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Adsorption / desorption

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Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: study not following any guideline, but monitoring study well documented.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Measures of element concentration in the suspended particulate matter and the liquid phase (water)
GLP compliance:
no
Type of method:
other: difference between concentration of the element in the suspended matter and in the filtered water
Media:
other: water from Czech rivers
Radiolabelling:
no
Test temperature:
not given
Analytical monitoring:
yes
Details on sampling:
Filtered (0.4 µm) and unfiltered samples were collected from 54 Czech reivers. Filtration through perforated polycarbonate filters 0.4µm was done in the field immediately after collection of river water samples and then cooled.
Samples were acidified by adding 1 ml of HNO3, to attain a pH of about 1,5.
Filters were boiled with distilled water acidified by HNO3 for 10 min before use, dried at 105°C and weighed.
Details on matrix:
COLLECTION AND STORAGE
water samples were collected from 54 CZECH rivers at 119 localities over the state territory in summers 1997 and 1998

PROPERTIES
- pH: mean of 7.74
- ionic strengh: 7.8 mmol/L
- conductance: 538 µS/cm
- alkalinity: 1.9 mmol/L
- mean content of suspended particulate matter: 9.9 mg/L
Phase system:
suspended matter-water
Type:
log Kp
Value:
1.78 L/kg

vanadium retrieved in the dissolved fraction: 1.20 µg/L

and in the suspended particulate matter: 86 mg/kg

Validity criteria fulfilled:
not applicable
Executive summary:

The partitioning of 41 elements between solids and water was studied by filtration and dialysis in situ in Czech freshwaters. Field-based partition coefficient between suspended particulate matter and filtrate water (dissolved fraction) for vanadium element was found to be log Kd= 1.78, showing a better affinity of vanadium for suspended matter.

Endpoint:
adsorption / desorption
Remarks:
other: monitoring study
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guideline study but well documented monitoring data
Qualifier:
no guideline followed
Principles of method if other than guideline:
Measures of element concentration in the suspended particulate matter and the liquid phase (water)
GLP compliance:
not specified
Type of method:
other: monitoring study
Media:
other: suspended particulate matter
Radiolabelling:
no
Test temperature:
22.3 to 25.4°C
Analytical monitoring:
yes
Details on sampling:
see details on matrix
Details on matrix:
- Details on collection: study area is situated in the North of Morocco and includes the river Sebou and its tributary Fez river. The Stream Mehrez, which drains the South quarter of Fez discharges huge amounts of municipal and industrial untreated wastewater into the Fez river, is also included.
- pH at time of collection: 7.3 to 8.5
- Organic carbon (%): 1.9 to 95.8 mg/L (mean 39.7)
- Electrical conductivity: 1154 to 1761 µS/cm
- total suspended solids: 56 to 525 mg/L
Details on test conditions:
see details on matrix
Phase system:
suspended matter-water
Type:
log Kp
Value:
1.68
Remarks on result:
other: for sampling station 1
Phase system:
suspended matter-water
Type:
log Kp
Value:
2.07
Remarks on result:
other: sampling station 2
Phase system:
suspended matter-water
Type:
log Kp
Value:
1.28
Remarks on result:
other: sampling station 3
Phase system:
suspended matter-water
Type:
log Kp
Value:
1.36
Remarks on result:
other: sampling station 4

table 1: vanadium content in river water, µg/L:

  sampling station 1  sampling station 2     sampling station 3    sampling station 4
 pH  8.5 7.3  8.1  7.9 
 total suspended solids (mg/L)  56  144 245  525 
 dissolved organic carbon (mg/L) 1.9  12.4  48.9  95.8 
 vanadium 2.20  0.73  1.94  2.24 

Table 2: trace vanadium element in suspended particulate matter, µg/g:

sampling station 1  sampling station 2     sampling station 3    sampling station 4
 105 86  37  51 

Calculated Kp are 48, 118, 19 and 22.8, from sampling station 1 to 4 respectively.

Validity criteria fulfilled:
not applicable
Executive summary:

Water quality assessment in the region of Fez was investigated through 4 sample sites. Traces of vanadium element was searched in the river water phase and in the suspended particulate matter. Within these four sample sites, the mean Kd values were found to be 1.6, which show a strong affinity of metal element to particulate phase.

