Journal of Ecology and Toxicology
Open Access

Carbon Sequestration; Coastal Saline-Alkali Soils; Calcium Carbonate Formation; Soil Amendment; Climate Change Mitigation

Introduction

The quest for effective carbon sequestration methods is critical in mitigating climate change, particularly given the growing concerns about rising atmospheric CO₂ levels [1]. Coastal saline-alkali soils, often characterized by high salinity and alkalinity, represent a significant but underutilized opportunity for enhancing carbon sequestration. This article explores the potential of exogenous calcium-induced carbonate formation as a strategy to increase carbon sequestration in these challenging environments [2,3].

Coastal saline-alkali soils: characteristics and challenges

Coastal saline-alkali soils are typically found in coastal areas where seawater intrusion and high evaporation rates contribute to high salinity and alkalinity. These soils present unique challenges for agriculture and land management due to their harsh chemical properties. The high pH and saline conditions can limit plant growth and reduce soil fertility, further exacerbating environmental degradation. Despite these challenges, coastal saline-alkali soils have considerable potential for carbon sequestration if managed effectively. Their mineralogical composition, often rich in calcium and magnesium, provides a foundation for carbonate formation, which can play a crucial role in capturing and storing atmospheric CO₂ [4].

Carbon sequestration mechanisms

Carbon sequestration involves the capture and storage of atmospheric CO₂ in various forms, including organic matter, minerals, and carbonates. In coastal saline-alkali soils, one promising method is the formation of calcium carbonate (CaCO₃) through the reaction of exogenous calcium with soil carbonates. This process not only helps to sequester carbon but also ameliorates soil properties, making these soils more conducive to plant growth [5,6].

The primary mechanisms for calcium-induced carbonate formation include:

Calcium carbonate precipitation: Adding calcium salts to the soil can lead to the precipitation of calcium carbonate, a stable mineral that effectively locks away carbon. This process can be enhanced by increasing the availability of calcium and carbon sources in the soil [7,8].

Soil pH modification: Exogenous calcium can help to neutralize soil acidity, improving soil structure and enhancing the conditions for carbonate formation. A more neutral pH promotes the precipitation of calcium carbonate and increases the soil's capacity to sequester carbon.

Microbial activity: Calcium-induced carbonate formation can also stimulate microbial activity in the soil. Microbes play a crucial role in the carbon cycle, and their activity can enhance the conversion of soil organic matter into stable forms of carbon.

Application of exogenous calcium

The application of exogenous calcium involves introducing calcium-containing amendments to the soil. Common sources of calcium include calcium carbonate (lime), calcium chloride, and calcium sulfate [9]. The choice of calcium source depends on the specific soil conditions and the desired outcomes.

Calcium carbonate (lime): Lime is widely used to improve soil pH and promote carbonate formation. It reacts with soil acids to form calcium carbonate, thereby sequestering CO₂ and enhancing soil fertility.

Calcium chloride and calcium sulfate: These salts provide calcium in a more soluble form, which can quickly react with soil components to form calcium carbonate. They are particularly useful in soils with high salinity where lime might be less effective [10].

Benefits and implications

The benefits of exogenous calcium-induced carbonate formation in coastal saline-alkali soils extend beyond carbon sequestration. Key advantages include:

Improved soil quality: Calcium-induced carbonate formation can help to neutralize soil pH, improve soil structure, and increase nutrient availability, leading to enhanced plant growth and agricultural productivity.

Enhanced carbon storage: By converting atmospheric CO₂ into stable calcium carbonate, this method offers a long-term solution for carbon sequestration, contributing to climate change mitigation efforts.

Ecosystem restoration: Improved soil conditions can support the restoration of coastal ecosystems, such as salt marshes and mangroves, which are crucial for coastal protection and biodiversity.

Economic benefits: Enhanced soil fertility and productivity can lead to increased agricultural yields, providing economic benefits to farmers and landowners in coastal regions.

Conclusion

Exogenous calcium-induced carbonate formation offers a promising approach to enhancing carbon sequestration in coastal saline-alkali soils. By leveraging the unique properties of these soils and applying targeted calcium amendments, it is possible to improve soil quality, increase carbon storage, and support ecosystem restoration. As we continue to seek effective solutions for climate change mitigation, this innovative method represents a valuable tool in our efforts to create a more sustainable and resilient future.

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