SOUTHAMPTON SOLENT UNIVERSITY

A comparative study of the spatial distribution

of marine microplastics in the Solent area and

East Anglia. The study of Microplastics in marine sediments

Aldous Rees, Jean-Pascal Beecroft, Rory Hill and Georgie Frary

3/1/2012

1

Contents page

List of Figures and Graphs 2

List of Tables 2

Abstract 3

Acknowledgements 3

1. Introduction

1.1 Background microplastics 4

1.2 Background investigation 6

1.3 Hypothesis 6

2. Method

2.1 Data collection 8

2.2 Data analysis 9

2.3 Retrieval rate experiment 11

2.4 Limitations and problems 12

2.5 Risk Assessment 13

3. Results

3.1 Graphs 14

3.2 Statistical tests 16

4. Discussion

4.1 Levels of microplastic found 17

4.2 Statistical tests 18

4.3 Retrieval experiment 19

4.4 Potential routes of microplastic to beaches – Longshore drift 19

4.5 Potential routes of microplastics to beaches – Tides 20

4.6 Future changes to experiment and future of microplastic 20

5. Conclusion 22

6. References 23

Appendix 1 25

Appendix 2 26

Appendix 3 27

Appendix 4 28

2

List of Figures and Graphs

Figure 1 - Location maps for each area surveyed 7

Figure 2 – Image showing measuring of a transect down beach 8

Figure 3 – Model of transect layout on beaches 9

Figure 4 – Shape classification of microplastics 10

Graph 1 – Retrieval rate experiment 12

Graph 2 – Microplastic distribution along transect lines 14

Graph 3 – Shapes of microplastics found 15

Graph 4 – Box and whisker diagram 16

List of tables

Table 1 – Beaches surveyed 6

Table 2 – Potential sources in each area 10

3

A comparative study of the spatial distribution of marine microplastics in the Solent

area and East Anglia.

Abstract:

Microplastics are pieces of plastic less than 5mm in size. They have become common in the

marine environment in recent years within the water column and in beach sediments. All

studies conducted thus far have found microplastics. This study looked at the levels of

microplastic within estuarine sediments and beach sediments at a number of locations within

Southampton Water, Poole Bay, the Norfolk coast and the Essex coast. 20 beaches were

surveyed with three transect lines being used on each beach. Sediment samples were taken

from high water, mid water and low water. The microplastic was floated out of the sediments

using super saturated saline solution and examined under a microscope. All of the 20 beaches

surveyed had plastic present, with 160 out of the 174 samples having plastic within them. The

most common shape was fibres, which is thought to come from clothes. This study showed

that marine microplastics are wide spread but more research is still needed to show the true

distribution.

Acknowledgements: The authors would like to thank Dr Paul Wright for guidance and

support throughout the project. We would also like to thank all those that helped with data

collection and processing. Finally like to thank Kevin Thatcher and Polly Schoolcraft for

allowing us use of the laboratory and using up all their sodium chloride and Petri dishes and

the support they gave us during the project.

Article info

Keywords

Microplastics, Essex Coast, Norfolk Coast, Southampton Water, Poole Bay

4

1. Introduction

1.1 Background microplastics

Microplastics are pieces of plastic under the size of 5mm. They were first identified as a

problem in the 1970s (Frais et al 2010). There are two main sources of microplastic: larger

pieces of plastic being broken up by waves and sunlight, from industrial processes and

sewage works (Thompson et al 2004 and Browne et al 2011). Fibres make up most of the

plastic found in the marine environment. An experiment by Browne et al (2011) collected

waste water from a washing machine and this research showed that a piece of clothing can

shed 1900 bits of polymer fibres per wash. The majority of these particles then enter into

water courses. More clothes are worn in winter, so more washes occur meaning higher fibre

levels area released during the winter period (Browne et al 2011). They cause many problems

in the marine environment as many animals ingest them. The effects on these animals are not

yet properly understood and very little research has been carried out on the spatial

distribution of marine microplastics (Murray and Cowie 2011 and Fendall and Sewell 2009).

