Citation:

PANGAEA.923890

Name: Experiment on washing procedures to extract positively buoyant microplastics (> 500 µm) from beach wrack
Published: 2020-10-15
License: https://creativecommons.org/licenses/by/4.0/
Keywords: beach wrack; empirical method evaluation; Microplastics; particle extraction; Western Baltic Sea

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Abstract:

The "beach wrack - plastic separator" is the prototype of a simple construction that we used to assess two methods for washing beach wrack. Its main component is a polypropylene container that is 40 x 30 x 22 cm in size and has a volume of 20.8 l. Furthermore, we used two grids (39.5 cm x 25.5 cm) that could be inserted horizontally into the container and between which a beach wrack sample of 500 g could be placed. The grids were made of aluminium and had a mesh size of 1 cm x 1 cm. Two handles were attached to the lower of the two grids that allowed to move the grids vertically inside the container. As soon as the container was filled with 10 litres of tap water, the upper grid prevented the beach wrack from floating to the surface, while the lower kept it from settling on the bottom of the container. The separation of the plastic particles from the sample material was induced by moving the grids up and down manually or by bubbling pressured air, which was supplied through air inlets, through the beach wrack material.For assessing the extraction efficiency of the two washing procedures, 48 kg of beach wrack were collected at the beach of Falckenstein, which is located at the western shore of the outer Kiel Fjord, Germany, (N 54.391250, E 10.190728) from May to August 2018.

After collection, we divided the 48 kg into 96 batches of 500 g each, which were then spiked with microplastic particles. Half of the batches consisted of Zostera leaves, while the other half consisted of thalli of Fucus spp. We did not dry the material prior to spiking and we used two types of polymers of three size classes to be able to assess the influence of polymer type and particle size on the recovery rate. We have used polypropylene (PP) fragments with a density of 0.88 to 0.91 g/cm3 (Herrera et al., 2018) and spheres of expanded polystyrene (EPS), with a density of 0.01 to 0.05 g/cm3 (Herrera et al., 2018). The densities of both polymer types are lower than seawater. The different particle size classes were either manually created or directly purchased. We tested the following three size classes: 500 to 1000 µm, 1000 to 2000 µm and 2000 to 5000 µm.

We have produced PP fragments from plastic cups (wall thickness: 0.5 mm) that we collected at the driftline of the beach of Falckenstein, and which had the polymer type indicated on their bottom. The cups, which were free of epibionts, were cut into quadratic fragments that fell into the three size classes using a scissor. The EPS spheres were purchased in the same size classes. A defined number of particles from each of the three size classes was weighed on a laboratory scale. Then the particles were carefully mixed into the beach wrack at a weight ratio of 1 : 1x104 (2000 to 5000 µm) or 1 : 1x105 (the two remaining size classes).

To achieve the weight ratios mentioned above, we either added a) 19 particles of PP or 15 particles of EPS in the size range of 1000 to 2000 µm, b) 30 particles of PP or 20 particles of EPS in the size range of 500 to 1000 µm or c), 12 particles of PP or 26 particles of EPS in the size range of 2000 to 5000 µm to one individual batch. For each replicate, the PP and EPS particles were counted and weighed individually. After spiking, we let the beach wrack rest for a maximum of 20 minutes and then placed the material between the two grids in the beach wrack - plastic separator. The lower grid was at a distance of 1 to 2 cm to the bottom, what would allow negatively buoyant microplastic particles (not tested in this study) to sink to the bottom of the container and to accumulate underneath the lower grid.

The separation efficiency of both procedures was then analysed regarding the following four factors: 1. type of beach wrack, 2. polymer type 3. polymer size and 4. duration of washing. The principle component of the separation process was the induction of a water flow, which detached the plastic particles from the surface of the macrophyes and also released them from hollows between their leaves or thalli. In the manual washing process, this was achieved by moving the grids up and down ten times in quick succession with an amplitude of 15 cm. The amplitude as well as the speed and number of repetitions then resulted in an up- and downward flow of water through the sample material that was strong enough to separate the microplastic particles from the macrophytes. The released particles floated up and were picked manually from the water surface. The particles were identified as either PP or EPS particles belonging to one of the three size classes. This was done after each single movement of the grids (up and down), so that particle extraction success could be assessed for each polymer type/size class as a function of the washing effort. This procedure was repeated with both types of beach wrack (Zostera marina L. and Fucus spp.), for both particle types (PP fragments and EPS spheres) and for all size classes within each particle type. For each of these 12 treatment combinations (beach wrack type with two levels x particle type with two levels x size class with three levels), we had four replicates and we used new beach wrack and new plastic material for each of them.

