Does "heavy" here mean "serious"?

Context:

Chemists and physicists have begun 2016 heavy with resolution—superheavy, in fact. Two days before 2015 came to end the guardians of the periodic table of the elements—the International Union of Pure and Applied Chemistry—announced that it was okay to add four new ones, filling out the seventh row. Atoms of each new element are packed with protons in their nuclei, giving the four atomic numbers of 113, 115, 117 and 118.

More:
http://www.scientificamerican.com/article/4-new-superheavy-elements-verified/