Little is known about the amount of microplastics compared to macro plastics as it is harder

and more time consuming to collect the data.

Another major source of microplastics apart from washing are facial cleaners; originally

organic materials were used such as almond husks or pumice, but more recently plastic beads

have been used, due to their small size they get through waste water treatment plants and end

up in the oceans. Recent research has shown that they are one of the main sources of

microplastics in the oceans and fibres make up most of the plastic in sediments (Fendall and

Sewell 2009 and Browne et al 2011).

Anthony (2011) looked at where plastics are used in the marine environment, 18% of which

come from the fishing industry. Marysia (2009) tries to come up with solutions to

microplastic in the marine environment by identifying the main sources and then identifying

ways to limit them, such as better public awareness and better filters.

Microplastics have an impact on marine life, as they ingest plastic thinking it is food which

either blocks up their guts or deprives them of nutrients they would gain from other food

sources. Murray and Cowie (2011) carried out research on the effects to decapods crustacean

Nephrops norvegicus and 83% of the nephrops sampled contained plastics in their guts. This

study shows that a large number of crustaceans are consuming plastics. The true extent and

5

how far up the food chain plastics travel is as yet unknown. Some indications show it could

even affect humans (Gordon 2000). Microplastics can also release Persistent Organic

Pollutants (POPs), these are organic compounds that are resistant to environmental

degradation. They include PAH and PCBs (Noren 2010). This leads to further problems for

marine life and the wider environment (Zaffl et al 2011).

A number of investigations have been carried out on the amount of microplastics present in

marine sediments across the world. Every beach sampled seems to have some microplastics

within the sediment. An investigation carried out off the Belgian coast (Claessens et al 2011)

looked at sediment cores to see the build up over time, the problems with this method are that

sand is disturbed through tides and tourist activity. The paper did highlight this; the samples

seemed to show an increase over time. All of the samples collected were found to contain

microplastics. The levels were high for studies in the area, only investigations in India near to

a ship breaking yard yielded higher results to date. In Belgium the concentrations of

microplastics were higher in coastal waters and a trend appeared to show that as plastic

production increases in general the levels found on the beaches as microplastics also increase.

An investigation of the Portuguese coast (Frias et al 2010) surveyed two beaches both near to

ports and a wide range of plastic was found in the sediment samples. Investigations off the

Singapore coast (Ng and Obbard 2006) showed large amounts of plastic were present. It is

thought that this plastic comes from Asian countries such as India. The data were collected

from beaches and also the water column, both were found to have microplastics present.

Corcorana et al (2009) surveyed 18 beaches in Hawaii and these all contained plastic. Studies

by Zarfl and Matthies (2010) indicated that plastics have reached the Arctic and it is thought

ocean gyres transport plastic to the region. A survey in Malta carried out by Turner and

Holmes (2011) on sandy beaches of which there are only a small percentage in Malta and a

few rocky shores. Most of the plastics found were at the backshore, rather than the swash

zone. On the rocky shores, pellets were found embedded in tar deposits. What the currents

investigations show is that large amounts of microplastics are present, but there is no

standardised method to collect data. This makes it hard to compare results from different

investigations. In the future a method that works and can be used worldwide need to be

created, (NOAA 2008). These investigations also show that more research is needed to better

understand the spatial distribution of microplastics.

6

1.2 Background investigation

This investigation studied the levels of microplastics present within sediment at a number of

different sites in the Solent area and East Anglia (See table 1 and figure 1). This will show

the spatial distribution of marine microplastics and will help to determine how much of a

problem they are in the marine environment. A number of different beaches and mudflats

were surveyed. The Solent area was split into two groups: estuarine sediments within

Southampton Water and beach sediments on South coast in Poole Bay and Christchurch Bay

between Bournemouth and Milford on Sea. Data were also collected on the Norfolk and

Essex (see table 1).

