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plastic and other artefacts on South African beaches: temporal trends in abundance and composition

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28. Walker R.S. (1988). Long-term dala series from South African Grasslands.
In Proc. Conference on Long-Term Data Series Relating to southern
Africa's Renewable Natural Resources, edit. I.A.W. Macdonald and R.J.M.
Crawford. South African National Scientific Programmes Report No. 157,
253 -267, Pretoria.
29. Weisser P.J., Backer A.P. and Van
EdenS.
(1988). Aerial photographs as a
long-term data source for vegetation studies.
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Proc.
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Long-Term Data Series Relating to southern Africa's Renewable Natural
Resources, edit. I.A.W. Macdonald and R.J.M. Crawford. South African
National Scientific Programmes Report No. 157. 253 -267. Pretoria.
30. Van Zyl J.H. and Viljoen M.F. (1986).
Die
sosio-ekonomiese gevolge van
waterbeperkings
op
besproeiingsboerderye, mynbou, elektrisiteitsvoor-
siening en die sentrale owerheid. Water Research Commission, Report No.
167/1/87,Pretoria.
31. Schlemmer L., Stewart G. and Whittles J. (1989). The socio-economic
effects
of
water restrictions
on
local authorities, selected industrial and
commercial establishments and other private agencies. Water Research
Commission, Report No. 168/I/89,Pretoria.
32. Van Zyl J., Van der Vyver A. and Groenewald J.A. (1987). The influence
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drought and general economic effects on agriculture: a macro-analysis.
Agrekon26,
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J.
and Nel H.J.G. (1988).
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drought for non-village populations
living in remote areas in the Sandveld. In Drought in Rural Botswana:
Socio-economic Impact
and
Governmental Policy, edit. H. Vierich and C.
Sheppard. Rural Sociology Unit, Ministry
of
Agriculture, Gaborone.
35. Vierich H. and Sheppard C. (1980). Drought in Rural Botswana: Socio-
economic Impact
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Government Policy. Rural Sociology Unit, Ministry
of
Agriculture, Gaborone.
36. Muller N.D. (1984). Aspects
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the
political economy
of
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drought on rural Tswana
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Plastic and other artefacts
African beaches: temporal
abundance and composition
on
South
trends
in
Plastic debris has rapidly become one
of
lhe most abundant
marine pollutants, wilh economic as well
as
ecological conse-
quences. Surveys
of
50 Soulh African beaches in 1984 and
again in 1989 show lhat lhe densities
of
all types of plastic
objects have increased significantly. The greatest increase has
been in packaging and other disposable items, lhe vast majority
of which are manufactured locally. Urgent steps are needed
now to stem lhe tide
of
plastic debris at sea off Soulh Africa.
Man-made articles enter the sea from ships and from a dif-
fuse array
of
land-based sources. Most artefacts found
at
sea
are comprised
of
plastics, a group
of
artificial polymers de-
. veloped during the last fifty years lhat are virtually immune
to
biodegradation. As a result
of
long lifespans, plastics lhat float
in sea-water disperse far from source areas, and are the most
abundant contarninents of oceanic surface waters. Off Soulh
Africa, the mean density
of
plastic is 3600 particles km-2,
intermediate between low densities typical of polar regions and
high densities typical
of
coastal waters abutting industrial
centres.1
Floating plastic objects and other artefacts have three main
impacts on the marine environment:
1))
they are ingested by
and entangle many marine animals;
2)
they increase the
amount
of
substratum available for epiphytic organisms; and
3)
when stranded, they reduce the aesthetic appeal and tourism
potential
of
beaches. These impacts can have serious ecological
South African Journal
of
Science
Vo/.86
July-
October 1990
and economic consequences, and recently have been the focus
of
international concem.2.3 It is often assumed that the density
of
plastic
at
sea
is
increasing, but
then~
are few actual measures
of temporal changes in lhe abundance and composition
of
arte-
facts. Such measures are needed to assess lhe dynamics of
marine debris and to determine lhe efficacy
of
measures intro-
duced
to
reduce lhe amount of marine debris. We present pre-
liminary measures
of
trends in plastic abundance off South
Africa, estimated from sampling bolh micro- and macro-plastic
particles stranded at a range
of
beaches over a five-year period.
