Toxicity of Metal-Contaminated Sediments to Benthic Invertebrates

Department of the InteriorU. S. Geological Survey

John Besser, Bill Brumbaugh, and Chris Ingersoll

Columbia Environmental Research Center, Columbia, Missouri

TESNAR Workshop: ‘Understanding the Impacts of Mining in the Western Lake Superior Region’

September 12-14, 2011 Bad River Convention Center, Odanah, Wisconsin

1

Mining activities produce metal-contaminated sediments

• Metals enter aquatic ecosystems from mining, ore processing, and smelting.

• At neutral pH, metals tend to move from water to sediment:

– settling of particulates (e.g. mine wastes);

– precipitation of insoluble metal species;

– sorption of metals on sediment particles.

High concentrations of metals in bed sediments can lead to toxic effects on benthic organisms.

2

Applications of sediment toxicity testing

• Ecological risk assessment (e.g., Superfund)

• Document ecological injury (e.g., NRDAR)

• Pre- and post-remediation assessment

• Effluent monitoring/Toxicity Identification Evaluation

• Characterize waste or dredged material

• Establish or validate sediment quality guidelines

3

CERC mining-related sediment studies

4

Upper Columbia River (WA)

Clark Fork River (MT)

Whiskeytown NRA (CA)

San Carlos Reservoir (AZ)

Upper Animas River (CO)

Tri-State (MO/KS/OK)

Old Lead Belt (MO)

Viburnum Trend (MO)

Palmerton smelter (PA)

Vermont Copper Belt

Types of sediment test methods

• Whole-sediment toxicity testing

– Simulate natural water+sediment exposure

• Pore-water toxicity testing

– Isolate water exposure route

• Elutriate testing (sediment-water suspension)

– Effects of dredging or resuspension

• Sediment extracts or leachates

– Source identification; prioritize cleanups

5

Whole-sediment testing

6

• Goal: simulate surficial sediments and overlying water

– Allow development of limited depth gradient (3-4 cm)

– Realistic role of overlying water (water quality, replacement rate)

Whole-sediment toxicity tests

• Direct measure of effects on benthic organisms

• Support cause-effect findings

• Wide applicability

• Limited special equipment is required

• Rapid and inexpensive

• Legal and scientific precedents

• Integrates interactions of contaminant mixtures

• Amenable to field validation

7

Pore-water testing

8

• Goal: isolate aqueous exposure route

– Use standard aquatic test organisms

• Advantages:

– Simplicity and sensitivity of test methods

– Compare aqueous vs. solid-phase exposure

• Disadvantages

– Difficulty of pore-water collection

– Artifacts of testing with water-column organisms

Daphnid

Fathead Minnow

Comparison of exposure routesPalmerton smelter, PA (Besser et al. 2009)

Tested surface water, pore water, and sediment with Hyalella

Toxicity in surface water and pore water from same three sites

Limited toxicity of whole sediment (one site)

Consistent with metal inputs from groundwater seepage

Fine sediments scarce in contaminated stream reach

9

Surface water

BC1

(R)

AC8

(R)

AC6

AC5

AC2/

3AC1

LR4

(R)

LR3.

5LR

3LR

2

LR2

(D)

Su

rviv

al (o

f 10)

0

2

4

6

8

10

* * *

Green = referencePink = smelter

Yellow = downstream

Pore water

BC1

(R)

AC8

(R)

AC6

AC5

AC5

(D)

AC2/

3AC1

LR5

(R)

LR3.

5LR

30

2

4

6

8

10

*

*

*

BC1

(R)

AC8

(R)

AC6

AC5

AC2/

3AC1

LR5

(R)

LR4

(R)

LR3.

5LR

30

2

4

6

8

10

*

Sediment

Sediment vs. Pore-water testsViburnum Trend MO (Besser et al 2008a)

Whole-sediment tests with Hyalella (left) identified several toxic sites

Pore-water tests with Ceriodaphnia (right) were more sensitive, but had variable survival in reference sites (green)

Limited tolerance for PW constituents (e.g. ammonia)

10

Hyalella Ceriodaphnia

MT

01

MT

02

MT

03

MT

04

MT

06

MT

07

MT

10

MT

12

MT

14

MT

20

CL

1C

L2

CL

3C

L4

CL

5Am

ph

ipo

d s

urv

iva

l (%

)

0

20

40

60

80

100

*

*

MT14

MT12

MT3

MT4

MT2

MT1

MT10

MT7

MT6

MT20

CL3

CL2

CL5

CL4

CL1

Ce

rio

da

ph

nia

su

rviv

al (%

)

0

20

40

60

80

100

Characteristics of sediment test organisms

• Sensitivity to toxicants (metals)

• Availability / Ease of culture

• Life cycle / Potential endpoints

• Taxonomic group

• Distribution and abundance

• Ecological importance

11

Standard sediment test organisms

12

Amphipod (Hyalella) Midge (Chironomus) Oligochaete (Lumbriculus)

Mussel (Lampsilis)

Alternative test organismsMayfly (Hexagenia)

Sensitivity of benthic taxa to metalsNi-spiked sediment (Besser, unpublished data)

