#Japan #Water Quality #Hokkaido #Hokkaido Earthquake #Microbial Communities

Understanding the Environmental Changes from Landslides

In September 2018, the Hokkaido Eastern Iburi Earthquake struck, causing devastating landslides across the mountainous regions of Atsuma and Abira in Hokkaido, Japan. Over 6,000 shallow landslides were reported, marking a significant natural disaster that raised concerns about its environmental implications. This article discusses recent findings by researchers from the National Institute of Advanced Industrial Science and Technology (AIST) regarding how these landslides affected river water quality and microbial communities.

Background

The earthquakes and subsequent landslides caused a rapid alteration in the landscape, leading to significant environmental impacts that were previously underexplored. While landslides are widely recognized for their role in triggering disasters, their lesser-known effects on water quality and microbial ecosystems are crucial for effective environmental management and protection.

Research Findings

The research, led by Naoyuki Yoshihara and his team, aimed to clarify the relationships between the scale of surface collapse and changes in river water quality and microbial communities. The findings revealed a positive correlation between the occurrence of landslides and changes in the concentration of dissolved ions in river water.

During the study, researchers measured various water quality parameters, including electrical conductivity, pH, dissolved oxygen, and concentrations of critical ions such as ammonium (), manganese (+), and iron (+). The analyses found that as the landslide area increased, concentrations of these ions appeared elevated, while nitrate and sulfate levels decreased. This suggested that the environment within the landslide deposits became more reductive compared to surrounding areas.

Furthermore, environmental DNA analyses showcased distinct differences in microbial communities between river water and landslide deposits, underscoring the consequences of the landslides on microbial diversity and river ecology. The ongoing redox reactions within the landslide deposits potentially affect river water quality and the broader microbial ecosystem.

Significance of the Study

This research provides critical insights into how landslide events, particularly in high-risk regions like Hokkaido's mountainous areas, can influence not just the immediate environment but also long-term water resource management and ecosystem health. It signifies a growing need to integrate geological disaster analysis with ecological assessments to foster a comprehensive understanding of environmental and ecological changes following such disasters.

Future Directions

The team is now focused on further examining the microbial activities within landslide deposits and their implications for water quality. As climate change increases the frequency of heavy rainfall events, the risk of landslides may escalate, warranting further investigation into their long-term environmental impacts and necessary management strategies.

Understanding the complex relationships between geological phenomena and aquatic environments is essential for ensuring healthy ecosystems and sustainable water resources. The findings from this research provide a foundation for future studies aimed at mitigating risks associated with landslide-induced changes in water quality.

Conclusion

The Hokkaido Eastern Iburi Earthquake has brought to light the profound impacts of shallow landslides on river water quality and microbial communities. As we adapt to changing climatic conditions and disaster risks, recognition of the ecological significance of such events is paramount in safeguarding our water resources and fostering biodiversity.

This study was supported by the Japan Society for the Promotion of Science's Grant-in-Aid for Scientific Research and emphasizes the need for collaborative efforts in understanding and mitigating the consequences of natural disasters.

Publication Information

The research has been published in the Journal of Hydrology, revealing insights into the physical and biological dynamics within affected water systems. The full article detailing these findings can be accessed here.