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

kjohanne@tulane.edu

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)