The air-facilitated washing of the beach wrack was also done with tap water. For this, three cylindrical diffusor stones (diameter: 50 mm) were connected to an electric air compressor (Pontec PondoAir Set 200) via tubes (diameter: 4 mm, total length: 100 cm) and placed underneath the lower grid. Again, individual batches of 500 g of beach wrack were placed in between the two grids and were then bubbled with air for four hours at an overall discharge rate of 200 l pressured air/h. This rate generated a water flow through the sample material with a velocity that was sufficient to separate the microplastic particles from the beach wrack material. In addition to this, the air bubbles themselves presumably released particles from macrophyte surfaces or from hollows between their thalli or leaves. This was done by the shear stress they exerted when getting in direct contact with a particle or by transferring a momentum that set the particle in motion.

Keyword(s):

beach wrack; empirical method evaluation; Microplastics; particle extraction; Western Baltic Sea

Supplement to:

Dittmann, Sinja; Lenz, Mark (2020): Two simple washing procedures allow the extraction of positively buoyant microplastics (>500 μm) from beach wrack. Marine Pollution Bulletin, 161, 111762, https://doi.org/10.1016/j.marpolbul.2020.111762

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Comment
1	Replicate	Repl		Lenz, Mark
2	Type	Type		Lenz, Mark	polymer
3	Size	Size		Lenz, Mark	particle
4	Species	Species		Lenz, Mark
5	Experiment	Exp		Lenz, Mark
6	Counts	Counts	#	Lenz, Mark	before
7	Counts	Counts	#	Lenz, Mark	after
8	Recovery	Recovery	%	Lenz, Mark
9	Counts	Counts	#	Lenz, Mark	after 0.5h
10	Counts	Counts	#	Lenz, Mark	after 1h
11	Counts	Counts	#	Lenz, Mark	after 1.5h
12	Counts	Counts	#	Lenz, Mark	after 2h
13	Counts	Counts	#	Lenz, Mark	after 2.5h
14	Counts	Counts	#	Lenz, Mark	after 3h
15	Counts	Counts	#	Lenz, Mark	after 3.5h
16	Counts	Counts	#	Lenz, Mark	after 4h
17	Counts	Counts	#	Lenz, Mark	after 1 movement
18	Counts	Counts	#	Lenz, Mark	after 2 movements
19	Counts	Counts	#	Lenz, Mark	after 3 movements
20	Counts	Counts	#	Lenz, Mark	after 4 movements
21	Counts	Counts	#	Lenz, Mark	after 5 movements
22	Counts	Counts	#	Lenz, Mark	after 6 movements
23	Counts	Counts	#	Lenz, Mark	after 7 movements
24	Counts	Counts	#	Lenz, Mark	after 8 movements
25	Counts	Counts	#	Lenz, Mark	after 9 movements
26	Counts	Counts	#	Lenz, Mark	after 10 movements

License:

Creative Commons Attribution 4.0 International (CC-BY-4.0)

Size:

