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Polar Macroalgae
Published in Donat-P. Häder, Kunshan Gao, Aquatic Ecosystems in a Changing Climate, 2018
The CO2 concentration in the atmosphere has been rising from about 280 ppm before the Industrial revolution (Thomas et al. 2016) to the current level of about 400 ppm (Franks et al. 2013). Currently our atmosphere holds about 735 Gt carbon (not carbon dioxide). Each year about 7 Gt is released from fossil fuel burning and another 2 Gt from changed land usage, such as tropical deforestation. Both the terrestrial vegetation and the oceans take up about 50 Gt carbon each annually by photosynthetic activity, but this amount is released again to the atmosphere when the vegetation decays. However, a significant fraction of the anthropogenically released carbon is taken up by natural sinks. In the oceans decaying phytoplankton as well as organic material excreted by predators falls to the deep sea ocean; the sediments hold the largest amount of carbon (about 36,000 Gt compared to an estimated 7,500 Gt bound in fossil fuel). About 72% of the global dissolved organic carbon (DOC) is located in long-term deep ocean storage (Arrieta et al. 2015). This effective removal of part of the anthropogenically released carbon in the ocean is called biological pump (Meyer et al. 2016).
Ocean Biological Deserts
Published in Ajai, Rimjhim Bhatnagar, Desertification and Land Degradation, 2022
It is remarkable to note here that unlike terrestrial plants, which accumulate the living biomass, the marine environment does not accumulate (Sarmiento and Bender 1994) but keeps on refreshing while maintaining the earth's carbon pool (Broecker, 1982) through a two-way cycle. The phytoplankton fix inorganic carbon from the atmosphere and the reverse way is achieved through the sinking of dead organisms into the ocean interior (often called marine snow), where it is returned to dissolved inorganic carbon and nutrients by bacterial decomposition. This process is called a ‘biological pump'. It is called so because it removes (uses) carbon dioxide from the ocean surface and atmosphere, changes it into living matter and distributes it to the deeper water layer of the ocean (Volk and Hoffert 1985). The organic matter sinking to the seafloor gets almost completely decomposed to the dissolved chemicals (Martin et al. 1987, Emerson and Hedges 2003). Thus, through photosynthesis by phytoplankton, the greenhouse gas carbon dioxide, is sequestered into organic matter which holds the possibility of lowering the average future temperatures and thus mitigating the impact of climate change. The carbon dioxide, after disintegration, is further replaced from the atmosphere, in accordance with Henry's law which states that the dissolved gas content of water is proportional to the percentage of gas in the air above it. This cycle helps in the reduction of carbon dioxide as a greenhouse gas. This biological carbon pump removes approximately 10 trillion kg of carbon from the atmosphere every year. Thus, even small changes in the phytoplankton population can drastically affect the climate and the whole marine ecosystem.
Zooplankton of the Past, Present and Future
Published in Neloy Khare, Climate Change in the Arctic, 2022
Jasmine Purushothaman, Haritha Prasad, Kailash Chandra
The possible risks of biomagnification in the Arctic food webs, energy adaptation of the zooplankton community, the role of biological pump, and diel vertical migration in Arctic ecosystem are also extensively studied in the recent past. Several studies reported that PCBs and hydrophobic organic contaminants (HOCs) cause biomagnification in aquatic Arctic food webs (Fisk et al. 2001; Hop et al. 2002; Borga et al. 2002). A study on persistent organic pollutants (POPs) present in Arctic zooplankton by Fisk et al. (2001) revealed that hydrophobic POP concentrations present in zooplankton are more likely to reflect water concentrations. This study also suggested that POPs do not undergo biomagnification in small, herbivorous zooplankton. The occurrence of polychlorinated biphenyls (PCBs) in the Arctic is also well documented. But these studies mainly addressed the pollutant transfer upward in the food web from zooplankton and, thus, did not focus much on the potential biomagnification taking place from phytoplankton to zooplankton. A study conducted by Sobek et al. (2006) supported equilibrium partitioning of PCBs between zooplankton of the size range from 20 to >500 µm and Arctic seawater. The results suggest minimal uncertainty in the modelling of trophic transfer in the aquatic food webs, and hence, significant biomagnification does not have to be considered in zooplanktons. Characteristics of organic matter and its consequences on the sorption of organic pollutants are the study areas which demand future research efforts to understand both spatial and seasonal variability in partition coefficients.A study by Riser et al. (2008) clearly showed the importance of zooplankton for vertical flux regulation. Zooplanktons ingest POC or particulate organic carbon (about 22%-44% of the daily primary production). However, through the production of fast-sinking faecal pellets, they can accelerate vertical flux. Miquel et al. (2015) also highlighted the significance of the zooplankton community in transforming carbon, issued as a result of primary production, and its transition from the productive surface layer to the interior of the Arctic Ocean. Furthermore, Turner (2015) discussed the role of zooplankton in driving the ‘biological pump’ which is the exporting of photosynthetically produced carbon from the surface to the ocean interiors. Zooplankton faecal pellets are essential components in the biological pump.
Microalgae biofilm carbon and nitrogen sequestration as a tool for economic and environmental sustainability
Published in Critical Reviews in Environmental Science and Technology, 2023
Adamu Yunusa Ugya, Hui Chen, Qiang Wang
The anthropogenic nature of chemical industries engineers the release of GHG that cause pollution in the environment (Ugya et al., 2021). These GHG such as carbon and nitrogen oxides pose negative effect by contributing to the deterioration of global climate change (Akhtar et al., 2021). Both gases are powerful greenhouse gases that trap heat in the atmosphere and continue to increase due to the increase in human anthropogenic activities (Cassia et al., 2018). Nature plays a vital role in the regulation of the concentration of GHG in the atmosphere through the natural carbon sink (Jain et al., 2012). The different natural sinks for GHG include land, oceans, and plants (Walsh et al., 2017). The oceans are the main natural carbon sinks because they capture carbon and stored in the deep depths of the ocean via physical or biological pump. The biological pump in the ocean is facilitated by marine planktons and plants that are able to utilize carbon dioxide (CO2) from the atmosphere for photosynthesis and multiplication (Jin et al., 2020). About 24% of the total carbon emission between 2007 and 2016 was stored in the ocean, while about 30% was concentrated on land, and 46% remain in the atmosphere (Nawkarkar et al., 2022). The ocean is able to absorb 25% of the CO2 emissions generated by anthropogenic activities via sequestration and produce 50% of the oxygen needed by the earth’s biota.