Page 1
Concentrations and speciation of potentially toxic trace elements in waters of an urban estuary; Bayou Bienvenue, New Orleans,
Louisiana
Karen Johannesson
Department of Earth and Environmental Sciences, Tulane University, New Orleans, Louisiana
http://tulane.edu/sse/eens/faculty/kjohanne/index.cfm
[email protected]
Page 2
Acknowledgements
U.S. Geological Survey
Long-term Estuary Assessment Group (LEAG)
Tulane/Xavier Center for Bioenvironmental Research
Page 3
Why Study Heavy Metals in Estuaries?
• Estuaries serve as nurseries for marine organisms
– Commercially important shell-and fin-fishes
– Shrimp, oysters, redfish
• Estuaries can act as natural “filters” for heavy metals and other pollutants
Bayou Bienvenue, Louisiana
Page 4
Why Study Heavy Metals in Estuaries?
• Current paradigm →estuaries filter heavy metals
• Reality → little is actually known about the biogeochemical cycling and transport of heavy metals in Louisiana’s numerous estuaries
Page 5
Metal Speciation
• It’s not enough to measure the concentrations of heavy metals
– Tells us little about their bioavailability, toxicity, mobility
• Need to determine speciation 0 2 4 6 8 10 12 14
–.5
0
.5
1
pHE
h (v
olts
)
Sb(OH)6-
Sb(OH)3(aq)
Sb(OH)2+
Sb(OH)5 (aq)
SbO2-
Sb2S4--
Sb2S3(c)
25°C
Karen Johannesson Tue Apr 21 2009
Page 6
Metal Speciation
• The particular chemical form that an element exists in water
– Free ion, e.g., [Cu2+]F
– Bound to organic ligands
– Complexed to inorganic ligands
– Different redox species, e.g., As3+ vs. As5+
Rf1 N1 R1 Ks1 N3 Pt1 Pcw1 Pl1 Ac Sma
Perc
enta
ge (N
d)
0
20
40
60
80
100
Nd3+
NdHMNdCO3
+
Nd(CO3)2-
NdSO4+
NdPO4o
Rf1 N1 R1 Ks1 N3 Pt1 Pcw1 Pl1 Ac Sma
Per
cent
age
(Gd)
0
20
40
60
80
100
Gd3+
GdHMGdCO3
+
Gd(CO3)2-
GdSO4+
GdPO4o
Rf1 N1 R1 Ks1 N3 Pt1 Pcw1 Pl1 Ac Sma
Perc
enta
ge (E
r)
0
20
40
60
80
100
Er3+
ErHMErCO3
+
Er(CO3)2-
ErSO4+
ErPO4o
7.32 6.79 6.55 6.64 6.13 6.48 7.38 8.34 8.68 8.12
Page 7
Metal Speciation
• Speciation controls trace element’s:
• Bioavailability
– Free-ion activity model
• Toxicity
– As3+ is 10 – 60 more toxic than As5+
• Effective solubility
• Mobilization and transport in the environment
Page 8
Methods/Description
• Collect series of surface waters samples along Bayou Bienvenue
• Ultra clean trace element techniques
• Clean hands – dirty hands
Page 10
Bayou Bienvenue
Dr. Alex Kolker from LUMCON will assist us with boat time
Page 11
Bayou Bienvenue
Blue dots show sampling sites on Bayou Bienvenue
Page 12
Speciation Analysis
• Filtration
• Unfiltered samples
• Filtered through 0.45 um– colloidal
• Filtered through 0.02 um– “truly dissolved”
Page 13
Trace Element Analysis
• Inductively Coupled Plasma Mass Spectrometry
• As, Se, Sb, Cr, Pb, Ni, Zn, Tl, Mo, W, V, U
• Fe, Mn
• Measure in each filtration aliquot
Organic carbon will be determinedin each aliquot too.
Magnetic Sector ICP-MS at Tulane University
Page 14
Partition Coefficients
• KdPOC-DOC = {[MPOC]/[POC]}/[MDOC]/[DOC]
• KdCOC-DOC = {[MCOC]/[COC]}/[MDOC]/[DOC]
• [POC], [COC], & [DOC] are the concentration of particulate, colloidal, and dissolved organic carbon, respectively.
• [MPOC], [MCOC], & [MDOC] are the concentration of individual trace elements associated with different size fractions of OC.
• MPOC > 0.45 um• 0.45 um ≥ MCOC ≥ 0.02 um• MDOC < 0.02 um
Page 15
Lanthanide Series
Page 16
Anthropogenic Gd anomalies
• Gd is used in medical magnetic resonance imaging
• Gd has high magnetic moment
• Administered as:
• Gadodiamide
• gadopentetic acid
• Gd-diethylenetriaminepenta-acetate, i.e., Gd(DPTA)
Kilometer0 2 4 6 8 10 12 14 16
Gd
Ano
mal
y
1.4
1.6
1.8
2.0
2.2
2.4Elizabeth River, Norfolk, Virginia
Town Point Park
Naval Base
ER10
ER13
ER8
ER6
ER4
Gd/Gd* = log{GdNASC/(2TbNASC - DyNASC)}
WWTP Effluent
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Wat
er/N
ASC
1e-6
Page 17
Anthropogenic Gd anomalies
• We will measure the lanthanide series elements in aliquots of our Bayou Bienvenue samples
• Direct measure of anthropogenic influences on these waters
Kilometer0 2 4 6 8 10 12 14 16
Gd
Ano
mal
y
1.4
1.6
1.8
2.0
2.2
2.4Elizabeth River, Norfolk, Virginia
Town Point Park
Naval Base
ER10
ER13
ER8
ER6
ER4
Gd/Gd* = log{GdNASC/(2TbNASC - DyNASC)}
WWTP Effluent
La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Wat
er/N
ASC
1e-6
Page 18
Anthropogenic Gd anomalies
• Non-impacted estuaries do not have substantial Gd anomalies
• Indian River Lagoon in Florida
Indian River Lagoon, Florida
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Wat
er/P
AAS
1e-7
1e-6
1e-5
1e-4
1e-3
Johannesson et al. (in prep)