Where is all the plastic?
De Meester Steven1, Claessens Michiel2 & Janssen R. Colin2
1
2
EnVOC: Environmental Organic Chemistry and Technology, Ghent University, Coupure Links 653, B-9000 Gent, Belgium
Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, B-9000 Ghent, Belgium
Contact: Steven.DeMeester@UGent.be
Introduction
A large amount of plastic debris originating from fishery, shipping, tourism and sewers ends up in our marine environment each year. Plastic degrades very
slowly and thus accumulates year after year. While the distribution and hazards of large marine debris are well documented, the occurrence and dangers of socalled microplastics are less well known. Indeed, in short-term there is no real degradation of plastic, but under influence of UV light, the large plastic items
become brittle and fractionate into small fragments. Some studies have shown the widespread distribution of this type of litter, but there is no agreement yet
about the worldwide concentrations and practically no studies have investigated potential adverse effects on marine organisms. This study investigated the
occurrence of microplastics in the Belgian Coastal zone, including potential trends in time. Additionally, a first attempt was made to assess the potential of
microplastics to transfer pollutants to marine organisms.
1mm
0
UV + fragmentation
The Great Pacific Garbage Patch: over 100 million tons
of marine debris in the Central North Pacific Ocean
Floating plastic debris and plastic
drifted ashore
Microplastics
Method
Sediment samples were taken from 2 beaches with a steady sediment accumulation to find a potential trend in time: Koksijde-Bad & Groenendijk at the hightide mark, the intertidal and the subtidal. Other samples were taken from the sandbank near the harbour of Zeebrugge, the Belgian Continental Shelf and from
the 3 Belgian coastal harbours: Nieuwpoort, Oostende and Zeebrugge. After stirring the sediment in a saline solution, floating microplastics were filtered out
and identified with IR. Results are displayed in amount per kg dry weight and in 4 categories: fibers, granular particles, plastic films and polystyrene spherules.
Microplastics
Saline solution
Sediment
Stirring sediment in
a saline solution
Taking sediment samples
Filtration of top layer
Identification with IR
Results
Occurrence
Effects
All sediment samples contained microplastics, giving clear evidence of the widespread
distribution and high occurence in the Belgian coastal area.
High-tide mark
180
Intertidal
94
1200
947
Subtidal
140
Concentration microplastics (µg/kg)
Number of particles/kg dry weight
160
109
120
81
100
58
80
60
46
40
30
20
8
4
6
9
4
4
0
Fibers
Granular
1
0
Sandbank
1000
2
Belgian Continental
800
418
600
257
400
196
136 189 113
200
82 61
35 44
94
71
40
13
0
Fibers
Plastic films
Granular
Plastic films
The average results from the samples taken at Koksijde-Bad, Groenendijk, the sandbank and the Belgian Continental Shelf.
The figure on the left shows results the results in amount and the figure on the right shows the same result in weight.
120
OO1
100
80
OO2
94
OO3
77
73
OO4
61
60
46
46
35
40
24
24 26
20
2
0
Fibers
Granular
Polystyrene spherules
2
0
2
Plastic films
Results from the harbours were very variable. The samples
contained a high amount of granular particles, suggesting
shipping as a source of this class of microplastics. Also a
serious amount of polystyrene spherules was found (up to
100 spherules/m³ sediment). Most likely these particles
origin from scrubbers used for cleaning.The figure below
shows the results of 4 sampling points in the harbour of
Oostende.
Number of particles/kg dry weight
Number of particles/kg dry weight
100
77
Physical effects: Plastics can block the digestive
system of marine organisms. Evidence exists for
macroplastics, but there is little or no research
so far for microplastics.
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
GHWL-Top layer
132
GHWL-2nd layer
Chemical effects: microplastics can sorb pollutants
like PCB and phenanthrene and can contamine
marine organisms. Further research, with practical
experiments is needed!
GHWL-3th layer
GHWL-Deepest layer
85
Plastic
Pollutant
Plastic
Pollutant
74
48
10
Fibers
8
14
8
Granular
5
8
5
1
Plastic films
In Koksijde-Bad a time period of 4 years was covered by
examining 4 layers of 1 year sediment accumulation each.
In Groenendijk 16 years were covered by examining 4
layers of 4 years each. The samples of Koksijde-Bad
showed no significant difference, but in Groenendijk the
deeper layers contained significantly less microplastics.
 The problem seems to be growing in the
long-term
Worstcase calculations were made of phenanthrene and PCB
concentrations on microplastic, and their possible transfer to
organisms (Arenicola marina) through pore water. Assuming a
non-polluted, closed system, contaminated microplastics
could possibly cause concentrations of 0.0077ng
phenanthrene and 0.0706ng PCB per worm at plastic
concentrations of 1117µg/kg (the highest concentration found
on the beaches).