Registration Dossier

Administrative data

Endpoint:
monitoring data
Type of information:
other: report
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Cross-reference
Reason / purpose:
reference to same study
Reference
Endpoint:
adsorption / desorption, other
Remarks:
monitoring data in water and sediment
Type of information:
other: Calculation of Kd values based on environmental field data
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Kd-values are based on reliable field data of concentration levels in water and sediment; no standard guideline test was conducted to generate Kd-values. Kd-values are calculated based on the hypothesis that equilibrium exists between the baseline levels in water and in sediment.
Reason / purpose:
reference to same study
Qualifier:
no guideline followed
Principles of method if other than guideline:
Evaluation of high quality environmental geochemical data for Europe, which is provided by the Forum of European Geological Surveys (FOREGS), with respect to Ti concentrations in stream water and stream sediment. Baseline levels of titanium in water and sediment were determined in 751 paired sample locations. Assuming equilibrium between both environmental compartments, site-specific Kd's were derived.
GLP compliance:
no
Type of method:
other: field data of baseline levels in water and sediment
Media:
sediment
Radiolabelling:
no
Test temperature:
environmental relevant temperatures
Analytical monitoring:
yes
Details on sampling:
FOREGS:
-The FOREGS sampling grid was based on GTN grid cells developed for Global Geochemical Baseline mapping. This grid divides the entire land surface into 160 km x 160 km cells covering an area of 4,500,000 km2.
- Sampling methodology, preparation and analysis are described by Salminen et al. (2005).
- A total of 808 stream water samples and 852 sediment samples were processed in the FOREGS-program, including 757 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment that are summarised below. However, Ti concentrations in six stream water samples were reported with “0.0” (five samples) or “-1.0” (1 sample), and respective samples were excluded from the analysis, resulting in a total of 751 paired samples summarised below. However, including these six samples with estimated concentrations of ½ LOD (=0.005 µg/L) does shift the summary statistics negligibly.
- High quality and consistency of the obtained data were ensured by using standardised sampling methods and by treating and analysing all samples in the same laboratory of each country.
Key result
Phase system:
sediment-water
Type:
log Kp
Value:
6.57 L/kg
Adsorption and desorption constants:
- Regarding the partitioning of titanium in the water column, stream water/sediment partition coefficients range from 182,527 L/kg to 119,329,191 L/kg. Country-specific stream water/sediment partition coefficients are reported in Table 1, and median values range from a log Kd of 6.22 to 7.29 (Table 1). Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, a European median log Kd value of 6.57 is derived (Table 2).

- Even though Ti concentrations of sediments can be as high as 3 %, dissolved/dispersed Ti concentrations in the water column of European stream waters are well below 20 µg/L. These monitoring stream water and sediment data provide strong evidence that Ti is sparingly soluble in a wide representative range of European stream waters.

Table 1: Country-specific stream water/sediment partition coefficients

Country

# of data

Area (km2)

