Environmental effects of WW1?

Buried unexploded ammunition(Gunpowder gets more unstable the older it is.)And they found a Japanese torpedo buried in the muck at the bottom of Pearl Harbor(65 years old.It was detonated by the local ordnance disposal unit).Compared to Nuclear Warships with the danger of Radiation,not much danger to the environment as Coal,and Iron occur in nature and will decompose given enough time.Still finding buried ammo in England and France.(RMS Titantic is expected to collapse in a heap of rust within 25-50 years)