Concentrations and speciation of potentially toxic trace...
Transcript of Concentrations and speciation of potentially toxic trace...
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
Acknowledgements
U.S. Geological Survey
Long-term Estuary Assessment Group (LEAG)
Tulane/Xavier Center for Bioenvironmental Research
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
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
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
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
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
Methods/Description
• Collect series of surface waters samples along Bayou Bienvenue
• Ultra clean trace element techniques
• Clean hands – dirty hands
Bayou Bienvenue
Bayou Bienvenue
Dr. Alex Kolker from LUMCON will assist us with boat time
Bayou Bienvenue
Blue dots show sampling sites on Bayou Bienvenue
Speciation Analysis
• Filtration
• Unfiltered samples
• Filtered through 0.45 um– colloidal
• Filtered through 0.02 um– “truly dissolved”
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
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
Lanthanide Series
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
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
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)