Introduction

The release of radionuclides from nuclear and mining sites and their subsequent mobility in the environment is a subject of intense public concern and has promoted much recent research into the environmental fate of radioactive waste (Lloyd & Renshaw 2005b). Naturally occurring radionuclides can input significant quantities of radioactivity into the environment while both natural and artificial/manmade radionuclides have also been released as a consequence of nuclear weapons testing in the 1950s and 1960s, and via accidental release, e.g., from Chernobyl in 1986. The major burden of anthropogenic environmental radioactivity, however, is from the nuclear facilities themselves and includes the continuing controlled discharge of process effluents produced by industrial activities allied to the generation of nuclear power.

Wastes containing radionuclides are produced at the many steps in the nuclear fuel cycle, and vary considerably from low level, high-volume radioactive effluents produced during uranium mining to the intensely radioactive plant, fuel and liquid wastes produced from reactor operation and fuel reprocessing (Lloyd & Renshaw 2005b). The stewardship of these contaminated waste-streams needs a much deeper understanding of the biological and chemical factors controlling the mobility of radionuclides in the environment. Indeed, this is highly relevant on a global stage as anthropogenic radionuclides have been dispersed to the environment both by accident and as part of a controlled/monitored release, e.g., in effluents.