Table 2.
Trace element concentrations in water at floc collection depth and in suspended floc fractions accessible to bacteria
| Parameter | Concnc |
|||
|---|---|---|---|---|
| Hamilton | Toronto | Guelph | Coldspring | |
| Aqueousa total TEb (μmol liter−1) | 0.182 | 0.043 | 0.019 | 0.020 |
| Floc total TE associated with exchangeable fraction (μmol g−1) | 0.05 | 0.06 | 0.01 | 0.00 |
| Floc total TE associated with acid-soluble carbonate/sulfide fraction (μmol g−1) | 0.39 | 0.13 | 0.01 | 0.01 |
| Floc total TE associated with amorphous Fe/Mn oxyhydroxide fraction (μmol g−1) | 0.52 | 0.25 | 0.10 | 0.65 |
| Floc total TE associated with crystalline Fe/Mn oxide fraction (μmol g−1) | 0.93 | 0.26 | 0.16 | 0.28 |
| Floc total TE associated with organic/sulfide fraction (μmol g−1) | 0.21 | 0.38 | 0.24 | 0.66 |
a
0.22-μm filtered.
b
TE, trace elements Ag, As, Cu, and Pb.
c
Trace element concentrations are mean concentrations of three replicate samples. Standard deviations were on the order of 10−3 μmol liter−1 for aqueous-element concentrations and 10−2 μmol g−1 for floc element concentrations.