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Adsorption / desorption

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Endpoint:
adsorption / desorption, other
Remarks:
desorption
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The available identification data for the Target and the Source substance support the read-across hypothesis. Adequate, reliable and available scientific information indicate that the Target and Source substance have, or are very likely to have, similar (eco)toxicological properties. There are no indications that constituents other than those identified for the substances or impurities may influence the validity of the read-across. There is no evidence that additional toxicological mechanisms, other than those identified in the read-across hypothesis, may be acting or have an adverse effect on the validity of the read-across.
Reason / purpose for cross-reference:
read-across source
Key result
Type:
Kd
Value:
> 20 L/kg
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: As in slag and basalt
Key result
Type:
Kd
Value:
> 70 L/kg
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cd in slag, >20 in basalt
Key result
Type:
Kd
Value:
800 000 L/kg
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cr in slag, > 10000 in basalt
Key result
Type:
Kd
Value:
> 9 400 L/kg
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cu in slag, > 6000 in basalt
Key result
Type:
Kd
Value:
> 700 L/kg
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Ni in slag, > 4000 in basalt
Key result
Type:
Kd
Value:
> 760 L/kg
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Pb in slag, > 130 in basalt
Key result
Type:
Kd
Value:
40 000 L/kg
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Zn in slag, > 6600 in basalt
Validity criteria fulfilled:
not applicable
Remarks:
recalculation of existing data
Conclusions:
The reavaluation of existing data showed that trace elements are tightly bound into slags with high kd values for Ni (> 700 L/kg), Cu (> 9400 L/kg), Zn (> 40000 L/kg) and Cr (> 800000 L/kg). Due to high limits of determination/detection, no estimate could be made for other trace elements.
Executive summary:

To determine the kdvalues of trace elements of toxicological relevance for REACH Registration, existing concentration data of theslags ABS, BOS, and EAF C, existing concentration data of trace elements in solid slags and natural rocks were compared with their respective concentrations in leachates of slags and natural rocks.

The kdvalues of Hg and Tl could not be determined, because no data had been measured in leachates. The Kdvalues of As and Cd are low (e.g. >20 L/Kg) because these elements (and Hg and Tl) are not present in slags and basalt at relevant levels. The same is most likely correct for Pb. For Ni (>700, >4000 L/kg), Cu (> 9400, > 6000 L/kg), Zn (> 40000, >6600 L/kg) and Cr (> 800000, > 10000 L/kg) high Kdvalues have been obtained, suggesting a very tight binding of these elements into slag and basalt, respectively.

Kd values of EAF C and basalt with the data used for calculation

Parameter

EAF C (mg/kg)*

Basalt (mg/kg)**

Leachates

Kd slags

Kd basalt

As

2

2

< 0.1

>20

> 20

Cd

0.7

0.2

< 0.01

> 70

>20

Cr

approx. 8000

approx. 100

< 0.01

> 800000

>10000

Cu

94

 approx. 60

< 0.01

> 9400

 > 6000

Hg

<0.2

0.08

not determined

No data

No data

Ni

14

 approx. 80

< 0.02

 > 700

 > 4000

Pb

76

13

< 0.1

> 760

> 130

Tl

< 0.5

 

not determined

No data

No data

Zn

390

 approx. 70

slags = < 0.007

basalt = < 0.011

> 40000

7000

BOS and EAF C: 8 – 11 mm. No data on grain size of ABS.

*Hygiene-Institut des Ruhrgebiets (2001) Pruefbericht A 5006c D/01/C, Gelsenkirchen, on behalf of the FEhS