Min

Max

Mean

5thP

50thP

90thP

95thP

AL

3

28,748

7.38

7.74

7.57

7.39

7.52

7.70

7.72

AT

20

83,879

6.18

7.66

7.12

6.28

6.81

7.56

7.56

BE

5

32,545

6.43

7.20

6.87

6.48

6.68

7.12

7.16

CH

9

41,285

5.92

6.94

6.65

6.17

6.65

6.85

6.89

CZ

10

78,866

6.25

7.19

6.72

6.25

6.44

7.09

7.14

DE

74

357,121

5.60

7.58

6.66

6.04

6.52

6.98

7.03

DK

5

43,098

5.92

6.82

6.48

5.95

6.50

6.72

6.78

EE

11

45,227

6.11

6.87

6.50

6.16

6.31

6.76

6.82

ES

82

504,645

5.26

7.86

7.10

5.77

6.75

7.56

7.76

FI

64

338,144

5.36

7.64

6.67

5.48

6.22

7.07

7.31

FR

117

543,965

5.49

7.80

6.83

6.07

6.62

7.13

7.23

GR

27

131,957

5.96

7.74

6.95

6.16

6.80

7.17

7.28

HR

10

56,542

5.96

7.21

6.80

6.20

6.66

7.05

7.14

IE

11

70,273

6.04

6.67

6.52

6.19

6.56

6.63

6.65

IT

45

301,336

5.42

7.80

6.92

5.67

6.56

7.32

7.50

LT

14

64,589

5.97

6.81

6.45

6.00

6.36

6.65

6.71

LV

7

65,301

5.97

6.60

6.36

6.03

6.36

6.55

6.57

NL

9

41,526

5.68

6.79

6.43

5.83

6.41

6.65

6.72

NO

55

323,759

5.64

8.08

7.42

6.11

7.24

7.80

7.89

PL

56

312,685

5.29

6.98

6.33

5.89

6.22

6.61

6.68

PT

19

92,345

5.84

7.79

7.33

6.53

7.29

7.62

7.70

SE

20

449,964

5.79

7.63

6.89

5.80

6.49

7.24

7.58

SK

15

49,034

6.10

7.02

6.66

6.24

6.58

6.88

6.94

SL

4

20,253

6.95

7.27

7.11

6.97

7.07

7.23

7.25

UK

59

219,331

5.99

7.83

7.03

6.19

6.64

7.39

7.67

Table 2: Paired titanium and titanium dioxide concentrations of stream water, sediments and respective partitioning

Parameter

#

Unit

Min.

Max.

Mean

STDEV

5thp

50thp

90thp

95thp

water

pH1

7432

7314

-

9.8

4.5

6.6

6.6

5.85

5.84

8.5

8.5

7.7

7.7

6.5

6.5

6.1

6.1

water

Ca

751

7394

mg/L

0.23

592.00

56.58

56.43

62.47

62.02

1.72

1.70

43.10

43.10

117.60

117.76

148.25

148.21

water

Cl

751

7394

mg/L

0.14

4560.00

34.92

35.35

198.40

199.97

0.49

0.51

9.48

9.50

43.79

44.03

69.78

72.31

water

HCO3

7495

7374

mg/L

0.69

1804.42

156.11

156.12

145.92

146.41

5.96

5.84

134.00

131.67

335.72

335.91

372.40

374.55

water

K

751

7394

mg/L

0.01

182.00

3.15

3.18

7.57

7.62

0.15

0.15

1.65

1.66

6.87

6.91

9.83

9.87

water

Mg

751

7394

mg/L

0.05

230.00

11.74

11.75

19.60

19.71

0.48

0.49

6.25

6.25

26.55

26.52

38.37

38.80

water

Na

751

7394

mg/L

0.23

4030.00

24.15

24.41

163.76

165.07

1.01

1.03

6.80

6.80

25.69

25.72

48.31

48.39

water

NO3

751

7394

mg/L

0.02

107.00

9.38

9.47

13.67

13.75

0.02

0.02

3.10

3.19

29.03

29.08

39.80

39.90

water

DOC

7463

7374

mg/L

0.25

57.94

7.38

7.45

8.08

8.10

0.60

0.61

4.78

4.82

16.31

16.40

23.01

23.08

water

SO4

751

7394

mg/L

0.15

2420.00

54.11

53.73

157.74

157.22

1.19

1.19

16.96

17.49

103.64

103.13

172.22

168.04

water

Dissolved/dispersed Ti

751

7394

µg/L

0.10

16.80

1.46

1.47

1.96

1.97

0.10

0.10

0.90

0.90

2.90

2.90

4.25

4.21

sediment

Ti

751

7394

%

0.01

2.99

0.42

0.42

0.24

0.24

0.14

0.14

0.39

0.39

0.63

0.63

0.80

0.81

Partitioning (Kd)

Ti (sed / water)

751

7394

L/kg

182,527

119,329,191

8,922,560

8,862,395

14,215,816

14,182,762

747,891

733,573

3,792,985

3,695,949

21,616,304

21,348,598

40,635,455

40,084,060

Log Kd

Ti (sed / water)

751

7394

-

5.26

8.08

6.62

6.62

0.51

0.51

5.87

5.87

6.58

6.57

7.33

7.33

7.61

7.60

1Statistics are based on H+concentrations rather than pH.