13

•Differences among species:HA=Hyalella (amphipod)

GP=Gammarus (amphipod)

HS=Hexagenia (mayfly)

CD, CR=Chironomus (midge)

TT=Tubifex (oligochaete)

LV=Lumbriculus (oligochaete)

LS=Lampsilis (mussel)

•Sediment differences Metal bioavailability

Sediment Nickel

Toxicitty threshold (EC-20, g/g)

100 1000 10000

Cu

mu

lati

ve p

rop

ort

ion

0.0

0.2

0.4

0.6

0.8

1.0

GP*

HA

HS

LV*

CD*

CR*

LS*

TT*

HA

GP

HS

TT

CD

CR

LV

LS*

SR sediment

WB sediment

Differences in sensitivityBig River, Missouri (Besser et al. 2010)

Toxicity to mussels was more closely associated with

sediment metals. 14

LampsilisHyalella

Amphipod growth

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18

Len

gth

(m

m)

2

3

4

5

Mussel length

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18

Len

gth

(m

m)

1.0

1.5

2.0

2.5

Sediment metals

1 2 3 4 5 6 7 9 10 11 12 13 14 15 17 18

Su

m (

PE

Q)

0

10

20

30 Pb

Zn

Cd

Test endpoints

• Survival

– Severe effect; acute or chronic test

• Growth (length or weight)

– Often more sensitive than survival

• Biomass production

– Sensitive; integrates effects on survival and growth

• Reproduction

– Sensitive but variable; long/complex test methods;

• Bioaccumulation

– Document bioavailability; characterize dietary exposure of fishes

15

Hyalella survival and reproductionViburnum Trend, MO (Besser et al. 2008a)

Survival was high in reference sediments (green); few toxic sites

Reproduction was sensitive, but varied among reference sites

Influence of nutrients, organic matter, etc.

16

MT

01

MT

02

MT

03

MT

04

MT

06

MT

07

MT

10

MT

12

MT

14

MT

20

CL

1C

L2

CL

3C

L4

CL

5Am

ph

ipo

d s

urv

iva

l (%

)

0

20

40

60

80

100

*

*

MT

01

MT

02

MT

03

MT

04

MT

06

MT

07

MT

10

MT

12

MT

14

MT

20

CL

1C

L2

CL

3C

L4

CL

5

Yo

un

g p

er

fem

ale

0

2

4

6

8

10

12

14

**

*

Interpretation of toxicity data

• Control sediments – define test performance

– Quality assurance for studies with field-collected sediment

– Treatment comparisons in experimental studies

• Reference sediments – define ‘baseline’ conditions

– Single site for simple study area (e.g. upstream/downstream)

– Multiple sites (‘reference envelope’) to represent broader area

• Concentration-response relationship

– Experimental studies (e.g., spiking) or field data with gradient of metal concentrations

– Estimate toxicity value (e.g., LC50, EC20)

17

Comparisons to reference site(s)(Seal et al. 2010; Besser et al. 2010)

Ely Mine, VT: upstream reference sites to match each stream segment

Big River, MO: multiple reference sites (both upstream and regional) – Wide range of sediment type from headwaters to mouth

18

Ely Mine, Vermont

EB1

EB2

EB3

EB4

SB1

SB3

SB4

SB5a

SB5b

OR1

OR3

Mid

ge g

row

th, m

g

0.0

0.5

1.0

1.5

2.0Reference

Mining

*

* ** *

Old Lead Belt, Missouri

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 17 18 19 20 21

Mu

ssel le

ng

th (

mm

)

1.0

1.5

2.0

2.5

Reference

Toxic

Non-toxic

Laboratory-Field Comparisons

• Establish cause-effect relationships

– Community data can be influenced by historic impacts (e.g. species loss) and habitat alteration

– Lab tests use taxa of interest, minimize influence of habitat

• Estimate site-specific toxicity thresholds

– Use of local species or surrogate

– Simulate ambient water quality

19

Laboratory vs. field responses(Besser et al. 2010; Seal et al 2010, in press)

Missouri: reduced mussel growth predicts community impacts

Vermont streams: gradient of amphipod survival vs. benthos taxa richness

Acid sites (red): low taxa richness, but sediment not toxic

20

Old Lead Belt, Missouri

Mussel length (mm)

1.2 1.4 1.6 1.8 2.0 2.2 2.4

Mu

ssel ta

xa

0

10

20

30

Non-toxic

Toxic

Vermont Copper Belt

Amphipod survival (%)

0 20 40 60 80 100

Nu

mb

er

of

taxa

0

10

20

30

40

50

E1

O1

O3

S1

S3

S4

S5 S5

E2

E3

C10

C10A

C10B

C10C

C10D

P4P4A

P4C

P4E

P5

P5AP5

P6

Metal bioavailability in sediment

• Estimate available metal fractions

– Selective extractions (e.g., Luoma 1989, Tessier et al. 1984)

• Characterize major metal-binding phases

– Acid-volatile sulfide and total organic carbon (Ankley et al 1996; USEPA 2005)