**Bavarian Landesamt fuer Umweltschutz (LfU), Verwendung von MV-Rostschlacke in Bauvorhaben, 2002.

Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
other: literature review
Adequacy of study:
weight of evidence
Study period:
2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented. Study meets generally accepted scientific principles. Study acceptable for assessment
Principles of method if other than guideline:
Literature review on soil−liquid partitioning coefficients (Kd) of several trace elements to predict elemental mobility and bioavailability. Multiple linear regression analysis accounting for pH of the soil solution, the content of metals and organic matter of the soil (SOM). Development of simple model for trace element solubility
GLP compliance:
no
Type of method:
other: Data compilation
Media:
soil
Radiolabelling:
no
Type:
Kd
Value:
13 119
Remarks on result:
other: As soil
Type:
Kd
Value:
3 434
Remarks on result:
other: Ba soil
Type:
Kd
Value:
2 869
Remarks on result:
other: Cd soil
Type:
Kd
Value:
14 290
Remarks on result:
other: Cr soil
Type:
Kd
Value:
4 799
Remarks on result:
other: Cu soil
Type:
Kd
Value:
8 946
Remarks on result:
other: Hg soil
Type:
Kd
Value:
16 761
Remarks on result:
other: Ni soil
Type:
Kd
Value:
171 214
Remarks on result:
other: Pb soil
Type:
Kd
Value:
43 937
Remarks on result:
other: Se soil
Type:
Kd
Value:
11 615
Remarks on result:
other: Zn soil
Details on results (Batch equilibrium method):
Compilation of results of approximately 70 studies

Element Arithmetic means of Kd values (L/kg)
As 13119
B 160
Ba 3434
Cd 2869
Cr 14920
Cu 4799
Hg 8946
Mo 36
Ni 16761
Pb 171214
Se 43937
Sr 137
Zn 11615
(Details see IUCLID, 3 tables in "Any other information on results incl. tables")
Temperature and organic carbon of soil not known

Table 1.  Soil-water partitioning coefficients for several trace elements (Kd in L/kg)

element

Kd (mean)

SD

CV

median

min

max

log10 Kd

N

As

13119

65086

4.96

1825

1.6

530000

4.12

66

B

160

96

0.60

136

61

389

2.20

12

Ba

3434

3152

0.92

2455

1414

14375

3.54

15

Cd

2869

12246

4.27

390

0.44

192000

3.46

830

Cr

14920

16899

1.13

4778

125

65609

4.17

64

Cu

4799

9875

2.06

2120

6.8

82850

3.68

452

Hg

8946

5641

0.63

7500

4286

16500

3.95

4

Mo

36

19

0.52

38

14

52

1.55

4

Ni

16761

45350

2.71

2333

8.9

256842

4.22

139

Pb

171214

304089

1.78

102410

60.56

2304762

5.23

204

Se

43937

119534

2.72

15

1.6

600000

4.64

63

Sr

137

42

0.31

130

89

195

2.14

10

Zn

11615

30693

2.64

1731

1.4

320000

4.07

302

Arithmetic Means of untransformed Kd values, SD = standard deviations, CV= coefficients of variability, medians, min = minimum, max = maximum, log (Kd), N = number of data points

Table 2.  Linear Regression coefficients of Kd (L/kg) against the soil solution pH

log10 Kd

 

parameters

 

constant

N

log Kd Cd

=

0.49 ± 0.02 • pH

−

0.60 ± 0.49

830

log Kd Cu

=

0.27 ± 0.02 • pH

+

1.49 ± 0.13

447

log Kd Ni

=

0.72 ± 0.05 • pH

−

1.75 ± 0.36

138

log Kd Pb

=

0.49 ± 0.04 • pH

+

1.37 ± 0.25

204

log Kd Zn

=

0.62 ± 0.03 • pH

−

0.97 ± 0.21

298

Table 3.  Coefficients for the Linear Regressions of Kd (L/kg) against the soil solution pH combined with Log10 of soil organic matter (SOM) or Log10 of total metal (total)

Kd Cd

=

0.48 ± 0.02  •  pH***  +  0.82 ± 0.05  •  log (SOM)

−

0.65 ± 0.10

751

Kd Cu

=

0.21 ± 0.02  •  pH***  +  0.51 ± 0.06  •  log (SOM)

+

1.75 ± 0.12

353

Kd Ni

=

1.02 ± 0.09  •  pH***  +  0.80 ± 0.20  •  log (SOM)

−

4.16 ± 0.60

69

Kd Pb

=

0.37 ± 0.04  •  pH***  +  0.44 ± 0.07  •  log (total)

+

1.19 ± 0.22

204

Kd Zn

=

0.60 ± 0.03  •  pH***  +  0.21 ± 0.06  •  log (total)

−

1.34 ± 0.23

298

a SOM, in % C.bIn mg (kg dry soil)-1.c Statistical significance:  * for p < 0.1, ** for p < 0.01, *** for p < 0.001, and NS for p > 0.1.