Methods
Monitoring lhe density
of
artefacts
at
sea is time-consuming
and costly ,1 whereas marine debris stranded on beaches is
readily surveyed. Assuming that within-beach variation in
artefact density (both spatially and
on
a short temporal scale) is
not too great, beach surveys provide an effective method for
assessing temporal changes. We sampled artefacts
at
52 sandy
beaches in lhe Cape Province, Soulh Africa, between Saldanha
Bay and the Kei river mouth during the austral winters of 1984
and 1989. Sampling sites were selected from relatively uniform
areas in lhe centre
of
beaches, and similar sites were sampled
at
each beach during 1984 and 1989. Beaches were categorized
as
urban (within towns or at beach resorts; n = 27) or rural
(distant from large settlements or resorts; n = 25).
Sampling was performed
at
two levels: micro-artefacts
( < 20 mm diameter) were collected from a 0.5-m-wide tran-
sect running up the beach by sieving lhe top 50 mm
of
sand
through a 2-mm mesh sieve (n =
51
beaches); and macro-arte-
facts
(>
20 mm) were collected from 50-m stretches
of
beach
(n = 51) and were identified
as
far
as
possible
to
determine
their origin.
In
addition, pumice was collected along with
micro-artefacts in 1984.
Micro-plastics were grouped into three categories: virgin
industrial pellets that form the feedstock for the plastics
industry, expanded polystyrene, and fragments
of
plastic
articles (e.g. pieces
of
bottles and bags, rope fibres, etc.).
Macro-plastics were grouped into four categories: packaging
and other disposable items (e.g. bags, bottles, straps, etc.),
fishing equipment (nets, line, floats, etc.), non-disposable user
objects (shoes, gloves, etc.), and unidentified pieces.
Results
More than 40 000 artefacts were sampled during the two
surveys. Plastics comprised more than 90% of artefacts on
South African beaches, making up 88%
of
macro- and 98% of
micro-artefacts. Non-plastic macro-artefacts were, in
descending order
of
importance, made from wood, glass,
metal, paper, clolh and wax products. Most non-plastic micro-
artefacts were cigarette stubs.
There were consistent inter-beach differences in the
abundance
of
plastics, both between lhe various types of
plastics, and between lhe 1984 and 1989 surveys (Fig.
1)
.
Significant correlations between lhe numbers
of
pumice and
bolh microplastics (r, = 0.61; n = 51; P < 0.001) and macro-
plastics (r, = 0.34; n = 50; P < 0.05), suggest that inshore
currents ralher than local sources are responsible
for
most of
lhe inter-beach variation in plastic abundance, because pumice
on beaches derives from offshore sources and is dispersed by
lhe sea. However, the relatively weak correlation between
pumice and macro-plastics indicates lhat local sources play a
larger role in the distribution
of
macro-plastics compared
to
that
of
micro-plastics.
There were significant increases in lhe abundance
of
all
plastic types between 1984 and 1989 (Figs 2 and
3).
The mean
density
of
micro-plastic particles increased from 491 m-1 of
beach
in
1984 to 678 m-1 in 1989 (Fig.
2;
Wilcoxon paired-
Suid-Afrikaanse Tydskrifvir Wetenskap Vol. 86
Julie-
Oktober 1990
451
1000o.------------------,
a>
00
a>
~
Q)
1000
1l
100
:I
c
'Iii
10
0
1-
Micro-plastics
1+---~~~r-~~~~~-~~~~~
1
10
100
1000
Total numbers 1984
10000
a>
Macro-plastics
00
a>
1000 .
~
. .
..
Q)
.
. . .
..
..
.c
.,
~
E 100 .
.
.
.
:I
•...
.
c
..
<U
10 . .
0
1-
1 1
10
100
1000
10000
Total numbers 1984
Fig.
1.
Correlations between counts of plastics on beaches in
1984 and 1989, showing consistent inter-beach differences in
the density of both micro- and macro-plastics.
sample test; T = 262.5; n = 51; P < 0.001). Most micro-
plastics were virgin industrial pellets, which were proportion-
ately less abundant in 1989 (68%) than in 1984 (80%),
although there was a significant increase in absolute abundance
between 1984 and 1989 (mean density up by 17%; T = 368;
n = 51; P < 0.01). The increase in the abundance
of
other
micro-plastics was much greater, with a 54% increase in
expanded polystyreny (T = 244; n = 42; P < 0.01) and a
145% increase in fragments
of
other user items (T = 127; n =
51; p < 0.001).
The density
of
macroplastic objects increased from an
average
of
1.09 m-1
of
beach in 1984 to 2.99
m-
1 in 1989 (Fig.