Table 1: Survey areas and beaches/mudflats sampled

Southampton water South Coast between

Bournemouth and Milford

on sea

Norfolk coast Essex coast

Northam Bournemouth Mundesley Walton

Chessel bay Nature

reserve

Boscombe Old Hunstanton Frinton on Sea

Netley Frairs Cliffe Caistor on Sea Clacton on Sea

Hythe Avon Sea Palling Brightlingsea

Warsash Milford on Sea East Runton East Mersea

1.3: Hypothesis

There will be more plastic on beaches than estuaries, due to it being transported out of river

systems by tides and currents and onto the beaches. The majority of the plastics found will

fibres, as this is mainly what other investigations have found.

7

Figure 1: Maps to

show sample areas

(Edina Digimaps 2012

and Broadland storage

2012).

8

2. Method

2.1 Data Collection

A total of four areas were investigated for the concentration

of micro-plastics. These were:

Southampton Water and estuaries

Poole Bay

North Norfolk coast

Essex coast

At each area 5 different beaches were visited and at each

beach a total of 9 sediment samples were collected.

On each beach, three transect lines were taken: one on the right, one in the centre and one on

the left (see Figure 2 and 3). The difference between the transects varied on each beach

depending on the total length. For example on Bournemouth beach the samples were 300

metres apart whereas on Chessel beach they were only 50 metres. This method was adapted

from Thompson et al (2004) who sampled at high water on a number of beaches. Ng and

Obbard (2006) used a different method by collecting 0.5 metres from the tide line.

At each transect, the position was logged by GPS and the length of the transect was recorded.

3 sediment samples were taken down the transect line: at the mean high water mark, halfway

down the transect and at the mean low water mark.

Sediment was collected using a trowel which was cleaned after each sample, and the sample

was placed in a sterile sample bag, sealed and labelled. This was done to avoid the

contamination of the sample.

Figure 2:

Measuring a

transect line

on

Boscombe

beach

(Author,

2011).

9

Figure 3: Diagram showing an example beach with transect lines.

2.2 Data analysis

The samples were then analysed in a laboratory to establish the levels of microplastic present

within them. Firstly the samples were taken out of the sample bags and placed into trays and

if the samples were damp they were left to dry out. The samples were then coned and

quartered to ensure that a representative part of the sample was used in analysis.

A 250 gram portion of the coned and quartered sediment was then mixed in a beaker with

250 millimetres of super saline solution (distilled water with Sodium Chloride added to the

saturation point). This was 540 grams per 1.5 litres. The sample was mixed for 30 seconds

and then left to stand until the sediment had settled. The time varied between samples, muddy

sediments took several hours to settle whereas stony or sandy samples only took minutes.

Mixing with a super-saline solution would cause any plastic within the sample to float to the

surface as it has a lower density. Thompson et al (2004) suggested this method. His study

may have used a different technique for dissolving Sodium Chloride in water, as the same

levels of salinity (1.2kg NaCl l-1

) could not be achieved in this study. The level of salinity

suggested by Thompson isn’t possible, as the maximum saturation of Sodium Chloride in

water is 360 grams of Sodium Chloride per litre of water. Another explanation for this could

be a printing error.

Mean High Water

Mean Low Water Tran

sect

1

Tran

sect

2

Tran

sect

3

10

Once the sediment had settled, the top layer of water was extracted using a pipette. This was

then filtered using a funnel and Whatman GF/A filter paper. The rest of the water was then

also poured through the filter. The pipette was used so that any plastics floating on the

surface would be gathered. The filter paper was then placed in a dish, labelled and left to dry.

The remaining sediment was disposed of.

Once the sample had dried, it was examined under a microscope. This was done in a

systematic way so that the whole sample was viewed. Any objects that weren’t salt crystals,

sediment or organic matter were measured using a ruler and their characteristics, such as

colour and shape were recorded (see Figure 4). The potential sources in each area were

identified (see Table 2).