Validity criteria fulfilled:
yes
Conclusions:
The presence of soil will further decrease the already very low trace element levels in leachates of slag. Kd of soils is influenced most strongly by
pH, cation-exchange capacity (CEC, for cations), and by the content of amorphous iron oxides and aluminum oxides.
Element Arithmetic Means of Kd values (L/kg)
As 13119
B 160
Ba 3434
Cd 2869
Cr 14920
Cu 4799
Hg 8946
Mo 36
Ni 16761
Pb 171214
Se 43937
Sr 137
Zn 11615
Executive summary:

A literature review was done on soil−liquid partitioning coefficients (Kd) of several trace elements of toxicological relevance. Although the reported values scattered, mobility and bioavailability of the elements could be predicted. The kd values especially for the metals cadmium, copper, lead, nickel, and zinc exhibited a relationships to variations in the pH of the soil solution, the content of metals and organic matter of the soil (SOM). Multiple linear regressions showed highest correlations to linear regression with pH or with pH and log of one of the other parameters. Solubility of trace metals was interpreted as competitive adsorption of metal cations and hydrogen ions.

Endpoint:
adsorption / desorption
Remarks:
desorption
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study using national guideline. Study meets generally accepted scientific principles. Study acceptable for assessment
Reason / purpose for cross-reference:
reference to same study
Principles of method if other than guideline:
The Kd values of trace element were calculated as the ratio of the detected concentrations in slags versus the respective leaching data of these slags. If a trace element was only detectable in the solid slag but not in the leachate, the leachate concentration was assumed as being half of the detection limit. The specific Kd values of the trace elements for each slag were calculated from the arithmetic means of these values.
GLP compliance:
not specified
Type of method:
other: ASTM
Media:
soil
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable
Radiolabelling:
no
Test temperature:
study performed at room temperature
Details on study design: HPLC method:
Kd calculated
Analytical monitoring:
yes
Details on sampling:
Mixed samples compiled from several slag producers (study sponsors)
Details on matrix:
slags are similar to natural material like granite with regard to their chemical composition (in general, slags contain far less silicate), physico-chemical properties, toxicity and ecotoxicity. The faster the slag melt is cooled, the higher is the ratio of glass phase to crystalline phase
Details on test conditions:
The TCLP (Toxicity Characteristic Leaching Procedure) of the US EPA (United States Environmental Protection Agency) was originally designed to determine the transfer of organic and inorganic pollutants from wastes into the environment. The TCLP analysis simulates landfill conditions in regard to leaching by rain and groundwater. Water which percolates through the solid slag layer will take up trace elements. The TCLP simulates extended leaching periods in the ground. It identifies which trace elements in the leachate exceed standards set by the US EPA and thereby may pose public and environmental health risks.
The TCLP is a leaching procedure which determines the mobility of trace elements under acidic and basic conditions. The TCLP applied on slags includes a determination of the pH-value of the slag leachate, followed by leaching with acetic acid solution at a 1:20 mixture of slag to solvent for 18 h under shaking (tumbling).
Maximum concentration of contaminants for Toxicity Characteristic (the D List of the EPA)
EPA
Hazardous
Waste code Contaminant Regulated Level (mg/L or ppm)
D004 Arsenic 5.0
D005 Barium 100.0
D018 Benzene 0.5
D006 Cadmium 1.0
D019 Carbon Tetrachloride 0.5
D020 Chlordane 0.03
D021 Chlorobenzene 100.0
D022 Chloroform 6.0
D007 Chromium 5.0
D023 o-Cresol 200.0
D024 m-Cresol 200.0
D025 p-Cresol 200.0
D026 Cresol 200.0
D016 2,4-D 10.0
D027 1,4-Dichlorobenzene 7.5
D028 1,2-Dichloroethane 0.5
D029 1,1-Dichloroethylene 0.7
D030 2,4-Dinitrotoluene 0.13
D012 Endrin 0.02
D031 Heptachlor 0.008
D032 Hexachlorobenzene 0.13
D033 Hexachlorobutadiene 0.5
D034 Hexachloroethane 3.0
D008 Lead 5.0
D013 Lindane 0.4
D009 Mercury 0.2
D014 Methoxychlor 10.0
D035 Methyl ethyl ketone 200.0
D036 Nitrobenzene 2.0
D037 Pentachlorophenol 100.0
D038 Pyridine 5.0
D010 Selenium 1.0
D011 Silver 5.0
D039 Tetrachloroethylene 0.7
D015 Toxaphene 0.5
D040 Trichloroethylene 0.5
D041 2,4, 5-Trichlorophenol 400.0
D042 2,4,6-Trichlorophenol 2.0
D017 2,4,5-TP (Silvex) 1.0
D043 Vinyl Chloride 0.2

