Sodium dithionite

Monitoring data

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

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Unnamed

Year:

2005

Report date:

2005

Reference 2

Reference Type:

other: GEMAS database

Title:

Chemistry of Europe’s agricultural soils - Part A: Methodology and interpretation of the GEMAS data set.

Author:

Reimann et al.

Year:

2014

Reference 3

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

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 sulfur and sulfate concentrations in stream water, stream sediment, sub- and topsoil, as well as in agricultural soil and grazing land.

GLP compliance:

no

Type of measurement:

other: Geochemical background and ambient sulfur/sulfate 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

Test material information

Constituent 1

Reference substance name:

Sulfur

EC Number:

231-722-6

EC Name:

Sulfur

Cas Number:

7704-34-9

Molecular formula:

S

IUPAC Name:

sulfur

Test material form:

other: elemental concentrations

Details on test material:

Naturally occuring sulfur and sulfate

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 845 sediment samples were processed in the FOREGS-program, including 750 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment that are summarised below.
- The FOREGS dataset reports sulfur concentrations for 837 topsoil and 784 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 775 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 data base 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 sulfur concentrations for 2108 samples (including field duplicates) from the regularly ploughed layer (Ap-horizon) of agricultural land (arable land; 0 20 cm) and for 2023 samples (including field duplicates) from the top layer of 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 extend over several magnitudes. Sulfate water levels range from < 0.30 mg/L to 2,420.00 mg/L with 5^th and 95^th percentiles of 1.18 mg/L and 163.83 mg/L, respectively.

- The FOREGS dataset also reports sulfur concentrations in sediment. In the sediment, sulfur concentrations range from < 50 mg/kg to 33,495 mg/kg with 5^th and 95^th percentiles of 150.85 mg/kg and 2,816.85 mg/kg sulfur, respectively (Table 1).

- Taking into account the high quality and representativeness of the data set, the 50^th percentile of 16.88 mg/L can be regarded as typical background concentration for sulfate in European surface waters and the 50^th percentile of 508 mg/kg as typical background concentration of sulfur in European stream sediments.

- Regarding the partitioning of sulfur in the water column, stream water/sediment partition coefficients range from 1.28 L/kg to 15,728.31 L/kg. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, a European median log K_p value of 2.02 is derived.

Table 1: Water parameters and sulfur concentrations of stream sediment and stream water and respective partitioning

	Parameter	#	Unit	Min.	Max.	5^thP	50^thP	95^thP
water	pH ^1	742 ^2 730 ^4	-	9.80	4.50	8.50 8.50	7.70 7.70	6.10 6.10
water	Ca	750 738 ^4	mg/L	0.23	592.00	1.65 1.62	42.50 42.50	146.48 145.84
water	Cl	750 738 ^4	mg/L	0.14	4,560.00	0.48 0.49	8.96 9.00	66.57 68.13
water	HCO3	748 ^5 736 ^4	mg/L	0.69	1,804.42	5.41 5.35	131.52 128.02	370.00 371.00
water	K	750 738 ^4	mg/L	0.01	182.00	0.15 0.14	1.62 1.62	9.80 9.81
water	Mg	750 738 ^4	mg/L	0.05	230.00	0.46 0.46	6.20 6.17	37.94 38.07
water	Na	750 738 ^4	mg/L	0.23	4,030.00	0.99 1.00	6.66 6.68	48.23 48.28
water	NO3	750 738 ^4	mg/L	< 0.04	107.00	0.02 0.02	3.09 3.10	39.81 39.90
water	DOC	745 ^3 736 ^4	mg/L	< 0.50	57.94	0.60 0.60	4.76 4.80	23.02 23.09
water	SO4^2-	750 738 ^4	mg/L	< 0.30	2,420.00	1.18 1.18	16.77 16.88	165.29 163.83
water	S (based on measured SO4^2-)	750 738 ^4	mg/L	< 0.10	807.78	0.40 0.39	5.60 5.63	55.17 54.68
sediment	S	750 738 ^4	mg/kg	< 50.00	33,495.00	151.90 150.85	508.00 508.00	2,794.80 2,816.85
Partitioning (Kp)	S (sed / water)	750 738 ^4	L/kg	1.28	15,728.31	9.62 9.74	104.66 104.18	1,164.88 1,182.91
Log Kp	S (sed / water)	750 738 ^4	-	0.11	4.20	0.98 0.99	2.02 2.02	3.07 3.07

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

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

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

⁴ Values from Switzerland and Albania are not included.

