Post on 16-Dec-2015
An REU Experience and An REU Experience and Research Project: Research Project:
Photolysis of DOM Produced Photolysis of DOM Produced by a Marine Cyanobacteria by a Marine Cyanobacteria
in the Gulf of Mexicoin the Gulf of Mexico
byby
Michael D’AmicoMichael D’Amico
Karenia Karenia BrevisBrevis
HAB’sHAB’s
TrichodesmiuTrichodesmiumm
??
??
Photoproduction of Labile Photoproduction of Labile Substrates from Dissolved Substrates from Dissolved Organic Matter Produced Organic Matter Produced
by by TrichodesmiumTrichodesmiumMichael D’AmicoMichael D’Amico
Mentored byMentored by
Dr. Deborah BronkDr. Deborah Bronk&&
Marta SandersonMarta Sanderson
Processes of photochemical transformation of DOM play Processes of photochemical transformation of DOM play an important part in the global marine biogeochemical an important part in the global marine biogeochemical
cycle. cycle.
DOMDOMPhytoplankton
NHNH44++ NO NO22
-- DPA PO DPA PO443-3-
Trichodesmium Bloom
•Hypothesis:Hypothesis:Water withWater withTrichodesmiumTrichodesmium DOM DOM will have higher rates of will have higher rates of photoproduction than those photoproduction than those without.without.
•Goal:Goal: To quantify rates of DOM To quantify rates of DOM photoproduction of NHphotoproduction of NH44
++, NO, NO22--, DPA, , DPA,
and POand PO443-3- in filtered sea water and in filtered sea water and
water containing DOM produced by water containing DOM produced by TrichodesmiumTrichodesmium..
0.2µm filtered seawater from chlorophyll max0.2µm filtered seawater from chlorophyll max
Incubated in flow through Incubated in flow through seawater tubseawater tub
At 3 hrs. and dusk (~12 hrs.) At 3 hrs. and dusk (~12 hrs.) samples from each bottle were collectedsamples from each bottle were collected
This was done for two experiments in the Gulf of MexicoThis was done for two experiments in the Gulf of Mexico
Sea WaterSea WaterSea Water + Sea Water +
Trichodesmium DOMTrichodesmium DOM
Quartz Quartz DarkDark
TrichodesmiumTrichodesmium DOMDOM2 days prior to each experiment,2 days prior to each experiment,
• Plankton tows using a 64Plankton tows using a 64μm mesh net at μm mesh net at 10m for 10 minutes collected 10m for 10 minutes collected TrichodesmiumTrichodesmium..
•Approx. 1000 colonies of Approx. 1000 colonies of TrichodesmiumTrichodesmium were incubated in 0.2μm Supor filtered were incubated in 0.2μm Supor filtered seawater for 24 hours.seawater for 24 hours.
•At 24 hours, the water containing At 24 hours, the water containing TrichodesmiumTrichodesmium was filtered through a was filtered through a 0.2μm Supor filter, and refrigerated 0.2μm Supor filter, and refrigerated overnightovernight
Chemical AnalysesChemical Analyses
NHNH44+ + concentrationsconcentrations and and POPO44
3-3-
concentrationsconcentrations::•spectrophotometer spectrophotometer •Grasshoff et al. (1983) colorimetric.Grasshoff et al. (1983) colorimetric.
NONO22- - concentrationsconcentrations::
•Alpkem Flow Solution IV nutrient Alpkem Flow Solution IV nutrient autoanalyzerautoanalyzer•Parsons et al. (1984)Parsons et al. (1984)
DPA concentrationsDPA concentrations::•SpectrofluorophotometerSpectrofluorophotometer•Parsons et al. (1984)Parsons et al. (1984)
Photoproduction and Photoproduction and consumption occurconsumption occur
NHNH44++ Photoproduction/balance between Photoproduction/balance between
consumption occursconsumption occurs
POPO443- 3- photoproduction occursphotoproduction occurs
NONO22- - is consumedis consumed
DPA concentrations showed no trendsDPA concentrations showed no trends
•P1 Seawater*:P1 Seawater*:Consumption in Consumption in darkdarkMinor consumption Minor consumption in quartzin quartz•P1 DOM P1 DOM water*:water*:Photoproduction Photoproduction @3h@3hAnd @12hAnd @12h
•P2 Seawater*:P2 Seawater*:Consumption in Consumption in darkdarkMinor Consumption Minor Consumption in quartzin quartz•P2 DOM P2 DOM water*:water*:Consumption in Consumption in darkdarkMinor consumption Minor consumption in quartzin quartz
NHNH44+ + concentrationsconcentrations
PHOTO #1
0.0000
1.0000
2.0000
3.0000
4.0000
5.0000
6.0000
3hrs 12hrs
Co
ncen
trati
on
(u
m)
PHOTO #2
0.0000
1.0000
2.0000
3.0000
4.0000
5.0000
6.0000
3hrs 12hrs
Co
ncen
trati
on
(u
m)
Ambient Dark Quartz Ambient w/DOM Dark w/DOM Quartz w/DOM
•P1 P1 Seawater*:Seawater*:Photoproduction Photoproduction @3h? Not @12h@3h? Not @12hQuartz Quartz ConsumptionConsumption•P1 DOM P1 DOM water*:water*:No No PhotoproductionPhotoproductionQuartz Quartz ConsumptionConsumption