1632 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Repl	2 Type (polymer)	3 Size (particle)	4 Species	5 Exp	6 Counts [#] (before)	7 Counts [#] (after)	8 Recovery [%]	9 Counts [#] (after 0.5h)	10 Counts [#] (after 1h)	11 Counts [#] (after 1.5h)	12 Counts [#] (after 2h)	13 Counts [#] (after 2.5h)	14 Counts [#] (after 3h)	15 Counts [#] (after 3.5h)	16 Counts [#] (after 4h)	17 Counts [#] (after 1 movement)	18 Counts [#] (after 2 movements)	19 Counts [#] (after 3 movements)	20 Counts [#] (after 4 movements)	21 Counts [#] (after 5 movements)	22 Counts [#] (after 6 movements)	23 Counts [#] (after 7 movements)	24 Counts [#] (after 8 movements)	25 Counts [#] (after 9 movements)	26 Counts [#] (after 10 movements)
1	EPS	500-1000 µm	Fucus spp.	Air facilitated washing	20	19	95.00	15	17	18	19	19	19	19	19
2	EPS	500-1000 µm	Fucus spp.	Air facilitated washing	20	20	100.00	14	18	20	20	20	20	20	20
3	EPS	500-1000 µm	Fucus spp.	Air facilitated washing	20	20	100.00	13	17	17	19	20	20	20	20
4	EPS	500-1000 µm	Fucus spp.	Air facilitated washing	20	20	100.00	14	19	20	20	20	20	20	20
1	EPS	1000-2000 µm	Fucus spp.	Air facilitated washing	15	15	100.00	8	12	14	15	15	15	15	15
2	EPS	1000-2000 µm	Fucus spp.	Air facilitated washing	15	15	100.00	6	10	13	14	15	15	15	15
3	EPS	1000-2000 µm	Fucus spp.	Air facilitated washing	15	15	100.00	5	11	12	14	14	14	14	15
4	EPS	1000-2000 µm	Fucus spp.	Air facilitated washing	15	15	100.00	10	13	14	14	14	15	15	15
1	EPS	2000-5000 µm	Fucus spp.	Air facilitated washing	26	25	96.15	12	20	23	23	24	25	25	25
2	EPS	2000-5000 µm	Fucus spp.	Air facilitated washing	26	24	92.31	10	16	20	20	22	23	23	24
3	EPS	2000-5000 µm	Fucus spp.	Air facilitated washing	26	26	100.00	13	19	20	23	25	25	25	26
4	EPS	2000-5000 µm	Fucus spp.	Air facilitated washing	26	23	88.46	15	17	20	23	23	23	23	23
1	PP	500-1000 µm	Fucus spp.	Air facilitated washing	28	25	89.29	13	13	13	13	13	13	13	13
2	PP	500-1000 µm	Fucus spp.	Air facilitated washing	28	25	89.29	15	19	22	25	25	25	25	25
3	PP	500-1000 µm	Fucus spp.	Air facilitated washing	28	25	89.29	16	20	21	22	23	24	24	25
4	PP	500-1000 µm	Fucus spp.	Air facilitated washing	28	26	92.86	15	19	22	24	25	25	25	26
1	PP	1000-2000 µm	Fucus spp.	Air facilitated washing	18	18	100.00	12	15	16	17	17	18	18	18
2	PP	1000-2000 µm	Fucus spp.	Air facilitated washing	18	15	83.33	12	13	14	14	14	15	15	15
3	PP	1000-2000 µm	Fucus spp.	Air facilitated washing	18	17	94.44	13	16	17	17	17	17	17	17
4	PP	1000-2000 µm	Fucus spp.	Air facilitated washing	18	18	100.00	12	13	15	17	18	18	18	18
1	PP	2000-5000 µm	Fucus spp.	Air facilitated washing	12	12	100.00	10	12	12	12	12	12	12	12
2	PP	2000-5000 µm	Fucus spp.	Air facilitated washing	12	12	100.00	11	12	12	12	12	12	12	12
3	PP	2000-5000 µm	Fucus spp.	Air facilitated washing	12	12	100.00	12	12	12	12	12	12	12	12
4	PP	2000-5000 µm	Fucus spp.	Air facilitated washing	12	12	100.00	11	11	12	12	12	12	12	12
1	EPS	500-1000 µm	Zostera marina L.	Air facilitated washing	20	17	85.00	10	13	14	16	17	17	17	17
2	EPS	500-1000 µm	Zostera marina L.	Air facilitated washing	20	17	85.00	11	15	16	16	17	17	17	17
3	EPS	500-1000 µm	Zostera marina L.	Air facilitated washing	20	16	80.00	10	14	15	16	16	16	16	16
4	EPS	500-1000 µm	Zostera marina L.	Air facilitated washing	20	15	75.00	10	14	14	15	15	15	15	16
