This the last paragraph of a composition:
In sum, protecting the environment should always be an important concern of all the countries. However, when it’s possible to minimize the harm to environment in the exploitation of these valuable natural resources in the wilds, it is at best unwise and at worst heartless to leave all the treasures sleeping in the bleak wilderness while billions of people are suffering from extreme poverty and starving to death.
I’m not quite sure about “an important concern”.
BTW: Do you think there’s any other problem in this paragraph?
Yes, “an important concern” is fine in such context. The New Oxford American Dictionary gives the following as one definition for “concern” as a noun:
a matter of interest or importance to
oil reserves are the concern of the Energy Department
the survival of an endangered species is of concern to wildlife biologists
However, as for the preposition to go with it, this would sound slightly better to me:
In sum, protecting the environment
should always be an important concern
to all the countries.
(But “of” seems to be fine too. Googling similar phrases using “of” vs “to” didn’t reveal compelling evidence either way. Maybe some of the native speakers here can weigh in on this one?)