As most HKers know there is a nuclear power plant less than 100km away in nearby Longgang District of Shenzhen. Have you ever wondered wether it’s leaking radioactivity into the sea close to HK?
Well, a study about to be published in the Journal of Environmentsl Radioactivity looked at a sediment core just off the water spout if the Daya Bay Nuclear Power Plant (NPP) to see if the power plant had caused any new radioactivity in the sediment beyond normal background radiation. A sediment core is sort of like a layered-cake with each layer capturing the chemistry of the environment at a certain time. The deeper you dig the further back in time you go. In the deep sea at 5000 meters a sediment slice of 1 mm can be the result of 1000 years of sedimentation, but in coastal environment it’s more like 10 cm per year depending on local sediment inputs.
The answer to the question of extra radiation from the Daya Bay NPP seems to be no. No new radiation was added to the marine ecosystem, as nothing more than natural background radiation was found in the layers following the operation of the NPP. But the researchers did find a substantial impact on the marine ecosystem from the NPP’s cooling water discharge which caused changes in the level of organic carbon in the sediment. NPP’ require a lot of cooling water taken from nearby seawater. This water should not come into contact with radioactive material but should just absorb heat. The heated water is then discharged back into the sea where it raises the sea temperature locally creating localised changes to the environment.
But at least we can rest at ease that we are not eating radioactive seafood! (unless it’s imported from the Fukushima Coast…)