Transport of pollutants by ocean currents

Ocean currents move slowly, and transport of pollutants from industrialised and densely populated areas may take several decades. Pollutants which are soluble in water and are discharged straight into the sea, or land on the sea as rain, are transported northwards by the ocean currents. Depending on how soluble in water they are, the pollutants may become bound to particles and sink to the seabed. Some areas of this kind may become what are called sinks, repositories for pollutants.

none

SLOW PROCESS  Transport of pollutants in the sea is a slow process and it may take years before they reach the Arctic. Photo: Ann Kristin Balto / Norwegian Polar Institute

Sea transport of pollutants to the Arctic is controlled by the current systems and the layering in the sea. Transport of pollutants in the sea is a slow process and it may take years before they reach the Arctic. They may then remain in the sea for a few years up to several centuries. Studies suggest that sea transport is the primary means of transport of PFOA to the Arctic.[1] It is also estimated that some 35 % of long-transported PCBsreaching Svalbard do so via the sea.

Depending on how different radioactive substances behave in the marine environment, some may be transported by ocean currents over long distances. For instance, technetium-99, discharged into the sea from the nuclear fuel reprocessing plants at Sellafield and Cap de la Hague, may be traced along the entire North Atlantic coast right into the Barents Sea.

The slow movement of the ocean currents towards the pole also gives a time delay in respect to measures undertaken to prevent pollutants reaching the environment.

PFOA may occur in many products used on an everyday basis. The substance has water and fat repelling properties and is used as an impregnation agent to make products waterproof and dirt repellent. PFOA is toxic with repeated exposure, carcinogenic and may harm the reproductive system.

References

  1. I. Stemmler and G. Lammel 2010. Pathways of PFOA to the Arctic: variabilities and contributions of oceanic currents and atmospheric transport and chemistry sources. Atmos. Chem. Phys., 10, 9965-9980, 2010. DOI:10.5194/acp-10-9965-2010