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EC number: 910-356-7 | CAS number: -
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
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- Repeated dose toxicity
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- Carcinogenicity
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- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Adsorption / desorption
Administrative data
Link to relevant study record(s)
- Endpoint:
- adsorption / desorption, other
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Justification for type of information:
- For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “read-across: supporting information”.
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across: supporting information
- Key result
- Type:
- log Kd
- Value:
- 3.4 dimensionless
- pH:
- 7
- Matrix:
- soil
- % Org. carbon:
- 2
- Remarks on result:
- other: based on Log Kd = 1.75 + 0.21pH(soil solution)+ 0.51 log(OC%)
- Validity criteria fulfilled:
- not applicable
- Conclusions:
- The Kd value for copper was 2363 L/kg / log Kd 3.4 assuming a soil solution pH of 7 and OC of 2%; the value may be adapted to site-specific conditions.
- Executive summary:
The study used as source reference investigated the solid-solution partitioning of metals in contaminated soils: dependence on pH, total metal burden, and organic matter (13 metals). Results for copper are presented here. First available Kd values from literature were collected (over 70 studies), and second an empirical linear regression and semi-mechanistic model were developed in order to derive partitioning coefficients against soil solution pH combined with soil organic matter or total soil metal. In total 452 Kd values were collected to derive the empirical linear regression, which was used to determine the generic Kd value for non-site-specific risk assessment. The work of Sauvé et al. 2000 has been used in the CA assessment report on copper oxide (Directive 98/8/EC concerning the placing of biocidal products on the market, Inclusion of active substances in Annex I or IA to Directive 98/8/EC Assessment Report, Copper (II) oxide, 2011, France) and in the VRAR on copper compounds (Voluntary risk assessment reports - Copper and Copper Compounds, European Copper Institute, 2008). The derived log Kd value of 2120 L/kg (log Kd: 3.3) and the empirical linear regression model, integrating pH and soil organic matter (OC) in case of site-specific information, has been proposed for copper oxide by the CA France (2011) and copper compounds by VRAR (2008). The work of Sauvé et al. 2000 was considered reliable and adequate for the evaluation of the environmental fate of the targes compounds. Justification and applicability of the read-across approach (structural analogue) is outlined in the attached document (see section 13 or find a link in cross reference).
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- Not reported
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: see 'Remark'
- Remarks:
- Study conducted to a current guideline. Since Manganese dioxide is comprised of Mn4+, this form of the substance can be expected to adsorb to soil to a slightly greater extent than Mn2+, and the Kd median result is considered to be sufficiently representative at present to use in risk assessment.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
- Deviations:
- no
- GLP compliance:
- not specified
- Type of method:
- batch equilibrium method
- Media:
- soil
- Specific details on test material used for the study:
- 54Mn2+ was added to 35 soils. In addition, MnO2 was added alongside for 5 selected soils.
- Radiolabelling:
- yes
- Remarks:
- 54Mn at about 143 Bq/g for acid soils (pH < 6) and 667 Bq/g for pH neutral soils (pH > 6)
- Test temperature:
- Room temperature
- Analytical monitoring:
- yes
- Details on sampling:
- - Sampling interval: two consecutive extractions
- Sample storage before analysis: 3 days, 100 days and 6 months - Details on matrix:
- Soils sampled for the Mn adsorption/desorption studies.
Nr† Location Country pH total C Organic C CaCO3 CEC Total Mn
% % % cmolc/kg mg/kg
1 Gudow Germany 3.0 5.1 5.1 0 5.8 5
2 Nottingham UK 3.4 5.2 5.2 0 6.7 37
3 Houthalen Belgium 3.4 1.9 1.9 0 1.9 4
4 Lommel Belgium 4.1 1.6 1.6* n.d. 1.2 5
5 Kasterlee Belgium 4.7 2.1 2.1 0 3.5 23
6 Zegveld Netherlands 4.7 23.3 23.3 0 35 68
7 Kövlinge Sweden 4.8 1.6 1.6 0 2.4 42
8 Rhydtalog UK 4.8 7.8 7.8 0 15 86
9 Wageningen Netherlands 5.0 1.5 1.5 0 1.9 126
10 Montpellier France 5.2 0.8 0.8 0 2.5 29