3;
T = 57.5; n = 51; P < 0.001). Packaging and other dispos-
able products accounted for 69%
of
identifiable macro-plastics
in 1989 (up from 65% in 1984), with an absolute increase
in
abundance
of
175% (T = 61; n = 51; P < 0.001). Fishing
equipment, which comprised most of the remaining macro-
plastic objects, also increased in abundance between 1984 and
1989 (mean density up
by
117%; T =
166;
n = 49; P <
0.001), but to a lesser extent than packaging and disposable
items.
The country
of
origin could be determined for 1300 (17%)
macro-plastic objects sampled in 1989; 96% were produced in
South Africa. The proportion
of
locally produced articles was
significantly greater
on
urban (98%) than on rural beaches
(92%; x2 = 25.10; d.f. =
1;
p < 0.001). The density
of
pack-
aging and disposable items was 65% greater
on
urban than on
rural beaches, and the proportion
of
packaging was larger on
urban (71%) than
on
rural beaches (50%; Mann-Whitney
U25,
26
= 433; Z = 2.03; P < 0.05 for 1989 data).
Discussion
The results demonstrate that the abundance of plastic objects
on South African beaches has increased between 1984 and
1989.
It
is not immediately clear whether this result reflects an
increase in the amount
of
plastic entering the sea over the last
five years,
or
that the long life-spans
of
plastic articles in the
environment has lead to a greater accumulated amount
of
plastics on beaches. For some relatively short-lived objects
such
as
bags and wrappers, the marked increase in abundance
.r::
500
0
m
Q)
.c
0 400
~
Qi
300
E
Q;
~
200
Q)
.c
E
::J 100
<::
<::
m
Q) 0
:2 Pellets Pieces
0 1984
1:3
1989
Polystyrene
Fig.
2.
Changes in the mean abundance of
three
categories of
micro-plastic particles
on
South Mrican beaches between
1984
and 1989.
and the preponderance
of
recently introduced packaging
designs suggests that there has been a large increase in the
sources
of
plastic pollution. However, for long-lived objects
such as virgin industrial pellets, which showed the smallest
absolute increase in abundance, there may actually have been a
decrease in the amount entering the sea. More information is
needed on the life-spans
of
various types
of
plastics (at sea,
and exposed and buried on beaches) and on beach-sea inter-
change
of
plastics before the dynamics
of
plastic populations
on beaches can be resolved.
However, given the strong marine influence on the distribu-
tion of plastics on beaches, it is safe
to
assume that the
increase in beach pollution reflects an increase in the density
of
plastic
at
sea off South Africa. There is evidence from a wide
range of organisms that plastic debris has a deleterious effect
on the marine environment off South Africa,4 where among the
greatest frequencies
of
plastic ingestion
by
seabirds have been
recorded.5 Because the impact of plastic pollution is a function
of
its density at sea, concerted action is necessary
to
halt the
uncontrolled disposal
of
plastic products.
Much plastic debris is dumped from ships, but international
legislation (Annex V
of
the International Convention for the
Prevention
of
Pollution from Ships, to which South Africa has
agreed
to
accede) recently has outlawed the dumping of plas-
tics at sea for more than half the world's shipping.6 This mea-
sure, coupled with the positive attitude expressed
by
the major
merchant fleets, should greatly reduce pollution from ships.
More difficult to control is litter from the flotilla
of
pleasure
craft and small fishing boats that operate around the South
African coast. Dumping from these vessels also is banned
under the new legislation, but enforcement is all but impossi-
ble. Education
of
small boat users
is
essential
to
stop this
littering.
However, a large proportion
of
plastic pollution also derives
from local, land-based sources: hence the predominance of
0 1984
121
1989
Fig.
3.
Changes in the mean abundance of four categories of
macro-plastic particles
on
South African beaches between
1984
and 1989.
452
South Afri.can
manuf~ctured
products and the differences
between the composition
of
litter on urban and rural beaches.
Education
of
the public is needed to change complacent atti-
tudes towards littering, but current concerns about the efficacy
of education campaigns7 also necessitate a reduction in the
amount
of
plastic being used in disposable applications.8 Con-
sequently, a multifaceted approach incorporating education,
product substitution, retycling and legislation is required to
reduce the flow
of
plastics and other persistent synthetic
objects into the marine environment.
We thank the Plastics Federation of South Africa for sponsoring the
1989 survey. Support for the 1984 survey was received from CSIR,
the
South African National Committee for Oceanographic Research
and the South African Scientific Committee for Antarctic Research.
Access to the Overberg Testing Range is gratefully acknowledged.
P.G. RYAN and C.L. MOLONEY
FitzPatricklnstitute and Marine Biology
Research Institute, Univ1rsity
of
Cape Town,
Rondebosch, 7700 Soutli Africa.
