Mercury

Transport and transfomation of
PCBs in the atmosphere
• PCBs enter into the atmosphere during the process of
using and disposing.
• The depletion of different PCBs depends on their
environmental, phycial and chemical properties.
• There are two main ways of depletion of PCBs in the
atmosphere: direct photodecomposition; reaction with
radicals like OH and NO 3 and also ozone.
The radical OH has the most influence. The half-life of
the reactions with PCBs activated by OH is 2~34 days; with
every one more Cl ion in the PCBs molecule, the reactivity is
reduced in half.