large plastic enclosures were suspended in east twin lake , ohio , usa , and duplicates were either untreated controls ( ph 8.8 ) , acidified to ph 4.5 over a 23 day period , or acidified and also spiked with incremental additions of al , to produce a final inorganic monomeric al level of 180 microg/liter at ph 4.5 .
C0028905
ohio
C0041703
usa