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B. Yan et al.
of phytoplankton, change the structure of the phytoplankton community, thereby
reducing the intensity of photosynthesis, and ultimately disrupting the ocean carbon
cycles [78, 80].
In fact, microplastics affect not only phytoplankton but also zooplankton. As the
first and foremost important consumer of phytoplankton, zooplankton plays a vital
role in the regeneration of marine nutrients, the recycling of biological elements,
the transfer of energy, and the transmission of genetic information through the food
web. The organic carbon in the ocean can be consumed by zooplankton, which would
indirectly influence the remineralization of organic carbon and the ocean-atmosphere
carbon dioxide cycle.
Microplastics in the ocean can affect zooplankton and balance the ocean’s carbon
cycle. Phytoplankton has a certain carbon sequestration ability, but the exposure of
microplastics will lead to a reduction in the carbon sequestration ability of phytoplankton and a decrease in the feeding ability of zooplankton. Cole et al. [98] have
shown that the microplastics would not only increase the mortality of zooplankton
(copepods), but also cause zooplankton to feel full, thereby reducing absorption and
consumption of carbon [98]. Over time, the organic carbon consumed by zooplankton
may decrease dramatically as the concentration of microplastics increases.
The ubiquitous distribution of microplastics in the ocean has been demonstrated
clearly and may influence the ecological balance in the marine food chain/net,
thereby interfering with the sea-air exchange and organic carbon processes [97].
The microbial carbon dioxide pump and the micro-biological carbon pump are the
main methods for the marine sequestration of carbon dioxide. The former refers to
the process of transferring carbon elements from the surface of the ocean to the deep
layer in the marine ecological environment, which is driven by biology or biological
behavior. Phytoplankton converts inorganic carbon into particulate organic carbon
through photosynthesis, self-deposition, and feeding by zooplankton, and finally
transfers it to the area of the deep sea. The latter is used by microorganisms to
convert active dissolved organic carbon into refractory organic carbon to increase its
residence time in the ocean [97].
The zooplankton converts the ingested phytoplankton into feces, through which
microplastics are transported to the deep ocean, where the microplastic-containing
feces eventually end up in seafloor sediments. However, some studies had pointed
out that when microplastics are contained in fecal particles, the sinking rate of fecal
particles will slow down and be more prone to rupture, which is not conducive to
the deposition to the floor of the deep sea. And this shall reduce the ability of carbon
sequestration of the ocean and damage the carbon cycle balance of the ocean.
The existing studies had shown that the presence of microplastics can seriously
impact the carbon sequestration capacity of the ocean. As the number of microplastics
entering the marine environment increases, its impact on the marine carbon cycle will
accelerate as well. Therefore, it is urgently needed to study the effects of microplastics
on the marine carbon cycle and to further investigate the potential mechanisms and
the scale of such effects.
B. Yan et al.
of phytoplankton, change the structure of the phytoplankton community, thereby
reducing the intensity of photosynthesis, and ultimately disrupting the ocean carbon
cycles [78, 80].
In fact, microplastics affect not only phytoplankton but also zooplankton. As the
first and foremost important consumer of phytoplankton, zooplankton plays a vital
role in the regeneration of marine nutrients, the recycling of biological elements,
the transfer of energy, and the transmission of genetic information through the food
web. The organic carbon in the ocean can be consumed by zooplankton, which would
indirectly influence the remineralization of organic carbon and the ocean-atmosphere
carbon dioxide cycle.
Microplastics in the ocean can affect zooplankton and balance the ocean’s carbon
cycle. Phytoplankton has a certain carbon sequestration ability, but the exposure of
microplastics will lead to a reduction in the carbon sequestration ability of phytoplankton and a decrease in the feeding ability of zooplankton. Cole et al. [98] have
shown that the microplastics would not only increase the mortality of zooplankton
(copepods), but also cause zooplankton to feel full, thereby reducing absorption and
consumption of carbon [98]. Over time, the organic carbon consumed by zooplankton
may decrease dramatically as the concentration of microplastics increases.
The ubiquitous distribution of microplastics in the ocean has been demonstrated
clearly and may influence the ecological balance in the marine food chain/net,
thereby interfering with the sea-air exchange and organic carbon processes [97].
The microbial carbon dioxide pump and the micro-biological carbon pump are the
main methods for the marine sequestration of carbon dioxide. The former refers to
the process of transferring carbon elements from the surface of the ocean to the deep
layer in the marine ecological environment, which is driven by biology or biological
behavior. Phytoplankton converts inorganic carbon into particulate organic carbon
through photosynthesis, self-deposition, and feeding by zooplankton, and finally
transfers it to the area of the deep sea. The latter is used by microorganisms to
convert active dissolved organic carbon into refractory organic carbon to increase its
residence time in the ocean [97].
The zooplankton converts the ingested phytoplankton into feces, through which
microplastics are transported to the deep ocean, where the microplastic-containing
feces eventually end up in seafloor sediments. However, some studies had pointed
out that when microplastics are contained in fecal particles, the sinking rate of fecal
particles will slow down and be more prone to rupture, which is not conducive to
the deposition to the floor of the deep sea. And this shall reduce the ability of carbon
sequestration of the ocean and damage the carbon cycle balance of the ocean.
The existing studies had shown that the presence of microplastics can seriously
impact the carbon sequestration capacity of the ocean. As the number of microplastics
entering the marine environment increases, its impact on the marine carbon cycle will
accelerate as well. Therefore, it is urgently needed to study the effects of microplastics
on the marine carbon cycle and to further investigate the potential mechanisms and
the scale of such effects.