30/15,
5/27/15,and6/23/15.
DuringturbidwaterconditionsorwhenSAVwasnotvisibleinthewatercolumn,theSAV
assessment in Cell 3 was performed using a systematic collection method, whereby a
garden rake was dragged three times along the bottom (~1 m distance) to collect the
vegetation. Note that this rake method was not used if dense SAV was present. The
coverageofeachspecieswasscoredbasedonthefive‐pointscalebelow.ForSAV,eachof
thesecoveragecategoriesincludedvegetationobservedwithinthewatercolumnaswellas
anyvegetationcollectedwiththerake.
Vegetationcoverage(relativeabundance)categorieswerereportedasfollows:
None Sparse:0–10percent ModeratelyDense:10–40percent Dense:10–80percent Verydense:>80percent
Resultsof theFAVsurveysreflectamonthly increase inmoderately‐dense tovery‐dense
(hereafterreferredtoas“dense”)coverageofwaterhyacinth(Figure18)inCells1and2
between late October 2014 andmid‐February 2015 (Figure 19). In Cell 1, the extent of
“dense” hyacinth coverage increased from 56 to 95 percent of stations during this time
period, then remained relatively constant, at ca. 90 percent of stations, during the
subsequent months, through June 2015. During the same time periods, the extent of
“dense”hyacinthcoverage inCell2 increasedfrom33percent to81percent, thenvaried
between67and93percent.Duringallbutonemonitoringevent“dense”hyacinthcoverage
wasgreaterinCell1thaninCell2,presumablyduetothehigherconcentrationsofplant‐
available nutrients in Cell 1. Hyacinthwas present at all stations in Cell 1 during every
31
monitoring event, while in Cell 2 hyacinth was found at all stations during all but two
events(Figure20).
CoverageofPistiastratiotes(waterlettuce)wasconsistentlylowerthanhyacinthcoverage,
in both cells (Figure 21). In Cell 1, “dense” coverage ofPistiawas found at less than 30
percentofstationsduring thecourseof themonitoringperiod(Figure19).Theextentof
“dense”coveragedecreased to less than10percentduringMarch through June inCell1.
Initial “dense”coverageofPistiawas lower inCell2 than inCell1,but theextentof this
coverage slowly increased to 19 percent by the end of March. During the subsequent
monitoringevents(April–June),“dense”Pistiacoveragedecreasedtolessthan15percent.
PresenceofPistia,atalldensities,wasinitiallyhighinCell1(94percentofstations),but
thefrequencyofoccurrencedecreasedsteadilythroughMarchto24percent(Figure20).
PistiawasmorefrequentlyobservedinCell2thaninCell1,primarilyatverylowdensities,
during all but the first monitoring event in late October, when it was found at only 20
percentof stations.During the last survey in themonitoringperiod (June23),Pistiawas
presentat19percentofstationsinCell1and43percentofstationsinCell2.
The spatial distributionsof hyacinth andPistia are shown forbi‐monthly intervals, from
October2014throughJune2015,inFigure22.Thetimeseriesofcoveragemapsatthetop
ofthefigureshowthespreadofmoderatetoverydensehyacinthtowardtheCell1inflow
and Cell 2 outflow during theOctober – April period. A slight decrease in coveragewas
observed in the western portion of Cell 2 during June, likely due to wind‐induced
movement of the plants. Relatively dense stands of Pistia filled in considerably from
OctoberthroughDecembertowardtheCell2inflowandoutflowregions(bottomofFigure
22), and during subsequent months the coverage varied in location and total extent. In
contrast,PistiacoveragetendedtorecedetowardthesouthinCell1,downstreamfromthe
systeminflow.
32
Figure18.VerydensematofEichhorniacrassipes(waterhyacinth)andPistiastratiotes(waterlettuce)inCell1
33
Cell 1:
Cell 2:
Figure19.Time‐seriesforFAVspecieswithinCells1and2depictingthepercentofstationsthatwasmoderatelydenseorgreaterforeachspecies.
0102030405060708090100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15% of stations moderately
den
se or greater
E. crassipes P. stratiotes
0102030405060708090100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15% of stations moderately
den
se or greater
E. crassipes P. stratiotes
34
Cell 1:
Cell 2:
Figure20.Time‐seriesforFAVspecieswithinCells1and2depictingthepercentofstationsthateachspeciespresent.
0102030405060708090100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
% of stations present
E. crassipes P. stratiotes
0102030405060708090100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
% of stations present
E. crassipes P. stratiotes
35
Figure21.MixedspeciesmatwithEichhorniacrassipes(waterhyacinth)andPistiastratiotes(waterlettuce)inCell1.
