Critical Review of the Longterm Implications of Carbon Dioxide Burial in Aquatic Ecosystem

Critical Review of the Longterm Implications of Carbon Dioxide Burial in Aquatic Ecosystem

Sony Emeka Ali¹, Esang Lazarus Esitikot^1*, Gerald Ndubuisi Okeke¹, Cynthia Amaka R. Obiorah², Ugah Theophilus Aku¹, Mateines Nesiama¹, Cletus Onyemhese Agbakhamen¹ and Ogheneteme Pupu Okoro¹.

¹Highstone Global University, Texas, USA

²Centre for Occupational Health, Safety and Environment, Universality of Port Harcourt, Nigeria

*Corresponding Author

DOI: https://dx.doi.org/10.47772/IJRISS.2025.9010340

Received: 11 January 2025; Accepted: 20 January 2025; Published: 21 February 2025

ABSTRACT

This review examines the effects of burying carbon dioxide (CO₂) in the depths of oceans or rivers as a method of mitigating climate change. Carbon sequestration techniques, such as ocean and river-based CO₂ burial, are being explored as potential solutions to the escalating global crisis of atmospheric CO₂ buildup. By delving into the science behind carbon capture and storage (CCS) in aquatic environments, the study assesses both the potential benefits and the environmental risks associated with this approach. The findings suggest that while deep-sea and river CO₂ storage may offer temporary reductions in atmospheric CO₂, further research is necessary to evaluate long-term ecological impacts and safety.

Keywords: Carbon-capture, carbon dioxide, climate change, global warming, acidification, carbon sequestration

INTRODUCTION

Climate change, driven primarily by the increase in atmospheric greenhouse gases such as carbon dioxide (CO₂), has become one of the most urgent challenges facing the world today [1-4]. At global level, the rise in the average temperature is higher than one-degree Fahrenheit since the late 1800s, with much of the rise occurring in just the past few decades [4]. According to [3], the concentration of atmospheric CO₂ has risen above 400 parts per million and are currently at levels not experienced in more than the past 800,000 years. As global temperatures continue to rise, the need for effective solutions to mitigate the effects of CO₂ emissions has never been more critical [1, 4]. Many sources [1, 2, 4] have noted that curtailing fossil fuel utilization alone is not adequate to save the earth and that unless something more drastic is done, the planet is at risk. Among various carbon capture and storage (CCS) strategies, the concept of burying CO₂ in the deep ocean or riverbeds has garnered increasing attention as a potential method to reduce the concentration of this harmful greenhouse gas in the atmosphere [1]. A source [1] specifically recommended capturing anthropogenically produced carbon gas and discharging it into the ocean at a depth of 3000 metres to sink into the bottom of the ocean.

The idea of utilizing large natural reservoirs such as the deep ocean or river beds stems from their ability to store vast quantities of CO₂, thereby preventing it from contributing to global warming [1. 2]. The oceans, in particular, have long been considered a major carbon sink, absorbing roughly one quarter of all anthropogenic CO₂ emissions each year [1]. The oceans have the capacity to store about 59 times more carbon gas than the atmosphere [1]. However, the potential for enhancing this natural process through deliberate CO₂ sequestration presents both opportunities and challenges [5]. The ability to inject and store carbon in the deep ocean or beneath riverbeds could offer a significant method for reducing the atmospheric concentration of CO₂ and potentially stabilizing the climate [1, 4].

Despite its promise, the proposal to bury CO₂ in these environments raises a number of scientific, environmental, and ethical concerns [1, 9]. Key questions remain regarding the long-term stability of such storage, the potential for leaks, and the impact on marine and freshwater ecosystems. Additionally, there are concerns about the acidification of oceans and rivers and the potential disruption to local biodiversity if CO₂ were to interact with the surrounding water and sediment in unexpected ways [6]. The issue also extends to the technical feasibility of transporting and injecting CO₂ into these environments in a manner that is both effective and sustainable.

This research aims to explore the various effects of burying CO₂ in the heart of the ocean or rivers, examining both the scientific mechanisms that would govern such processes and the potential environmental consequences. By investigating these factors, the study hopes to contribute to the ongoing debate about the viability of large-scale CO₂ sequestration strategies and provide insight into the risks and benefits of this approach as a climate change mitigation tool.

Through an in-depth analysis of current research, experimental models, and real-world case studies, this paper will evaluate the effectiveness, safety, and environmental impacts of CO₂ burial in aquatic ecosystems. Ultimately, the research will provide a clearer understanding of whether this method could serve as a viable and sustainable strategy for reducing global CO₂ emissions and mitigating the effects of climate change. .