I
l.
Ryan P.G. (1988). The characteristics and distribution
of
plastic particles at
the sea-surface off the southwestern Cape province, South Africa Mar.
Environ. Res. 25,
249-
273.
2.
Shomura R.S. and Yoshida H.O. (Eds) (1985). Proceedings
of
the
Workshop on the Fate and Impact
of
Marine Debris. U.S. Dept Commerce,
NOAA Tech. Memo., NMFS 54, 1 - 580.
3.
Wolfe D.A. (Ed.) (1987). Plastics
in
the sea. Mar. Polful. Bull. 18, 303 -
365.
4.
Ryan P.G. (in press). The marine debris problem 'off southern Africa: types
of
debris, their environmental effects, and control measures. Proceedings
of
the Second International Conference on Marine Debris, Honolulu, April
1989, ediL R.S. Shomura and M.L. Godfrey. U.S. Department
of
Commerce.
5. Ryan P.G. (1987). The incidence and characteristics
of
plastic particles
ingested by seabirds. Mar. Environ. Res. 23,
175-206.
6.
Paul
L.
(in press). Legal strategies for discouraging the dumping
of
plastics
into the marine environmenL Proceedings
of
the Second
111/ernational
Conference on Marine Debris, Honolulu, April 1989, edit.
RS.
Shomura
and M.L. Godfrey. U.S. Department
of
Commerce.
7.
Laska S. (in press). Designing effective educational campaigns: the
attitudinal basis
of
littering. Proceedi'ngs
of
the Second /11/ernationa/
Conference
on
Marine Debris, Honolulu, April 1989, edit. R.S. Shomura
and M.L. Godfrey. U.S. Department
of
Commerce.
8.
Wirka J. (1988). Wrapped in plastic.•: the environmental case for reducing
plastics packaging. Environmental Action Foundation, Washinglon,D.C.
Environmental shifts
in
the last
20 000 years: isotopic evidence from
Equus Cave
13
C/
2C ratio analysis
of
grazing bovids provides a means for
determining shifts in the distribution
of
c3
and
c4
grasses in
the
past
Since the distribution
of
these grasses is essentially
constrained by temperatures during the growing season
(~
grasses favour cool growing seasons, C4 grasses warm1
),
depending on the locality, the distribution would change
if
the
·season
of
rainfall were to change. Thus predictions
of
major
shifts in summer and winter rainfall zones in southern Africa
during the last 25 000 years,2 based on a recent model for the
present climate,3 may be tested.
In
this preliminary study
of
grazers from Equus Cave in the northern Cape, enamel apatite
is used as an alternative sample material45 to the usual bone
collagen, which is poorly preserved at the site. The results
show that there were periods in the last 20 000 years with
relatively higher proportions
of
c3
grasses than
at
present, but
c4
grasses always dominated. Therefore, the data do not
support a complete change to winter
rainf~ll
in this area.
Recently, models developed for the contemporary South
African
climatJ
have been extended to provide explanations
for climatic shifts in the late Quaternary? The model predicts a
SouJhAfricanJournal
of
Science Vol.86
July-
October 1990
substantial northeasterly shift
of
the winter rainfall belt into the
Transvaal between 25 000 and
15
000 years ago, with the ex-
ception
of
the period 20-18 000 BP.2 (The Last Glacial
Maximum is generally held to have ·been about
18
000 BP.6)
This prediction may be tested by stable carbon isotope analysis
of grazers from suitable archaeological sites, according
to
the
following rationale. The present distribution
of
grasses
following the
~
and
~
photosynthetic pathways is sharply
patterned in South Africa; in general, the latter predominate in
the summer rainfall zone, while the former predominate in the
winter rainfall (southwestern Cape) and high Drak:ensberg
regions.1 This pattern has been ascribed to temperature
constraints during the growing season - C4 grasses are
favoured where daily maximum temperatures in the rainy
season remain above 25°C, and minimum temperatures above
8°C.
1 These constraints are met in most
of
the summer rainfall
zones. Below a mean daily maximum of 25°C in the growth
season,
~
grasses become more successful (i.e. winter rainfall
zones and cool high altitude areas).
In
the uniform rainfall belt
between the summer and winter rainfall zones, the distribution
of
the two types seems to be related to microclimatic
conditions.1
Major shifts in the rainfall belts, such as those predicted
for
the last 25
()()()
years,2 would also affect the distribution
of
c3
and
C4 grasses. Since the
13
C;t2C ratios
of
the two groups are
distinct, and herbivore tissues reflect the isotopic ratios of the
plants eaten,57-9
13
C/
2C ratios from bones or teeth of grazers
from archaeological sites will reveal shifts in the proportion of
c3
and
c4
grasses in the area.
