<sod >BEIJING - A top Chinese leader says a "proper balance" must be struck between environmental and economic interests in Antarctica as climate change exposes the frozen continent's vulnerabilities.< eod>< sod > BEIJING - A Chinese leader on Tuesday urged international representatives to strike a "proper balance" between environmental and economic interests in Antarctica, as the frozen continent's vulnerability to climate change raises worries that some nations could seek to exploit its natural resources.< eod>