EPA Publication SW-846 Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, EPA Publication SW-846 [Third Edition (November, 1986), as amended by Updates I (July, 1992), II (September, 1994), IIA (August, 1993), and IIB (January, 1995)] (document number 955-001-00000-1), U.S. Government Printing Office, Washington, DC.
Computational methods:
Calculation of Kd values from concentrations of trace elements in solid slags and their leachates
Used data:
Arithmetic mean of the concentrations of the trace elements in solid slag (mg/kg)
Arithmetic mean as determined with the ASTM method (mg/L)
Result is the arithmetic mean of the Kd value (L/kg)
Type:
Kd
Value:
20 835
% Org. carbon:
0
Remarks on result:
other: Al
Type:
Kd
Value:
1 686
% Org. carbon:
0
Remarks on result:
other: Ba
Type:
Kd
Value:
78 292
% Org. carbon:
0
Remarks on result:
other: Cr
Type:
Kd
Value:
7 967
% Org. carbon:
0
Remarks on result:
other: Cu
Type:
Kd
Value:
1 297 600
% Org. carbon:
0
Remarks on result:
other: Fe
Type:
Kd
Value:
7 112 857
% Org. carbon:
0
Remarks on result:
other: Mn
Type:
Kd
Value:
1 320
% Org. carbon:
0
Remarks on result:
other: Mo
Type:
Kd
Value:
20 667
% Org. carbon:
0
Remarks on result:
other: Pb
Type:
Kd
Value:
1 015
% Org. carbon:
0
Remarks on result:
other: Se
Type:
Kd
Value:
11 753
% Org. carbon:
0
Remarks on result:
other: V
Details on results (HPLC method):
Kd measured by analysis of solid slag and its leachate
Adsorption and desorption constants:
see Tables below
Recovery of test material:
see Tables below
Concentration of test substance at end of adsorption equilibration period:
not applicable
Concentration of test substance at end of desorption equilibration period:
as reported in the Tables below
Transformation products:
no
Details on results (Batch equilibrium method):
The calculated Kd values are higher than 1000 L/kg with few exceptions due to calculation procedure using half the detection limit value as an estimate for concentration in leachates. These calculated results comprise arsenic and tin in blast furnace slag (Kd = 300 and 500 L/kg, for arsenic and tin, respectively).
The Kd values of different slags were similar. Their differences between the slags did no exceed one order of magnitude.
Statistics:
see Tables below

Kd values calculated from concentrations of trace elements in solid blast furnace slags (ABS/GBS) and in slag leachates

 

Mean

Mean leachate

Mean Kd

 

concentration

concentration

value

 

(mg/kg)

(mg/L)

(L/kg)

Aluminum

38420

3.8

20835

Antimony

ND

ND

ND

Arsenic

0.45

ND

300

Barium

290

0.22

1686

Beryllium

8.2

ND

16480

Cadmium

ND

ND

ND

Chromium

120.8

0.0038

78292

Chromium (VI)

ND

ND

ND

Copper

11

ND

7967

Iron

32440

ND

1297600

Lead

31

ND

20667

Manganese

7820

0.0014

7112857

Molybdenum

3.3

ND

1320

Mercury

ND

ND

ND

Nickel

3.3

ND

1300

Selenium

4.8

0.0075

1015

Silver

ND

0.0037

ND

Thallium

ND

ND

ND

Tin

2.5

ND

500

Vanadium

34

0.010

11753

Zinc

33

ND

3348

ND, not detected.

Validity criteria fulfilled:
yes
Remarks:
calculation based on scientific principles
Conclusions:
The calculated Kd values of trace elements occurring in slag are high (mostly >1000 L/kg).
The Kd values of different slags were similar. Their differences between the slags did no exceed one order of magnitude.
The high Kd values suggest that the trace elements are very tightly bound into the matrix. Leaching is extremely low and transport in soil will be very slow.
Executive summary:

Soil-to-water partition coefficients Kd of individual trace elements occurring in slag were calculated from their concentration in the solid slag, divided by their concentrations in leachate.