•P2 Seawater:P2 Seawater:No No PhotoproductionPhotoproductionQuartz Quartz ConsumptionConsumption•P2 DOM P2 DOM water:water:No No PhotoproductionPhotoproductionQuartz Quartz ConsumptionConsumption
NONO22- - concentrationsconcentrations
Ambient Dark Quartz Ambient w/DOM Dark w/DOM Quartz w/DOM
PHOTO 1
0.0000
0.0500
3hrs 12hrs
Co
nce
ntr
atio
n (
um
)
PHOTO 2
0.0000
0.0500
0.1000
0.1500
0.2000
0.2500
0.3000
3hrs 12hrs
•P1 Seawater:P1 Seawater: Photoproduction Photoproduction @3h@3hAnd @12hAnd @12h•P1 DOM P1 DOM water*:water*: Photoproduction Photoproduction @3h@3hAnd @12hAnd @12h
•P2 Seawater:P2 Seawater: No No PhotoproductionPhotoproduction•P2 DOM P2 DOM water:water: Photoproduction Photoproduction @3h@3hAnd @12hAnd @12h
Ambient Dark Quartz Ambient w/DOM Dark w/DOM Quartz w/DOMPOPO44
3-3-concentrationsconcentrationsPHOTO 1
0.0000
0.0500
3hrs 12hrs
Co
nce
ntr
atio
n (
um
)
PHOTO 2
0.0000
0.0500
0.1000
0.1500
0.2000
0.2500
0.3000
3hrs 12hrs
Co
nce
ntr
atio
n (
um
)
•DPA: DPA: No No consistentconsistent trends observed trends observed
Ambient Dark Quartz Ambient w/DOM Dark w/DOM Quartz w/DOMDPA concentrationsDPA concentrations
PHOTO 1
0.0000
0.1000
0.2000
0.3000
0.4000
0.5000
0.6000
3hrs 12hrs
Co
nce
ntr
atio
n (
um
)
PHOTO 2
0.0000
0.1000
0.2000
0.3000
0.4000
0.5000
0.6000
3hrs 12hrs
Co
nce
ntr
atio
n (
um
)
Evidence for Evidence for PhotoproductionPhotoproduction
EstuaryEstuary NHNH44++, DPA, DPA Bushaw-Newton and Bushaw-Newton and
Moran (1999) Moran (1999)
EstuaryEstuary NHNH44++ Bushaw et al. (1996) Bushaw et al. (1996)
Groundwater, EstuariesGroundwater, Estuaries NHNH44++ Koopmans and Bronk Koopmans and Bronk
(2002) (2002)
Coastal WatersCoastal Waters NONO22-- Kieber et al. (1999)Kieber et al. (1999)
Lake WaterLake Water POPO443-3- Francko and Heath Francko and Heath
(1982) (1982)
Lake WaterLake Water POPO443-3- Vähätalo and Salonen Vähätalo and Salonen
(1996)(1996)
Evidence for ConsumptionEvidence for Consumption
Inconsistent TrendsInconsistent Trends
EstuaryEstuary NHNH44++ Bushaw-Newton and Moran Bushaw-Newton and Moran
(1999) (1999)
EstuaryEstuary NHNH44++ Bushaw et al. (1996) Bushaw et al. (1996)
Groundwater, EstuariesGroundwater, Estuaries NHNH44++ Koopmans and Bronk (2002) Koopmans and Bronk (2002)
Natural WatersNatural Waters NONO22-- Jankowski et al. (1999) Jankowski et al. (1999)
Natural WatersNatural Waters NONO22-- Jorgensen et al. (1998, 1999)Jorgensen et al. (1998, 1999)
Lake WaterLake Water NONO22-- Vähätalo and Salonen (1996)Vähätalo and Salonen (1996)
Groundwater, EstuariesGroundwater, Estuaries NONO22--, DPA, DPA Koopmans and Bronk (2002) Koopmans and Bronk (2002)
Diatom CultureDiatom Culture POPO443-3- Gobler et al. (1997)Gobler et al. (1997)
Fresh Water LakeFresh Water Lake POPO443-3- Jorgensen et al. (1998)Jorgensen et al. (1998)
ConclusionsConclusionsNHNH44
++::
•increasing concentrations in quartz increasing concentrations in quartz tubestubes•decreasing concentrations in dark tubesdecreasing concentrations in dark tubes
•Quartz: NHQuartz: NH44++ photoproduction photoproduction
Or Or Balance between consumption and Balance between consumption and productionproduction
•Dark: NHDark: NH44++ consumption consumption
Humics absorb NHHumics absorb NH44++
ConclusionsConclusionsNONO22
--::
•decreasing concentrations in quartz decreasing concentrations in quartz tubestubes
•Quartz: NOQuartz: NO22-- consumption consumption
Photolysis of NOPhotolysis of NO22- - in sea water:in sea water:
NONO22
-- + h + hvv → NO + → NO + OO--
ConclusionsConclusionsPOPO44
3-3-::
•increasing concentrations in quartz increasing concentrations in quartz tubestubes
•Quartz: POQuartz: PO443-3- photoproduction photoproduction
DPA ???????DPA ???????
Trichodesmium Bloom
Phytoplankton
NHNH44++ NO NO22
-- DPA DPA POPO44
3-3-
Importance:Importance:
Photoproduction of Photoproduction of labile substrates labile substrates
from DOM from DOM influences the influences the availability of availability of nutrients to nutrients to
phytoplanktonphytoplankton
DOMDOM
•Hypothesis:Hypothesis: The treatments that added water with The treatments that added water with TrichodesmiumTrichodesmium DOM will have higher rates of photoproduction DOM will have higher rates of photoproduction than those without.than those without.
•General Trends show yes in some casesGeneral Trends show yes in some cases
•Not true in all casesNot true in all cases
Mahalo!Mahalo!