11 De Meern Netherlands 5.2 10.2 10.2 0 30 88
12 Zwijnaarde Belgium 5.2 1.8 1.8 n.d. 4.1 18
13 Hygum Denmark 5.4 2.3 2.3 0 8.6 177
14 Aluminusa Italy 5.4 0.9 0.9 0 23 48
15 Lovenjoel Belgium 5.5 3.2 3.2* n.d. 10 49
16 Zeveren Belgium 5.7 3.5 3.5 0 19 116
17 Plombières France 5.8 5.4 5.4* n.d. 10 43
18 Wilsele Belgium 6.1 2.1 2.1* n.d. 3.3 396
19 London UK 6.3 4.3 4.3* n.d. 20 610
20 Woburn UK 6.4 4.4 4.4 0 23 248
21 Rijswijk Uzimet Nederland 6.6 4.6 0.2 1.7 26 265
22 Lille Exide France 6.6 4.6 0.2 1.7 26 325
23 Ter Munck Belgium 6.7 0.9 0.9 n.d. 12 246
24 Bordeaux France 6.8 1.6 n.d. n.d. 14 103
25 Florival Exide Belgium 6.8 2.0 0.0 0.3 15 85
26 Paris France 7.2 1.4 n.d. n.d. 11 109
27 Rots France 7.3 2.8 1.3 13 14 82
28 Vault de Lugny France 7.3 2.2 1.5 6.0 26 2397
29 Souli Greece 7.4 8.3 2.6 47 36 133
30 Barcelona Spain 7.5 2.3 1.5 7.2 14 102
31 Brécy France 7.5 3.6 1.5 17 23 4088
32 Marknesse Netherlands 7.5 2.5 1.3 10 20 150
33 Guadalajara Spain 7.5 4.8 0.4 36 17 45
34 Nagyhörcsök Hungary 7.6 2.7 2.1 5.0 25 160
35 Granada Spain 8.5 n.d 0.9 25 7.9 88
† Numbering according to soil pH; *Organic C was assumed to be equal to total C, as these low pH soils most likely do not contain CaCO3. n.d: not determined. - Details on test conditions:
- Soils were collected with a metal spade from the plough layer. Stones and vegetation were cleared from the soil samples before being put in 60 litre plastic drums. Soils were stored at 4 °C until drying and sieving. The time between sampling and cold storage was never more than one week. The soils were dried in a thin layer at 25 °C in a plant growth cabinet with continuous illumination. After partial drying, soils were sieved through a 4 mm sieve. The sieved soil was thoroughly mixed to ensure homogeneity and further dried. Air dry, sieved soils were stored in 60 litre plastic drums.
Of each soil, about 25 g dried soil sample was wetted to field capacity and incubated during 2 weeks in aerobic conditions. After that, carrier-free 54Mn2+ was added at about 143 Bq/g for acid soils (pH < 6) and 667 Bq/g for pH neutral soils (pH > 6) and thoroughly mixed.
Selected soil properties were measured for the 35 uncontaminated topsoils. Results are expressed on an oven dry basis. All analyses were performed in duplicate. The average values of the analysis are shown.
Total carbon (C) was measured by ignition using a Variomax CN analyser. The CaCO3 content of the soils was determined from pressure increases after addition of HCl to the soil in closed containers (including FeSO4 as a reducing agent). The organic carbon content was determined by difference between total and inorganic carbon content. The pH of the soils was measured in 0.01 M CaCl2 (1:5 soil/solution ratio) after shaking for 1 h and allowing to settle for 30 minutes before pH measurement.
The silver-thiourea method was used to measure cation exchange capacity (CEC) at soil pH and exchangeable cations, with concentrations in extracts determined by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES, Perkin Elmer Optima 3300 DV). Total metal concentrations in soil, including Mn, were determined for all soils by boiling aqua regia extraction and analysis with ICP-OES. - Type:
- Kd
- Value:
- >= 1 - <= 20 550 L/kg
- Temp.:
- 25 °C
- Matrix:
- 35 soils sampled at 3 days
- % Org. carbon:
- >= 0 - <= 23.3
- Remarks on result:
- other: pH ranged from 3.0 to 8.5 in initial soil samples.
- Remarks:
- Total 54Mn Kd: Average was 4131 L/kg; median 1598 L/kg and geomean 344 L/kg
- Type:
- Kd
- Value:
- >= 1.1 - <= 6 516 L/kg
- Temp.:
- 25 °C
- Matrix:
- 35 soils sampled at 100 days
- % Org. carbon:
- >= 0 - <= 23.3
- Remarks on result:
- other: pH ranged from 3.0 to 8.5 in initial soil samples.
- Remarks:
- Total 54Mn Kd: Average was 1184 L/kg; median 650 L/kg and geomean 265 L/kg
- Type:
- Kd
- Value:
- >= 1 - <= 10 818 L/kg
- Temp.:
- 25 °C
- Matrix:
- 35 soils sampled at 180 days
- % Org. carbon:
- >= 0 - <= 23.3
- Remarks on result:
- other: pH ranged from 3.0 to 8.5 in initial soil samples.
- Remarks:
- Total 54Mn Kd: Average was 2180 L/kg; median 601 L/kg and geomean 424 L/kg
- Transformation products:
- not specified
- Details on results (Batch equilibrium method):
- DETERMINATION OF MANGANESE ADSORPTION Kd
The 54Mn Kd values obtained at 3, 100 and 180 days (Kd* values) are shown below, where average, median and geomean have been also summarised. Previous studies have recommended the use of geometric means to summarise Kd data. The variation in pH with time was 0.28 units in average.