2Removal of 2 outliers < pH 4.3 and 6 negative values.

3Removal of 1 outlier > 70 mg/L and 4 negative values.

4Values from Switzerland and Albania are not included.

5Removal of 2 outliers < 0.01.

Conclusions:
Reliable baseline levels of titanium in pristine water/sediment samples were determined in 751 samples. Sampling and analytical procedures are considered adequate and resulted in reliable data. Assuming equilibrium between the typical concentration in water and sediment, relevant KD-values were generated. Data are therefore considered useful for the determination of a relevant KD for the sediment compartment. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, a European median log Kd value of 6.57 is derived.

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Unnamed
Year:
2005
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
no guideline required
Principles of method if other than guideline:
Evaluation and summary of high quality environmental geochemical data for Europe, which is provided by the Forum of European Geological Surveys (FOREGS) and the European Geochemical Mapping of Agricultural and Grazing Land Soil (GEMAS), with respect to Ti concentrations in stream water, stream sediment, sub- and topsoil, as well as in agricultural soil and grazing land. In addition, an overview of titanium solubility, possible chemical species and their calculated areas of thermodynamic stability under environmentally relevant conditions is included.
GLP compliance:
no
Type of measurement:
other: Geochemical background and ambient Ti concentrations in environmental compartments across Europe
Media:
other: Natural stream water, stream sediment and soil (top- and subsoil), as well as agricultural and grazing land soils

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: elemental concentrations
Details on test material:
naturally occuring titanium

Study design

Details on sampling:
FOREGS:
-The FOREGS sampling grid was based on GTN grid cells developed for Global Geochemical Baseline mapping. This grid divides the entire land surface into 160 km x 160 km cells covering an area of 4,500,000 km2.
- Sampling methodology, preparation and analysis are described by Salminen et al. (2005).
- A total of 808 stream water samples and 852 sediment samples were processed in the FOREGS-program, including 757 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment that are summarised below. However, Ti concentrations in six stream water samples were reported with “0.0” (five samples) or “-1.0” (1 sample), and respective samples were excluded from the analysis, resulting in a total of 751 paired samples summarised below. However, including these six samples with estimated concentrations of ½ LOD (=0.005 µg/L) does shift the summary statistics negligibly.
- The FOREGS dataset reports titanium concentrations as titanium dioxide concentrations for 845 topsoil and 788 subsoil samples sampled on a grid across Europe. Two different depth related samples were taken at each site: a topsoil sample from 0-25 cm (excluding material from the organic layer where present), and a subsoil sample from a 25 cm thick section within a depth range of 50 to 200 cm (the C soil horizon). Data from sampling locations with similar coordinates were selected to match subsoil with topsoil samples resulting in 782 paired samples.
- High quality and consistency of the obtained data were ensured by using standardised sampling methods and by treating and analysing all samples in the same laboratory of each country.

GEMAS:
- Samples from 33 out of 38 European countries were analysed to develop a suitable harmonised geochemical database for soils. The sampling started in the spring 2008 and the first four months of 2009.
- The whole GEMAS project area of 5,600,000 km2 was divided into a grid with 50 km x 50 km cells.
- To generate harmonised data sets, all project samples were processed by a central sample preparation facility in Slovakia.
- The GEMAS dataset reports titanium and titanium dioxide concentrations for 2108 samples (including field duplicates) from the ploughing soil layer (Ap-horizon) of agricultural land (arable land; 0 - 20 cm) and for 2023 samples (including field duplicates) from the topmost part soil on grazing land (soil under permanent grass cover; 0 – 10 cm) sampled on a grid across Europe.