Endpoint:
adsorption / desorption
Remarks:
other: monitoring study
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: no guideline study but well documented and analysed
Qualifier:
no guideline followed
Principles of method if other than guideline:
Trace elements were analysed in water and sediment samples from a mine water
GLP compliance:
no
Type of method:
other: monitoring of vanadium element in water and sediment samples
Media:
sediment
Radiolabelling:
no
Test temperature:
5.7 to 24.2°C
Analytical monitoring:
yes
Details on sampling:
monitoring study, see details on matrix
Details on matrix:
- Details on collection: surface water and sediment samples were collected from 20 randomly chosen sites throughout the marsh around the mines, in the East Rand near Johannesbourg, south Africa.

- Storage conditions: sealed bottles, at 4°C for water samples, and anoxic conditions, on ice for sediment samples

- Textural classification for sediment: quartzose sand and silt with minor amounts of gravel and clay
- Organic carbon (%): 0.5 to 9% with an average of 2.3%

for surface water:
- pH at time of collection: 7 to 9.2
- DO: 2.5 to 10.8 mg/L
- Electrical conductivity: 521 to 2400 µS/cm
- Redox potential (mV): Eh 54 to 539 mV
Details on test conditions:
TEST CONDITIONS/ TEST SYSTEM
see details on matrix and analytical method

Computational methods:
- Adsorption and desorption coefficients (Kd): Kd= Cs/ Cw
where Cw an Cs denote the trace metal concentration in water and solid phases, respectively. (Zhang et al., 1994)
Type:
other: log Kd
Value:
4.57
% Org. carbon:
2.3
Remarks on result:
other: (mean log Kd value and average %OC)
Adsorption and desorption constants:
concentration in surface water samples: mean of 3.07 µg V/L
concentration in sediment samples: mean of 93.7 mg V/kg
Validity criteria fulfilled:
not applicable
Executive summary:

A suite of trace metals was analized in water and sediment samples from the Blesbokspruit, a Ramsar certified riparian wetland, to assess the impact of mining on the sediment quality and the fate of trace metals in the environment. The calculated log Kd for vanadium element was found to be 4.57 (mean of 20 sample sites). This high partition coefficient suggested that there is a large tendency for trace metals to precipitate out from the stream waters or that the sediments have a large capacity to adsorb the trace metals. (These Kd values were not very different than the range of Kd values calculated in major world rivers.) But these partition cofficients leads to accumulation of trace metals in the wetland and it seems that they are preferentially partitioned in the carbonate and the Fe-Mn oxide fraction compared to the organic or the exchangeable fraction.

Endpoint:
adsorption / desorption
Remarks:
other: monitoring study
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guideline study, but very well documented field study, sufficient for evaluation of results.
Qualifier:
no guideline followed
Principles of method if other than guideline:
aim of the study was to determine the concentration and distribution of 33 elements in the sediment and pore water of 2 rivers.
GLP compliance:
not specified
Type of method:
other: field study
Media:
other: sediment and pore water
Radiolabelling:
no
Test temperature:
not given
Analytical monitoring:
yes
Details on matrix:
- Details on collection: Sediment samples were collected from the To Lich and Kim Nguu rivers, both of which receive wastewater from urban Hanoi. Hanoi covers an area of 921 km² and had a population of 3.1 million people in 2004 (HSO, 2005). The discharge per day of wastewater was estimated at a total volume of 458 000 m3, 41% of which was of domestic origin, 57% of industrial origin and 2% from hospitals. Only about 4% of the wastewater is subjected to treatment before discharge.
Sediment samples were collected from three sites in both rivers, with a stainless steel Kajak core sediment sampler equipped with a polymethylmethacrylat (PMMA) inner liner with an inner diameter of 46 mm. Three replicates were collected from each site.
- Storage conditions: The collected waterlogged sediment samples were immediately closed with a lid and stored in a cool box until return to the laboratory where the sediment samples were stored at 4°C for a maximum of one and a half days until further treatment.
- Textural classification (i.e. %sand/silt/clay): no data
- pH at time of collection: 7.4- 8.1 in the pore water from the upper 10 cm sediment
- Organic carbon (%): 1.2- 5.3% and 1.8- 10.6% in the To Lich and Kim Nguu rivers, respectively
- Redox potential (mv): - 257 to -185 mV in the pore water
Phase system:
solids-water in sediment
Type:
log Kp
Value:
>= 4.59 - <= 5.81 L/kg
Remarks on result:
other: range for the six investigated sites (vanadium concentration range= 0.19- 2.85 µg/L)
Statistics:
Through analyses of linear models it was tested if the concentrations of the different elements in sediment or pore water were significantly affected by the categorical variables ’ site and depth and the covariates’ concentrations of organic carbon, pH and redox potential. Further, the interaction between site, depth and covariates were included in the model. The procedures General Linear Models (GLM) and Mixed Linear Models in the statistical computer program SAS ver. 9.1 (SAS Institute Inc., Cary, NC, USA) were applied. Replicate sediment cores were introduced as random effects. Pair-wise student t-tests between mean values for sites and depths corrected for other significant variables or interactions were performed for elements with sample concentrations significantly affected by these variables at 95% level or greater.

Table 1: Mean and standard deviation (n = 3) for sediment elemental concentrations [mg/ kg d.w.] in To Lich River

Depth (cm)

Site 1

Site 2

Site 3

0 - 10

70.0±1.4

136±57

157±47

10 - 20

84.5±5.6

93.0±6.9

109±3

20 - 30

110±16

134±61

133±61

 

Table 2: Mean and standard deviation (n = 3) for sediment elemental concentrations [mg/ kg d.w.] in the Kim Nguu River

Depth (cm)

Site 1

Site 2

Site 3

0 - 10

60.4±6.5

100±16

93.2±12.1

10 - 20

88.7±7.5

162±58

73.5±30.2

20 - 30

89.3±4.8

87.8±54.3

122±101

 

Validity criteria fulfilled:
not applicable
Executive summary:

Untreated industrial and domestic wastewater from Hanoi city is discharged into rivers that supply water for various agricultural and aqua- cultural food production systems. The aim of this study was to assess the content, distribution and fate of 33 elements in the sediment and pore water of the main wastewater receiving rivers. Observed distribution coefficients (log 10 K d,obs ) were calculated as the ratio between sediment (mg/kg d.w.) and pore water (mg/ L) concentrations. For vanadium element, a range of log Kd of 4.59- 5.81 was shown. These high values indicate high retention of the elements in the sediment phase as a result of sorption and/ or precipitation processes.

Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Not a GLP satndardized study, but very well described with enough details to consider results valid.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Vanadium adsorption to soils of different types from Germany has been studied. For 30 soils ‘Freundlich’ type sorption isotherms have been deduced from laboratory vanadium (V) adsorption experiments.
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
no
Test temperature:
test tubes were shaken at room temperature ; 22°C
Analytical monitoring:
yes
Details on sampling:
for each soil, 8 to 15 (mean 12) adsorption experiments have been conducted
Details on matrix:
30 soils representing different soil types have been selected from a population of 388 soil samples from different sites of the German long-term soil monitoring program. The 30 soils have been selected to give a pH-range which is approximately representative for the whole population.
Aside of that the soils have been selected to represent a large variability of sorption relevant soil properties namely organic carbon
content, clay content and oxalate soluble Mn.

