Fig. 2From: Arsenic in the Pearl River Delta and its related waterbody, South China: occurrence and sources, a reviewGeologic map of parent rocks for the Pearl River Basin (modified from Xu and Han 2009). The global average concentration of arsenic in different parent rocks indicated by Smedley and Kinniburgh (2002) is used as a reference to provide an overview that does not necessarily pertain to a specific site in the Pearl River DeltaBack to article page