1	EPS	1000-2000 µm	Zostera marina L.	Air facilitated washing	15	10	66.67	4	7	10	10	10	10	10	10
2	EPS	1000-2000 µm	Zostera marina L.	Air facilitated washing	15	11	73.33	4	9	10	11	11	11	11	11
3	EPS	1000-2000 µm	Zostera marina L.	Air facilitated washing	15	11	73.33	5	8	9	9	11	11	11	11
4	EPS	1000-2000 µm	Zostera marina L.	Air facilitated washing	15	10	66.67	4	6	7	7	8	10	10	10
1	EPS	2000-5000 µm	Zostera marina L.	Air facilitated washing	26	20	76.92	10	12	18	20	20	20	20	20
2	EPS	2000-5000 µm	Zostera marina L.	Air facilitated washing	26	19	73.08	10	14	17	19	19	19	19	19
3	EPS	2000-5000 µm	Zostera marina L.	Air facilitated washing	26	20	76.92	11	16	17	19	20	20	20	20
4	EPS	2000-5000 µm	Zostera marina L.	Air facilitated washing	26	20	76.92	10	15	18	18	19	20	20	20
1	PP	500-1000 µm	Zostera marina L.	Air facilitated washing	28	18	64.29	9	11	16	17	18	18	18	18
2	PP	500-1000 µm	Zostera marina L.	Air facilitated washing	28	17	60.71	8	12	15	16	17	17	17	17
3	PP	500-1000 µm	Zostera marina L.	Air facilitated washing	27	18	66.67	9	13	14	16	18	18	18	18
4	PP	500-1000 µm	Zostera marina L.	Air facilitated washing	28	16	57.14	9	12	14	15	15	16	16	16
1	PP	1000-2000 µm	Zostera marina L.	Air facilitated washing	18	17	94.44	10	13	14	15	17	17	17	17
2	PP	1000-2000 µm	Zostera marina L.	Air facilitated washing	18	14	77.78	7	9	11	12	14	14	14	14
3	PP	1000-2000 µm	Zostera marina L.	Air facilitated washing	18	15	83.33	10	12	14	15	15	15	15	15
4	PP	1000-2000 µm	Zostera marina L.	Air facilitated washing	18	15	83.33	9	12	13	15	15	15	15	15
1	PP	2000-5000 µm	Zostera marina L.	Air facilitated washing	12	10	83.33	2	3	5	6	9	10	10	10
2	PP	2000-5000 µm	Zostera marina L.	Air facilitated washing	12	11	91.67	3	5	8	9	10	11	11	11
3	PP	2000-5000 µm	Zostera marina L.	Air facilitated washing	12	10	83.33	3	4	6	7	8	10	10	10
4	PP	2000-5000 µm	Zostera marina L.	Air facilitated washing	12	11	91.67	2	4	5	6	10	11	11	11
1	EPS	500-1000 µm	Fucus spp.	Manual Washing	20	20	100.00									13	20	20	20	20	20	20	20	20	20
2	EPS	500-1000 µm	Fucus spp.	Manual Washing	20	20	100.00									14	18	20	20	20	20	20	20	20	20
3	EPS	500-1000 µm	Fucus spp.	Manual Washing	20	19	95.00									13	16	17	19	19	19	19	19	19	19
4	EPS	500-1000 µm	Fucus spp.	Manual Washing	20	20	100.00									13	20	20	20	20	20	20	20	20	20
1	EPS	1000-2000 µm	Fucus spp.	Manual Washing	15	15	100.00									6	12	14	15	15	15	15	15	15	15
2	EPS	1000-2000 µm	Fucus spp.	Manual Washing	15	15	100.00									6	12	13	15	15	15	15	15	15	15
3	EPS	1000-2000 µm	Fucus spp.	Manual Washing	15	15	100.00									3	10	12	14	14	15	15	15	15	15
4	EPS	1000-2000 µm	Fucus spp.	Manual Washing	15	15	100.00									4	10	12	13	14	14	15	15	15	15
1	EPS	2000-5000 µm	Fucus spp.	Manual Washing	26	20	76.92									12	12	12	13	13	13	15	16	16	20
2	EPS	2000-5000 µm	Fucus spp.	Manual Washing	26	26	100.00									10	16	20	23	23	25	25	26	26	26
3	EPS	2000-5000 µm	Fucus spp.	Manual Washing	26	26	100.00									11	17	20	23	25	25	25	25	25	26
4	EPS	2000-5000 µm	Fucus spp.	Manual Washing	26	23	88.46									12	17	20	21	21	21	22	22	22	23
1	PP	500-1000 µm	Fucus spp.	Manual Washing	28	26	92.86									15	18	20	23	24	24	25	25	25	26
2	PP	500-1000 µm	Fucus spp.	Manual Washing	28	25	89.29									11	13	19	21	22	22	23	23	24	24
3	PP	500-1000 µm	Fucus spp.	Manual Washing	27	25	92.59									16	20	21	22	22	23	24	24	25	25
