spirodiclofen (ISO);3-(2,4-dichlorophenyl)-2-oxo-1-oxaspiro[4.5]dec-3-en-4-yl 2,2-dimethylbutyrate

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

365 days

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EPA Subdivision N Pesticide Guideline 162-3 (Anaerobic Aquatic Metabolism)

Version / remarks:

1989

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Oxygen conditions:

anaerobic

Inoculum or test system:

other: Total Water-Sediment Test System

Details on source and properties of surface water:

Number: 092998-W
Origin: Lost Lake in Fresno, CA
pH: 8.7
Sodium: 54 ppm
Calcium: 16 ppm
Magnesium: 13 ppm
Hardness mg equivalent CaCO3/L: 95 ppm
Conductivity: 0.47 mmhos/cm
Sodium Absorption Ratio (SAR): 2.42
Total Dissolved Solids: 236 ppm
Total Nitrogen: 5 ppm
Total Phosphorus: 0.3 ppm
Redox Potential: 244.3 mV
Turbidity: 1.9 NTU
Chemical Oxygen Demand: 44.1 mg/LO2
Dissolved Organic Carbon: 8.7 ppm
Total Organic Carbon: 8.7 ppm

Details on source and properties of sediment:

Origin: Lost Lake in Fresno, CA
Number: 092998-D
Sand: 80 %
Silt: 18 %
Clay: 2%
USDA Textural Class (hydrometer method): Loamy Sand
Bulk Density (disturbed) gm/cc: 1.14
Cation Exchange Capacity (meq/100 g): 11.9
Percent Moisture at 1/3 Bar: 11.1
Percent Moisture at 15 Bar: 4.9
Percent Organic Carbon: 1.7
Percent Organic Matter: 3.0
pH: 7.3
Redox Potential at 21.0 C & pH 7.3 (mvolts): 185
Olsen Phosphorus (ppm): 8
Total Nitrogen (%): 0.109
Soluble Salts (mmhos/cm): 0.38

Initial conc.:

12.5 µg/L

Based on:

test mat.

Details on study design:

[Dihydrofuranone-3-14C]Spirodiclofen was applied to a water-sediment system under non-sterile conditions.
The sediment and the water were collected from Fresno, California. The application concentration was 12.5 µg as/L. The test system was incubated under anaerobic conditions by continuously bubbling nitrogen through the water layer at a temperature of 20 ± 1°C in the dark for 365 days. Sampling dates were 0, 2, 7 14, 34, 56, 92, 120, 183, 246, 295 and 365 days after application. Anaerobic conditions, i.e. in the supernatant water, were maintained throughout the study. At each interval the samples (sediment after extraction) were analysed by thin layer chromatography (TLC) and additionally for qualitative confirmation by high performance liquid chromatography (HPLC). The content of radioactivity was determined by liquid scintillation measurement. Metabolites were identified by cochromatography with authentic reference compounds or with spectroscopic methods.

Key result

Compartment:

entire system

DT50:

11.5 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Remarks on result:

other: degradation anaerobic

Other kinetic parameters:

first order rate constant

Transformation products:

yes

No.:

#1

Details on transformation products:

Major metabolite: Spirodiclofen-enol
The major metabolite Spirodiclofen-enol (M01) increased from an average of 4.5 % at day 0 to 93.9 % at day 56, and then slowly decreased to 84.6 % by day 365. Other metabolites in the total system increased from a combined total of 0.9 % of the total applied radioactivity at day 0 to a maximum of 15.5 % by day 295. No individual metabolite, with the exception of M01, was >5 % of the total applied radioactivity.

Details on results:

Volatile compounds remained low throughout the study with 14CO2 levels between 0.0 and 1.0%, and organic volatiles between 0.0 and 0.5% of the total applied radioactivity.

Conclusions:

The DT50 and DT90 of Spirodiclofen under anaerobic conditions in a Fresno, CA sediment-water system was determined to be 11.5 and 38.2 days, respectively.

