Methane and Mercury

Read the following articles:
Arctic Melt Releasing Ancient Methane  and
Toxic mercury, accumulating in the Arctic, springs from a hidden source

Why is methane being released into the atmosphere from the arctic and why is this a concern?

Where is Mercury coming from and why is it concentrated at the poles? Why is this a serious problem? 

What does bioaccumulative mean?

What groups of people are most impacted by the mercury pollution?  Why do you think it is now recommended that pregnant women and children under three not eat fish that have high concentrations of mercury?

What are some possible solutions to these environmental and human health problems?