Figure 4: Microplastics

classification system (authors

2011).

11

Table 2: Potential sources of plastics each region

2.3 Retrieval rate experiment

This experiment aimed to determine if the type of sediment had an effect on the amount of

microplastic retrieved. This was of interest as it could have an effect on the overall results of

this investigation. Three types of sediment were used in this investigation: sand, shingle and

mud. These were chosen as they were the main types of sediment encountered over the

course of this investigation. Ten brightly coloured microplastic beads were placed in 250g of

each sediment, 250ml of super saline solution was added and the mixtures were stirred to

suspend the sediment in the solution. These were then left to settle out.

Once the sediment and solution had settled, the beads were visually identified and removed

from each test sample. If not all beads had been retrieved, the samples were re-suspended and

left to settle once again, and the process was repeated (see graph 1 and Appendix 3).

Source

Classification

Southampton Water Poole and

Christchurch Bay

Essex Norfolk

Natural Rivers, Itchen, Test and

Hamble, Beaulieu and

Lymington

River Stour, Avon and

Mude. Passford

Water

River Colne,

Chelmer,

Blackwater,

Crouch, Roach

River Great Ouse,

Breydon water,

Burn

Industrial Shipping activity:

Marchwood Military

port, Fawley Oil

terminal, Southampton

Port.

Industrial park, Scrap

yard, Fishing activity

Fishing activity, Felixstowe port,

Fishing activity

Fishing activity,

Kings Lynn port,

Bacton gas works,

Kings Lynn

Chemical works

Residential Sewage works @ St

Denys, Woolston,

Hamble Le Rice,

Marchwood, Hythe,

Eastleigh, Lower

Swanwick, Milbrook

Sewage works @

Bournemouth,

Ensbury (edge of

Bournemouth),

Lymington, East

Boldre,

Sewage works @

Colchester,

Maldon, Clacton

and Holland on

Sea, Fingringhoe,

Tollesbury, West

Mersea, Salcott,

Brightlingsea,

Great Wigborough

Sewage works @

Mundesley,

Hunstanton,

Caistor on Sea,

Corton, Great

Yarmouth, Cromer,

Heacham, Kings

Lynn

Infrastructure Debris off roads, Boat

yards, Marinas, Outfall

pipes

Debris off roads,

Holiday parks,

Marinas, Boat yards,

Outfall pipes

Debris off roads,

Boat yards, Outfall

pipes, Marinas

Tourists Debris off

roads Outfall pipes

12

Graph 1: Retrieval rate experiment

2.4 Limitations and problems

During sample collection, there were sometimes difficulties in defining where the beach

began and ended. This was especially found in Poole Bay. On Friars Cliff, for example, the

beach had many access points and stretched for a long distance; the transects were taken

down the beach at the access point and then 100 metres on either side.

Another problem found whilst sample collecting was the tide, although the method states that

a sample was collected at the mean low water mark, this was only true for a number of

beaches. This occurred especially on the North Norfolk beaches where the inter-tidal zone is

long and relatively flat. This caused the tide to come in quickly and so at each beach, the low

water sample was taken further up the transect. To try and counter this, the sampling started

an hour and a half before high water and finished around an hour and a half after.

In the first few laboratory sessions the levels of salt being dissolved was too much, due to

Thompson’s method. Once this was changed it worked better as an error meant it wasn’t

possible to dissolve that much salt in water.

0

10

20

30

40

50

60

70

80

90

Sand Shingle Mud

Re

trie

val r

ate

(%

)

Sediment type

Retrieval rate of microplastic beads from different types of sediment

Graph 1 shows that 80% of microplastic beads inserted into the sand

and shingle were retrieved, whereas only 40% of beads inserted into the

mud were retrieved.