Executive summary:

Over the course of the study, radioactive residues in water increased from 5.1 % of the applied radioactivity at day 0 to 80.0 % at day 56 and then remained relatively constant (between 79.3 and 82.8 % of the applied radioactivity) through day 365. The opposite trend was observed in the sediment where the radioactive residues decreased from an average of 93.4 % at day 0 to 20.1 % by day 56, and then gradually declined to 15.3 % by day 365. The large quantity of radioactive residues present in the sediment at day 0 was indicative of the extremely low water solubility of Spirodiclofen and its rapid partitioning from the water , where it was applied, to the sediment. The shifting of radioactive residues from the sediment to the water, as the study progressed, was a result of Spirodiclofen degrading to a more water soluble metabolite, Spirodiclofen-enol (M01). Unextractable bound residues increased from an average of 1.5 at day 0 to 3.6 % by day 365. Volatile compounds remained low throughout the study with ¹⁴CO₂ levels between 0.0 and 1 %, and organic volatiles between 0.0 and 0.5 % of the total applied radioactivity. The concentration of Spirodiclofen in the entire system declined from 93.2 % at day 0 to 0 % at day 365. The calculated half-life for the degradation of the parent compound was 11.5 days using first
order linear regression kinetic calculations. The DT90 was calculated to be 38.2 days.
The major metabolite Spirodiclofen-enol (M01) increased from an average of 4.5 % at day 0 to 93.9 % at day 56, and then slowly decreased to 84.6 % by day 365. Other metabolites in the total system increased from a combined total of 0.9 % of the total applied radioactivity at day 0 to a maximum of 15.5 % by day 295. No individual metabolite, with the exception of M01, was >5 % of the total applied radioactivity. 

Reference 2

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

key study

Study period:

In-life initiated/completed: 26-Aug-1997 to 16-Sep-1998 (110 day contact time)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This experimental study report is reliable for use in the risk assessment as it has been conducted by a trusted laboratory, under GLP and following BBA, EEC and SETAC Guidelines relevant at the time of the study being conducted. There are no known deviations from the guidelines stated, so this data has been deemed appropriate to use.

Qualifier:

according to guideline

Guideline:

other: BBA-Guidelines for Testing of Plant Protectants in the Registration Process Part IV, 5-1, Degradability and Fate of Plant Protectants in the Water/Sediment System

Version / remarks:

1990

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

other: Commission Directive 95/36/EC, Placing Plant Protection Products on the Market; Official Journal of the European Communities

Version / remarks:

14. July 1995

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

other: SETAC-Europe Procedures for Assessing the Environmental Fate and Ecotoxicity of Pesticides

Version / remarks:

March 1995

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on source and properties of surface water:

Hönniger pond water: water pH 7.7, dissolved organic carbon 1.5 to 4.4% (natural water source).
Anglerweiher pond water: water pH 7.8, dissolved organic carbon 2.3 to 7.3% (natural water source).

Details on source and properties of sediment:

Hönniger pond sediment: sediment texture sandy loam silt, pH 5.9, organic carbon 4.04%. Location of pond sediment: Wipperürth, Germany.
Anglerweiher pond sediment: sediment texture silty sand, pH 6.4, organic carbon 0.95%. Location of pond sediment: Leverkusen, Germany.

Duration of test (contact time):

110 d

Initial conc.:

0.052 mg/L

Based on:

act. ingr.

Remarks:

Trial 2 - based on water volume of 450ml

Initial conc.:

0.049 mg/L

Based on:

act. ingr.

Remarks:

Trial 1 - based on water volume of 450ml

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

Please see 'Any other information on materials and methods' section for details on study design.