The calculated Kd values are higher than 1000 L/kg with few exceptions due to calculation procedure using half the limit of detection as an estimate for concentration in leachates. These calculated results comprise arsenic and tin in blast furnace slag (Kd= 300 and 500 L/kg, for arsenic and tin, respectively). 

The Kd values of different slags were similar. Their differences between the slags did not exceed one order of magnitude.

The high Kd values suggest that the trace elements are very tightly bound into the matrix. Leaching of trace elements is extremely low and transport in soil will be very slow (Proctor et al. 2000).

Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
other: data compilation and assessment
Adequacy of study:
weight of evidence
Study period:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented. Study meets generally accepted scientific principles. Study acceptable for assessment
Qualifier:
according to guideline
Guideline:
other: DIN 38414-4:1984-10 German standard methods for the examination of water, waste water and sludge; sludge and sediments (group S); determination of leachability by water (S4)
Deviations:
not specified
GLP compliance:
no
Type of method:
other: data compilation and modelling
Media:
soil
Radiolabelling:
no
Test temperature:
not applicable (mostly data for 20 °C)
Details on matrix:
soil with different properties in regard to retention of certain ions
Type:
Kd
Value:
200 - 1 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: As
Type:
Kd
Value:
100 - 1 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cd
Type:
Kd
Value:
30 000 - 53 750
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cr(total)
Type:
Kd
Value:
6 000 - 20 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cu
Type:
Kd
Value:
2 000 - 5 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Hg
Type:
Kd
Value:
750 - 1 500
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Ni
Type:
Kd
Value:
3 500 - 5 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Pb
Type:
Kd
Value:
2 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Zn
Details on results (HPLC method):
Calculations and temperature estimates by IUCLID editor

There are no relevant differences in the adsorption/desorption properties of the 2 subtypes (ABS and GBS) of blast furnace slag in regard to the Kd of the trace elements tested

Validity criteria fulfilled:
not applicable
Conclusions:
The Kd values (L/Kg) for ABS are
As 100-1000
Pb 3500-5000
Cd 100-1000
Cr(total) 30000 -53750
Cu 6000-20000
Ni 750-1500
Hg 2000-5000
Zn 2000
There are no relevant differences in the adsorption/desorption properties of the 2 subtypes (ABS and GBS) of blast frunace slag in regard to the Kd of the trace elements tested
Executive summary:

For determination of the environmental behaviour of slags, the concentrations of the elements were determined in solid slags and in the corresponding leachates. The Kd values were calculated for REACH Registration using these existing data.

Almost all Kd values were >1000 L/kg. Exceptions were due to the very low concentrations of elements both in the solid slags as well as in the leachates. The Kd values (L/kg) for ABS are As 100-1000, Cd 100-1000, Cr(total) 30000 -53750, Cu 6000-20000, Hg 2000-5000, Ni 750-1500, Pb 3500-5000, and Zn 2000 L/kg.

These Kd values indicate that slags will retain trace elements embedded in the solid matrix/crystal lattice.

Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
other: data compilation and assessment
Adequacy of study:
weight of evidence
Study period:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented. Study meets generally accepted scientific principles. Study acceptable for assessment
Qualifier:
according to guideline
Guideline:
other: DIN 38414-4:1984-10 German standard methods for the examination of water, waste water and sludge; sludge and sediments (group S); determination of leachability by water (S4)
Deviations:
not specified
GLP compliance:
no
Type of method:
other: data compilation and modelling
Media:
soil
Radiolabelling:
no
Test temperature:
not applicable (mostly data for 20 °C)
Details on matrix:
soil with different properties in regard to retention of certain ions
Type:
Kd
Value:
1 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: As
Type:
Kd
Value:
1 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cd
Type:
Kd
Value:
30 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cr(total)
Type:
Kd
Value:
6 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Cu
Type:
Kd
Value:
2 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Hg
Type:
Kd
Value:
1 500
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Ni
Type:
Kd
Value:
5 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Pb
Type:
Kd
Value:
2 000
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Zn
Details on results (HPLC method):
Calculations and temperature estimates by IUCLID editor
Adsorption and desorption constants:
The Kd values (L/kg) for GBS are
As 200-1000
Pb 5250
Cd 2000
Cr(total) 14400
Cu 6000
Ni 10000
Hg 4200
cyanide(total) 300
There are no relevant differences in the adsorption/desorption properties of the 2 subtypes of blast frunace slag in regard to the Kd of the trace elements tested (Oekoinstitut 2007).