Results and discussion

Any other information on results incl. tables

FOREGS DATABASE STREAM WATER/SEDIMENT:

- Sampled stream water and sediments cover a wide range of environmental conditions. Water parameters such as pH, hardness and organic carbon concentrations cover several magnitudes. Dissolved/dispersed titanium water levels range from < 0.1 to 16.80 µg Ti/L with 5thand 95thpercentiles of 0.10 and 4.21 µg Ti/L, respectively.

- The FOREGS dataset reports titanium dioxide concentrations of the sediment. Respective TiO2-data were converted into titanium concentrations to enable comparison of sediment with dissolved/dispersed stream water concentrations. Sediment concentrations of Ti range from 0.01 to 2.99 % Ti with 5thand 95thpercentiles of 0.14 and 0.81 % Ti, respectively (Table 1).

- Taking into account the high quality and representativeness of the data set, the 95thpercentile of 4.21 µg Ti/L can be regarded as typical background concentration for dissolved/dispersed titanium in European surface waters and the 95thpercentile of 0.81 % Ti as typical background concentration of European stream sediments.

- Even though Ti concentrations of sediments can be as high as 3 %, dissolved/dispersed Ti concentrations in the water column of European stream waters are well below 20 µg/L. These monitoring stream water and sediment data provide strong evidence that Ti is sparingly soluble in a wide representative range of European stream waters.

Table1: Paired titanium and titanium dioxide concentrations of stream water, sediments and respective partitioning

Parameter

#

Unit

Min.

Max.

Mean

STDEV

5thp

50thp

90thp

95thp

water

pH1

7432

7314

-

9.8

4.5

6.6

6.6

5.85

5.84

8.5

8.5

7.7

7.7

6.5

6.5

6.1

6.1

water

Ca

751

7394

mg/L

0.23

592.00

56.58

56.43

62.47

62.02

1.72

1.70

43.10

43.10

117.60

117.76

148.25

148.21

water

Cl

751

7394

mg/L

0.14

4560.00

34.92

35.35

198.40

199.97

0.49

0.51

9.48

9.50

43.79

44.03

69.78

72.31

water

HCO3

7495

7374

mg/L

0.69

1804.42

156.11

156.12

145.92

146.41

5.96

5.84

134.00

131.67

335.72

335.91

372.40

374.55

water

K

751

7394

mg/L

0.01

182.00

3.15

3.18

7.57

7.62

0.15

0.15

1.65

1.66

6.87

6.91

9.83

9.87

water

Mg

751

7394

mg/L

0.05

230.00

11.74

11.75

19.60

19.71

0.48

0.49

6.25

6.25

26.55

26.52

38.37

38.80

water

Na

751

7394

mg/L

0.23

4030.00

24.15

24.41

163.76

165.07

1.01

1.03

6.80

6.80

25.69

25.72

48.31

48.39

water

NO3

751

7394

mg/L

0.02

107.00

9.38

9.47

13.67

13.75

0.02

0.02

3.10

3.19

29.03

29.08

39.80

39.90

water

DOC

7463

7374

mg/L

0.25

57.94

7.38

7.45

8.08

8.10

0.60

0.61

4.78

4.82

16.31

16.40

23.01

23.08

water

SO4

751

7394

mg/L

0.15

2420.00

54.11

53.73

157.74

157.22

1.19

1.19

16.96

17.49

103.64

103.13

172.22

168.04

water

Dissolved/dispersed Ti

751

7394

µg/L

0.10

16.80

1.46

1.47

1.96

1.97

0.10

0.10

0.90

0.90

2.90

2.90

4.25

4.21

sediment

Ti

751

7394

%

0.01

2.99

0.42

0.42

0.24

0.24

0.14

0.14

0.39

0.39

0.63

0.63

0.80

0.81

Partitioning (Kd)

Ti (sed / water)

751

7394

L/kg

182,527

119,329,191

8,922,560

8,862,395

14,215,816

14,182,762

747,891

733,573

3,792,985

3,695,949

21,616,304

21,348,598

40,635,455

40,084,060

Log Kd

Ti (sed / water)

751

7394

-

5.26

8.08

6.62

6.62

0.51

0.51

5.87

5.87

6.58

6.57

7.33

7.33

7.61

7.60

1Statistics are based on H+concentrations rather than pH.