Reference substance:

other: 951128ELB01

Remarks:

colourless crystals (Purity 97.5%)

Reference substance:

other: M00390 working standard

Remarks:

white crystals (Purity 96.0%)

Compartment:

water

Sampling date:

1997

% Recovery:

53.1

St. dev.:

19.6

Remarks on result:

other: Hönniger

Compartment:

sediment

Sampling date:

1997

% Recovery:

45

St. dev.:

19.3

Remarks on result:

other: Hönniger

Compartment:

entire system

Sampling date:

1997

% Recovery:

98.9

St. dev.:

1.3

Remarks on result:

other: Hönniger

Compartment:

water

Sampling date:

1997

% Recovery:

71.5

St. dev.:

19.4

Remarks on result:

other: Anglerweiher

Compartment:

sediment

Sampling date:

1997

% Recovery:

29.2

St. dev.:

19.6

Remarks on result:

other: Anglerweiher

Compartment:

entire system

Sampling date:

1997

% Recovery:

101.6

St. dev.:

3.6

Remarks on result:

other: Anglerweiher

Key result

Compartment:

water

DT50:

0.5 d

Temp.:

20 °C

Remarks on result:

other: Hönniger

Key result

Compartment:

sediment

DT50:

<= 4.5 d

Temp.:

20 °C

Remarks on result:

other: Hönniger

Key result

Compartment:

entire system

DT50:

4.5 d

Temp.:

20 °C

Remarks on result:

other: Hönniger

Key result

Compartment:

water

DT50:

0.9 d

Temp.:

20 °C

Remarks on result:

other: Anglerweiher

Key result

Compartment:

sediment

DT50:

<= 3.7 d

Temp.:

20 °C

Remarks on result:

other: Anglerweiher

Key result

Compartment:

entire system

DT50:

3.7 d

Temp.:

20 °C

Remarks on result:

other: Anglerweiher

Transformation products:

yes

Remarks:

Spirodiclofen-Enol - found in water and sediment in both Hönniger and Anglerweiher.

No.:

#1

Details on transformation products:

Hönniger water-sediment: The major transformation product detected in water was Spirodiclofen-Enol which reached a maximum concentration of 73.8% of the applied amount on the 37th day of incubation. The corresponding concentration in water at the end of the study period was 54.9% of the applied amount. The major transformation product detected in sediment was Spirodiclofen-Enol which reached a maximum concentration of 29.6% of the applied amount at study termination. No minor transformation product comprised >3.6% of the applied amount in either the sediment or the water. The total unidentified radioactivity in water and sediment was <5% of the applied amount at all intervals. No sterile treatments were used or required for the current study.

Anglerweiher water-sediment: The major transformation product detected in water was Spirodiclofen-Enol which reached a maximum concentration of 87.3% of the applied amount at study termination. The major transformation product detected in sediment was Spirodiclofen-Enol which reached a maximum mean concentration of 15.5% of the applied amount at study termination. No minor transformation product comprised >2.8% of the applied radioactivity in either the sediment or the water. The total unidentified radioactivity in water and sediment was <3.5% of the applied amount at all intervals. No sterile treatments were used or required for the current study.

Residues:

yes

Details on results:

Hönniger water-sediment: The major transformation product detected in water was Spirodiclofen-Enol which reached a maximum concentration of 73.8% of the applied amount on the 37th day of incubation. The corresponding concentration in water at the end of the study period was 54.9% of the applied amount. The major transformation product detected in sediment was Spirodiclofen -Enol which reached a maximum concentration of 29.6% of the applied amount at study termination. No minor transformation product comprised >3.6% of the applied amount in either the sediment or the water. The total unidentified radioactivity in water and sediment was <5% of the applied amount at all intervals. No sterile treatments were used or required for the current study.

Anglerweiher water-sediment: The major transformation product detected in water was Spirodiclofen-Enol which reached a maximum concentration of 87.3% of the applied amount at study termination. The major transformation product detected in sediment was Spirodiclofen–Enol which reached a maximum mean concentration of 15.5% of the applied amount at study termination. No minor transformation product comprised >2.8% of the applied radioactivity in either the sediment or the water. The total unidentified radioactivity in water and sediment was <3.5% of the applied amount at all intervals. No sterile treatments were used or required for the current study

VOLATILIZATION: Hönniger water-sediment: At the end of the study, 2.6 and 0% of the recovered radioactivity was present as ¹⁴CO2 and organic volatile compounds, respectively. No sterile treatments were used or required for the current study. Anglerweiher water-sediment: At the end of the study, 2.4 and 0.1% of the recovered radioactivity was present as 14CO2 and organic volatile compounds, respectively. No sterile treatments were used or required for the current study.

