Ammonium ions can be introduced into the
atmosphere from industrial burning or agriculture. When
combined with water, ammonia (either produced naturally
by many plants or added to agricultural fields by humans
for fertilizing) is converted to ammonium ions. In dry
areas, the ammonium ions can then escape into the atmosphere.
9. What might account for high ammonium
ion (NH4+) concentrations in the central portion of
the United States?