2Removal of 2 outliers < pH 4.3 and 6 negative values.

3Removal of 1 outlier > 70 mg/L and 4 negative values.

4Values from Switzerland and Albania are not included.

5Removal of 2 outliers < 0.01.

FOREGS DATABASE STREAM TOP-AND SUBSOIL:

- Sampled soils cover a wide range of environmental conditions. Soil parameters, including pH and TOC, cover several magnitudes.

- Baseline titanium levels in topsoil range from 0.013 % Ti to 2.496 % Ti with 5thand 95th percentiles of 0.113 and 0.663 % Ti, respectively. In subsoil, concentrations of Ti range from 0.007 % to 1.881 % with the 5thand 95thpercentiles of 0.085 % and 0.645 % Ti, respectively (seeTable 2).

- Taking into account the high quality and representativeness of the data set, the 95th percentiles of 0.663 and 0.645 % Ti can be regarded as typical background concentrations of titanium dioxide in top- and subsoils of EU countries, respectively.

Table 2: Concentrations of titanium dioxide in top- and subsoil samples

Parameter

Unit

#

Min

Max

Mean

STDEV

5thp

50thp

90thp

95thp

topsoil

pH1

-

756

7472

7.55

3.38

4.85

4.85

4.54

4.54

4.28

4.28

5.45

5.45

4.44

4.44

7.26

7.26

TOC

%

759

7502

0.07

46.61

2.47

2.39

3.24

2.91

0.58

0.58

1.72

1.72

4.56

4.45

5.97

5.86

TiO2

%

784

7742

0.021

4.165

0.600

0.602

0.325

0.326

0.185

0.188

0.570

0.570

0.951

0.953

1.11

1.11

Ti3

%

784

7742

0.013

2.496

0.360

0.361

0.195

0.195

0.111

0.113

0.341

0.341

0.570

0.571

0.663

0.663

subsoil

pH1

-

759

7502

7.86

2.89

5.05

5.05

4.22

4.21

4.53

4.34

5.79

5.80

4.74

4.74

7.56

7.56

TOC4

%

760

7522

0.001

48.52

0.94

0.93

2.86

2.86

0.01

0.01

0.40

0.39

1.75

1.72

2.72

2.72

TiO2

%

784

7742

0.012

3.139

0.588

0.589

0.322

0.323

0.142

0.143

0.565

0.563

0.935

0.936

1.074

1.076

Ti3

784

7742

0.007

1.881

0.353

0.353

0.193

0.194

0.085

0.085

0.338

0.337

0.560

0.561

0.644

0.645

1 Statistics are based on H+concentrations rather than pH.

2Values from Switzerland and Albania are not included.

3Values converted from TiO2.

4For 26 samples with a value of 0 has been replaced by DL/2 (DL=0.01%)

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Baseline titanium levels in agricultural land range from < 0.01 to 2.45 % Ti with 5thand 95th percentiles of 0.11 and 0.60 % Ti, respectively (seeTable 3). In grazing land, concentrations of Ti range from 0.01 to 2.38 % with 5thand 95thpercentiles of 0.09 and 0.61 % Ti, respectively (see Table 4).