4	PP	500-1000 µm	Fucus spp.	Manual Washing	28	26	92.86									15	19	22	24	24	24	24	25	25	25
1	PP	1000-2000 µm	Fucus spp.	Manual Washing	18	18	100.00									12	15	16	17	17	17	17	17	18	18
2	PP	1000-2000 µm	Fucus spp.	Manual Washing	18	15	83.33									12	13	14	14	14	14	14	14	15	15
3	PP	1000-2000 µm	Fucus spp.	Manual Washing	18	18	100.00									13	16	17	18	18	18	18	18	18	18
4	PP	1000-2000 µm	Fucus spp.	Manual Washing	18	18	100.00									12	14	16	17	17	17	18	18	18	18
1	PP	2000-5000 µm	Fucus spp.	Manual Washing	12	12	100.00									7	9	10	11	11	11	12	12	12	12
2	PP	2000-5000 µm	Fucus spp.	Manual Washing	12	12	100.00									11	11	12	12	12	12	12	12	12	12
3	PP	2000-5000 µm	Fucus spp.	Manual Washing	12	12	100.00									8	11	11	11	12	12	12	12	12	12
4	PP	2000-5000 µm	Fucus spp.	Manual Washing	12	12	100.00									10	10	10	11	12	12	12	12	12	12
1	EPS	500-1000 µm	Zostera marina L.	Manual Washing	20	17	85.00									10	15	15	16	17	17	17	17	17	17
2	EPS	500-1000 µm	Zostera marina L.	Manual Washing	20	16	80.00									11	15	16	16	16	16	16	16	16	16
3	EPS	500-1000 µm	Zostera marina L.	Manual Washing	20	16	80.00									10	14	15	15	15	15	16	16	16	16
4	EPS	500-1000 µm	Zostera marina L.	Manual Washing	20	17	85.00									10	14	16	17	17	17	17	17	17	17
1	EPS	1000-2000 µm	Zostera marina L.	Manual Washing	15	10	66.67									4	7	10	10	10	10	10	10	10	10
2	EPS	1000-2000 µm	Zostera marina L.	Manual Washing	15	11	73.33									4	7	10	11	11	11	11	11	11	11
3	EPS	1000-2000 µm	Zostera marina L.	Manual Washing	15	10	66.67									5	8	9	9	10	10	10	10	10	10
4	EPS	1000-2000 µm	Zostera marina L.	Manual Washing	15	10	66.67									4	6	7	7	8	9	9	9	10	10
1	EPS	2000-5000 µm	Zostera marina L.	Manual Washing	26	21	80.77									10	14	19	20	20	21	21	21	21	21
2	EPS	2000-5000 µm	Zostera marina L.	Manual Washing	26	19	73.08									10	14	17	18	18	18	18	18	18	19
3	EPS	2000-5000 µm	Zostera marina L.	Manual Washing	26	20	76.92									11	15	18	19	20	20	20	20	20	20
4	EPS	2000-5000 µm	Zostera marina L.	Manual Washing	26	20	76.92									10	15	17	18	19	20	20	20	20	20
1	PP	500-1000 µm	Zostera marina L.	Manual Washing	28	20	71.43									9	11	16	17	19	20	20	20	20	20
2	PP	500-1000 µm	Zostera marina L.	Manual Washing	28	17	60.71									8	12	15	16	17	17	17	17	17	17
3	PP	500-1000 µm	Zostera marina L.	Manual Washing	27	18	66.67									9	12	14	16	16	17	17	18	18	18
4	PP	500-1000 µm	Zostera marina L.	Manual Washing	28	18	64.29									9	12	14	15	15	16	16	18	18	18
1	PP	1000-2000 µm	Zostera marina L.	Manual Washing	18	17	94.44									10	13	14	14	16	16	17	17	17	17
2	PP	1000-2000 µm	Zostera marina L.	Manual Washing	18	13	72.22									8	10	11	12	13	13	13	13	13	13
3	PP	1000-2000 µm	Zostera marina L.	Manual Washing	18	15	83.33									10	13	14	15	15	15	15	15	15	15
4	PP	1000-2000 µm	Zostera marina L.	Manual Washing	18	16	88.89									9	12	13	15	16	16	16	16	16	16
1	PP	2000-5000 µm	Zostera marina L.	Manual Washing	12	10	83.33									2	3	5	6	9	10	10	10	10	10
2	PP	2000-5000 µm	Zostera marina L.	Manual Washing	12	11	91.67									3	5	8	9	10	11	11	11	11	11
3	PP	2000-5000 µm	Zostera marina L.	Manual Washing	12	11	91.67									3	4	6	7	8	10	12	12	12	12
4	PP	2000-5000 µm	Zostera marina L.	Manual Washing	12	10	83.33									2	4	5	6	8	9	10	10	10	10