⁵ Removal of 2 outliers < 0.01.

FOREGS DATABASE Background soil concentrations

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

- Baseline sulfur levels in topsoil range from < 50.00 mg/kg to 6,518.00 mg/kg sulfur with 5^th and 95^th percentiles of 75.00 mg/kg and 645.00 mg/kg sulfur, respectively. In subsoil, concentrations of sulfur range from < 50.00 mg/kg to 32,768.00 mg/kg with the 5^th and 95^th percentiles of < 50.00 mg/kg and 468.00 mg/kg sulfur, respectively (see Table 2).

- Taking into account the high quality and representativeness of the data set, the 50^th percentiles of 222 mg/kg and 104 mg/kg sulfur can be regarded as typical background concentrations of sulfur in top- and subsoils of EU countries, respectively.

Table 2: Concentrations of sulfur in top- and subsoil samples

	Parameter	Unit	#	Min	Max	5^thP	50^thP	95^thP
topsoil	pH ^1	-	747 738 ^2	7.55	3.38	7.26 7.26	5.45 5.45	4.28 4.29
	TOC	%	758 749 ^2	0.07	46.61	0.57 0.56	1.72 1.72	6.20 5.86
	sulfur	mg/kg	775 765 ^2	< 50.00	6,518.00	75.00 75.00	223.00 222.00	670.90 645.00
subsoil	pH ^1	-	750 741 ^2	7.86	2.89	7.56 7.56	5.79 5.80	4.52 4.53
	TOC ^3	%	749 741 ^2	0.001	48.52	0.01 0.01	0.39 0.39	2.72 2.72
	sulfur	mg/kg	775 765 ^2	< 50.00	32,768.00	< 50,00 < 50.00	105.00 104.00	479.20 468.00

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

² Values from Switzerland and Albania are not included.

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

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Sulfur levels of agricultural soil range from < 5.00 mg/kg to 68,226.33 mg/kg sulfur with 5^th and 95^th percentiles of 59.69 mg/kg and 783.91 mg/kg sulfur, respectively (see table 3). In grazing land, soil concentrations of sulfur range from < 5.00 mg/kg to 98,189.68 mg/kg with 5^th and 95^th percentiles of 67.26 mg/kg and 1,288.61 mg/kg sulfur, respectively (see table 4)

Table 3: Agricultural soil concentrations

Parameter	Unit	Method	#	Min	Max	5th P	50th P	95th P
CEC	meq/100g	AAS	2108 ^1 1867 ^2	1.80	48.30	6.24 6.10	16.40 15.80	34.67 33.30
pH (CaCl2)	pH	pH-meter	2108 ^1 1867 ^2	3.32	7.98	4.18 4.14	5.77 5.71	7.45 7.45
TOC	%	IR	2095 ^1 1854 ^2	0.40	46.00	0.70 0.70	1.80 1.70	5.40 5.67
sulfur	mg/kg	AR	2108 ^1 1867 ^2	< 5.00	68,226.33	64.02 59.69	206.97 209.31	728.65 783.91
sulfur	mg/kg	MMI	2108 ^1 1867 ^2	< 0.50	2.620	9.84 9.80	24.20 24.90	69.32 74.01