There are no relevant differences in the adsorption/desorption properties of the 2 subtypes (ABS and GBS) of blast furnace slag in regard to the Kd of the trace elements tested

Validity criteria fulfilled:
not applicable
Conclusions:
The Kd values (L/Kg) for GBS are
As 1000
Cd 1000
Cr(total) 30000
Cu 6000
Hg 2000
Ni 1500
Pb 5000
Zn 2000
Executive summary:

For determination of the environmental behaviour of slags, the concentrations of the elements were determined in solid slags and in the corresponding leachates. The Kd values were calculated for REACH Registration using these existing data.

The Kd values were >1000 L/kg. The Kd values (L/kg) of Slags, ferrous metal, blast furnace (granulated - GBS) are As 1000, Cd 1000, Cr(total) 30000, Cu 6000, Hg 2000, Ni 1500, Pb 5000, and Zn 2000 L/kg.

These Kd values indicate that slags will retain trace elements included in the solid matrix.

Endpoint:
adsorption / desorption, other
Remarks:
solubility and leachability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1999-2002
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study using national guideline. Study meets generally accepted scientific principles. Study acceptable for assessment
Qualifier:
according to guideline
Guideline:
other: NT ENVIR 003
Deviations:
yes
Remarks:
but not relevant for Kd determination
Qualifier:
according to guideline
Guideline:
other: NT ENVIR 006
Deviations:
yes
Remarks:
but not relevant for Kd determination
Principles of method if other than guideline:
2 types of leaching experiments performed:
ordinary availability test consisting of two leachings at neutral and acidic pH (NT ENVIR 003)
oxidised availability test at fully oxidising conditions by addition of hydrogen peroxide (NT ENVIR 006, 1999)
GLP compliance:
no
Type of method:
batch equilibrium method
Media:
other: solid/liquid
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No surrogate used
Radiolabelling:
no
Test temperature:
room temperature (20 °C)
Analytical monitoring:
yes
Details on sampling:
For the leaching experiments, 8.00+/-0.01 g of dried material were ground to 125 µm (95 % w/w).
For the ordinary availability test two leachings at a liquid to solid ratio (L/S) of 100 were applied, first at pH 7.0 for 3 h, second at pH 4 for 4 h, or later to increase leachate concentrations, for 18 h (NT ENVIR 003). The pH was automatically controlled by a titrator using 0.5 M nitric acid and the two leachates were combined before analysis (NEN 7341, 1992).
For the oxidised availability test same leaching conditions were applied, with the exception that at fully oxidising conditions hydrogen peroxide (H2O2) was added (NT ENVIR 006, 1999).
Details on matrix:
Slag and rock materials consist of crystalline and glassy matrix
Type:
other: solubility and leachability
Value:
> 0 - < 100 other: %
Remarks on result:
other:
Remarks:
Solubility and leachability presented in percentage in the study, see tables for more information.

will be calculated

Validity criteria fulfilled:
yes
Remarks:
valid analysis and reasonable data obtained. Analysis done by licenced laboratory
Conclusions:
Kd values of trace elements in blast furnace slag are very similar to these in natural rock materials
Executive summary:

To elucidate the risk of the use of slags in the environment in comparison to natural rock, the 2 types of leaching experiments were performed: Ordinary availability tests consisting of two leachings at neutral and acidic pH (NT ENVIR 003) and oxidised availability tests at fully oxidising conditions by addition of hydrogen peroxide (NT ENVIR 006, 1999). 9 different types of natural rock material were used for comparison.

