These can be incorporated into the ice along with sediments at the mouth of a polluted river or be deposited directly on the ice surface from the air.
(These; can be incorporated; into the ice along with sediments at the mouth of a polluted river) (These; be deposited directly; on the ice surface from the air)
These These
can be incorporated be deposited directly
into the ice along with sediments at the mouth of a polluted river
on the ice surface from the air