36
Figure22.RelativecoveroftheFAVspeciesEichhorniacrassipesandPistiastratiotesinCells1and2oftheCaloosahatcheewetlandduringOctoberandDecember2014andFebruary,April,andJune2015.Theblackdotsrepresenttheobservationlocations,andthesixsemi‐quantitativedensitycategoriesareshowninthelegend.
37
SAV survey results for Cell 3 revealed that, out of eight species reported during the
monitoringperiod, only twospecies,Najas (Figure23) andUtricularia (Figure24),were
commonly found (greater than 50 percent of stations) at amoderate or greater density,
whileathirdspecies,Hydrilla,increaseddramaticallyincoveragebytheendoftheperiod
after being passively introduced (not inoculated) (Figure 25). Coverage of “dense”
Utriculariavariedbetween42and70percent,withnoapparenttemporaltrend,duringthe
period,whilecoverageof“dense”Najasshowedanoverallincreasethroughouttheperiod,
from9to70percent(Figure26).“Dense”Hydrilla occurredatonlyafewstationsduring
thefirstsixmonitoringevents,butsteadilyincreasedinextentthroughJuneto≥30percent
ofstations.“Dense”BacopawasobservedwithinCell3duringallmonitoringevents,butat
less than 15 percent of stations, on a consistent basis. Similarly, “dense” Chara was
observedduringallsurveys,butatonlyafewstations.Ceratophyllum,Ludwigiarepensand
Potamogetonwerefoundathigherdensitiesatonlyafewstationsandonlyduringasubset
ofmonitoringevents.
UtriculariaandNajas(duringlatersurveys)werebyfarthemostcommonSAVspeciesin
Cell 3, occurring at the majority of monitoring stations (Figure 27). Bacopa was
consistentlypresent inCell3duringallmonitoringevents,withamore limitedextentof
about10to30percentofstations.Charawasalsopresentduringallevents,butataneven
lowerspatialextentoflessthan10percent.OverallpresenceofLudwigiadecreased,while
CeratophyllumandPotamogetonwererelativelyscarcethroughoutthemonitoringperiod.
Incontrast,theoccurrenceofHydrillawasextremelylimitedduringOctober‐February,the
extentof coverage rapidly increasedduring theperiodApril‐June2015, to45percentof
stations.
The spatial extent of the most prevalent SAV species, Najas, Utricularia and Hydrilla,
exhibiteduniquespatialpatternsduring themonitoringperiod(Figure28).Forexample,
NajastendedtocolonizetheinflowandoutflowregionsofCell3overtime,whileHydrilla
proliferatedprimarilyinthemid‐regionofCell3,towardtheendofthemonitoringperiod.
UtriculariamaintainedarelativelyconsistentdensityacrossCell3forthedurationofthe
monitoring period, although the coverage became somewhat “patchy” near the Cell 3
38
inflowandoutflowregions.Changes indensityandspeciescompositionduring theearly
stages of system operation will likely continue during the short term as water and soil
chemistry across the system stabilize. In addition, inter‐specific competition will play a
largeroleintheeventualdistributionofSAVspeciesinCell3.
Continued monitoring of both SAV and FAV will be performed in FY 2016, in order to
enhancesystemoperationsandmanagementpractices,andtofacilitateourunderstanding
ofspatialandtemporalpatternsinTPremovalperformance.
Figure23.Najasguadalupensis(southernnaiad)growingneartheoutflowofCell3.
39
Figure24.MixedSAVassemblagecontainingUtriculariasp.(bladderwort)andotherspeciesinCell3.
Figure25.Hydrillaverticillata,aninvasiveSAVspecies,attheCell2culvert.
40
Figure26.Time‐seriesforSAVspecieswithinCell3depictingthepercentofstationsthatstationsthatwasmoderatelydenseorgreaterforeachspecies.
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
Bacopa spp.
% of stations moderately den
se or greater
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
C. dermersum
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
Chara
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
H. verticillata
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
L. repens
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
N. guadalupensis
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
P. illinoensis
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
Utricularia spp.
41
Figure27.Time‐seriesforSAVspecieswithinCell3depictingthepercentofstationsthateachspeciesispresent.
0
20
40
60
80
10010/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
Bacopa spp.
% of stations present
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
C. dermersum
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
Chara
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
H. verticillata
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
L. repens
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
N. guadalupensis
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
P. illinoensis
0
20
40
60
80
100
10/28/14
11/30/14
12/30/14
1/30/15
2/24/15
3/30/15
4/30/15
5/27/15
6/23/15
Utricularia spp.
42
Figure28.RelativecoverofNajasguadalupensis,Utriculariaspp.,andHydrillaverticillatainCell3oftheCaloosahatcheewetlandduringOctoberandDecember2014,andFebruary,April,andJune2015.Theblackdotsrepresenttheobservationlocations,andthesixsemi‐quantitativedensitycategoriesareshowninthelegend.