In
practice, over most of the
country, this also reflects whether rain falls predominantly in
the winter or summer, subject to the important constraint that
temperatures do not fall below 25°C in the growing season in
the summer rainfall zone.
To date,
the
only study using these principles to address
palaeoenvironmental questions in southern Africa used a
limited number
of
grazer collagen specimens from a site in
Lesotho (Melik:ane Cave) and in Namibia (Apollo 11).10 Re-
sults for the latter site led
to
the conclusion that the winter
rainfall zone had not extended much further than its present
range; and for the former site, that there had been an expansion
of
high altitude
c3
grasses due to a decrease in temperature
during the Last Glacial period.10
In
this study, predictions from the climatic
modd
pertaining
to
approximately the last
20
000 years are compared with
13
CPC
results obtained from a stratigraphic sequence of
grazers from Equus Cave. The cave is situated on the Ghaap
escarpment near Taung in the northern Cape. The site, exca-
vated in 1978 and 1982,
11
was a prehistoric brown hyena den,
rather than a human occupation site.
12
It yielded one of the
largest Pleistocene faunal assemblages in the world,
12
as
well
as
brown hyena (Hyena brunnea) coprolites, which have been
used to establish a palynological sequence,
13
and a few human
fragments.14 Dating has been a problem owing to lack of
suitable material. Three radiocarbon dates are available: 2390
±
55
BP (Pta-2452), 7480 ± 80 BP (Pta-2495) from layer
1A,
and 16300 ± 160
BP
(Pta-4409) from the top of layer
2B
(Fig.
1);
the site may thus be considered to span about 20 000 years.
At present, the climate is semi-arid, less than
5%
of
rain
falls in
wintet
5 and grass cover is almost entirely C41
According to the climate model.Z this area would have fallen
within the expanded winter rainfall belt during the period
15-17 000 BP. Some palaeoclimatic data have been obtained.
Faunal analysi;2 suggests that conditions were grassier, cooler
and perhaps moister in the periods
of
layers
lB,
2A and 2B.
The pollen sequence
13
indicates that temperatures were not
more than
~oc
lower during the coolest part
of
the late
Pleistocene, although a 5-6°C lowering
of
temperature has
... (a) Standing-stock surveys Standing-stock surveys can show gross changes in the abundance and distribution of plastic litter (e.g. Ryan & Moloney 1990; Willoughby et al. 1997; figure 2), but there are significant problems with the interpretation of results. The amount of litter on a beach is determined by several factors in addition to the abundance of litter in adjacent coastal waters. ...
... Patterns of beach use tend to increase with growing human populations, coastal development and improved access. For example, many beaches categorized as 'rural' with little human influence in an initial survey of 50 South African beaches in 1984 (Ryan & Moloney 1990) have become resort beaches over the following two decades. There has been a concomitant increase in formal beach-cleaning efforts over this period (Ryan & Swanepoel 1996). ...
... Comparisons of standing stocks have shown marked increases in some litter types (e.g. Ryan & Moloney 1990; Willoughby et al. 1997; figure 2), but this may reflect long-term accumulation rather than absolute increases in the amount of debris at sea. Accumulation studies are preferred because they demonstrate unambiguous trends in macro-debris abundance at sea (Ribic et al. 1992, 1997). ...
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Chapter
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Microplastics are classified as emerging pollutants of the aquatic environment, necessitating a comprehensive understanding of their properties for successful management and treatment. Wastewater treatment plants (WWTPs) serve as point sources of microplastic pollution of the aquatic and terrestrial (eco)systems. The first part of this review explores the basic definitions of microplastics, sources, types, physical and chemical methods of identifying and characterizing microplastics in WWTPs. The next part of the review details the occurrence of microplastics in various unit processes of WWTPs and sewage sludge. Followed by this, various methods for removing microplastics from wastewater are presented. Finally, the research gaps in this area were identified, and suggestions for future perspectives were provided. HIGHLIGHTS Wastewater treatment plants act as point sources of microplastic pollution.; Microplastics in wastewater treatment plants are diverse in composition, size, shape and origin.; Microplastics are seen in all unit processes of wastewater treatment plants.; Wastewater treatment plants remove bulk of microplastics entering them.; Majority of microplastics enter the environment from sludge generated in wastewater treatment plants.;
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