Table 3: Agricultural soil concentrations

Parameter

Unit

Method

#

Min

Max

Mean

STD

5p

50p

90p

95p

CEC

meq/100g

AAS

2108*1

1867*2

1.80

48.30

17.93

17.25

8.77

8.45

6.24

6.10

16.40

15.80

30.33

29.10

34.67

33.30

pH (CaCl2)

pH

pH-meter

2108*1

1867*2

3.32

7.98

5.88

5.85

1.10

1.12

4.18

4.14

5.77

5.71

7.36

7.37

7.45

7.45

TOC

%

IR

2095*1

1854*2

0.40

46.00

2.55

2.62

3.98

4.21

0.70

0.70

1.80

1.70

3.90

4.10

5.40

5.67

Ti

mg/kg

AR

2108*1

1867*2

2.50

7860.10

247.77

265.37

399.66

413.01

16.95

16.94

85.70

96.37

711.08

746.57

973.51

1,006.83

Ti3

%

XRF

2108*1

1867*2

0.01

2.45

0.36

0.36

0.18

0.18

0.11

0.11

0.36

0.35

0.54

0.54

0.60

0.60

mg Ti/kg

2108*1

1867*2

89.90

24,549.01

3,617.17

3,586.34

1,797.22

1,839.66

1,108.78

1,132.76

3,620.03

3,524.14

5,383.90

5,402.48

5,955.37

6,028.79

Ti

mg/kg

MMI

2108*1

1867*2

< 0.01

13.20

0.25

0.28

0.60

0.64

< 0.01

< 0.01

0.04

0.05

0.72

0.80

1.26

1.39

Ti

%

AR/XRF

2108*1

1867*2

0.05

52.12

6.70

7.22

8.08

8.33

0.52

0.50

2.89

3.40

18.62

19.73

24.72

25.24

Ti

%

MMI/AR

2107*1+

1866*2+

< 0.01

42.40

0.27

0.28

1.34

1.40

< 0.01

< 0.01

0.05

0.05

0.49

0.52

1.05

1.05

*1EU – ALB, BEL, MAL, MLD, ROM

*2EU-28 plus NOR without MAL

3Values converted from TiO2.

+one sample of MMI could not be paired

Table 4: Grazing land soil concentrations

Parameter

Unit

Method

#

Min

Max

Mean

STD

5p

50p

90p

95p

CEC

meq/100g

AAS

2023*1

1781*2

2.54

49.88

20.42

20.01

9.40

9.32

8.17

8.27

18.75

17.96

33.87

33.42

38.12

37.74

pH (CaCl2)

pH

pH-meter

2022*1

1780*2

3.26

8.06

5.68

5.63

1.16

1.17

4.04

4.03

5.45

5.38

7.33

7.33

7.45

7.45

TOC

%

IR

2022*1

1780*2

0.41

49.00

4.05

4.24

5.36

5.64

0.92

0.94

2.70

2.80

6.80

7.00

10.00

11.05

Ti

mg/kg

AR

2023*1

1781*2

2.50

10,420.82

213.14

229.53

413.52

432.49

15.21

15.35

73.71

77.70

594.94

642.45

859.47

910.45

Ti3

%

XRF

2023*1

1781*2

0.01

2.38

0.35

0.35

0.18

0.19

0.09

0.09

0.36

0.35

0.54

0.54

0.60

0.61

mg/kg

2023*1

1781*2

113.88

23,757.96

3,537.06

3,516.91

1,829.73

1,851.70

894.22

911.00

3,566.09

3,518.14

5,364.12

5,370.11

6,031.79

6,065.35

Ti

%

AR/XRF

2023*1

1781*2

0.05

56.22

5.91

6.39

7.67

7.99

0.43

0.42

2.69

3.04

16.25

17.41

22.58

23.81

*1EU – ALB, BEL, MAL, MLD, ROM

*2EU-28 plus NOR without MAL

3Values converted from TiO2.

Speciation of TiO2in stream water: Thermodynamic stability areas of Ti species as a function of pH

