Mercury in the Environment – Science to End Mercury Pollution

Tom Cresswell, Australian Nuclear Science and Technology Organisation, and Tarren Reitsema, National Offshore Petroleum Safety and Environmental Management Authority

The session “Mercury in the Environment – Science to End Mercury Pollution,” presented at the SETAC Europe 35th Annual Meeting this spring in Vienna, explored mercury contamination in aquatic systems and its implications for both ecological integrity and human health. A recurring concern is the bioaccumulation and biomagnification of mercury, particularly methylmercury, through aquatic food webs. Mercury levels in fish and other biota often exceed safety thresholds, with variability linked to species, trophic level and environmental conditions. Consumption of contaminated seafood presents dietary risks, particularly where small-scale gold mining and industrial emissions have contributed to elevated mercury in local ecosystems.

Registered participants of the SETAC Europe 35th Annual Meeting can access on-demand content through the meeting platform for three months after the meeting, until 15 August.

New analytical techniques are emerging to improve detection and monitoring. One method enables rapid, selective identification of methylmercury in biological samples without the complexity of traditional approaches. This technique has proven effective for high-throughput biomonitoring, revealing strong correlations between seafood consumption and human exposure. Another method applies radiotracing to simulate the behavior of mercury in marine environments, particularly from decommissioned offshore infrastructure. Mercury compounds, such as nanoparticulate metacinnabar, can persist inside pipelines and may transform into more toxic forms over time, especially under changing redox conditions.

Freshwater studies underscore mercury’s presence, even in areas without obvious contamination sources. Bioindicator species, such as clams and gammarids, have been used to track mercury exposure and bioavailability. These organisms show clear uptake from sediments, often reflecting broader patterns in local food chains. Mercury concentrations in aquatic species have been found to correlate with age and size, indicating cumulative exposure and potential long-term effects.

Together, this session stressed the need for improved monitoring tools, better understanding of mercury speciation, and more robust environmental management strategies. The findings support precautionary approaches to offshore infrastructure decommissioning, stricter controls on emissions, and the development of targeted public health advice related to seafood consumption. These efforts are critical to addressing ongoing and legacy sources of mercury contamination across diverse aquatic environments. Outcomes of the session include planning to introduce a new Oil and Gas Working Group to the UNEP Global Mercury Partnership to further investigate potential human and environmental impacts of mercury in oil and gas systems.

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