A flow of contaminated liquid phase water migrates toward the freeze front and a concentration of impurities is established in {HEAD ~ front} of {TAIL ~ the advancing freeze front} 
A flow of contaminated liquid phase water migrates toward the freeze front and a concentration of impurities is established in { HEAD ~ front } of { TAIL ~ the advancing freeze front }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL