138
of oceans and freshwater has different consequences; therefore, they are discussed separately.
Oceans can be regarded the “reservoirs” of
pollution as almost all rivers (except for endorheic
areas) transport pollution into them while settlements and factories onshore also emit a huge
amount of municipal and industrial pollution
directly into seawater. Nearshore agricultural
areas are diffusive pollution sources from where
fertilisers and pesticides are washed into the seas.
There are a number of anthropogenic pollution
sources on the oceans as well: derricks, ships
with their engines and partly with the material
transported or with the litter from their passengers. The two most frequent pollution material
groups are plastics and crude oil or its refined
derivatives (lubricant, diesel, petrol).
Pollution in the oceans—based on their
sources—shows the following distribution
(Potters 2013)
• runoff and discharges from land 44%,
• airborne emissions from land 33%,
• shipping and accidental spills 12%,
• ocean dumping (garbage and sewage) 10%,
• offshore mining, oil and gas drilling 1%.
Most pollution comes from municipal and
industrial sewage, however, agricultural pollution
is also significant. These contain large amounts
of nitrogen and phosphorus causing eutrophication or even algal blooms in extreme cases in
nearshore water. Fertiliser pollution has been
released into the oceans from all land sources in
the last decades and has become the most urgent
issue related to oceans.
Scientists become increasingly aware of plastic pollution in seas and oceans (Eriksen et al.
2013, 2014; van Sebille et al. 2015; Gubek 2016a,
b; Lebreton et al. 2017; Royer 2018). Severity of
the problem is indicated by that the UN declared
plastic pollution of the hydrosphere a global
environmental problem in 2011. According to
certain estimations, the mass of plastic waste
(bottles, packaging material, fishing equipment,
used toys, sport devices, etc.) occurring in seas
and oceans increased to a hundredfold from the
1970s to the 2010s. In 2017 their total mass was
estimated to be 100 million tonnes and this
amount increases by 5–6 million tonnes each
year. Plastic pollution of land origin is transported mostly by rivers since settlements and
industrial factories along their shores release
plastics. According to Lebreton et al. (2017)
around 1.15–2.41 million tonnes of plastics are
transported by rivers into the ocean and two
thirds of this are transported by rivers in Asia.
(The authors draw attention to the fact that the
above estimation seems to be small compared to
the global 6 million tonnes if rivers are the main
plastic transporters.) Plastics are released in
abundance into the ocean apart from rivers by
nearshore settlements, their waste depositories,
ships and offshore drilling rigs.
Information on enormous “floating plastic
islands” composed of waste accumulated by oceanic currents (Fig. 4.49) is widespread. The term
can be misleading as most “islands” cannot be
seen easily but they do exist. Plastic waste entering the ocean is transformed both physically and
chemically. It is fragmented by physical effects
and additives used in the course of production
could be released like stabilisers, softeners, flame
retardants thus it is transformed chemically as
well. Micro-sized fragments can bound pollutants
present in the water on their surface. Such pollutants are frequently toxic like pesticides, dioxins
from industrial activities, polychlorinated biphenyls (PBC), etc.
Figure 4.49d shows that large plastic fragments give most of the total mass of “plastic
islands”. Although the amount fragments smaller
than 1 mm in “plastic islands” is great (almost 1
million fragments/km
2
) their total mass is significantly less than that of large fragments.
Many material are used by humans that originally contain microplastics in large quantity.
These include, for example, hand cleaners, toothpastes, face washers and other cosmetics that
contain polyethylene (PE), polypropylene (PP)
and polystyrene (PS) granules with the size of
10–100 μm. Most of them are released into the
sewage system and finally into the sea either
directly or via rivers.
Synthetic textiles are also widely used.
Experiments proved that more than 1900 microfi4 Changes on Earth as a Result of Interaction Between the Society and Nature
of oceans and freshwater has different consequences; therefore, they are discussed separately.
Oceans can be regarded the “reservoirs” of
pollution as almost all rivers (except for endorheic
areas) transport pollution into them while settlements and factories onshore also emit a huge
amount of municipal and industrial pollution
directly into seawater. Nearshore agricultural
areas are diffusive pollution sources from where
fertilisers and pesticides are washed into the seas.
There are a number of anthropogenic pollution
sources on the oceans as well: derricks, ships
with their engines and partly with the material
transported or with the litter from their passengers. The two most frequent pollution material
groups are plastics and crude oil or its refined
derivatives (lubricant, diesel, petrol).
Pollution in the oceans—based on their
sources—shows the following distribution
(Potters 2013)
• runoff and discharges from land 44%,
• airborne emissions from land 33%,
• shipping and accidental spills 12%,
• ocean dumping (garbage and sewage) 10%,
• offshore mining, oil and gas drilling 1%.
Most pollution comes from municipal and
industrial sewage, however, agricultural pollution
is also significant. These contain large amounts
of nitrogen and phosphorus causing eutrophication or even algal blooms in extreme cases in
nearshore water. Fertiliser pollution has been
released into the oceans from all land sources in
the last decades and has become the most urgent
issue related to oceans.
Scientists become increasingly aware of plastic pollution in seas and oceans (Eriksen et al.
2013, 2014; van Sebille et al. 2015; Gubek 2016a,
b; Lebreton et al. 2017; Royer 2018). Severity of
the problem is indicated by that the UN declared
plastic pollution of the hydrosphere a global
environmental problem in 2011. According to
certain estimations, the mass of plastic waste
(bottles, packaging material, fishing equipment,
used toys, sport devices, etc.) occurring in seas
and oceans increased to a hundredfold from the
1970s to the 2010s. In 2017 their total mass was
estimated to be 100 million tonnes and this
amount increases by 5–6 million tonnes each
year. Plastic pollution of land origin is transported mostly by rivers since settlements and
industrial factories along their shores release
plastics. According to Lebreton et al. (2017)
around 1.15–2.41 million tonnes of plastics are
transported by rivers into the ocean and two
thirds of this are transported by rivers in Asia.
(The authors draw attention to the fact that the
above estimation seems to be small compared to
the global 6 million tonnes if rivers are the main
plastic transporters.) Plastics are released in
abundance into the ocean apart from rivers by
nearshore settlements, their waste depositories,
ships and offshore drilling rigs.
Information on enormous “floating plastic
islands” composed of waste accumulated by oceanic currents (Fig. 4.49) is widespread. The term
can be misleading as most “islands” cannot be
seen easily but they do exist. Plastic waste entering the ocean is transformed both physically and
chemically. It is fragmented by physical effects
and additives used in the course of production
could be released like stabilisers, softeners, flame
retardants thus it is transformed chemically as
well. Micro-sized fragments can bound pollutants
present in the water on their surface. Such pollutants are frequently toxic like pesticides, dioxins
from industrial activities, polychlorinated biphenyls (PBC), etc.
Figure 4.49d shows that large plastic fragments give most of the total mass of “plastic
islands”. Although the amount fragments smaller
than 1 mm in “plastic islands” is great (almost 1
million fragments/km
2
) their total mass is significantly less than that of large fragments.
Many material are used by humans that originally contain microplastics in large quantity.
These include, for example, hand cleaners, toothpastes, face washers and other cosmetics that
contain polyethylene (PE), polypropylene (PP)
and polystyrene (PS) granules with the size of
10–100 μm. Most of them are released into the
sewage system and finally into the sea either
directly or via rivers.
Synthetic textiles are also widely used.
Experiments proved that more than 1900 microfi4 Changes on Earth as a Result of Interaction Between the Society and Nature