providing a source of water for flowing through a floway, said water containing {HEAD ~ a quantity} of {TAIL ~ pollutants} and having a pH lower than a pH of precipitation of said pollutants on entry into said floway 
of
providing a source of water for flowing through a floway , said water containing { HEAD ~ a quantity } of { TAIL ~ pollutants } and having a pH lower than a pH of precipitation of said pollutants on entry into said floway
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH