Search for journal articles on most topics. This multi-disciplinary database is a good place to start if you don't know where else to begin. (EBSCO)
Search for peer-reviewed articles in geography, geology and ecology. (Elsevier)
In addition to searching for scholarly articles via library databases, consider going directly to scholarly journals and searching through their records. You can do the same keyword-level searching in a more focused manner. Here are links to some (but not all!) scholarly journals: