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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
The aim of the study was to assess how much municipal wastewater contributes to the loading of metals in the St. Lawrence River, Canada.
GLP compliance:
no
Type of method:
other: monitoring study
Media:
suspended matter
Radiolabelling:
no
Test temperature:
Not reported.
Analytical monitoring:
yes
Details on sampling:
Samples of water from St. Lawrence river were collected from the plant well, using a pneumatic pump and acid-washed Teflon tubes. The samples were kept at 4°C in low density polyethylene containers and delivered to the laboratory within 6 h. The samples were filtered through 0.45 µm Nuclepore polycarbonate membrane filters and the filters were frozen with their content of suspended matter. The filtrate was acidified with ultrapure nitric acid to pH 2. Treated urban effluents were collected at the Montreal City wastewater treatment plant once a month. Samples were taken proportionally to flow rate during a 24-h period in the middle of the week. The samples were than filtered as described above.

The filters and filter holders were leached for 3 d in dilute nitric acid at room temperature. The low-density polyethylene bottles containing the samples were immersed for successive 3-d periods in concentrated and diluted nitric acids at 50°C, rinsed several times with Milli-Q demineralized water and placed individually within a double layer of plastic bags.

Details on matrix:
St Lawrence River water was sampled monthly at the Levis municipal water filtration plant located near the mouth of the St. Lawrence River between July 2000 and July 2001. This plant takes its water via a concrete pipe whose intake is located 300 m from the shore at a depth of 10 m in a well mixed water column. The composition of the water entering the plant is typical of St. Lawrence River water with respect to nutrients, major elements, and some trace metals.
Computational methods:
According to the ECHA guidance R.7.13-2 the distribution of metals between the aqueous phase and soil/sediment/suspended matter can be described on the basis of measured suspended matter/water equilibrium distribution coefficients according to the following equation:

Kp = Cs / Caq

where:
Cs = total concentration of test substance in the solid phase (mg/kg)
Caq = concentration of test substance in aqueous phase (mg/L)

The log Kp value was calculated based on the concentration of bismuth in the suspended matter and the concentration of dissolved bismuth in the aqueous phase in the St. Lawrence River water and in the Montreal waster water treatment plant.
Phase system:
solids-water in suspended matter
Type:
log Kp
Value:
>= 5.62 - <= 5.71 L/kg
Remarks on result:
other: See 'Remarks'
Remarks:
The log Kp value was calculated based on the concentration of bismuth in the suspended matter and the concentration of dissolved bismuth in the aqueous phase in the St. Lawrence River water and in the Montreal waste water treatment plant.

Table 1. Average Concentrations of Dissolved (D), defined as Filtration through 0.45 ím, and Suspended Particulate Matter (SPM) bismuth at the St. Lawrence River Mouth and in the

Montreal Effluent

Average concentrations of dissolved bismuth in suspended matter from the St. Lawrence river

 

Average concentrations of dissolved bismuth in suspended matter from the effluent of Montreal waste water treatment plant

 

Concentration in suspended matter phase

Concentration in solution phase

Concentration in suspended matter phase

Concentration in solution phase

0.29±0.11 mg Bi/kg dw

 

0.0007±0.0003 µg Bi/L

 

2.86±1.52 mg Bi/kg dw

0.0056±0.004 µg Bi/L

Validity criteria fulfilled:
not specified
Conclusions:
Log Kp for bismuth (solids-water in suspended matter) was determined to be in a range of 5.62-5.71 L/kg dw.
Executive summary:

A monitoring study was conducted in order to assess how much municipal wastewater contributes to the loading of 23 metals and 1 metalloid in the St. Lawrence River, Canada. The assessment was based on samples taken during 13 consecutive months at the outlet of the wastewater treatment facility for Montreal, the most populated urban centre in the St. Lawrence Valley. The concentrations of 24 dissolved elements in water samples were measured using inductively coupled plasma mass spectrometer (ICP-MS).

Average concentrations of dissolved bismuth from the St. Lawrence river were 0.29±0.11 mg Bi/kg dw in suspended matter, and 0.0007±0.0003 µg Bi/L in solution phase. Average concentrations of dissolved bismuth from the effluent of a Montreal purification plant were 2.86±1.52 mg Bi/kg dw in suspended matter and 0.0056±0.004 µg Bi/L in solution phase.

The log Kp value was calculated according to ECHA guidance R.7.13-2 on Environmental risk assessment for metals and metal compounds (2008) based on the concentration of bismuth in the suspended matter and the concentration of dissolved bismuth in the aqueous phase in the St. Lawrence River water and in the Montreal waster wate treatment plant.

