Note that the majority of
studies related to the urbanization impact were conducted in cities
with temperate climates in the northern hemisphere. Based on the
information provided by Morrison et al. (1984) for the southern
hemisphere, this source of heavy metals may not be as critical in
cities with tropical climates, which experience higher amounts of
rain and higher temperatures than cities in the northern hemisphere;
however, the high urban concentration in Rio de Janeiro
justifies this hypothesis.