zn ecotoxicological endpoints in metal contaminated soils gary pierzynski, arline novak, and walter...

Zn Ecotoxicological Endpoints in Metal Contaminated Soils

Zn Ecotoxicological Endpoints in Metal Contaminated Soils

Gary Pierzynski, Arline Novak, and Walter Fick

Kansas State University

ObjectivesObjectives

• Assess the potential for Zn phytotoxicity in the Tri-State Mining region through field and greenhouse studies

• Evaluate the use of diffusive gradients in thin film (DGT) for the assessment of Zn bioavailability to plants

Methods – Field StudyMethods – Field Study

• Eight 100 m transects laid out in areas impacted by mine wastes

• Plant community structure was assessed every 5 m in 0.5 m2 frames in June 2002– Species identification– Relative abundance of each species– Soil samples collected from 0-5 and 5-10 cm around

perimeter of each frame

• Biomass production determined every 10 m in October 2002

y = -0.7125Ln(x) + 10.417R2 = 0.2794

0

2

4

6

8

10

12

14

0 10000 20000 30000 40000 50000 60000 70000 80000

Total Zn at 0-5 cm (mg/kg)

Num

ber

of S

peci

es

y = -0.4836Ln(x) + 7.4786

R2 = 0.1605

0

2

4

6

8

10

12

14

0 1000 2000 3000 4000 5000

CE (umol/L)

Nu

mb

er o

f S

pec

ies

Total Zn No. Species Biomass

Dominant Species

- mg/kg - -- kg/ha --

>2000 3.3a 973a C. Ragweed

<2000 6.2b 1328b B. Bluestem

>1000 3.9a 978a C. Ragweed

<1000 7.2b 1436b B. Bluestem

>500 4.0a 1000a C. Ragweed

<500 7.6b 1532b B. Bluestem

Sample n No. Species Dominant Species

Chat,>2000 65 3.5a C. ragweed, moss

Chat,<2000 5 4.8a S. sumac,

G. goldenrod

Soil, >2000 43 4.7a C. ragweed, moss

Soil, <2000 47 6.3b B. bluestem,

L. bluestem

Total Zn (mg kg-1)

0 10000 20000 30000 40000 50000 60000

Sho

ot Z

n C

onc

en

trat

ion

(mg

kg-1

)

0

2000

4000

6000

8000

10000

Common Ragweed

r2 = 0.03

Total Zn (mg kg-1)

0 5000 10000 15000 20000 25000 30000

Sho

ot Z

n C

onc

en

trat

ion

(mg

kg-1

)

0

2000

4000

6000

8000

10000

Common Ragweed

r2 = 0.21

CE (mol L-1)

0 500 1000 1500 2000 2500 3000 3500

Sh

oot

Zn

Con

cent

ratio

n (m

g kg

-1)

0

2000

4000

6000

8000

10000

Common Ragweed

r2 = 0.47

Methods – GreenhouseMethods – Greenhouse

• Sand/nutrient cultures– Zn sources: ZnSO4, chat, smelter slag

– Zn sources mixed with sand to provide a wide range of Zn concentrations

– Big bluestem, pigweed, switchgrass– Zn bioavailability assessed with DGT and 0.1 M Ca(NO3)2 extraction

Total Zn in Media (mg/kg)

0 2000 4000 6000 8000 10000 12000 14000 16000

CE ( m

ol L

-1)

-500

0

500

1000

1500

2000

2500

ChatDearingZnSO4

0

0.2

0.4

0.6

0.8

1

1.2

Rel

ativ

e Y

ield

0 1 2 3 4 5

Zn Level

00.10.20.30.40.50.60.70.80.9

1

Rel

ativ

e Y

ield

0 5 10 25 50 100

Zn Level (mg/kg)

ZnSO4 -Pigweed

Chat - Pigweed

0

50

100

150

200

250

300

350

400

450

Pla

nt

Zn

(m

g/k

g)

0 1 2 3 4 5

Zn Level

0

200

400

600

800

1000

1200

1400

Pla

nt

Zn

(m

g/k

g)

0 5 10 25 10 100

Zn Level (mg/kg)

ZnSO4 – Big bluestem

Chat – Big bluestem

0

50

100

150

200

250

300

350

400

450

Pla

nt

Zn

(m

g/k

g)

0 1 2 3 4 5

Zn Level

0100200300400500600700800900

1000

Pla

nt

Zn

(m

g/k

g)

0 1 2 3 4 5

Zn Level (mg/kg)

Chat - Switchgrass

Chat – Big bluestem

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Pla

nt

P (

mg

/kg

)

0 1 2 3 4 5

Zn Level

05

1015202530354045

Pla

nt

Fe

(mg

/kg

)

0 1 2 3 4 5

Zn Level (mg/kg)

ZnSO4 – Big bluestem - Fe

ZnSO4 – Big bluestem - P

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Pla

nt

P (

mg

/kg

)

0 1 2 3 4 5

Zn Level

05

1015202530354045

Pla

nt

Fe

(mg

/kg

)

0 1 2 3 4 5

Zn Level (mg/kg)

Chat – Big bluestem - Fe

Chat – Big bluestem - P

Ca(NO3)2 - extractable Zn (mg/kg)

0 50 100 150 200 250 300

Pla

nt T

issu

e Z

n C

once

ntra

tion

(mg/

kg)

0

200

400

600

800

1000

1200

1400

1600

1800Big bluestemPigweedSwitchgrass

r2=0.49

r2=0.25

r2=0.13

CE (mol/L)

0 500 1000 1500 2000 2500 3000

Pla

nt T

issu

e Z

n C

once

ntra

tion

(mg/

kg)

-200

0

200

400

600

800

1000

1200

1400

1600

1800

2000Big bluestemPigweedSwitchgrass

r2=0.59

r2=0.67

r2=0.71

Critical values for 75% of control yield – Big bluestem

Critical values for 75% of control yield – Big bluestem

--------------- critical value -------------

Zn Source Total Zn DGT Zn Ca(NO3)2 Shoot Zn

- mg/kg - -umol/L- ------ mg/kg ------

Chat 5547a 1592a 195a 352ab

Dearing 6901a 600b 163a 185b

ZnSO4 61b 1292a 81b 600a

Critical values for 75% of control yield – Pigweed

Critical values for 75% of control yield – Pigweed

--------------- critical value -------------

Zn Source Total Zn DGT Zn Ca(NO3)2 Shoot Zn

- mg/kg - -umol/L- ------ mg/kg ------

Chat 4127b 1438a 174b 1210a

Dearing 10062a 583b 213a 1237a

ZnSO4 44b 1204a 55c 1607a

Critical values for 75% of control yield – SwitchgrassCritical values for 75% of

control yield – Switchgrass--------------- critical value -------------

Zn Source Total Zn DGT Zn Ca(NO3)2 Shoot Zn

- mg/kg - -umol/L- ------ mg/kg ------

Chat 2216a 700a 121a 220a

Dearing 3360a 379a 103a 208a

ZnSO4 23b 558a 24a 244a

ConclusionsConclusions

• Field data suggest that Zn may play a role in species richness, species present, and biomass production.

• Greenhouse data indicate Zn phytotoxicity can be induced with mine wastes.

• DGT was superior to batch extractions

• Further evaluation of DGT for assessment of ecotoxicologial endpoints is warranted