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For the sample processing, the filtering method was changed during the investigation. At first

the filter paper was in a Coors Buchner funnel, but it was found that the filter paper would lift

and consequently water and micro-plastics were potentially flowing down the edges. This

was then changed to the filter paper being folded into a conventional conical funnel.

Another flaw in the method was that when pouring particularly silty sediments, the sediment

could end up on the filter paper and this then made it hard to distinguish any plastics through

the microscope.

2.5 Risk assessment

When collecting the samples there was always more than one person present and at least one

person had a mobile telephone. Due to the nature of the collecting, the tidal times were

known and the height of the water was observed. All of the collectors wore sensible footwear.

At Chessel bay, towards the low water mark there was thick mud. Here a platform was used

to stand on and on one transect; the final sample was collected a little way from the low water

mark due to the nature of the ‘beach’. In the laboratory, whilst working with the super-saline

solution, laboratory coats and safety glasses were worn.

14

0

5

10

15

20

25

30

35

Mic

rop

last

ic C

ou

nt

Estuary Location Type Open Sea beach

Graph showing the distribution of Microplastics along transect lines at sample sites

High Water

Mid Water

Low Water

3. Results

3.1 Graphs

Graph 2: Distribution of microplastics along transect lines at each site

Graph 2 - Graph showing the distribution of Microplastics along

transect lines at sample sites. Anomalies: Low water at Warsash

shows a significantly higher count of microplastics than other

sites, as does high water at Walton on the Naze. Due to tidal

restrictions, there is only data for high water at Milford.

15

639

17 22 52

0

100

200

300

400

500

600

700

Fibre Straight edged Rounded Irregular

Nu

mb

er

Microplastic type

Graph showing the total frequency of shapes of Microplastics across all sample

sites

Graph 3: Frequency of microplastics shapes

Graph 3 - Graph showing the total frequency of shapes of Microplastics

across all sample sites.

This shows the total number of microplastics found and their shape. The total

found was 730 pieces. As it’s clearly shown in the graph, fibrous plastics were

by far the most common making up 87.5% of all found. The next highest was

irregular pieces accounting for 7.1% of all plastic found. Appendix 2 shows the

raw data with the totals for each individual sample site.

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Graph 4: Box and Whisker plot

3.2 Statistical tests

The standard deviation results for the two areas:

Estuaries Beaches

Standard Deviation 6.93 6.17

Coefficient of

Variation 66.80% 47.80%

T-test

P = 0.027

The T Test demonstrates the validity of the hypothesis. If the probability (P), result is lower

than 0.05 then the hypothesis can be accepted. The hypothesis can be viewed on Page 7. The

P result shows that there were more Microplastics found on Open water beaches then those in

an estuarine setting. This result is however insignificant.

0

5

10

15

20

25

30

35

Estuaries Beaches

Nu

mb

er

of

Mic

rop

last

ics

Box and Whisker Diagram showing spread of data

q1

Min

Mean

Max

q3

17

4. Discussion

4.1 Levels of microplastic found

Microplastics can cause many problems in the marine environment and are a major source of

marine pollution (Murray and Cowie 2011). There are a number of sources of microplastics:

the breakdown of macroplastics already present in the environment, or from industrial and

domestic uses (Noren 2011). This investigation looked at microplastic levels within estuaries

and on beaches on the South Coast in comparison to the East Coast. Every beach sampled

had microplastic present. Out of 174 transect samples, 160 contained microplastics.

The shape classification data shows that irregular and straight edged pieces made up 9.4% of

the total plastic count. This type of microplastic is more likely to have stemmed from the

breakdown of macroplastics. The data shows that a greater percentage (10.7%) of this type of

microplastic was found in a beach setting in comparison to estuarine environments (6.3%)

(see graph 3). This could be due to wave action being more prominent on open beaches than

in estuaries, breaking down macroplastics at a greater rate.

Rounded microplastics made up 3% of the total plastic count. These are likely to have

resulted from the industrial use of plastic beads as stock for the production of plastic goods.