TRANSFORMATION PATHWAY: The major biotransformation pathway for [dihydrofuranon-3-14C]Spirodiclofen in the aerobic water-sediment system is rapid hydrolysis to Spirodiclofen-Enol. Spirodiclofen-Enol was relatively stable in the water-sediments systems, but there was some degradation to CO2 and bound residues (see Figure below).

SUPPLEMENTARY STUDY- RESULTS: The supplementary study, performed in both the Hönniger and Anglerweiher test systems, analyzed the water layer directly without any sample processing (unlike the main study). The only product observed in the water layer from this study was Spirodiclofen-Enol which clearly demonstrated that a second transformation product found in the main study was actually an artifact formed from the Enol during processing. Thus, for quantitation in the main study, the amount of artifact produced during processing was added to the amount of Enol observed to give a total amount for the Enol.

Table 7a - Biotransformation of [dihydrofuranon-3-14C]Spirodiclofen, expressed as percentage of applied radioactivity (mean), in the Hönniger water-sediment system under aerobic conditions.

Compund	Medium	day 0	day 1	day 3	day 7	day 14
Spirodiclofen	water	40.3	3.7	1.3	0.0	0.0
Spirodiclofen	sed.	54.4	68.2	57.3	30.7	9.0
Spirodiclofen- Enol	water	0.9	13.9	26.9	43.5	61.4
Spirodiclofen- Enol	sed.	0.5	5.5	9.9	21.4	23.8
Unidentified radioactivity, if any	water	0.0	0.3	0.2	0.1	1.1
Unidentified radioactivity, if any	sed.	0.0	0.4	0.0	0.0	0.7
Total ^14CO2	entire system	0.0	<0.1	<0.1	0.2	0.3
Total volatile organic compounds	entire system	0.0	0.0	0.0	0.0	0.0
Non-ext. residues	sed.	2.1	3.5	2.4	2.2	2.4
Total % recovery	water	41.2	17.9	28.4	43.6	62.5
Total % recovery	sed.	58.4	78.7	69.6	54.3	36.0
Total % recovery**	entire system	99.7	96.6	98.1	98.8	100.1

* = At Day 37 only one sample (spare) was analyzed, therefore the result provided is not a mean value.

** = Day 0 and Day 1 samples had water extracts of the sediment, and the extracts only accounted for 1.4% and 1.2%
of the mean total percent recoveries.

 

Table 7b - Biotransformation of [dihydrofuranon-3-14C]Spirodiclofen, expressed as percentage of applied radioactivity (mean), in the Hönniger water-sediment system under aerobic conditions.

Compund	Medium	day 30	day 37*	day 59	day 100	day 110
Spirodiclofen	water	0.0	0.0	0.0	0.0	0.0
Spirodiclofen	sed.	1.6	0.2	0.6	0.7	0.1
Spirodiclofen- Enol	water	71.4	73.8	68.6	60.8	54.9
Spirodiclofen- Enol	sed.	18.4	16.6	25.0	28.5	29.6
Unidentified radioactivity, if any	water	3.4	0.0	0.2	3.6	0.0
Unidentified radioactivity, if any	sed.	1.5	1.4	0.5	1.4	3.4
Total ^14CO2	entire system	0.9	1.5	1.0	1.4	2.6
Total volatile organic compounds	entire system	0.0	0.0	0.0	0.0	0.0
Non-ext. residues	sed.	1.7	6.3	2.9	4.2	7.4
Total % recovery	water	74.9	73.8	68.9	64.7	54.9
Total % recovery	sed.	23.4	24.8	29.0	34.9	40.5
Total % recovery**	entire system	100.1	100.2	98.8	101.0	98.0

 

Table 8a: Biotransformation of [dihydrofuranon-3-14C]Spirodiclofen, expressed as percentage of applied radioactivity (mean), in the Anglerweiher water-sediment system under aerobic conditions.

