Introduction

Poly- and perfluoroalkyl substances (PFAS) are a broad range of families of synthetic hydrocarbons that have replaced hydrogen atoms with fluorine atoms in their alkyl chain. This structure has created unique properties in these materials (Kah et al., 2020; Lu et al., 2020). Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the most well-known PFASs, which have been repeatedly detected in various environmental compartments (Abunada et al., 2020). The unique properties of PFAS-containing products are film-forming, water-proof, oil-proof, stain-proof, and low friction. These materials also have excellent water solubility with low reactivity of their carbon–fluorine bond (Yamashita et al., 2008). They are also highly resistant and almost not degraded in the environment; therefore, many scientists called them “forever chemicals” (Pelch et al., 2019). These distinguishing features have made PFAS useful in producing various consumer products since the 1950s (Gardener et al., 2020). Food packaging, Teflon cookware, firefighting foams, carpets, cosmetics, personal care products, glass, paper, stain-proof textile, plastics articles, paints, rust inhibitors, electronics, ski wax, polishers, pesticides, aqueous film-forming foams (AFFF), medical products such as personal protective equipment (PPE), and hundreds of daily goods are examples of consumer products containing PFAS (Cui et al., 2020; Kwiatkowski et al., 2020; Le et al., 2020). PFASs are detected in surface-water, tap water, groundwater, soil, pole, indoor and outdoor air, human plasma, bird, sediment, and ocean, as well as aquatic food webs (Al Amin et al., 2020). For instance, it is reported that the average value of ∑10PFASs concentrations in groundwater in the alluvial–pluvial plain of in the North China Plain is about 2.35 ng/L (Liu et al., 2019). Moreover, the total concentrations of eight quantifiable PFAS (∑8PFAS) in surface waters of the Western Tropical Atlantic Ocean ranged from 11 to 69 pg/L (Han et al., 2022). Similarly, total PFAS mass concentration in the rainwater of eight National Trends Network sites across Wisconsin was between 0.7 and 6.1 ng/L with a median of 1.5 ng/L (Pfotenhauer et al., 2022). Further, according Barghi et al. (2018), median concentration of PFASs in the liver tissues of 10 Korean bird species was 294 ng/g wet weight. Furthermore, Wang et al. (2022) noted that PFAS concentration in sediment, water, muscle and liver tissues of fish in Jiulong River in the southeast of China, ranged from 0.24–1.9 ng g − 1 dw, 2.5 to 410 ng L − 1, 25–100 and 35–1100 ng g − 1 ww, respectively. Persistence, toxicity, and inherent tendency of PFAS to bioaccumulation made them a serious threat to all ecosystems (González-Gaya et al., 2019). Recently, scientists have turned their attention to the presence of PFAS in different depths of the ocean. The concentration of PFAS in the ocean, which has been detected so far, is about several thousand nanograms per liter. However, after firefighting activities, in groundwater and surface water, PFAS with higher concentrations (about mg/L) has also been observed (Abunada et al., 2020). Furthermore, it is expected to significantly increase PFAS concentrations in the ocean in the near future. This is especially true after the COVID-19 pandemic due to the increasing consumption of PFAs containing products, including food packaging, personal care products, single-use plastics, disinfectants, and medical products such as PPEs. As a result, significant amounts of PFAS enter various environment segments and eventually enter the oceans through dust, glacial sediment, storm water and continental shelf remobilization (Fig. 1). When concentrations of PFAS increase in the ocean, they may be ingested at a higher rate than excreted, resulting bioaccumulation. As these compounds are mostly lipophilic (which tend to dissolved in fat rather than water), they could be magnified up through the food web (biomagnification) and enriched in the top of ecosystem (fishes, marine mammals, sea birds, humans) most (Du et al., 2021). In this way, various scientists have pointed to the adverse effects of PFAS on both human and animal health (DeLuca et al., 2021; Fenton et al., 2021; Teunen et al., 2021).

Fig. 1
figure 1

Ocean carbon sequestration process. POC is particulate organic carbon; DOC is dissolved organic carbon; LPOC is labile dissolved organic carbon, and ROPC represents recalcitrant dissolved organic carbon. PFAS can threaten the development of phytoplankton and zooplankton; therefore, ocean PFAS pollution can disrupt carbon sequestration

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Carbon is called the chemical backbone of life on the planet. Carbon compounds regulate the planet’s temperature, make up the food that sustains us and supply energy that fuels our universal economy. The earth’s largest carbon reservoir is rocks and sediments, followed by the ocean, atmosphere, and living organisms. The carbon cycle is defined as carbon flows between different reservoirs in an exchange. As the earth is a closed system, the total quantity of carbon on the planet is constant. However, carbon transferring from one reservoir to another can change the carbon quantity in a specific reservoir. For example, changes that increase the atmosphere’s carbon level visibly contribute to global warming and climate change (Zhu et al., 2019).

The global oceans contain approximately 38,000 gigaton carbon, which is about 45 times more than atmospheric carbon. Moreover, it is estimated that nearly 40% of anthropogenic carbon emissions have already been consumed by oceanic uptake. Thus, global oceans play a prominent role in mitigating atmospheric carbon and maintaining a stable climate. It is even mentioned that in long timescales (more than 100 ka), the ocean and weathering will lessen the level of atmospheric carbon to values near preindustrial (Renforth & Henderson, 2017). But when the oceans’ carbon sequestration ability is disrupted, the global carbon cycle pattern will significantly change. Consequently, the primary conditions for human survival will be treated.