¹ EU – without ALB, BRU, MAL, MLD and ROM

² EU-27 plus UNK and NOR, without MAL and ROM

Table 4: Grazing land soil concentrations

Parameter	Unit	Method	#	Min	Max	5th P	50th P	95th P
CEC	meq/100g	AAS	2023 ^1 1781 ^2	2.54	49.88	8.17 8.27	18.75 17.96	38.12 37.74
pH (CaCl2)	pH	pH-meter	2022 ^1 1780 ^2	3.26	8.06	4.04 4.03	5.45 5.38	7.45 7.45
TOC	%	IR	2022 ^1 1780 ^2	0.41	49.00	0.92 0.94	2.70 2.80	10.00 11.05
sulfur	mg/kg	AR	2023 ^1 1781 ^2	< 5.00	98,189.68	68.97 67.26	295.43 309.96	1,168.98 1,288.61

¹ EU – without ALB, BRU, MAL, MLD and ROM

² EU-27 plus UNK and NOR, without MAL and ROM

Applicant's summary and conclusion

Conclusions:

Typical background or ambient concentrations of sulfur in various environmental compartments as derived from monitoring data are summarised below:

compartment, unit, concentration (50th P), concentration (95th P)
Background stream water, mg/L sulfate, 16.88, 163.83
, mg/L sulfur, 5.63*, 54.68*
Background stream water sediment, mg/kg sulfur, 508.00, 2,816.85
Background topsoil, mg/kg sulfur, 222.00, 645.00
Background subsoil, mg/kg sulfur, 104.00, 468.00
Agricultural soil, mg/kg sulfur, 209.31, 783.91
Grazing land soil, mg/kg sulfur, 309.96, 1,288.61
* based on measured sulfate

Sulfur is a non-metal element occurring in oxidation states -2, 0, +2, +4 and +6 and forms many sulfide and sulfosalt ore minerals, such as Chalcosite (Cu2S), pyrite (FeS2), sphalerite (ZnS), galena (PbS), cinnabar (HgS), stibnite (Sb2S3) and oldhamite (CaS) or anhydrous or hydrated sulfates, e.g., barite (BaSO4), gypsum (CaSO4.2H2O), anhydrite (CaSO4) and epsomite (MgSO4.7H2O). Evaporite minerals generally take the form of anhydrous or hydrated sulfates. Another form of sulfate in sediments is pyrite (FeS2) (Reimann et al. 2014 and Salminen et al., 2005 and references therein).

Sulfur exists predominantly as the free SO42- anion in stream water but some HSO4- may be present in acid water (pH<4) and H2S under very reducing conditions. Aquatic systems controlled by gypsum rarely contain more than 1500 mg/L SO42- and 650 mg/L Ca, but the tendency of SO42- to form neutrally charged ion-pair associations can result in oversaturation with respect to gypsum. Magnesium sulfate is very soluble, so sulfate concentrations may be high in Mg-dominated systems in the absence of Ca (Salminen et al. 2005 and references therein).

Based on the FOREGS dataset, sulfate concentrations in European stream waters can extend up to 2,420 mg/L but are generally below 165 mg/L (95th P = 164 mg/L). Sulfur concentrations of sediments can be as high as 33,495 mg/kg but are typically below 3,000 mg/kg (95th P = 2,817 mg/kg).

Corresponding log sediment/water partition coefficients range from 0.11 to 4.20 with 5th and 95th percentiles of 0.99 and 3.07, respectively (Kp values range from 1.28 L/kg to 15,728.31 L/kg). A European median log Kp value of 2.02 is derived.

Adsorption and reduction processes govern the mobility of sulfur in soil. In poorly drained, peaty soil, sulfur is immobilised and enriched as sulfide. Micro-organisms control the redox state of sulfur, capable of oxidation or reduction depending on microbial species and environmental conditions (Salminen et al. 2005 and references therein).

Based on the FOREGS dataset, sulfur concentrations of topsoils can be as high as 6,518 mg/kg but are typically below 700 mg/kg (95th P = 645 mg/kg). According to the GEMAS dataset, typical sulfur concentrations of agricultural soils are below 800 mg/kg (95th P = 784 mg/kg) and below 1,300 mg/kg (95th P = 1,289 mg/kg) in grazing land soil with a maximum of 68,226 mg/kg and 98,190 mg/kg, respectively.