Other potential sources include facial scrubs and beauty products with plastic beads to

rejuvenate and revitalise (because you’re worth it). In estuaries, these microplastics made up

4.1% of the total plastic count, and 2.5% of the total plastic count on beaches. The levels may

be higher in an estuarine setting due to the higher frequency of sewage and water treatment

works in the locality (see Table 2 and appendix1 and 2). In studies by Thompson (2004) and

Browne et al (2011) these were relatively common after fibres.

Most of the plastic found in this study were of a fibrous nature (87.5%). Research has shown

that most fibrous microplastics result from domestic sources such as the breakdown of

polymers from clothes in washing machines. Macroplastics such as ropes, fishing lines and

nets can also breakdown into fibrous microplastics (Browne et al 2011). These are generally

polypropylene, nylon and polyester (Thompson 2004 and Browne et al 2011). On beaches,

fibres made up 86.6% of the total plastic count, and 93.8% in estuaries. This could be again

due to the sewage and water treatment works in the areas (see table 2), discharging water

from washing machines.

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4.2 Statistical tests

The Box and Whisker diagram (see Graph 4) shows how spread the data is away from the

mean. From this it can be seen that the range of plastic count for the two different regions is

not that different (Estuaries – 31, Beaches -29). However the boxes, which show 50% of the

data, are quite different. For the estuarine data, the box spans from 6 to 12 items found

whereas for the beach data it covers from 9 to 19. This difference means that for estuaries, the

data in more concentrated around the mean. This implies that for the samples collected in

locations on an estuary there is more consistency on the number of pieces of microplastics

found. However as the mean for open water beaches is higher, the total plastic found on each

beach is greater.

Standard Deviation demonstrates the distribution of the data around then mean. If the

standard deviation result is lower than the data is more closely grouped to the mean. The

results show that the estuarine beaches had a value of 6.93 and the open water beaches had a

value of 6.17. This result contradicts the results of the box and whisker test. However the

negative of using this test is that it doesn’t take the sample size into account. But this doesn’t

mean that the data/ statistical tests are wrong. A conclusion can be gathered from this: The

open water beaches had a greater number of plastics found on each site in comparison to

estuarine beaches. But, the amount of microplastics found on estuarine beaches was more

consistent. This could have several implications to the distribution of microplastic: More is

found in open water however its distribution is not consistent with more being found in some

locations compared to others. Within an estuarine environment, less is found but the amounts

are more consistent.

Explanations for this pattern could be explained by the sources of microplastics shown in

Table 2 (Page 11). This shows how many of the possible sources are situated in the estuarine

environment, such as the sewage works on the Itchen, a key source of microplastics

originating from washing machines etc. This would cause a greater concentration of

microplastics as seen in the standard deviation result. The reason there were averagely fewer

pieces found could be due to the retrieval rate as discussed in the next section.

Coefficient of Variation is similar to Standard Deviation but is not influenced by the sample

size and range; this makes it useful in this study. However the results in this case came to the

same conclusions as the standard deviation tests so nothing new can be interpreted.

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The final test used was the T Test; this measures how the means of two groups are

statistically different from each other. The result of the T Test gives a probability of

achieving the result. If this probability value is below 0.05 then it can be stated that there is a

significant difference between the two means. The result for the microplastic data was a

probability value of 0.027, this is below 0.05 therefore there is a significant difference

between the two means.

4.3 Retrieval rate experiment

The retrieval rate investigation has shown that there is a greater retrieval rate of microplastics

from sand and shingle than there is from mud (see graph 1 and appendix 3). This could be

due to the fact that sand and shingle are looser and therefore less dense, so sink back to the

bottom of the solution at a lesser rate than mud, allowing more time for the microplastics to

float to the top and be retrieved. In contrast to this, as mud is more dense than sand and

shingle, it would sink to the bottom of the solution faster, therefore trapping the microplastic

beads at the bottom and preventing them from rising to the top. This could have effects on

this experiment, as samples taken from areas of mud (such as Warsash) could actually have

had less than half of their actual microplastic content counted. The majority of estuarine

sediments collected were of a finer particle size, so could potentially have a lower retrieval

rate than the beach sediments.

