Zn Ecotoxicological Endpoints in Metal Contaminated Soils

1
Zn Ecotoxicological Endpoints in Metal
Contaminated Soils

• Gary Pierzynski, Arline Novak, and Walter Fick
• Kansas State University

2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
Objectives

• 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

6
Methods 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

7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
Total Zn No. Species Biomass Dominant Species
- mg/kg - -- kg/ha --
gt2000 3.3a 973a C. Ragweed
lt2000 6.2b 1328b B. Bluestem

gt1000 3.9a 978a C. Ragweed
lt1000 7.2b 1436b B. Bluestem

gt500 4.0a 1000a C. Ragweed
lt500 7.6b 1532b B. Bluestem
14
Sample n No. Species Dominant Species
Chat,gt2000 65 3.5a C. ragweed, moss
Chat,lt2000 5 4.8a S. sumac, G. goldenrod
Soil, gt2000 43 4.7a C. ragweed, moss
Soil, lt2000 47 6.3b B. bluestem, L. bluestem
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
Methods 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

19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
Chat - Pigweed
ZnSO4 -Pigweed
23
Chat Big bluestem
ZnSO4 Big bluestem
24
Chat Big bluestem
Chat - Switchgrass
25
ZnSO4 Big bluestem - P
ZnSO4 Big bluestem - Fe
26
Chat Big bluestem - P
Chat Big bluestem - Fe
27
(No Transcript)
28
(No Transcript)
29
Critical values for 75 of control yield Big
bluestem
--------------- critical value ------------- --------------- critical value ------------- --------------- critical value ------------- --------------- critical value -------------
Zn Source Total Zn DGT Zn Ca(NO3)2 Shoot Zn
- mg/kg - -umol/L- ------ mg/kg ------ ------ mg/kg ------
Chat 5547a 1592a 195a 352ab
Dearing 6901a 600b 163a 185b
ZnSO4 61b 1292a 81b 600a
30
Critical values for 75 of control yield Pigweed
--------------- critical value ------------- --------------- critical value ------------- --------------- critical value ------------- --------------- critical value -------------
Zn Source Total Zn DGT Zn Ca(NO3)2 Shoot Zn
- mg/kg - -umol/L- ------ mg/kg ------ ------ mg/kg ------
Chat 4127b 1438a 174b 1210a
Dearing 10062a 583b 213a 1237a
ZnSO4 44b 1204a 55c 1607a
31
Critical values for 75 of control yield
Switchgrass
--------------- critical value ------------- --------------- critical value ------------- --------------- critical value ------------- --------------- critical value -------------
Zn Source Total Zn DGT Zn Ca(NO3)2 Shoot Zn
- mg/kg - -umol/L- ------ mg/kg ------ ------ mg/kg ------
Chat 2216a 700a 121a 220a
Dearing 3360a 379a 103a 208a
ZnSO4 23b 558a 24a 244a
32
Conclusions

• 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