The adsorption Kd* values ranged from 1.0 to 20 550 L/kg (median 1598 L/kg) at 3 days and 1.0 to 6516 L/kg (median 601 L/kg) at 180 days. The Kd geometric mean increased circa 1.2-fold between day 3 and 180.
In general, the Kd* increased or remained constant over time for acid soils (pH< 6), whereas the Kd* decreased or remained constant for neutral-basic soils. The changes in Kd* with time were strongly related to the change in the fraction of isotope that was extractable with NH4Ac. A decrease in NH4Ac-extractable 54Mn corresponds to an increase in the Kd* and is most likely due to transformation of the added 54Mn2+ to 54MnIII/IV, i.e. the isotope equilibrated with the natural Mn that is partly present as MnIII/IV oxides. An increase in NH4Ac-extractable 54Mn and decrease in Kd (observed for some high pH soils) suggests that transformation of 54MnIII/IV to 54MnII occurred. Presumably, there was a fast oxidation of the added 54Mn2+, resulting in a low NH4Ac extractable fraction at 3 days of incubation. However, upon incubation of these samples, reduction of 54MnIII/IV presumably occurred in some of these soils.
There was a strong positive correlation (P< 0.05) between log Kd* and pH (measured at time of extraction): the correlation coefficient r was 0.85 at 3 days, 0.83 at 100 days and 0.65 at 180 days. Thus, pH explains most of the variation in (log)Kd*, in agreement with previous studies that pointed pH as main factor explaining Kd values of metals in soils.
SOILS SPIKED WITH MNO2
The concentration of dissolved (CaCl2-extractable) and NH4Ac-extractable Mn and the Kd* values at 3 days after amending soils with 200 mg Mn/kg (as MnO2) were shown. In general, addition of MnO2 is expected to increase the NH4Ac-extractable and dissolved Mn if the added Mn is transformed to MnII. If the added Mn remains as MnO2, no change in NH4Ac-extractable and dissolved Mn is expected. Thus, the observed increase in dissolved and NH4Ac-extractable Mn for the low pH soils (pH<5) suggests that MnO2 was transformed to MnII. In soils with high pH, MnO2 addition had little effect on NH4Ac- and CaCl2-extractable concentrations, suggesting that the added Mn remained as insoluble oxide, as thermodynamically expected.
The effect of MnO2 application on the Kd* values is less straightforward. If the isotope equilibrates completely with all Mn in soil, an increase in Kd* is expected if the added Mn remains as MnO2. If the added MnO2 is converted to MnII, little effect on Kd* is expected, unless pH changes occur or if the cation exchange complex is near saturation, in which case the Kd* would decrease because of the larger MnII pool. Overall, little effect on Kd* was observed, except for soil 29, where the increase in Kd* upon MnO2 addition suggests that the isotope indeed equilibrated with the insoluble Mn oxide.
In general, the data at 180 days of incubation showed the same trend as at 3 days, with some notable differences. The concentrations of extractable Mn were smaller for Rhydtalog in the unamended soil than at the first sampling, suggesting that oxidation occurred. The extractable concentrations were larger for both the amended and unamended Rijswijk soil. Most likely, reduction processes occurred, because this soil was rather ‘muddy’ after wetting. The Rijswijk soil is low in organic matter, and has therefore low water holding capacity. In the Aluminusa and Souli soil, the dissolved Mn concentrations were larger for the MnO2 amended soils than for the unamended soil (which was not the case at the first sampling) despite the similar NH4Ac-extractable content. However, the specific activity (radioactivity to stable concentration) of Mn in the CaCl2 extract was much smaller than in the NH4Ac extract for these two samples. This suggests that there were inert Mn colloids (not exchangeable with the Mn2+ isotope) in the CaCl2 solution. The labile Mn in the CaCl2 solution was estimated from the radioactivity (cpm/mL) divided by the specific activity (cpm/µg) of the NH4Ac extract (assumed to extract only exchangeable Mn), and was much smaller than the total Mn concentration in the CaCl2 solution.
PREDICTION OF THE SOLID-LIQUID PARTITIONING OF MN IN SOILS
Partitioning of Mn in soil
To predict the partitioning of Mn in soils, some understanding of the speciation of Mn in the whole soil is necessary. Manganese in soil may be in different redox states, most commonly +2, +3 or +4. In soil, MnIII and MnIV occur as insoluble oxides. At low pH or under reduced conditions, MnII is the most stable form which has much higher solubility than MnIII/IV. It is expected that MnII will adsorb on sorption sites (of organic matter, clay minerals and oxides).The Mn redox chemistry therefore plays an important role in Mn solubility.