The leaching behaviour of natural rocks and blast furnace slags was very similar. Most of the metals exmined were less soluble from slags than from natural rock. As both total content of the trace elements of toxicological relevance, as well as their solubilites under extreme environmental conditions, were supplied, Kd values can be derived (in the report inverse Kd values are given as the precentage of the total released into leachate). In general, these Kd were lower than typical Kd values of these elements in slags. The environmental relevance of the findings was clarified by comparison with natural rocks. The slags released less trace metals than the the natural rocks, suggesting that their use in the environment poses no hazard (Tossavainen 2002).

Endpoint:
adsorption / desorption
Remarks:
desorption
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
before 1991
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions. Study well documented. Study meets generally accepted scientific principles. Study acceptable for assessment
Principles of method if other than guideline:
24 h leaching L/S 10
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
other: leaching of slag
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not required
Radiolabelling:
no
Test temperature:
estimated to be 20 °C
Analytical monitoring:
not required
Details on sampling:
L/S 10
Type:
Kd
Value:
66 110
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Fe in ABS
Type:
Kd
Value:
1 684
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: SiO2 in ABS
Type:
Kd
Value:
1 312
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Ca in ABS
Type:
Kd
Value:
97 500
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Mg in ABS
Type:
Kd
Value:
329 220
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Mn in ABS
Type:
Kd
Value:
7 424
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: SiO2 in GBS
Type:
Kd
Value:
10 978
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Ca in GBS
Type:
Kd
Value:
19 500
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Mg in GBS
Type:
Kd
Value:
109 750
Temp.:
20 °C
% Org. carbon:
0
Remarks on result:
other: Mn in GBS

Mean solubilities and Kd values of ABS

 

pH

Fe

SiO2

Ca

Mg

P

Mn

sulfate

Cl

F

Na

K

Zn

Pb

Cu

Ni

Mean

10.7

0.10

97

226

0.4

0.1

0.02

666

13.7

0.56

122

99

0.15

0.36

0.18

0.08

 Kd (L/Kg)

 

66110

1684

1312

97500

 

329220

 

 

 

 

 

 

 

 

 

Mean solubilities and Kd values of GBS

 

pH

SiO2

Ca

Mg

P

Mn

sulfate

Cl

F

Na

K

Zn

Mean

9

22

27

2

0.03

0.06

87

27

2.4

13

7

0.4

 Kd (L/kg)

 

7424

10978

19500

 

109750

 

 

 

 

 ...

 

Temperatures are estimates by the IUCLID editor

Validity criteria fulfilled:
not applicable
Conclusions:
Slags have high kd values (sorption coefficients solid/liquid) for the following metals in basic elachate:

ABS (kd [L/kg]):
Ca 1312
Mg 97500
Fe 66110
Mn 329220
SiO2 1684

GBS (kd [L/kg]):
Ca 10978
Mg 19500
Mn 109750
SiO2 7424
Executive summary:

The environmental behaviour of slags was evaluated from the total content and the solubility of analytes in the slag. A re-evaluation of the existing data was done to determine the retention potential of slags for trace metals and other analytes. All Kd values obtained were very high suggesting that slags are only a minor source of heavy metals. The solid/liquid adsorption coefficients Kd of both ABS and GBS were high (L/kg): ABS: Ca 1312, Mg 97500, Fe 66110, Mn 329220, SiO2 1684; GBS: Ca 10978, Mg 19500, Mn 109750, SiO2 7424.

Description of key information

High Kd values for trace elements indicate that the distribution of trace elements between slags (solid phase) and their leachates (liquid pahse) is almost exclusively on the side of the solid phase, and very low mobility of trace elements is predicted.

Key value for chemical safety assessment

Additional information

Kd values of trace elements in soils

A literature review was done on soil−liquid partitioning coefficients (Kd) of several trace elements of toxicological relevance. Although the reported values scattered, mobility and bioavailability of the elements could be predicted. The kd values especially for the metals cadmium, copper, lead, nickel, and zinc exhibited a relationships to variations in the pH of the soil solution, the content of metals and organic matter of the soil (SOM). Multiple linear regressions showed highest correlations to linear regression with pH or with pH and log of one of the other parameters. Solubility of trace metals was interpreted as competitive adsorption of metal cations and hydrogen ions.