Compund	Medium	day 0	day 1	day 3	day 7	day 14
Spirodiclofen	water	51.0	17.9	6.9	0.1	0.0
Spirodiclofen	sed.	48.2	58.4	40.1	11.5	1.6
Spirodiclofen- Enol	water	0.5	17.8	45.0	77.1	83.6
Spirodiclofen- Enol	sed.	0.4	3.6	6.8	10.8	11.7
Unidentified radioactivity, if any	water	0.0	0.1	0.6	0.5	0.8
Unidentified radioactivity, if any	sed.	0.0	0.1	0.0	0.0	0.0
Total ^14CO2	entire system	0.0	<0.1	<0.1	0.2	0.6
Total volatile organic compounds	entire system	0.0	0.0	0.0	0.0	0.0
Non-ext. residues	sed.	1.4	2.2	1.1	0.7	0.6
Total % recovery	water	51.6	35.8	52.5	77.7	84.5
Total % recovery	sed.	50.5	64.6	48.0	23.0	13.9
Total % recovery**	entire system	102.1	100.4	100.5	100.8	99.0

 

Table 8b: Biotransformation of [dihydrofuranon-3-14C]Spirodiclofen, expressed as percentage of applied radioactivity (mean), in the Anglerweiher water-sediment system under aerobic conditions.

Compund	Medium	day 30	day 59	day 100	day 110
Spirodiclofen	water	0.0	0.0	0.0	0.0
Spirodiclofen	sed.	0.4	0.0	0.0	0.0
Spirodiclofen- Enol	water	83.7	84.3	82.8	87.3
Spirodiclofen- Enol	sed.	10.8	12.3	13.6	15.5
Unidentified radioactivity, if any	water	2.8	0.0	0.0	0.0
Unidentified radioactivity, if any	sed.	0.5	0.6	0.4	1.9
Total ^14CO2	entire system	1.0	1.8	1.6	2.4
Total volatile organic compounds	entire system	0.0	0.0	0.0	0.1
Non-ext. residues	sed.	0.9	1.1	1.5	3.7
Total % recovery	water	86.5	84.6	83.0	87.3
Total % recovery	sed.	12.6	13.9	15.5	21.1
Total % recovery*	entire system	100.1	100.3	100.0	110.8

* = Day 0 and Day 1 samples had water extracts of the sediment, and the extracts only accounted for 0.5% and 1.3% of the mean total percent recoveries.

 

Table 9a: DT50 and DT90 for the Hönniger pond water-sediment system (First order half-life)

System	Regression equation	R^2	DT50 (days)	DT90 (days)
water	y = 1.5546 - 0.6310 (x)**	0.9626	0.5	1.6
sediment	not calculated*	-	<=4.5	<14.9
entire system	y = 1.9599 - 0.0672 (x)**	0.9935	4.5	14.9

** The data provided by the regression analysis (see ref. 11 in this DER) provides a slope that can only be converted to a rate as follows. The rate (k which is -0.6310) in the table above is transformed to a DT50 using DT50 = log (0.5) ÷ k. For the current example, this would be calculated as follows: DT50 = -0.301÷-0.6310 or 0.477 days which rounds to 0.5 days. For the DT90, the calculation is as follows: DT90 = log (0.1) ÷ -0.6310 or 1.58 days which rounds to 1.6 days.

* The DT50 and DT90 for the parent in sediment should be less than those determined for the total system

 

Table 9b: DT50 and DT90 for the Anglerweiher pond water-sediment system (First order half-life)

System	Regression equation	R^2	DT50 (days)	DT90 (days)
water	y = 1.6547 - 0.3409 (x)**	0.9733	0.9	2.9
sediment	not calculated*	-	<=3.7	<12.2
entire system	y = 1.8227 - 0.0818 (x)**	0.8353	3.7	12.2

** The data provided by the regression analysis (see ref. 11 in this DER) provides a slope that can only be converted to a rate as follows. The rate (k which is -0.3409) in the table above is transformed to a DT50 usingDT50 = log (0.5) ÷ k. For the current example, this would be calculated as follows: DT50 = -0.301÷-0.3409 or 0.883 days which rounds to 0.9 days. For the DT90, the calculation is as follows: DT90 = log (0.1) ÷ -0.3409 or 2.933 days which rounds to 2.9 days.
* The DT50 and DT90 for the parent in sediment should be less than those determined for the total system

Conclusions:

For Spirodiclofen in the Hönniger pond system, the DT50 in water and in the total system were 0.5 and 4.5 days, respectively. For Spirodiclofen in the Anglerweiher water-sediment system, the DT50 in water and in the total system were 0.9 and 3.7 days, respectively. The DT50 for Spirodiclofen in either sediment was not determined, but this value should be similar to that observed in the total system since the majority of the Spirodiclofen partitioned into sediment during the first day of incubation.

