Radioactive activity from Fukushima has reached Fraser River Valley in Vancouver, British Columbia in Canada. Although the scientists uncovered very low levels of cesium-134 in the soil, they remain baffled as to how it arrived in the area.
"The sample provided was measured and we saw cesium-134, at a very low level and not a concern to public health," Krzysztof Starosta, an associate professor of chemistry at Simon Fraser University, said.
But what baffles scientists about this latest find was that the soil sample taken from a beach so far upriver.
"It's inland, so it could not come in from the ocean, since the water flows the other way," he said.
Scientists are speculating a number of guesses - it could have been airborne, landed on a hill or mountain and been washed down to the river.
"It's actually quite unexpected that we found it in soil so far inland," Mr Starosta said. "Common wisdom would be that Caesium would come through the ocean."
Juan Jose Alava, an adjunct professor in the school of resource and environmental management at Simon Fraser University, was shocked with the discovery.
"That was a surprise," he said. "It means there are still emissions ... and trans-Pacific air pollution. It's a concern to us. This is an international issue," Mr Alava told Vancouver Sun.
Mr Starosta said they made a follow-up visit and inspection to the same place but "didn't find comparable radiation levels... This could just be a one-time blip."
"We only have a single sample," Mr Starosta said.
Scientists are now planning to extract and test soil samples from Burnaby Mountain, closer to Vancouver.
Simon Fraser University got hold of the radioactive soil sample from citizen Aki Sano who discovered it from Kilby park, near the mouth of the Harrison River, on Nov 16, 2013. Slowly rising levels of cesium-134 have been recorded by monitoring stations in the ocean west of Vancouver, reaching 0.9 Becquerels per cubic meter in June 2013.