I can't find any reference to WWII munitions in the original article. What they are talking about are atmospheric nuclear tests carried out primarily in the period after WWII:
"For weapons-137Cs, the cessation of atmospheric tests resulted in no noteworthy new weapons-137Cs fallout after the last test in 1980 ... this study illustrates that strategic decisions to conduct atmospheric nuclear tests 60–80 years ago still impact remote natural environments, wildlife, and a human food source today."
"For weapons-137Cs, the cessation of atmospheric tests resulted in no noteworthy new weapons-137Cs fallout after the last test in 1980 ... this study illustrates that strategic decisions to conduct atmospheric nuclear tests 60–80 years ago still impact remote natural environments, wildlife, and a human food source today."