The Global Symposium on Soil Pollution #GSOP18 | 2 - 4 May 2018 | FAO Hq Ms. Lena Q. Ma, University of Florida, US

1. State of the art of soil
remediation: can we really do it?
Lena Q. Ma1,2
1
Research Center for Soil Contamination & Environmental
Remediation, SW Forestry University, Kunming, China
2
Soil & Water Science Department, University of Florida, USA

3. Of course, how and how much?

4. Contamin
ated soils
Immobilize
 Chemical: P binds Pb
 Biological: Cr6+
reduction to
Cr3+
 Thermal: glassify using Si
Mobilize
 Physical: excavation
 Chemical: washing
 Thermal: 6-phase heating
Nothing
 Biological: natural attenuation
Change
 Biological: bioremediation
 Chemical: oxidation/reduction
Soil Remediation
4

5. Contamin
ated soils
Soil Remediation
5
Remediation
methods
Cleanup
Standards

6.  Metal contamination in shooting range soils 10
 Metal Background concentrations in soils 13
 P-induced metal immobilization in soils 18
 Phytoremediation of contaminated soils 100
 Contaminant bioavailability in soils 30
My Research Experiences
Can we do it via bioavailability?

7. Outline
 Introduction
 Bioavailability concept
 Bioavailability measurement
 Applications

8. Based on total concentration: 100% bioavailability
Contaminant bioavailability varies but <100%
Soils
Oral exposure in risk assessment

9. Bioaccessibility
Dissolved in GI tract and
available for absorption
In vitro
Chemical
Soluble fraction
Bioavailability
Absorbed into living
organism
In vivo
Biological
Blood, urine & liver

10. China
Bioavailability Research Group of
Europe (BARGE)Bioavailability Research
of Canada (BARC)
Bioavailability
Research of China (BRC)
SBRC: Solubility Bioavailability
Research Consortium
Bioavailability research groups
CRC CARE

11. TR x BW x AT / RBA 0 − 100%
oral skin inhalation
/
arsenic
1.0
0.8 mg kg-1
Florida: before 2001

12. TR x BW x AT / RBA 0 − 100%
oral skin inhalation
/
arsenic
0.38
2.1 mg kg-1
Florida: after 2001

13. Outline
 Introduction
 Bioavailability concept
 Bioavailability measurement
 Applications

14. Metal contaminated soils
Li, S et al. 2015, JHM. 196:47; Li, J et al. 2015, JHM. 295:55; Li, S et al. 2016, EI. 94: 600
12 As soil samples
As: 22-4172 mg kg-1
12 Pb soil samples
Pb: 215-25329 mg kg-1
12 Cd soil samples
Cd: 3-296 mg kg-1

15. Take As for example: contaminated soil in Florida
 RBA = 38% SCTL= 2.1 ppm
 RBA = 73% SCTL= 1.1 ppm
 RBA = 6.4% SCTL= 12.5 ppm
Pb As Cd
blood urine liver
7.0–84% 6.4–73% 37–84%
Bioavailable metals in soils in
China via a mouse model
Li, S et al. 2015, JHM. 196:47; Li, J et al. 2015, JHM. 295:55; Li, S et al. 2016, EI. 94: 600

16. House
dust
Soil(Sm
ithetal.2011)
Soil(Denysetal.2012)
Soil(Casteeletal.2006)
Soil(Bannon
etal.2009)
Soil(Schroderetal.2004)
Soil(Juhaszetal.2009)
Soil(Marschneretal.2006)
Soil(Rubyetal.1999)
Pbrelativebioavailability(%)
0
30
60
90
120
150
n = 12
12
15 19
8
18
5
5
7
Comparison of Pb-RBA between
contaminated soils
Thisstudy
7.0–84%

17. House
dust
Soil(Bradham
etal.2011)
Soil(Juhaszetal.2014)
Soil(Juhaszetal.2009)
Soil(Rodrigezetal.1999)
Soil(Denysetal.2012)
Soil(Robertetal.2007)
Asrelativebioavailability(%)
0
20
40
60
80
100
n = 12
11
13
12
15
15
14
Comparison of As-RBA between
contaminated soils
Thisstudy
6.4–73%

18. Rice from Chinese market
55 rice samples from
15 provinces of
China
As-RBA in rice via mouse steady state urine excretion bioassay
Li, H et al.. 2017. Environ. Sci. Technol. 51:4689−4696

19. Sample ID
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
Asconcentration(µgkg
-1
)
0
50
100
150
200
250
300
350
400 Raw
Cooked
(B)
Sample ID
27
33
38
45
49
50
51
52
53
54
55
Aspercentage(%)
0
20
40
60
80
100
120
AsIII AsV DMA
(A)
As concentration, speciation & RBA
As concentration As urinary excretion
As RBA
As-RBA: 43-79%
As speciation
Li, H et al.. 2017. Environ. Sci. Technol. 51:4689−4696
16%

20. Cd-contaminated foods
Cd contamination from dark-red enamel pottery production
Cd–RBA in rice, wheat, & vegetables via mouse kidney Cd bioassay
Zhao et al., 2017, EST, 51, 6756–6764

21. (A) Rice
rice52
rice64
rice72
rice75
rice80
rice82
rice84
rice88
rice89
rice90
Cdrelativebioavailability(%)
0
20
40
60
80
100 (B) Wheat
wheat9
wheat12
wheat15
wheat16
wheat17
wheat20
wheat21
wheat22
(C) Vegetables
pumpkinvines
taro
amaranth
waterspinach
leek
pakchoi
Cd: 0.29-1.09 ppm 0.70-1.98 ppm 0.35-2.33 ppm
Cd RBA: 17-57%
rice
37-68%
wheat
Low Cd High Cd
18-78%
vegetable
Cd Relative bioavailability
Zhao et al., 2017, EST, 51, 6756–6764

22. Outline
 Introduction
 Bioavailability concept
 Bioavailability measurement
 Applications

23. Metal bioavailability
Media Sample RBA (%)
Pb As Cd
Contaminated soil 12 7.0–84 6.4–73 37–84
Contaminated housedust 15 7.2–52 7.6–37 20–94
Urban soil 38 17–87
Housedust 12 29–60 22–87
Rice 10-11 11–59 11–79 17–84
wheat 8 37–68
vegetables 6 18–78

24. Bioaccessible methods
As Pb Cd
Contaminated soils IVG
UBM
SBRC
UBM
IVG
SBRC
PBET
Urban soils SBRC
Contaminated housedust PBET UBM PBET
Housedust SBRC
DIN
SBRC
DIN
Rice PBET

25. 25
2015
2013
https://www.epa.gov/superfund/soil-bioavailability

26. 26 https://www.epa.gov/superfund/soil-bioavailability
default= 60%
2010

27. Nick Basta, Ohio State University
Application of bioavailability

28. Lena Q Ma lqma@ufl.edu