Table 1 : characteristic properties of the selected soil samples: see in free text field above
Details on test conditions:
Sorption experiments are carried out to derive vanadium sorption isotherms from laboratory experiments by adding different amounts
of NH 4 VO 3 to soil suspensions. The soil sample (8 g) was placed in a 50 ml PE test tube with ultrapure water. The amount of ultrapure
water was 40 ml minus the additions of Ca(NO 3) 2 and NH 4 VO 3 . The addition of Ca(NO 3) 2 varied soil-specifically between 0.1 and 1.8 ml
0.05 M Ca(NO 3) 2 . The NH 4 VO 3 additions were done by adding between 0.1 and 10 ml 0.0002 M or 0.002 M NH 4 VO 3 . The closed
test tube was shaken at room temperature for 24 h in an end-over-end shaker at 20 rpm under ambient conditions. 24 h were used according
to the kinetic studies of Naeem et al. (2007) who showed that for the vanadium adsorption onto Fe (hydr)oxides 90% of the adsorption
capacity is achieved by 24 h.
The suspended matter was removed from suspension by centrifuging (5000 ×g) followed by filtration (0.45 µm cellulose acetate). 10 ml of the filtrate was acidified with 0.1 ml nitric acid (65%, suprapure) and analysed for vanadium by HR-ICP-MS in medium-resolution mode. For every soil sample one experiment was carried out without NH 4 VO 3 addition.
Computational methods:
A ‘Freundlich’ type sorption model is used to describe vanadium adsorption by soils: see the equation and lok k and m values in the free text above

Phase system:
solids-water in soil
Type:
log Kp
Value:
>= 2.3 - <= 4.6
Remarks on result:
other: range for the 30 soils studied

vanadium contents:

The aqua regia soluble contents vary between 1.7 and 143 mg/kg (median 32 mg/kg) and are comparable to vanadium contents for uncontaminated soils given in other studies.

The vanadium concentrations in the solutions of the experiments without NH 4 VO 3 addition are in the range of 0.08 and 37 µg/l with a median of 2.1 µg/l. This median is comparable to the median for surface water in Germany (0.5 µg/l; Birke et al., 2006), for stream water in California (0.8 µg/l; Shiller and Mao, 2000) or for ground water in the USA (1.1 µg/l; Newcomb and Rimstidt, 2002).

adsoprtion:

The soils exhibit quite different adsorption behaviour for vanadium.

The parameter log k varies between 2.3 and 4.6, that means that k varies over more than two orders of magnitude. This indicates pronounced differences in the adsorption behaviour of the soils.

Validity criteria fulfilled:
not applicable
Executive summary:

Vanadium adsorption by soils representing different soil types from Germany has been studied. For 30 soils ‘Freundlich’ type sorption isotherms have been deduced from laboratory vanadium(V) adsorption experiments.

The native adsorbed vanadium quantity of a soil (S 0 ), which must be known to calculate the adsorbed quantities, has been determined together with the Freundlich parameters m and log k by non linear regression of the experimental data to the Freundlich model. Pronounced differences in vanadium adsorption of different soils exist and can be quantified. The vanadium adsorption data can be generalized by grouping the soils into four classes according to their vanadium adsorption properties.

For each class (sandy soils, top soils, sub soils with pH<5.5, and sub soils with pH>.5) mean Freundlich parameters m and log k are calculated.

The log K calculated ranged from 2.3 to 4.6, showing a strong affinity of vanadium element for solid phase in the soil and a low mobility.

Description of key information

Partitioning of vanadium element was tested in several ways, in an important number of studies with tested waters and soils all around the world.

The availability of metal compounds for uptake by biota can differ from site to site and may change over time due to many processes, including weathering and (de)sorption processes. It should also be noted that Kd’s are accurate only during an equilibrium state, which generally doesn’t exist for metals in the environment. As a consequence, part of the metal present in the solid phase may be encapsulated in the mineral fraction and is therefore not available.  

Since the partitioning coefficient is such an important parameter that can drive the outcome of the exposure assessment, the assessment of the data quality and relevance of all collected measured Kd-values was done with care. Preference was given to coupled measured data for which information is available on both sampling and analytical measuring techniques, as recommended by Metal Environmental Risk Assessment Guidance (MERAG).

The most recent and relevant are reported here in a weight of evidence approach. Log Kp found for partitioning between water and soil, sediment or suspended matter are reported in key values below.

All these coefficients confirmed a high adsorptivity of the substance on particulate matter and immobility in soils, leading to a poor availability to biota in water.

A Koc cannot be calculated as vanadium is inorganic, therefore the Kp value for suspended matter- water was set as key value for assessment.

Key value for chemical safety assessment

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
2.3
at the temperature of:
22 °C

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
3.45
at the temperature of:
23.5 °C

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
3.97

Additional information