4.4 Potential transport routes for microplastic to beaches - longshore drift

Microplastics could reach the beaches via Longshore drift with the sediment being deposited

on the beaches. This would indicate that plastic is also present in the water column. Studies in

a number of regions have shown this (Thompson et al 2005 and Browne et al 2011). The

sediment cells for each area show how the microplastic could reach the beach sediments. The

main sediment cell for Poole bay and the Solent has boundaries between Portland bill in the

west and Selsey Bill in the east. This is split into sub cells with their own sedimentary

budgets. On the East coast the sediment cell boundaries are from the River Humber to the

Thames, with sub cells around Clacton on Sea and the Norfolk Coast around Happisburgh

(see appendix 4) (Wallingford et al 2002 and Solent Forum 1996). In Poole and Christchurch

Bay there seems to be a gradual rise in sample one from Bournemouth to Milford on Sea.

This could be due to long shore drift taking sediment and plastics within it down the coast. It

is hard to see this trend properly as not a full data set is available for Milford on Sea. The

other beaches don’t seem to follow this trend. This could be due to the Norfolk and Essex

20

coast being less built up or that long shore drift has little effect on the movements of

microplastics. Even though this is hard to prove, it is clear that microplastics are being

brought to beaches via the sea and land based sources, so longshore drift will play some part

in where the microplastic is deposited. More investigation into this would help to determine if

this is the case (see Appendix 4).

4.5 Potential transport routes for microplastic to beaches - Tides

Tides have a similar effect to longshore drift moving water and sediment around the coast.

Their biggest influence is within the estuarine environment where they replenish the water

every six hours. This tidal action could also be used to transport microplastics. The estuaries

studied in this report: Southampton Water and the River Colne and Blackwater both have

strong tidal conditions with a mesotidal range in Southampton and a macrotidal range on the

Rivers Colne and Blackwater (Posey 2010 and Townsend 2008). In both cases the tidal

system is ebb dominated; this is when the out going tide has a higher velocity. In relation to

transportation of Microplastics, this tidal condition will cause plastic, which may have

sourced further up the estuary, to be taken seawards. This process could be used to explain

the larger number of plastic found at Warsash which was the furthest seaward sampling site

taken on Southampton Water.

4.6 Future changes to experiment and the future of microplastic

If this study were to be replicated in the future, improvements which could be made include

the use of cotton only clothing so that there is a smaller chance of sample contamination

when out in the field furthermore the use of laboratory coats when participating in the

experiment will again reduce the risk of contamination.

For a wider range of results, a larger sample area could be used. The study could have

extended to the Isle of Wight and the other side of Portsmouth. This would increase reliability

of the average and also create a larger view of microplastic distribution.

Different types of sample areas can be used which can then be compared to each other, for

example the use of sandy beaches compared to shingle beaches, or mud flats compared to salt

marshes.

21

The study can progress further by not just sampling sediment from beaches but from the

water column of the beaches and in rivers and estuaries. This would show if there is a

correlation between microplastic offshore and onshore.

Methods to stop microplastics getting into the environment need to be implemented. This can

be done through beach cleanup operations, better filtering methods of wastewater and finer

filters on washing machines. Fines could be given to persistent offenders.

22

5. Conclusions

This report investigated the levels of microplastics on Estuarine and Open water beaches

along the South and East Anglian coasts. Microplastics were present on every beach sampled

but there were discrepancies between Estuaries and Open water.

The results and subsequent statistical tests confirmed the hypothesis: That more plastics

would be found on Open water beaches in comparison to estuarine. Whilst the total

microplastics found on open water beaches was greater; the individual beaches had a greater

variance in amounts found in comparison to estuarine beaches. This was proven in the box

and whisker which showed that the results for estuarine beaches were grouped closer around

the mean.