The study does not follow a standard test guideline and is not GLP-compliant, however it is well-reported and is reliable with restrictions (Klimisch 2). This data may be used as key data, as bismuth is a suitable read-across source to the target substance.  

Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included under 'Attached justification' in Section 13 and 'Cross-reference'.
Reason / purpose:
read-across source
Phase system:
solids-water in suspended matter
Type:
log Kp
Value:
>= 5.62 - <= 5.71 L/kg
Remarks on result:
other: See 'Remarks'
Remarks:
The log Kp value was calculated based on the concentration of bismuth in the suspended matter and the concentration of dissolved bismuth in the aqueous phase in the St. Lawrence River water and in the Montreal waste water treatment plant.
Validity criteria fulfilled:
not specified
Conclusions:
Log Kp for bismuth (solids-water in suspended matter) was determined to be in a range of 5.62-5.71 L/kg dw.
Executive summary:

A monitoring study was conducted in order to assess how much municipal wastewater contributes to the loading of 23 metals and 1 metalloid in the St. Lawrence River, Canada. The assessment was based on samples taken during 13 consecutive months at the outlet of the wastewater treatment facility for Montreal, the most populated urban centre in the St. Lawrence Valley. The concentrations of 24 dissolved elements in water samples were measured using inductively coupled plasma mass spectrometer (ICP-MS).

Average concentrations of dissolved bismuth from the St. Lawrence river were 0.29±0.11 mg Bi/kg dw in suspended matter, and 0.0007±0.0003 µg Bi/L in solution phase. Average concentrations of dissolved bismuth from the effluent of a Montreal purification plant were 2.86±1.52 mg Bi/kg dw in suspended matter and 0.0056±0.004 µg Bi/L in solution phase.

The log Kp value was calculated according to ECHA guidance R.7.13-2 on Environmental risk assessment for metals and metal compounds (2008) based on the concentration of bismuth in the suspended matter and the concentration of dissolved bismuth in the aqueous phase in the St. Lawrence River water and in the Montreal waster wate treatment plant.

The study does not follow a standard test guideline and is not GLP-compliant, however it is well-reported and is reliable with restrictions (Klimisch 2). This data may be used as key data, as bismuth is a suitable read-across source to the target substance. 

Description of key information

Based on available monitoring data, the following log Kp values for bismuth were determined:

log Kp (solids-water in suspended matter): 5.62 - 5.71 L/kg dw (average: 5.67 L/kg dw)

Key value for chemical safety assessment

Additional information

The adsorption/ desorption endpoint is completed by read across from bismuth. Bismuth is the main component of bismuth silicate and therefore it is considered appropriate to use data on bismuth for assessing the behaviour of bismuth silicate in the environment.

 

Monitoring data on bismuth in the environment were used to derive adsorption / desorption partition coefficients.

 

Gobeil et al. (2005) investigated suspended matter from the St. Lawrence River, Canada. The average concentrations of dissolved bismuth from the St. Lawrence river were 0.29±0.11 mg Bi/kg dw in suspended matter, and 0.0007±0.0003 µg Bi/L in solution phase. Average concentrations of dissolved bismuth from the effluent of a Montreal purification plant were 2.86±1.52 mg Bi/kg dw in suspended matter and 0.0056±0.004 µg Bi/L in solution phase. The measured data were used to determine the adsorption coefficients (log Kp) according to ECHA guidance (2008). The adsorption coefficients (log Kp) for bismuth were in the range of 5.62 - 5.71 L/kg dw, with an average of 5.67 L/kg dw.

Karlsson et al. (2007) evaluated sediment chronologies of Bi, As and Ga in pelagic water samples from Swedish lakes. The non-guideline adsorption experiment demonstrated a log Kp (solids-water in sediment) range of 4.3 - 4.5 L/kg dw with an average of 4.4 L/kg dw.

 

In a study of the Famatina range, La Rioja (Argentina), Fernandez-Turiel et al. (1995) conducted an environmental monitoring experiment, which resulted in a log Kp (solids-water in sediment) range of 2.75 - 3.80 L/kg dw, with a geometric mean of 3.28 L/kg dw, determined based on the measured concentrations of bismuth in sediment and water samples.

 

The studies were not conducted according to standard guidelines and are not GLP-compliant. However, they are well-reported and were published in a peer-reviewed journals, therefore are reliable with restrictions (Klimisch 2) and are considered suitable for use for this endpoint. The dilution effects and removal from the aqueous medium by adsorption to suspended matter are important processes for evaluating exposure in the aquatic compartment. The study conducted by Gobeil et al. (2005) reported the concentrations of bismuth in suspended matter, therefore this study was chosen as a key study for this endpoint.