Solid-Liquid Partitioning of MnII
To estimate the partitioning of MnII between sorbed and solution pool, extraction with1 M NH4Ac was carried out after the CaCl2 extraction. The Mn concentration in the 10 mM CaCl2 extract is a measure of the soil solution concentration. The NH4Ac extract also extracts sorbed MnII. The solid–liquid distribution coefficient of MnII (KdII) was therefore calculated as the ratio between adsorbed 54MnII (=extractable with NH4Ac) and the 54Mn activity in the CaCl2 extract. The KdII was strongly related to pH and showed no consistent variations over time. Since there were no consistent variations over time, regression analysis was carried out taking the results for all three sampling occasions together. The Kd of MnII was related to pH and organic C content.
Log KdII (L/kg) = -3.01 +0.80 pH + 0.33 logOC (%) (R2 = 0.81, n = 114)
The KdII (L/kg) allows calculating the dissolved Mn concentration (c, mg/L) from the total MnII (mg/kg) in soil:
c = MnII / (KdII + L/S) ≈ MnII /KdII
where:
L/S is the liquid:solid ratio (in L/kg)
Partitioning of Mn Between MnII and MnIII/IV
Only part of Mn is present as MnII. A large fraction of Mn in soil can be precipitated as MnIII/IV oxides. The fraction of Mn in soil extracted by NH4Ac (assumed to correspond to MnII) varies between 1 and 100 % of total soil Mn and showed a negative correlation with total Mn in soil. The NH4Ac-extractable fraction was comparable at 3 and 180 days, though in some soils, more Mn was extracted at 180 days, presumably because Mn reduction occurred in some of the soils. The fraction of isotope added that was NH4Ac-extractable was generally a bit larger than for the in situ Mn at 3 days after the addition. However, after 180 days of incubation, the NH4Ac-extractable fraction of the isotope and of the in situ Mn was of the same order, indicating nearly full equilibration of the isotope with the soil Mn.
Solid-liquid partitioning of total Mn and suggested models for risk assessment
The Kd* gives the partitioning between total solid phase 54Mn (including sorbed and precipitated pools) and 54Mn in solution. The Kd* is larger than the KdII and is related as follows:
Kd*= KdII / f*NH4Ac
Where:
f*NH4Ac is the fraction of solid phase associated isotope that is NH4Ac-extractable (= MnII). The Kd* is also positively correlated with pH, but there is more variation than for the KdII, because of the variation in the NH4Ac extractable fraction.
The ‘desorption’ Kd gives the partitioning of total soil Mn between solid and solution (=10 mM CaCl2 extract) phase. As the isotope is nearly fully equilibrated with the soil Mn at 180d, the Kd is similar to the Kd* at 180 days. However, at 3 days after addition of the isotope, the Kd is generally larger than the Kd*, as the isotope has not fully equilibrated with the soil Mn yet.
Even though the distribution of soil (in situ) Mn and the added isotope (54Mn) was similar at 180 days of incubation, the regression analysis was not carried out with the isotope data at 180 days, since in some soils, reduction processes apparently occurred, as evident from the increase in NH4Ac extractable and CaCl2-extractable Mn with time. Therefore, it was chosen to use the Kd values of total soil Mn (‘desorption’ Kd) at shorter incubation times. Since 3 days of incubation probably did not allow for full equilibration of added Mn in the MnO2 amended soils, the 100-day results were selected for the regression analysis. However, also at 100 days, there were four soils where reduction processes apparently occurred, and for these soils (15, 21 with and without MnO2 and 23), the Kd after 3 days incubation was used. Following equation was tested:
Log Kd = a +b pH + c logOC +d log Mnsoil
Only pH was a significant (P<0.05) regressor, and following equation was obtained:
Log Kd (L/kg) = -2.21 +0.92 pH (R2 = 0.76, n = 40)
Thermodynamically, it is expected that the Mn solubility will be controlled by sorption processes at low pH and by precipitation at higher pH. If that is the case, it is expected that the dissolved Mn concentration is proportional to the total Mn concentration in soil at low pH (equilibrium between sorbed Mn and Mn in solution) and that the Kd is therefore independent of total Mn concentration at low pH. At high pH, it is expected that the dissolved concentration is independent of total Mn (since the dissolved Mn concentration will be at saturation with the precipitate) and that the Kd will therefore increase with increasing total Mn concentration.
The experimental data were in agreement with these theoretical considerations. For the soils with pH below 5.6, solution concentrations increased with total Mn concentration in soil, and there was no indication that the Kd depends on total soil Mn. However, for soils with pH above 5.6, the Kd indeed appeared to depend on total Mn concentration in soil. This was for instance clearly observed for the MnO2 amended soils: addition of MnO2 increased the dissolved Mn in the low pH soils, but had no effect in the high pH soils.