METHODOLOGY

The study adopted critical review of literature on different studies done on carbon capture. This design was adopted because it provided a holistic platform to enable effective review of technological, social, environmental concerns associated with carbon capture and the implications of burying carbon dioxide in the ocean or river. The literature reviewed included peer-reviewed articles, government reports, and environmental assessments concerning carbon sequestration techniques in aquatic systems. The data in the literature were assessed for relevance, reliability, and applicability, particularly focusing on ocean and river sequestration’s impact on biodiversity, water chemistry, and CO₂ stabilization. The data quality was high, but limitations in long-term studies were noted. Special attention was paid to studies on environmental toxicity and ecosystem models. The literature reviewed were retrieved from different reputable research databases such as Google Scholar, ScienceDirect, and JSTOR and generic searches across different internet sites.

THE CONCEPT OF CARBON CAPTURE

The concept of carbon capture and storage (CCS) has emerged as one of the primary strategies for mitigating the effects of climate change, especially in reducing the atmospheric concentration of CO₂ [1, 2, 4, 5, 9, 11]. While several technologies and approaches exist for capturing and storing CO₂, one of the more intriguing options is the burial of CO₂ in the deep ocean or riverbed sediments [1, 2, 9]. This method is predicated on the natural carbon sinks that oceans and rivers represent, with the idea being that these environments can effectively store CO₂ for long periods, potentially preventing it from contributing to global warming [1, 8, 9]. However, despite its potential, there remains considerable debate regarding the environmental, ecological, and technical viability of this approach [5, 8, 9, 12].

IMPLICATIONS OF CARBON DIOXIDE BURIAL

Carbon Sequestration in Oceans: The idea of oceanic CO₂ sequestration, often referred to as ocean fertilization or deep-sea CO₂ storage, has been researched for decades, with the aim of using the ocean’s vast volume and deep layers as a natural repository for atmospheric CO₂ [3, 5, 9]. According to the Intergovernmental Panel on Climate Change (IPCC), oceans absorb approximately 25% of anthropogenic CO₂ emissions annually, primarily through the physical process of diffusion at the surface and biological uptake via photosynthetic organisms [3, 5].

The deep ocean could serve as a long-term storage medium for CO₂, particularly when it is injected into specific deep-sea environments such as sub-seafloor reservoirs or under submarine geological formations [1, 9]. These areas are naturally rich in minerals and sediments that could potentially react with CO₂ to form stable solid carbonates, reducing the likelihood of CO₂ leakage. However, the stability of these storage sites over geological time scales remains uncertain, with studies highlighting concerns regarding the potential for leakage through underwater geological faults or cracks [9].

Furthermore, the effects of large-scale CO₂ injection on marine ecosystems are a subject of intense debate. One of the main concerns is the acidification of ocean waters. According to [8, 10], CO₂ dissolved in seawater forms carbonic acid, lowering the pH and making the water more acidic. This could have harmful effects on marine life, particularly on calcifying organisms such as corals, shellfish, and plankton, which rely on calcium carbonate for shell formation [8]. The International Ocean Carbon Working Group in 2019 conducted a series of modeling studies to assess the impact of CO₂ injection on deep-sea ecosystems and found that changes in pH could potentially disrupt food webs and biodiversity at various trophic levels.

However, some studies indicate that deep-sea ecosystems may have the ability to adapt to gradual changes in pH. Research suggests that certain species, particularly those in the deep benthic zones, might be more resilient to pH changes due to the naturally lower pH levels of deep-sea environments. Despite this, the risks associated with disrupting these delicate ecosystems remain significant, particularly when considering the unpredictable nature of large-scale human intervention.

Carbon Sequestration in Rivers and Freshwater Ecosystems: While most research on CO₂ sequestration has focused on the oceans, the burial of CO₂ in freshwater systems, including rivers, lakes, and underground aquifers, has begun to attract attention. Freshwater ecosystems are much more dynamic than the deep ocean and are thus subject to different environmental and biochemical conditions. The idea of injecting CO₂ into riverbeds or lake sediments to create geological sequestration sites involve significant technical challenges, especially in terms of ensuring that the CO₂ does not escape back into the atmosphere due to hydrodynamic forces or sediment erosion [25, 26].

 Researchers have examined the potential of CO₂ burial in riverbeds through a combination of geological modeling and experimental injection. Their findings suggested that deep riverbeds, particularly in regions with low river flow and high sedimentation rates, could act as effective CO₂ reservoirs [24 – 26]. However, this process is highly dependent on the local geology and hydrology of the river system, and many rivers may not have the necessary conditions for long-term CO₂ storage.

Research on riverine acidification due to CO₂ injection is still in its early stages. Some researchers explored the impact of elevated CO₂ levels on freshwater systems and found that similar to oceans, river acidification could have detrimental effects on aquatic life, including fish, macroinvertebrates, and plant species. River systems are often heavily influenced by land use, pollution, and nutrient loading, which could further exacerbate the negative effects of additional CO₂ inputs [14, 19].