– AVS strongly limits metal solubility: Ag, Cu, Pb, Cd, Zn, Ni

– TOC has weaker binding but high capacity; more stable

Allows estimation of pore-water metals (highly bioavailable)

21

Metal fractions and bioavailabilityLake Roosevelt, WA (Besser et al. 2008b; Paulson and Cox 2007)

Upstream site (LR7) was most toxic and had greatest total metals

Downstream toxic sites (LR3, LR2) had much lower total metals

Metals are in easily-extractable fractions (F1 and F2) 22

Midge Growth

REF LR7 LR6 LR5 LR4 LR3 LR2 LR1

Dry

we

igh

t (m

g)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

*

*

*

*

Sediment Pb fractions

LR7 LR6 LR5 LR4 LR3 LR2 LR1 SA8

Pe

rce

nt

of

tota

l

0

20

40

60

80

100

F4 (Residual)

F3 (Sulfide/OM)

F2 (Oxide)

F1 (Sorbed)

Total Sediment Metals

REF LR7 LR6 LR5 LR4 LR3 LR2 LR1

Su

m-P

EQ

0

20

40

60

80

100

Zn

Pb

Cu

Cd

Metal bioavailability in pore water

• Measure dissolved metal concentrations

– Field: Push-point (large volume) or airstone (small volume)

– Lab: Centrifuge or pressure (large volume)

– Lab or Field: Peeper (small volume)

• Free or labile metal fraction

– Specialized samplers (e.g., DGT)

– Geochemical modeling

– Biotic ligand models (BLM): model metal binding to site of uptake

23

Pore-water sampling methods

24

Peeper

Centrifuge

DGT (Zhang et al. 1995)

4 cm2-4 cm sediment

0-2 cm sediment

0-2 cm water

4 cm2-4 cm sediment

0-2 cm sediment

0-2 cm water

Push-point

BLM models for pore water?(Copper toxicity and DOC; Wang et al 2009)

BLM predicts acute copper toxicity across wide range of water quality

Few BLM studies with pore-water

25

50 100 150 200 250 3000

100

200

300

400

500

Water hardness (mg/L as CaCO3)

0 100 200 300 400 500 6000

100

200

300

400

500

Me

asu

red

Cu

EC

50

(µ

g/L

)

BLM predicted Cu EC50 (µg/L)

Pond

Eagle Bluffs

Ditch #6

Luther Marsh

Humic Acid

Variable Hardness

Reference tests

Sediment quality guidelines(to protect benthic organisms)

1. Empirical SQGs (MacDonald et al. 2000)

Based on frequency of toxicity in large datasets (sediments with multiple toxicants)

– Probable Effect Concentration (PEC) is concentration associated with increased frequency of toxicity

– PEC-Quotient = sediment metal concentration / PEC

• Can sum PEC-Quotients to characterize metal mixtures

26

Application of PEC Quotients(Besser et al. 2010; MacDonald et al 2009)

Big River, MO (left): mussel toxicity at Zn-PEQ >1.0

Tri-States (right): amphipod toxicity at Sum-PEQ near 1027

Amphipod survivalMussel shell length (mm)

Zinc PEQ

0 1 2 3 4 51.2

1.4

1.6

1.8

2.0

2.2

2.4

Reference

Toxic

Non-toxic

Sediment quality guidelines (continued)

2. Equilibrium Sediment Benchmarks (ESBs; USEPA 2005)

Assumes pore water is primary exposure route

– Normalize metals to acid-volatile sulfide (AVS):

• No toxicity if simultaneously-extracted metals (SEM) > AVS

• (SEM = sum of Ag, Cu, Pb, Cd, Zn, and Ni)

– Then normalize to TOC: (SEM‐AVS)/TOC

• Range of uncertain toxicity = 130 to 3000 umol/g (USEPA 2005)

28

29

AVS normalization of nickel toxicityNi-spiked sediments (Besser, unpublished data)

Wide range of toxicity (expressed as total Ni) among eight sediments

Normalizing to [SEM-AVS] reduces variation among sediments

[SEM Nickel - AVS]

SEM(Ni)-AVS (umol/g)

-40 -20 0 20 40 60 80 100S

urv

ival (o

f 10)

0

2

4

6

8

10

Total Nickel

TR-Nickel ( g/g)

0 2000 4000 6000 8000

Su

rviv

al (o

f 1

0)

0

2

4

6

8

10

30

Application of sediment ESB(Tri-State Mining District; MacDonald et al 2009)

Hyalella survival corresponds to [(SEM-AVS)/TOC]:

– Narrower range of uncertainty (low AVS, low TOC)

Amphipod toxicity -- Tristate 2007

SEM-AVS/foc, umol/g

10 100 1000 10000

Am

ph

ipo

d s

urv

iva

l (%

)

0

20

40

60

80

100

Logistic regression:

(r2 = 0.65)

EC20 ~1200

Take-home points

• Sediment toxicity testing has many applications.

• Whole-sediment tests are realistic and broadly applicable.

• Test with multiple species and endpoints.

• Select of appropriate reference site(s).

• Validate toxicity vs. evidence of community impacts.

• Characterize controls on metal bioavailability.

31