Therefore, the regression analysis was repeated for the soils with pH<5.6 and soils with pH≥5.6 separately. Two soils with pH 3.1 and 3.5 were excluded from the regression analysis, because their Kd was >100 L/kg despite the very low pH. The isotopic K was much smaller for these soils, even after 180 days of incubation, in contrast with the other soils. Most likely, a large fraction of Mn in these soils may be present in the crystal lattice of clay minerals (and is not isotopically exchangeable). For the low pH soils, pH was again the only significant (P<0.05) regressor. For the soils with pH ≥5.6, also total Mn was a significant regressor. Following equations were obtained:
pH <5.6: log Kd (L/kg) = -2.95 + 0.99 pH (R2 = 0.65, n = 16)
pH ≥5.6: log Kd (L/kg) = -2.01 + 0.67 pH + 0.71 log Mnsoil (R2 = 0.64, n = 22)
Using the predicted Kd, solution concentrations can be estimated as:
cpred = Mnsoil / (Kd,pred + L/S) ≈ Mnsoil / Kd,pred
where:
L/S is the liquid:solid ratio (in L/kg)
It should be noted that all predictions are for aerobic soils. Under saturated conditions, reduction of MnIII/IV oxides may occur, resulting in an increase in MnII concentration and dissolved Mn concentrations. - Statistics:
- See below
- Validity criteria fulfilled:
- not specified
- Conclusions:
- The Kd values of Mn in soil not only depend on pH or redox but also on the total Mn in soil.
The range of Kd for 35 soils sampled after 3 days was 1.0 to 20 550 L/kg; average 4131 L/kg, median 1598 L/kg and geomean 344 L/kg.
The range of Kd for 35 soils sampled after 100 days was 1.1 to 6516 L/kg; average 1184 L/kg, median 650 L/kg and geomean 265 L/kg.
The range of Kd for 35 soils sampled after 180 days was 1.0 to 10 818 L/kg; average 2180 L/kg, median 601 L/kg and geomean 424 L/kg.
The Kd median result is considered to be sufficiently representative to use in risk assessment. - Executive summary:
The adsorption/desorption of Mn in soils was assessed using a method equivalent to OECD Test Guideline 106 using a batch equilibrium method.
To be most relevant for the risk assessment, the ‘adsorption Kd’ was measured in soils. No such Mn adsorption studies have been made for European soils before and no comparison has been found between adsorption (of added Mn) and desorption (of native Mn) Kd values.
Manganese in soil is present in different redox states, most commonly +2, +3 or +4. In soil, MnIII and MnIV occur as insoluble oxides. At low pH or under reduced conditions, MnII is the most stable form and this species has much higher solubility than MnIII/IV. The Mn redox chemistry therefore plays an important role in mobility and availability of Mn. The Kd concept that is used in traditional exposure estimates for risk assessment refers to adsorption reactions, for which solution concentrations increase as the solid-phase concentrations increase. For Mn, this Kd concept does not hold when MnIII and MnIV are present as precipitates (oxides), because the solubility of a precipitate does not depend on the amount of precipitate. Mathematically, the Kd can still be derived in case of precipitation reactions, but this value increases with increasing total concentration once the precipitate is formed. For pragmatic reasons for risk assessment, the Kd values were derived in this study, even when precipitates formed. Practically, this means that Kd values of Mn in soil not only depend on pH or redox but also on the total Mn in soil.
Thirty-five European soils were selected to make a comprehensive assessment of the Kd values in European soils and to encompass the range of properties that may affect the Kd values, i.e. the cation exchange capacity, pH and organic matter content. Soils were amended with (carrier free) 54MnII (a Mn2+ salt) and subsamples were extracted with 10 mM CaCl2 at 3, 100 and 180 days after spiking. The adsorption Kd values ranged from 1.0 to 20 550 L/kg at 3 days and from 1.0 to 6516 L/kg at 180 days. The geometric mean Kd increased 1.2-fold between day 3 and day 180, from 334 to 424 L/kg. On a restricted set of soil, MnO2 was added. The added Mn reached the same speciation as native Mn in most soils by day 100.
The fraction of total Mn that is present as MnII was estimated by extraction with 1 M NH4Ac. At 180 days, the partitioning of the isotope and the soil Mn between extractable (MnII) and non-extractable (MnIII/IV) pools was similar for the isotope and the native Mn, indicating that the isotope nearly fully equilibrated within this period. Effectively, this means that the solid-liquid distribution of native Mn in soil may be used to predict the Kd of added Mn.
For risk assessment, regression models with R2 of 0.64-0.65 were derived from which appropriate Kd values can be selected that are valid for Mn added to aerobic soil as MnII salts or MnO2. The Kd in low pH soils (pH<5.6) is strongly related to pH and did not depend on the total Mn concentration in soil. In high pH soils (pH>5.6), both pH and total Mn concentration affects the partitioning of Mn in the soil. Practically, the Kd values can be implemented in the EU risk assessment schemes if generic values of soil pH and total Mn are selected. A look-up table allows selecting appropriate Kd values depending on pH and total Mn. These predictions are only valid for aerobic soils. Under saturated conditions, reduction of MnIII/IV oxides may occur, resulting in an increase in MnII concentration and dissolved Mn concentrations.