At typical environmental conditions (pH 4-10, elemental concentrations as reported in FOREGS stream waters), TiO2constitutes the predominating solid species according to modeling approaches using Outotec Oyjs HSC8 software (v8.2.0, Eh-pH Diagrams Module) . Aqueous neutral Ti(OH)4, the “hydrous” TiO2species, is prevalent in the pH range 3 – 10, however at nanomolar levels, i.e. < 50 ng/L at 25°C, 100 mM NaCl2, approx. 0.5 mg/L TiO2loading, pH 3 ‑ 11 according to Schmidt & Vogelsberger (2009). In aqueous solutions, unhydrolysed Ti4+(aq) does not remain as a free ion. As solution pH increases, a series of hydrolysed titanium species is formed, of which Ti(OH)4is the predicted predominant environmental aqueous species. This is in agreement with other studies which predicted that Ti(OH)4 constituting the dominant aqueous species and estimated a solubility of TiO2 - nanoparticles at environmentally relevant conditions in the nanomolar range. Based on the performed modelling approaches, TiO2does not dissolve to any significant extent under environmentally relevant conditions and is thus not expected to be bioavailable. Major ions (Ca, Cl, H, K, Mg, Na, S, N) as found in European freshwaters do not appear to affect titanium solubility or speciation.

Applicant's summary and conclusion

Conclusions:
Typical baseline concentrations for titanium in various environmental compartments as derived from monitoring data are summarised below:

Compartment Typical baseline level (95th P)
Background stream water µ µg dissolved/dispersed Ti/L 4.21
Background stream water sediment % Ti 0.81
Background topsoil % Ti 0.663
Background subsoil % Ti 0.645
Agricultural soil % Ti 0.603
Grazing land soil % Ti 0.607

According to Salminen et al. (2005), titanium is a common lithophile metallic element that forms several minerals, including ilmenite FeTiO3, rutile, brookite, anatase (all TiO2) and sphene CaTiSiO5, but it also occurs as an accessory element in pyroxene, amphibole, mica and garnet.
Titanium has very low mobility under almost all environmental conditions, mainly due to the high stability of the sparingly soluble TiO2 under all, but the most acid conditions, i.e., below pH 2 (Brookins 1988 as referenced in Salminen et al. 2005), a pH typically not observed in the environment. Titanium minerals are resistant to weathering, they occur practically undecomposed in soil. Titanium is mobilised more readily in peats and podzols (Hutton et al. 1972), at low pH (<4.5) and in the presence of organic acids. Based on the FOREGS dataset, Ti concentrations of topsoils can be as high as 2.5 % but are typically below 0.7 % (95th P = 0.663 %). Typical Ti concentrations below 0.7 % were also measured in agricultural and grazing land (95th P = 0.6 %) with a maximum around 2.4 %. Total Ti concentrations of agricultural and grazing land soil of the EU28+Norway are 3,524 and 3,518 mg/kg. However, only 3.40 % (agricultural land) and 3.04 % (grazing land) of total titanium was extractable by aqua regia (all median values).
Some Ti may dissolve in stream water through weathering of ferromagnesian minerals and authigenic phases, such as anatase, but dispersal is generally restricted by adsorption to clays. Titanium may further be removed from the water column by flocculation of colloidal material, adsorption and scavenging by precipitation of Mn and Fe oxides (Skrabal 1995 as referenced in Salminen et al. 1998).
Based on the FOREGS dataset, dissolved/dispersed titanium concentrations in European stream waters, can go up to 16.8 µg/L but are generally below 4.5 µg/L (95th P = 4.21 µg/L). Titanium exists only in a fully hydrated form, TiO2 * n H2O, in water above pH 2, and is, therefore, transported in a colloidal state rather than as dissolved ion (Skrabal 1995 as referenced in Salminen et al. 1998). This is further supported by thermodynamic stability data and speciation modelling, which suggests TiO2 * n H2O to consitute the dominating species within environmentally relevant pH values and within the ionic composition of stream waters as provided by the FOREGS dataset. Because of the propensity of TiO2 for hydrolysis, other titanium hydroxo complexes than TiO2 * n H2O are rare within a pH range of pH 4-10. According to Salminen et al. (2005), a large proportion of the Ti in stream water sediments is held in minerals, such as rutile, ilmenite and sphene, all of which are relatively insoluble. Based on the FOREGS dataset, Ti concentrations of sediments can be as high as 3 % but are typically below 0.9 % (95th P = 0.81 %).