Microplastics are a major source of pollution in the marine environment, the true extent of

their distribution is not fully understood. Further studies using similar methods are required to

help further understand the distribution of microplastics both in the UK and on a global scale.

Further studies are also required to investigate the environmental impacts of microplastics.

Due to the large level present plans need to be put in place to limit the levels of microplastics,

as preliminary studies have shown them to be harmful to the environment. This could be

improved through better filtering methods in wastewater treatment plants or better controls on

beach litter. These will help to control the levels of microplastic released into the marine

environment.

23

6. References

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environment: Marine Pollution Bulletin, v. 52, p. 761-767.

24

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2011

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25

Appendix 1 – Raw data showing total counts of microplastics for each site

Site

High

Water

Mid

Water

Low

water

Northam 12 12 10

Hythe 13 5 5

Warsash 5 10 32

Netley 19 6 12

East Mersea 6 8 6

Chessel Bay 6 7 1

Brightlingsea 16 7 20

Boscombe 2 11 6

Friar's Cliff 2 23 20

Bournemouth 6 22 11

Avon 9 13 15

Sea Palling 12 22 18

Caistor on Sea 22 15 21

East Runton 12 12 12

Mundesely 23 17 23

Old Hunstanton 17 7 11

Clacton on Sea 19 11 6

Frinton on Sea 18 9 8

Walton on the

Naze 31 8 9

Milford 16

26

Appendix 2 – Classified raw data

Site

Fibre Straight edged Rounded Irregular

Northam

34

Hythe

22 1

Warsash

45 2

Netley

36 1

East Mersea

14 3 6

Chessel Bay

7 1 3 3

Brightlingsea

39 1

Total: 197 3 9 11

Boscombe

15 1 1

Friar's Cliff

39 1 1

Bournemouth

35 2 2

Avon

37

Sea Palling

41 1 2

Caistor on Sea

57 1

East Runton

30 1 3 2

Mundesely

54 7

Old Hunstanton

26 4 1 2

Clacton on Sea

34 1 1

Walton on the Naze

28 2 18

Frinton on Sea

30 1 4

Milford

16

Total: 442 14 13 41

Total

Count 639 17 22 52

87.5% 2.3% 3.0% 7.1%

27

Appendix 3 – Retrieval rate experiment

Sediment type Retrieval rate (%)

Sand 80

Shingle 80

Mud 40

28

Appendix 4 - Sediment cells, to show possible transport routes of plastics to the

sediment

1A: Southampton Water

This shows the movement of sediment and tidal streams within the Solent. This shows how

plastic could be deposited in the sediments, within Southampton Water. Currents also come

into Southampton Water from the Solent, which could bring in more plastic. To the west of

the Isle of Wight tides and sediment flows out of the Solent, towards Poole Bay, contributing

more to this area (Solent Forum 1996).

1B: Poole Bay and Christchurch Bay

This shows the sediment moving

from Bournemouth along to

Hurst point. This is a sub cell

between Portland Bill and Selsey

Bill. It shows the regions plastic

could be transported from and

suggests a reason why levels

increase towards Milford on Sea.

The sediment moves along the

coast to Milford on Sea, meaning

more plastic should be present

(scopac 2011).

29

1C: Norfolk and Essex Coast

1D: Sub cell for Essex coast

This diagram of sediment transport shows sediment moves down the Essex coast towards the

Thames estuary, showing the movement around the sample areas (Anon 2010).

This shows the sediment

transport on the East coast, it

moves from Essex towards

Norfolk (Wallingford et al

2002). There are also sub

cells around Clacton and on

the Norfolk coast at

Happisburgh. This shows that

half of the sediment moves

towards the Thames while the

other half towards The Wash,

the divide is at Happisburgh.