Arithmetic Means of Kd values (L/kg) of elements in soil/water

As 13119

B 160

Ba 3434

Cd 2869

Cr 14920

Cu 4799

Hg 8946

Mo 36

Ni 16761

Pb 171214

Se 43937

Sr 137

Zn 11615 (Sauvé et al. 2000)

Kd values of trace elements of slags

Soil-to-water partition coefficients Kd of individual trace elements occurring in slag were calculated from their concentration in the solid slag, divided by their concentrations in leachate. In total, slag from 58 steel works with blast furnaces, basic oxygen furnaces (converters) and/or electric arc furnaces, were examined for leachability at acidic and neutral pH values.

The calculated Kd values are higher than 1000 L/kg with few exceptions due to calculation procedure using half the limit of detection as an estimate for concentration in leachates. These calculated results comprise arsenic and tin in blast furnace slag (Kd= 300 and 500 L/kg, for arsenic and tin, respectively) and mercury in the EAF slag (Kd= 900 L/kg). With very low levels both in the slag and in the leachate, the following Kd's were calculated: 700 L/kg for molybdenum in BOS, 535 L/kg for chromium-VI in EAF, and 819 L/kg for arsenic in EAF.

The Kd values of different slags were similar. Their differences between the slags did not exceed one order of magnitude.

The high Kd values suggest that the trace elements are very tightly bound into the matrix. Leaching of trace elements is extremely low and transport in soil will be very slow (Proctor et al. 2000).

These results were confirmed by data on total trace element levels in slags and the corresponding leaching data taken from a report of the German Oekoinstitut. The Kd values (L/Kg) calculated for ABS are

As 2500

Pb 3500

Cd 1667

Cr(total) 10000

Cu 4000

Ni 7143

Hg 3500

Zn 7500

cyanide(total) 250

The Kd values (L/kg) for GBS are

As 3214

Pb 5250

Cd 2000

Cr(total) 14400

Cu 6000

Ni 10000

Hg 4200

cyanide(total) 300

There are no relevant differences in the adsorption/desorption properties of the 2 subtypes of blast furnace slag in regard to the Kd of the trace elements tested (data taken from Oekoinstitut 2007).

To determine the kd values of trace elements of toxicological relevance in the slags ABS, BOS, and EAF C, existing concentration data of the BfG of trace elements in solid slag and natural rocks were compared with their respective concentrations in leachates of slags and natural rocks.

The kd values of Hg and Tl could not be determined, because no data had been measured in leachates. The Kd values of As and Cd are low (e.g. >20 L/Kg) because these elements (and Hg and Tl) are not present in slags and basalt at relevant levels. The same is most likely correct for Pb. For Ni (< 700, >4000 L/kg), Cu (> 9400, > 6000 L/kg), Zn (> 40000, >6600 L/kg) and Cr (> 800000, > 10000 L/kg) high Kd values have been obtained, suggesting a very tight binding of these elements into slag and basalt, respectively (data taken from BfG 2008).

The environmental behaviour of slags was evaluated from the total content and solubility of analytes in the slags. A simple re-evaluation of the existing data was done to determine the retention potential of slags for trace metals and other analytes. All Kd values obtained were very high suggesting that the analytes examined are effectively retained by slags. The solid/liquid adsorption coefficients Kd of both ABS and GBS were high (L/kg): ABS: Ca 1312, Mg 97500, Fe 66110, Mn 329220, SiO2 1684; GBS: Ca 10978, Mg 19500, Mn 109750, SiO2 7424 (data taken from LECES 1991).

Kd values of ABS and GBS in comparison with natural rocks

To elucidate the risk of the use of slags in the environment in comparison to natural rock, the 2 types of leaching experiments were performed: Ordinary availability tests consisting of two leachings at neutral and acidic pH (NT ENVIR 003) and oxidised availability tests at fully oxidising conditions by addition of hydrogen peroxide (NT ENVIR 006, 1999). 9 different types of natural rock material were used for comparison.

The leaching behaviour of natural rocks and blast furnace slags was very similar. Most of the metals exmined were less soluble from slags than from natural rock. As both total content of the trace elements of toxicological relevance, as well as their solubility under extreme environmental conditions, were supplied, Kd values can be derived (in the report inverse Kd values are given as the percentage of the total released into leachate). In general, these Kd were lower than typical Kd values of these elements in slags. The environmental relevance of the findings was clarified by comparison with natural rocks. The slags released less trace metals than the natural rocks, suggesting that their use in the environment poses no hazard (Tossavainen 2002).