Moreover, rivers are subject to rapid changes in flow and sediment deposition, which means that CO₂ injected into riverbeds may not remain trapped as effectively as it would in the deep ocean. While certain river systems may be able to store CO₂ for decades, the risk of leakage is much higher compared to oceanic sequestration due to the potential for water movement and changes in sediment dynamics [13, 15].

Environmental and Ecological Risks: The potential ecological risks associated with CO₂ sequestration in both oceans and rivers are a significant concern in the scientific community [5, 7, 12, 13]. The primary environmental risks include changes in water chemistry, disruption of nutrient cycles, and the possible creation of hypoxic or anoxic conditions in the deep ocean or river sediments [6, 8, 12]. Even small concentrations of dissolved CO₂ in water can lead to a reduction in dissolved oxygen levels, which in turn could affect marine or freshwater organisms’ respiration and survival [12, 16, 17, 18, 28].

Another critical factor is the potential leakage of CO₂ from the burial sites [5, 7, 8, 17]. While CO₂ injection into geological formations is generally considered safe, the risk of slow leakage over time through cracks or faults in the seabed or riverbed cannot be ruled out [9, 12, 23]. This leakage could potentially lead to “acidification hotspots” in surrounding ecosystems, further endangering biodiversity and the health of aquatic organisms [28]. Additionally, there are social and ethical concerns regarding the long-term monitoring and governance of CO₂ burial sites [9, 12]. Since CO₂ sequestration in oceans and rivers would likely take place in international waters or areas shared by multiple nations, questions about regulation, responsibility, and potential transboundary environmental impacts remain unresolved [13, 15].

Technological and Feasibility Challenges: The technical feasibility of CO₂ burial in the heart of the oceanor rivers is another major aspect explored in the literature [20 – 23, 26, 27, 29]. Though there are various CO₂ injection technologies [20 – 23, 26, 27], there are currently no publications dedicated for site selection for CO₂ injection [29]. While ocean-based storage techniques are more advanced, the idea of injecting CO₂ into freshwater environments requires the development of new technologies to deal with the unique challenges posed by river sediment dynamics and water flow patterns [29]. Furthermore, the logistics of transporting CO₂ from land-based facilities to deep ocean or river locations for burial poses significant infrastructure challenges [14, 15, 20 – 22].

Technologies such as subsea pipelines, pressurized transport tanks, and direct injection rigs would need to be developed and tested on a large scale [14, 21, 23, 28]. The economic implications of implementing such systems would be substantial, as studies indicate that current CO₂ sequestration projects are financially unfeasible without substantial government subsidies or regulatory incentives [21, 23 – 26, 29].

RESULTS

The findings form the different literature indicate that while ocean-based CO₂ sequestration could effectively reduce atmospheric CO₂ levels in the short term, it carries significant risks, such as altering marine chemistry and biodiversity. River CO₂ burial shows promise as a temporary storage solution, but it is not as effective on a large scale and raises concerns over water quality and aquatic life. Both methods, while potentially useful, require further investigation to address their long-term sustainability and ecological impact.

The results demonstrate that while CO₂ burial in oceans and rivers could help mitigate climate change temporarily, both methods present substantial environmental risks that must be considered. Ocean burial, for example, may cause acidification, which can harm marine life.

Similarly, burying CO₂ in rivers could disrupt aquatic ecosystems and pose risks to freshwater quality. Therefore, any potential solution must be coupled with other strategies, such as reducing emissions at the source and enhancing carbon capture technology. These findings underscore the need for a multidisciplinary approach to climate change mitigation [23 – 26].

The potential for burying CO₂ in the ocean or riverbeds as a means of mitigating climate change is promising. However, it is obvious from available literature that the research in this area is still evolving [29, 30]. The implication is that numerous scientific, ecological, and technical challenges must be addressed before large-scale deployment can occur [29, 30]. The risk of environmental harm, the potential for CO₂ leakage, and the unknown effects on aquatic ecosystems all warrant careful consideration in future research [30]. As the body of literature grows, it is critical to continue developing reliable monitoring systems, sustainable injection technologies, and regulations to ensure the safety and long-term effectiveness of these methods.

CONCLUSION AND RECOMMENDATIONS

The burial of CO₂ in aquatic environments presents both opportunities and risks. While it may offer a temporary solution to reduce atmospheric CO2, the long-term ecological consequences remain uncertain. More research is essential to evaluate its scalability and safety. Ultimately, burying CO₂ should be considered one tool in a larger suite of strategies aimed at tackling the climate crisis.

Further research is needed to develop more accurate models of CO₂ sequestration in both oceans and rivers. Governments and environmental organizations should prioritize interdisciplinary studies that evaluate the risks, benefits, and scalability of CO₂ burial in aquatic systems. Additionally, methods to minimize environmental impact, such as advanced monitoring technologies and ecosystem restoration strategies, should be incorporated into any large-scale implementation plans.

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