Strontium oxide

Monitoring data

Administrative data

Endpoint:

monitoring data

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

retrieval date: 2016-03-23

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: High-quality environmental geochemical baseline data for Europe provided by the Geochemical Baseline Program of the Forum of European Geological Surveys (FOREGS).

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

adsorption / desorption

Remarks:

other: Evaluation of geochemical baseline concentrations of water and sediment

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

retrieval date: 2016-03-23

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The Kd estimation is based on field data of strontium concentrations in stream water and collected within the FOREGS program. Kd values were calculated based on paired samples assuming a site-specific equilibrium partioning between sediment and water.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline available

Principles of method if other than guideline:

The Geochemical Baseline Program of the Forum of European Geological Surveys (FOREGS) sampled stream water and stream sediment across Europe and measured respective background concentrations of more than 60 determinants. Measured concentrations were statistically analysed for EU countries and Norway. Based on concentrations measured at the same location in stream water and sediment, site-specific partition coefficients were derived.

GLP compliance:

no

Type of method:

other: Statistical analysis of enviromental geochemical baseline data for Europe

Media:

sediment

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Sampling:

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.
Samples for stream water and sediment were collected across Europe to measure baseline background concentrations of strontium.

Water and sediment samples:
Running stream water was collected together with sediment samples from small drainage basins (<100 km²), when possible, during the winter and early spring months. Sampling during rain periods and flood events was avoided. The water samples were collected before sediments were sampled. Metal contaminations were avoided as far as possible, i.e. no hand jewellery or medical dressings were allowed, gloves are recommended, etc. A total of 808 stream water samples and 852 sediment samples were processed in the FOREGS-program.

Computational methods:

Data selection:
In the FOREGS-database, data are available for strontium concentrations of stream water (808 samples), stream sediment (852 samples). Data from sampling locations with similar coordinates were selected to match stream water with sediment samples (757 samples).
In the first tier, FOREGS data for all European countries were analysed using the statistical package of MS Excel. Secondly, only data for EU-28 countries plus Norway were considered, i.e., data from Albania and Switzerland were excluded from further analysis.

Key result

Phase system:

sediment-water

Type:

log Kp

Value:

2.96 L/kg

Remarks on result:

other: European median value

Statistics:

Kd = site specific sediment concentration/ site specific stream water concentration (paired samples)
The European median log Kd was derived based on all site-specific log Kd values.

Table: Paired strontium concentrations and other environmental parameters of stream water and sediments and respective partitioning

	Parameter	#	Unit	Min.	Max.	Mean	STDEV	50^thp	90^thp
water	pH^1	749^2 737^4	-	9.8	4.5	6.6 6.6	5.85 5.85	7.7 7.7	6.5 6.5
water	Ca	757 745^4	mg/L	0.23	592.00	56.43 56.28	62.36 61.92	42.70 42.70	117.92 118.08
water	Mg	757 745^4	mg/L	0.05	230.00	11.69 11.70	19.53 19.64	6.25 6.24	26.53 26.23
water	NPOC	752^3 743^4	mg/L	0.25	57.94	7.35 7.41	8.05 8.08	4.76 4.79	16.25 16.34
water	Sr	757 745^4	mg/L	0.001	13.6	0.34 0.33	1.04 1.03	0.11 0.11	0.50 0.49
sediment	Sr	757 745^4	mg/kg	31.00	1,352.00	167.45 167.50	146.27 147.28	122.00 122.00	278.60 280.00
Partitioning (Kd)	Ti (sed / water)	757 745^4	L/kg	38.64	459,000	6,987 7,058	29,888 30,120	915 915	12,297 12,400
Log Kd	Ti (sed / water)	757 745^4	-	1.59	5.66	3.12 3.13	0.68 0.68	2.96 2.96	4.09 4.09

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.

Validity criteria fulfilled:

not applicable

Conclusions:

Reliable baseline levels of strontium in pristine water/sediment samples were determined in 745 samples. Sampling and analytical procedures are considered adequate and resulted in reliable data. Assuming equilibrium between the typical concentration in water and sediment, relevant log Kp-values were generated. Data are therefore considered useful for the determination of a relevant log Kp for the sediment compartment. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, the 50th percentile concentrations of strontium across Europe were 122 mg/kg in sediment and 0.11 mg/L in stream water, respectively, yielding a log Kp for strontium across Europe of 2.96.

Data source

Reference

Reference 1

Reference Type:

other: FOREGS database

Title:

Geochemical Atlas of Europe - Part 1: Background information, Methodology and Maps

Author:

Salminen et al.

Year:

2005

Bibliographic source:

EuroGeoSurveys

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

The Geochemical Baseline Program of the Forum of European Geological Surveys (FOREGS) sampled sub- and topsoils across Europe and measured respective background concentrations of more than 60 determinants. Measured concentrations were statistically analysed for EU countries and Norway.

GLP compliance:

no

Type of measurement:

natural background concentration

Media:

soil

Test material

Test material information

Constituent 1

Reference substance name:

Strontium

EC Number:

231-133-4

EC Name:

Strontium

Cas Number:

7440-24-6

Molecular formula:

Sr

IUPAC Name:

strontium

Test material form:

other: total strontium in soil

Details on test material:

- Name of test material (as cited in study report): Strontium

Study design

Details on sampling:

Sampling:
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. Samples were collected across Europe to measure baseline background concentrations of strontium.

Soil samples:
Topsoil and subsoil samples were collected at the same site from small second order, drainage basins (<100 km²) at suitable sites above its alluvial plain and base of slope.
Strontium concentrations for 845 topsoil and 788 subsoil samples are reported. 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).

Results and discussion

Any other information on results incl. tables

Table:Strontium concentrations and environmental parameters of top- and subsoil samples

	Parameter	Unit	#	Min	Max	Mean	STDEV	50^thp	90^thp
topsoil	pH^1	-	756 747^2	7.55	3.38	4.85 4.85	4.54 4.54	5.45 5.45	4.44 4.44
	TOC	%	759 750^2	0.07	46.61	2.47 2.38	3.24 2.91	1.72 1.72	4.56 4.45
	Sr	mg/kg	784 774^2	8.00	883.00 873.00	125.31 124.67	112.13 109.38	88.00 88.00	245.00 245.00
subsoil	pH^1	-	759 750^2	7.86	2.89	5.05 5.05	4.22 4.21	5.79 5.79	4.74 4.74
	TOC^3	%	760 752^2	0.001	48.52	0.94 0.93	2.86 2.86	0.40 0.39	1.76 1.72
	Sr	mg/kg	784 774^2	6.00	2,010.00 1,167.00	142.86 141.01	150.53 135.64	95.00 95.00	269.70 269.70

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

²Values from Switzerland and Albania are not included.

³For 26 samples with a value of 0 has been replaced by DL/2 (DL=0.01%)

Applicant's summary and conclusion

Conclusions:

Baseline strontium levels in topsoil range from 8 to 873 mg/kg Sr with 50th and 90th percentiles of 88 and 245 mg/kg Sr, respectively. In subsoil, concentrations of Sr range from 6 to 1,167 mg/kg Sr with 50th and 90th percentiles of 95 mg/kg and 269.7 mg/kg Sr, respectively.