A generic environmental risk assessment framework for deep-sea tailings placement

Area of Science:

• Marine Ecology
• Environmental Science
• Risk Assessment

Background:

• Deep-sea tailings placement (DSTP) involves discharging mine tailings into the ocean.
• This process can impact pelagic and benthic organisms across various marine zones.
• Existing risk assessment methods may not fully capture DSTP's complex ecological effects.

Purpose of the Study:

• To develop and apply a novel stressor-driven environmental risk assessment (ERA) framework for DSTP.
• To identify and rank the risks associated with DSTP to marine ecosystems.
• To provide recommendations for monitoring DSTP operations.

Main Methods:

• Developed a conceptual model of DSTP exposure pathways and receptors.
• Utilized causal pathways and causal networks for eight pelagic and benthic impact zones.
• Scored causal pathway links based on likelihood and consequence to determine risk rankings.
• Applied the framework to the Batu Hijau copper mine DSTP operation as a case study.

Main Results:

• Identified 11 very high risk and 18 high risk causal pathways, primarily in benthic zones.
• Smothering of benthic biota was identified as a major risk, extending beyond predicted deposition zones.
• Recovery of affected communities is slow and may result in altered ecosystem structures.

Conclusions:

• The developed ERA framework effectively identifies significant risks associated with DSTP.
• DSTP poses substantial threats to benthic ecosystems, necessitating careful management and monitoring.
• Georeferenced causal networks are valuable tools for conducting ERAs in DSTP contexts.