Executive summary:

The aerobic biotransformation of [dihydrofuranone-3-14C]Spirodiclofen was studied in two different pond water/sediment systems. One system was from Hönniger pond (water pH 7.7, dissolved organic carbon 1.5 to 4.4%; sediment texture sandy loam silt, pH 5.9, organic carbon 4.04%; Wipperürth, Germany) which had a strong current through the pond system, and the second system was from Anglerweiher (water pH 7.8, dissolved organic carbon 2.3 to 7.3%; sediment texture silty sand, pH 6.4, organic carbon 0.95%; Leverkusen, Germany). Both studies were conducted for 110 days in the dark at 20 ± 1ºC. [dihydrofuranon-3-14C]Spirodiclofen was applied at the rate of 0.05 mg a.i./L. The sediment/water ratio used was 1:9. The experiment was conducted in accordance with the BBA Guidelines for Official Testing of Plant Protectants (references 1 and 2 in section V of this DER), EC Commission Directive 95/36/EC (ref 3 in section V), and the SETAC Procedures for Assessing the Environmental Fate and Ecotoxicity of Pesticides (ref 4 in section V), and in compliance with the OECD-GLP standards. The test system consisted of 1000-mL glass vessels equipped with a overhead stirrer which stirred only the water layer. The system had traps attached for the collection of CO2 and organic volatile compounds. Samples were analysed at 0, 1, 3, 7, 14, 30, 59, 100, and 110 days of incubation. Initially, the water samples were acidified, diluted with ACN and extracted with dichloromethane. However, the initial solvent extraction procedure produced an artifact from the major degradate, and the formation of this artifact was confirmed in a supplementary study using both test systems where the water layer was analyzed directly without extraction (i.e., the artifact was not detected in the direct analyses). The sediment layer was extracted with acetonitrile followed by acetonitrile/buffer mixtures. The [dihydrofuranon-3-14C]Spirodiclofen residues were analyzed by reverse phase TLC using autoradiography obtained via a bio-imaging analyzer. A second TLC system and LC/MS was used for confirmation of the major degradate, Spirodiclofen-Enol.

Description of key information

BIODEGRADATION IN WATER

In an aerobic aquatic degradation and metabolism study, spirodiclofen was tested in two different systems. In the Hönniger pond system, the DT₅₀ in water and in the total system were 0.5 and 4.5 days, respectively. Whilst in the Anglerweiher water-sediment system, the DT₅₀ in water and in the total system were 0.9 and 3.7 days, respectively. The DT₅₀ for spirodiclofen in either sediment was not determined, but this value should be similar to that observed in the total system since the majority partitioned into sediment during the first day of incubation.

Results are presented as the mean of the two measurements.

The half-life in freshwater was converted from 0.7 d at 20°C to 1.49 d at 12°C and for freshwater-sediment from 4.1 d at 20°C to 8.7 d at 12°C (using Arrhenius equation).

 

BIODEGRADATION WHOLE SYSTEM
The DT₅₀ and DT₉₀ of spirodiclofen under anaerobic conditions in a Fresno, CA sediment-water system was determined to be 11.5 and 38.2 days at 20°C, respectively. The half-life of 11.5 d at 20°C was converted to 24.41 d at 12°C (using Arrhenius equation).

Key value for chemical safety assessment

Half-life in freshwater:

1.49 d

at the temperature of:

12 °C

Half-life in freshwater sediment:

8.7 d

at the temperature of:

12 °C

Whole System

Half-life in whole system:

24.41 d

at the temperature of:

12 °C

Type of system:

fresh water and sediment