Legacy radioactive and hazardous waste deliberately dumped in the deep sea

Background

Between 1946 and 1990, roughly fourteen countries deliberately dumped radioactive waste into the deep ocean (Atlantic, Pacific, Arctic) under a prevailing "dilute and disperse" doctrine: the abysses were treated as a stable, empty sink able to absorb what societies no longer wanted to see. The best-documented site is the North-East Atlantic dump zone — a ~14,500 km² area of abyssal plain about 1,200 km off the Bay of Biscay / Nouvelle-Aquitaine, at depths beyond 4,700 m — where 200,000+ barrels (estimates run to ~300,000) were sunk, mostly between 1949 and 1982.

The dumping was overwhelmingly European. The United Kingdom accounted for the large majority; France (which dumped off the Bay of Biscay from 1968 until the 1983 moratorium), Belgium, the Netherlands and Switzerland were also among the dumping nations. The practice was halted by international agreement (moratorium 1983, permanent ban under the London Convention/Protocol from 1993).

Why it is a live problem, not just history

The drums were encased in resin, bitumen or cement and logged only approximately. Fifty years on, direct observation (CNRS-led NODSSUM campaigns, 2025–2026) shows many in advanced degradation, with some having spilled their contents onto the seabed. On-site measurements confirm radionuclides characteristic of the waste (cobalt-60, niobium-94, caesium-137, americium-241) at activity levels higher than expected for the zone, though so far limited. What is largely uncharacterised is how that radioactivity transfers into deep-sea sediments, water and food webs over decades — even as the drums themselves have become hard-substrate habitat for abyssal fauna.

Constraints that shape any response

Retrieval from ~4,700 m is effectively non-viable: the drums are fragile, and disturbing them risks dispersing contents that are currently semi-contained. The tractable levers are therefore locating and characterising the waste, monitoring its transfer into ecosystems, preventing future disturbance of the site, and — for the underlying practice — the prevention regime that stopped new dumping. This issue is the parent for those approaches; the NE Atlantic serves as the anchoring, best-documented instance of a global class.