Referenceopen allclose all
Determination of Manganese Adsorption Kd
Kd values of added 54Mn (mean and standard deviation of 2 replicates) obtained for a collection of 35 European soils. The Kd was determined at 3, 100 or 180 days after addition of the isotope.
Soil nr |
Soil name |
Total 54Mn Kd* (L/kg) |
Factor change 3 – 180 days |
|||||
3 days |
100 days |
180 days |
||||||
mean |
SD |
mean |
SD |
mean |
SD |
|||
1 |
Gudow |
1.4 |
0.8 |
8.6 |
2.1 |
10 |
0.8 |
7.2 |
2 |
Nottingham |
3.8 |
0.9 |
3.0 |
0.0 |
10 |
0.5 |
2.7 |
3 |
Houthalen |
1.0 |
0.1 |
15 |
3.4 |
32 |
16 |
31 |
4 |
Lommel |
1.1 |
0.3 |
1.1 |
0.2 |
1.0 |
0.3 |
0.9 |
5 |
Kasterlee |
14 |
1.6 |
45 |
3.7 |
55 |
2.2 |
4.1 |
6 |
Zegveld |
30 |
9.3 |
28 |
7.3 |
14 |
1.7 |
0.5 |
7 |
Kövlinge I |
5 |
0.5 |
40 |
0.4 |
147 |
6.3 |
32 |
8 |
Rhydtalog |
16 |
4.2 |
32 |
4.9 |
601 |
8.8 |
39 |
9 |
Wageningen |
34 |
9.0 |
933 |
67 |
420 |
138 |
12 |
10 |
Montpellier |
698 |
40 |
113 |
12 |
689 |
577 |
1 |
11 |
De Meern |
346 |
28 |
3094 |
486 |
5720 |
0.6 |
17 |
12 |
Zwijnaarde |
7.8 |
0.8 |
77 |
23 |
251 |
21 |
32 |
13 |
Hygum |
1800 |
1501 |
435 |
10 |
2320 |
394 |
1.3 |
14 |
Aluminusa |
1931 |
304 |
1462 |
10 |
8017 |
1512 |
4 |
15 |
Lovenjoel |
1788 |
362 |
14 |
0.2 |
18 |
2.1 |
0.01 |
16 |
Zeveren |
18 |
4.9 |
23 |
7 |
743 |
173 |
42 |
17 |
Plombières |
14 |
4.0 |
224 |
13 |
486 |
189 |
34 |
18 |
Wilsele |
2570 |
526 |
883 |
618 |
2152 |
801 |
0.8 |
19 |
London |
3052 |
736 |
2349 |
302 |
3425 |
249 |
1.1 |
20 |
Woburn |
88 |
10 |
959 |
15 |
2841 |
1692 |
32 |
21 |
Rijswijk Uzimet |
15 |
1.0 |
8.5 |
0.9 |
9.4 |
1.0 |
0.6 |
22 |
Lille Exide |
1598 |
781 |
1203 |
380 |
73 |
18 |
0.05 |
23 |
Ter Munck |
10 519 |
3992 |
775 |
869 |
86 |
27 |
0.01 |
24 |
Bordeaux |
20 550 |
11 373 |
688 |
124 |
2930 |
450 |
0.1 |
25 |
Florival Exide |
3591 |
363 |
502 |
258 |
232 |
84 |
0.1 |
26 |
Paris |
4331 |
2451 |
650 |
58 |
151 |
19 |
0.03 |
27 |
Rots |
8755 |
5308 |
1943 |
106 |
192 |
107 |
0.02 |
28 |
Vault de Lugny |
13 584 |
2562 |
3764 |
90 |
9053 |
1773 |
0.7 |
29 |
Souli |
1497 |
711 |
605 |
254 |
2146 |
1152 |
1.4 |
30 |
Barcelona |
19 180 |
8256 |
1900 |
100 |
4268 |
943 |
0.2 |
31 |
Brécy |
14 176 |
8256 |
5965 |
196 |
10 818 |
1836 |
0.8 |
32 |
Marknesse |
1810 |
297 |
1790 |
824 |
3081 |
735 |
1.7 |
33 |
Guadalajara |
11 595 |
11 907 |
3292 |
344 |
6081 |
2895 |
0.5 |
34 |
Nagyhörcsök |
17 512 |
10 615 |
6516 |
6809 |
4066 |
1166 |
0.2 |
35 |
Granada |
3454 |
663 |
1101 |
795 |
5155 |
562 |
1.5 |
|
|
|
|
|
|
|
|
|
Average |
4131 |
|
1184 |
|
2180 |
|
|
|
Median |
1598 |
|
650 |
|
601 |
|
|
|
Geomean |
344 |
|
265 |
|
424 |
|
|
Soils Spiked with MnO2
Concentrations of NH4Ac-extractable Mn and dissolved Mn in five soils with background Mn concentrations (MnBG) or amended with MnO2 at a rate of 200 mg Mn/kg. The soils were moistened and incubated for three days before extraction.