Yet, to our knowledge, there are no scientific studies that evaluate the role of PFAS in disturbing ocean carbon sequestration (OCS). To address this knowledge gap, the present study outlines the existing literature on PFAS and ocean ecosystem interactions to show (1) the effect of PFAS pollution on phytoplankton photosynthesis and growth, (2) the toxic effects of PFAS pollution on the development and reproduction of zooplankton, (3) the effect of PFAS pollution on the marine biological pump, and (4) ocean carbon stock. Moreover, this study has presented some appropriate strategies to address this issue as a complex problem.

Role of ocean PFAS pollution in disrupting OCS

The adverse effect of oceanic PFAS pollution on phytoplankton

As critical primary producers in marine ecosystems, phytoplankton is vital to the stability of the marine ecosystem’s productivity and ecological balance to consume adsorbed carbon from the atmosphere for producing O2 and organic matters by photosynthesis. It implies that phytoplankton supply nutritious food for primary consumers of the ocean (Fig. 1). Therefore, they are known as the foundation of the food web in aquatic ecosystems (Shen et al., Improving wastewater treatment plant efficiency

Wastewater treatment plants (WWTPs) are the last barrier to PFAS entering the environment. Currently, removal efficiencies for PFAS in most of WWTPs are low (Lenka et al., 2021a). For example, according to the study of Zhang et al. (2013) conducted in China, 16 PFAS were reported in both the influents (between 0.04 and 91 ng/L) and effluents (0.01–107 ng/L) of WWTPs. Thus, existing WWTPs remove only a part of PFAS, and even some studies reported an increase in the concentration of PFAS in the effluent of WWTP compared to influent (Gallen et al., 2018). Researches about remediation techniques at laboratory scale and/or full scale suggest that advanced processes, namely electrochemical degradation, nanofiltration, and adsorption using ion exchange resins, effectively treat PFAS (~ 95–100%) with conventional techniques (Lenka et al., 2021b). However, the applicability of these advanced processes in real-world WWTPs faces many challenges because of mass transfer limitations, the scaling-up requirements, management of treatment by-products, as well as costs. Also, since a significant portion of PFAS enters the sludge of WWTPs, develo** and upgrading the sludge treatment facilities in the WWTPs is a necessary step to prevent PFAS from entering the environment.

Improving clean-up and biodegradation technology

Bioremediation uses a biological agent (microorganisms and plants) to degrade and/or accumulate contaminants. This method can be known as a sustainable and cost-effective technique for treating PFAS-contaminated environments. There are known bacteria (primarily identified as Pseudomonas sp.) breaking down the strong F–C bound in PFAS in aerobic and anaerobic conditions (Shahsavari et al., 2020). For instance, it is reported that Pseudomonas parafulva can remove about 32% of PFAS within 96 h of incubation (Yi et al., 2016). Further, a decrease of around 67% in PFAS concentration was also reported during 48 h incubation of Pseudomonas aeruginosa (Kwon et al., 2014). Moreover, Because of the broad range of substrate reduction catalyzed by extracellular ligninolytic enzymes, study on the fungal degradation of PFASs has been ongoing. For example, it is reported that white-rot fungus Phanaerochete chrysosporium can significantly decrease (45%) PFAS concentration for 35 days (Kucharzyk et al., 2017). However, future researches on the implication of fungal enzymes for PFAS treatment seems to be necessary.

Conclusion and future prospective

Global oceans are one of the most extensive natural reservoirs for CO2, which have an essential role in the sequestration of atmospheric carbon and regulating climate change. However, presence of some micropollutans such as PFAS can pose a threat on the ocean’s ability to sequestrate atmospheric CO2. The present study showed that marine PFAS pollution could pose a significant threat to ocean carbon sequestration through four inter-connected scientific pieces of evidence. PFAS is used in a wide range of consumer products. As a result, its concentration in the oceans has incremented in the recent years. The high concentrations of PFAS in the ocean can have adverse effects on the growth and photosynthesis of phytoplankton and toxic effects on zooplankton. As a result, affect on marine biological pomp and carbon stock of the global ocean. However, research on oceanic PFAS on OCS is a new subject for research. Many conclusions are still in the hypothetical steps, and there are significant uncertainties in this subject. Therefore, given the substantial role of the oceans in the deposition of atmospheric carbon and the regulation of the earth’s climatic conditions, and the potential impacts of PFAS on OCS, further research is needed to understand the scale and scope of these effects. Further, herein some unanswered questions are presented that should be answered in future researches:

  • How much does the concentration of different PFAS compounds increase in the biotic and abiotic ocean ecosystem in the post-coronavirus pandemic?

  • What is the concentration threshold of PFAS toxicity for different oceanic biota?

  • Is it possible to produce new compounds of PFAS with less toxic effects on marine biota?

  • What is the effect of different concentrations of PFAS on the size and shape of zooplankton fecal pellets?

  • What is the synergistic effect of the co-existence of PFAS with other emerging pollutants such as Quaternary ammonium compounds (QACs) and/or microplastics on the carbon cycle of the oceans? (Given that in addition to PFAS, the concentration of microplastics and QACs in the environment is expected to increase after the COVID-19 pandemic.)

  • What is the best treatment technique for COVID-19 pandemic-induced waste material?

  • What is the best remediation technique for PFAS on an industrial scale?