Task: Question Generation
Input (English): Background Paragraph: Unfortunately, the layer of good ozone is being destroyed by air pollution. The chief culprits are chlorine and bromine gases. They are released in aerosol sprays, coolants, and other products. Loss of ozone has created an ozone hole over Antarctica. Ozone depletion results in higher levels of UV radiation reaching Earth. In humans, this increases skin cancers and eye cataracts. It also disturbs the nitrogen cycle, kills plankton, and disrupts ocean food webs. The total loss of the ozone layer would be devastating to most life. Its rate of loss has slowed with restrictions on pollutants, but it is still at risk. 
Story: Russian research spent most of their time in Antarctica to study the loss of ozone in the atmosphere. The Canadian team went north of the Polar Circle, close to the North Pole to do the same thing. They spent several months there. The Canadian team didn't find any ozone holes at the North Pole.
Output (English): Which team didn't observe the disruption of the nitrogen cycle?