Soil |
pH |
MnBG |
Kd* (L/kg) |
MnNH4Ac (mg/kg) |
Mndiss (mg/L) |
|||
-MnO2 |
+ MnO2 |
-MnO2 |
-MnO2 |
+ MnO2 |
+ MnO2 |
|||
3 |
3.7 |
17 |
1.0 |
1.1 |
0.3 |
47 |
0.03 |
14.3 |
8 |
4.7 |
86 |
16 |
16 |
53 |
83 |
4.4 |
8.8 |
14 |
5.7 |
49 |
1931 |
778 |
1.1 |
1.5 |
0.02 |
0.01 |
21 |
5.8 |
352 |
15 |
18 |
15 |
16 |
0.87 |
0.74 |
29 |
7.3 |
102 |
1497 |
2705 |
26 |
27 |
0.08 |
0.07 |
Concentrations of NH4Ac-extractable Mn and dissolved Mn in 5 soils with background Mn concentrations (MnBG) or amended with MnO2 at a rate of 200 mg Mn/kg. The soils were moistened and incubated for 180 days before extraction.
Soil |
pH† |
MnBG |
Kd* (L/kg) |
MnNH4Ac (mg/kg) |
Mndiss (mg/L) |
|||
-MnO2 |
+ MnO2 |
-MnO2 |
+ MnO2 |
+ MnO2 |
+ MnO2 |
|||
3 |
4.0 |
17 |
32 |
3.2 |
0.03 |
54 |
0.009 |
11.1 |
8 |
4.9 |
86 |
601 |
128 |
9.3 |
126 |
0.17 |
1.3 |
14 |
5.9 |
49 |
8017 |
12 442 |
2.7 |
3.3 |
0.003 |
0.17 (0.01)‡ |
21 |
5.8 |
352 |
9.4 |
9.1 |
80 |
54 |
8.05 |
5.3 |
29 |
7.7 |
102 |
2146 |
2659 |
36 |
36 |
0.02 |
0.20 (0.05)‡ |
†at 180 days of incubation; ‡most likely, there were inert Mn colloids in solution. The labile dissolved Mn (in brackets) was estimated based on the specific activity in the NH4Ac extract
Prediction of the Solid-Liquid Partitioning of Mn in Soils
Solid–liquid partitioning of MnII
Coefficients for regression equation relating the logarithm of the distribution coefficient of MnII (log KdII, in L/kg) to pH and OC content. The regression analysis was carried out for all soils at the three sampling occasions (R2 = 0.81, n = 114).
|
Coefficients |
Standard Error |
P-value |
Intercept |
-3.01 |
0.24 |
2.0 x 10^-23 |
pH |
0.80 |
0.04 |
3.2 x 10 ^-40 |
logOC (%) |
0.33 |
0.09 |
0.0007 |
Solid-Liquid Partitioning of Total Mn
Coefficients for regression equation relating the logarithm of the distribution coefficient of total Mn in soil (log Kd, in L/kg) to pH. The regression analysis was carried out for all soils at 100 days of incubation* (R2 = 0.76, n = 40).
|
Coefficients |
Standard Error |
P-value |
Intercept |
-2.21 |
0.50 |
8.8 x 10 ^-5 |
pH |
0.92 |
0.08 |
3.3 x 10^-13 |
*Data at 3 days of incubation used for soils 15, 21 and 23
Coefficients for regression equation relating the logarithm of the distribution coefficient of total Mn in soil (log Kd, in L/kg) to pH and total Mn in soil for soils with pH<5.6 and soils with pH ≥5.6. The regression analysis was carried out for results obtained after 100 days of incubation*. These models are proposed here for implementing in risk assessment on the fate of either MnII or MnO2 that is added to soil.
|
Coefficients |
Standard Error |
P-value |
Soils with pH <5.6 (R2 = 0.65, n = 16) |
|||
Intercept |
-2.95 |
0.94 |
0.0007 |
pH |
0.99 |
0.19 |
0.0001 |
Soils with pH ≥5.6 (R2 = 0.64, n = 22) |
|||
Intercept |
-2.01 |
1.06 |
0.07 |
pH |
0.67 |
0.14 |
9.3 x 10^-5 |
logMnsoil (mg/kg) |
0.71 |
0.21 |
0.003 |
*Data at 3 days of incubation used for soils 15, 21 and 23. Soils 1 and 3 excluded
Predicted effect of pH and total Mn concentration (Mnsoil, mg/kg) on the Kd (L/kg) and on the dissolved Mn concentration c (mg/L), as predicted. Cells for conditions outside the calibration range have been left blank. These values are proposed here for implementing in risk assessment on the fate of either MnII or MnO2 that is added to soil.
