harvesting {HEAD ~ a portion} of {TAIL ~ said algal turf} onto and into which said pollutants have precipitated 
of
harvesting { HEAD ~ a portion } of { TAIL ~ said algal turf } onto and into which said pollutants have precipitated
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH