Specialized Fungi Found to Enhance Heavy Metal Sequestration in Constructed Wetlands

The rise of industrial activities has become a significant threat to our ecosystems and health due to water pollution and contaminants like heavy metals. Vanadium, a metal used in steel production, aerospace, and chemical manufacturing, is among these pollutants that have raised significant environmental concerns. When vanadium ends up in bodies of water, it can accumulate in sediments and enter the food chain, harming fish, plants, and animals and eventually impacting human life. Vanadium exposure can result in neurological problems, developmental issues in children, and potential carcinogenic effects. In an effort to remove vanadium contamination in rivers, researchers have discovered that adding specialized fungi into constructed wetlands can help filter out the heavy metal from the waters, offering a practical and eco-friendly method to tackle this pressing environmental issue.

Constructed wetlands for contamination control

Constructed wetlands are artificial water systems that emulate the natural filtration processes observed in actual wetlands. These systems leverage wetlands’ physical and biological mechanisms to purify water and treat contamination. When water moves through constructed wetlands, it undergoes multiple purification processes that collectively remove pollutants. 

Constructed wetlands are considered a highly effective method of removing heavy metals from vanadium-contaminated waters. Research indicates that constructed wetlands can reduce vanadium pollution by a high percentage. However, the method is not always as effective as needed to achieve the high standards for safe water quality.

The role of arbuscular mycorrhizal fungi 

Arbuscular mycorrhizal fungi (AMF) are fungi that form symbiotic relationships with plants, such as those found in wetlands. AMF penetrate the root cells of plants, extending their root system and creating a two-way exchange for nutrients so both organisms benefit from the interaction. Because of this extended root system, there is a greater surface area for nutrient and water absorption, allowing the plants to absorb more contaminants, including vanadium, from the water. Furthermore, several studies have found that AMF are capable of cleaning up heavy metals by absorbing them and binding them into the soil, thereby reducing their mobility and bioavailability and preventing vanadium from being released back into the ecosystem. Yet, despite these promising qualities of AMF for heavy metal remediation, previous research has not observed the effects of AMF on constructed wetlands and their role in removing vanadium from contaminated water. 

Study setup and findings

To fill this knowledge gap and determine the effectiveness of AMF remediation for vanadium contamination, researchers set up two groups of constructed wetlands—one pre-inoculated with AMF and another without it. Both groups were subjected to similar conditions, with carefully measured concentrations of vanadium to mimic the pollution levels commonly found in industrial runoff to simulate real-world pollution levels. Throughout the experiment, researchers regularly monitored vanadium levels through water sampling. They also examined the growth and biomass of the plants to evaluate how AMF affected their health and took soil and root samples to understand how AMF influenced vanadium uptake and sequestration.

By the end of the study, the constructed wetlands inoculated with AMF showed a significant increase in vanadium removal compared to the control group wetlands without it. Quantitatively, the AMF-inoculated wetlands removed a notably higher percentage of vanadium from the water over the course of the study. The presence of AMF also positively impacted the health and growth of the wetland plants, as they exhibited faster growth rates, greater biomass, and improved overall health compared to the control group. This enhancement is likely due to the enhanced nutrient uptake facilitated by the AMF, which also contributed to the plant’s ability to absorb and sequester vanadium. Examination of the soil and root systems in the AMF-inoculated wetlands revealed an increased accumulation of vanadium in the root zone compared to the control, meaning that AMF not only assisted the uptake of vanadium but may also play a role in its sequestration within the soul and root systems, preventing its release back into the water (1).

Potential implications for pollution management

The enhanced removal capabilities observed in the AMF-inoculated wetlands indicate that these fungi significantly boost the efficiency of phytoremediation processes within the wetland ecosystem. These findings have substantial implications for pollution management, especially in areas affected by industrial discharge. Integrating AMF into constructed wetlands could be a strategic approach to improve the remediation of vanadium-contaminated waters, yet more studies are necessary to enhance these results. Given these promising findings, future research could focus on optimizing AMF-plant combinations for various contaminant and environmental conditions to expand the applicability of AMF in constructed wetlands. As research progresses, the integration of AMF in pollution control could become a fundamental aspect of modern environmental management, demonstrating the power of harnessing natural processes to enhance the well-being of our ecosystems and health.

References

1. Zhang, Shujuan, Jingfan Qi, Huafeng Jiang, Xinlong Chen, and Zhaoyang You. 2024. “Improving Vanadium Removal from Contaminated River Water in Constructed Wetlands: The Role of Arbuscular Mycorrhizal Fungi.” Environmental Pollution (1987), March, 123804–4. https://doi.org/10.1016/j.envpol.2024.123804.