Mnsoil (mg/kg) |
pH |
|||||
3.5 |
4 |
5 |
6 |
7 |
7.5 |
|
Kd (L/kg) |
||||||
10 |
3.3 |
10 |
101 |
509 |
|
|
32 |
3.3 |
10 |
101 |
1158 |
5385 |
11 613 |
100 |
3.3 |
10 |
101 |
2636 |
12 259 |
26 436 |
316 |
3.3 |
10 |
101 |
6001 |
27 908 |
60 181 |
1000 |
|
|
101 |
13 662 |
63 531 |
137 001 |
3162 |
|
|
|
|
144 626 |
311 878 |
c (mg/L) |
||||||
10 |
3.0 |
1.0 |
0.1 |
0.02 |
|
|
32 |
10 |
3.1 |
0.3 |
0.03 |
0.006 |
0.003 |
100 |
30 |
9.7 |
1.0 |
0.04 |
0.008 |
0.004 |
316 |
96 |
31 |
3.1 |
0.05 |
0.011 |
0.005 |
1000 |
|
|
9.9 |
0.07 |
0.02 |
0.007 |
3162 |
|
|
|
|
0.02 |
0.010 |
Description of key information
Kp (soil) = 2363 L/kg / log Kp: 3.4, pH: 7, OC: 2% (Sauvé et al. 2000, RL 2)
Median Kp (suspended matter) = 30246 L/kg / log Kp (pm/w) = 4.48 (OECD SIDS report, 2014; EU Assessment report, France, 2011)
Median Kp (sediment) = 24409 L/kg / log Kp (sed/w) = 4.39 (OECD SIDS report, 2014; EU Assessment report, France, 2011)
For STP partitioning coefficients the median Kp for suspended matter was adopted.
Key value for chemical safety assessment
Other adsorption coefficients
- Type:
- log Kp (solids-water in soil)
- Value in L/kg:
- 3.4
- at the temperature of:
- 25 °C
Other adsorption coefficients
- Type:
- log Kp (solids-water in sediment)
- Value in L/kg:
- 4.39
- at the temperature of:
- 25 °C
Other adsorption coefficients
- Type:
- log Kp (solids-water in suspended matter)
- Value in L/kg:
- 4.48
- at the temperature of:
- 25 °C
Other adsorption coefficients
- Type:
- log Kp (solids-water in raw sewage sludge)
- Value in L/kg:
- 4.48
- at the temperature of:
- 25 °C
Other adsorption coefficients
- Type:
- log Kp (solids-water in settled sewage sludge)
- Value in L/kg:
- 4.48
- at the temperature of:
- 25 °C
Other adsorption coefficients
- Type:
- log Kp (solids-water in activated sewage sludge)
- Value in L/kg:
- 4.48
- at the temperature of:
- 25 °C
Other adsorption coefficients
- Type:
- log Kp (solids-water in effluent sewage sludge)
- Value in L/kg:
- 4.48
- at the temperature of:
- 25 °C
Additional information
Two reliable key studies were available for the determination of the adsorption / desorption partitioning coefficient for the reaction mass of copper oxide and manganese dioxide.
Sauvé et al. 2000 derived an empirical linear regression and semi-mechanistic model for copper in order to calculate a partitioning coefficient depending on soil solution pH and soil organic matter (Sauvé et al. 2000, RL 2). The empirical model was applied to calculate the soil partitioning coefficient of copper for use in the environmental risk assessment. The derived Kd soil for copper was 2363 L/kg / log Kd: 3.4 assuming a soil solution of pH 7 and OC of 2% (parameters set acc. to REACH Guidance Chapter R.16: Environmental exposure assessment (2016)). The value may be adapted to site-specific conditions.
The reliable key study for manganese was performed similar to OECD 106, Equilibrium Partitioning Method (RL 2, Hernandez-Soriano, 2010). The partitioning characteristics of manganese were investigated in 35 European soils. Soils covered a pH range of 3.0–8.5. The organic carbon content was 0-23.3%. The measured median Kd soil for manganese was 1598 L/kg / log Kd: 3.2.
The Kd soil for copper and manganese were very similar, i.e. log Kd of 3.4 and 3.2, respectively. As hazard and risk assessment were based on soluble copper, which was the more hazardous element compared to manganese for the aquatic environment, the log Kd soil for copper was used as key value for further assessment of the submission substance.
Furthermore, typical Kp / Kd values for copper to freshwater suspended matter and freshwater sediment were provided in the OECD SIDS report (2014) and the EU Assessment report for copper(II)oxide (France, 2011). The following Kp values were used for the environmental risk assessment: Kp (suspended matter) = 30246 L/kg / log Kp (pm/w) = 4.48 (50th percentile); Kp (sediment) = 24409 L/kg / log Kp (sed/w) = 4.39 (50th percentile). For STP partitioning coefficients the median Kp for suspended matter was adopted.
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