IMO Assess Marine Mining


A new study from The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) claims that more work is needed to understand the environmental repercussions of mining operations.

GESAMP’s report, ‘The Impact of Mine Tailings in the Marine Environment’, has highlighted issues surrounding the disposal of waste from mining operations in marine environments. The report details the findings of an international workshop held in Lima, Peru (in 2015) and makes a number of recommendations for future mining work.

The report notes that there are major gaps that need to be addressed in the scientific understanding of the behavior of mine tailings in the sea at depths greater than 20m to 80 m and consequently the short- and long-term impacts on the marine environment and other potential users of marine resources.

Scientific gaps in measurement and monitoring techniques in assessing impacts of existing and proposed new deep-sea discharges of mine tailings need to be addressed.

Since the workshop in Lima, GESAMP has established a dedicated working group to assess the environmental impacts of wastes from mining operations which have been disposed into the marine environment, under the co-lead of IMO and UN Environment.

A number of large-scale mines worldwide use marine or riverine disposal for mine tailings, under Government permits. 

The report outlines an appraisal of what it believes are the best practical waste management options. These include:

• Marine discharge, i.e. in deep waters; • On land storage, i.e. tailings storage ponds; and • No mine tailings, i.e. no mine; • Evaluation of waste reduction, such as treatment before discharge; • Evaluation of recycling or reusing wastes; • Comprehensive baseline survey of proposed disposal site and surrounding areas; • Characterization of mine tailings, physical, chemical, and toxicity; • Suitable disposal site location (bathymetry, physical oceanography, and ecology); • Suitable discharge depth and conditions (no upwelling, subsurface tailings plumes and resuspension of deposited tailings); • Low productivity environment (i.e. not impacting a precious ecosystem); • Robust ecological risk assessment to demonstrate low risk of adverse effects to aquatic organisms, i.e. water quality and sediment quality; and • Advanced monitoring and ongoing improvements to management of waters at surface and at depth, including plumes; • Engineering elements of the discharge, the discharge pipe (e.g. physical safety of the pipeline from wave action and seismic activity), and location; • Adaptive management and mitigation procedures; and • Transparency and acknowledging what is known and what isn't known.

The IMO is the Secretariat for The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP), which is an advisory body, established in 1969, that advises the United Nations (UN) system on the scientific aspects of marine environmental protection. You can read the full GESAMP report here

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