Microplastic Pollution in Marine Environment: Occurrence, Fate …
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community composition than other natural substrates [94]. Moreover, the microbial colonization of plastics can also be considered as biofouling. The formation of
biofouling may lead to changes in the buoyancy density of the polymer and promote
the migration of microplastics from the ocean surface to deeper water columns and
sediments [95].
Microplastics are sometimes used not only as a carbon source, but also absorbing
organic particles from the ambient environment to provide a carbon source for
microorganisms with carbon metabolism functions [8]. According to relevant reports,
many bacterial strains have the ability to degrade microplastics. It was reported that
during their degradation process, microplastics can produce toxic substances, such
as phthalates, which can be toxic to microorganisms [78]. Generally, in the process
of biodegradation of microplastics, the first and foremost important step is the attachment and colonization of the microorganisms on the microplastics, followed by the
formation and utilization of microplastics as a carbon source for growth (Nava and
Leoni).
In the sedimentary environment, the influences of different microplastics on
microbial diversity are greatly diverse. The study shows that the microbial diversity is rich under the treatment of polylactic acid microplastics in the coastal salt
marsh sediment environment, while the microbial community diversity is significantly reduced in the presence of PE microplastics under the same environment [96].
Thus, further study is needed to explore the influence of microplastics on specific
functions of microorganisms, as well as the mechanisms involved.
4 Effects on Biogeochemical Carbon and Nitrogen Cycles
4.1 Effect of Microplastics on Carbon Cycles
The ocean is the world’s largest repository of activated carbon and plays a vital role
in global climate change. However, the release of large amounts of plastic particles
will not only damage the marine ecology, but also affect the carbon cycle system of
the marine environment.
Phytoplankton and zooplankton are the major producers and consumers in the
marine environment. And previous researches have evidenced that microplastics
could affect phytoplankton and zooplankton in various ways, which would ultimately
influence the marine carbon stocks. As is known to all, the ocean is an important
gathering place of CO 2 , and carbon sequestration in the ocean has a significant effect
in reducing global warming and the greenhouse effect. The global carbon cycle will
also undergo great fluctuations when the ocean’s ability to absorb carbon dioxide
is affected [97]. The primary productivity of marine accounts for about 80% of the
planet’s total oxygen production. The organic matter and O 2 can be produced by
phytoplankton using CO 2 for photosynthesis. They are the main producers in the
marine ecosystem. Some studies indicated that microplastics will inhibit the growth
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community composition than other natural substrates [94]. Moreover, the microbial colonization of plastics can also be considered as biofouling. The formation of
biofouling may lead to changes in the buoyancy density of the polymer and promote
the migration of microplastics from the ocean surface to deeper water columns and
sediments [95].
Microplastics are sometimes used not only as a carbon source, but also absorbing
organic particles from the ambient environment to provide a carbon source for
microorganisms with carbon metabolism functions [8]. According to relevant reports,
many bacterial strains have the ability to degrade microplastics. It was reported that
during their degradation process, microplastics can produce toxic substances, such
as phthalates, which can be toxic to microorganisms [78]. Generally, in the process
of biodegradation of microplastics, the first and foremost important step is the attachment and colonization of the microorganisms on the microplastics, followed by the
formation and utilization of microplastics as a carbon source for growth (Nava and
Leoni).
In the sedimentary environment, the influences of different microplastics on
microbial diversity are greatly diverse. The study shows that the microbial diversity is rich under the treatment of polylactic acid microplastics in the coastal salt
marsh sediment environment, while the microbial community diversity is significantly reduced in the presence of PE microplastics under the same environment [96].
Thus, further study is needed to explore the influence of microplastics on specific
functions of microorganisms, as well as the mechanisms involved.
4 Effects on Biogeochemical Carbon and Nitrogen Cycles
4.1 Effect of Microplastics on Carbon Cycles
The ocean is the world’s largest repository of activated carbon and plays a vital role
in global climate change. However, the release of large amounts of plastic particles
will not only damage the marine ecology, but also affect the carbon cycle system of
the marine environment.
Phytoplankton and zooplankton are the major producers and consumers in the
marine environment. And previous researches have evidenced that microplastics
could affect phytoplankton and zooplankton in various ways, which would ultimately
influence the marine carbon stocks. As is known to all, the ocean is an important
gathering place of CO 2 , and carbon sequestration in the ocean has a significant effect
in reducing global warming and the greenhouse effect. The global carbon cycle will
also undergo great fluctuations when the ocean’s ability to absorb carbon dioxide
is affected [97]. The primary productivity of marine accounts for about 80% of the
planet’s total oxygen production. The organic matter and O 2 can be produced by
phytoplankton using CO 2 for photosynthesis. They are the main producers in the
marine ecosystem. Some studies indicated that microplastics will inhibit the growth