ABSTRACT
Phosphorus and load concentration:
Water and sediment samples were collected from Pewaukee Lake (Pewaukee, WI) and analyzed for total phosphorus (P) concentration. Water flow rates were measured to determine P loading from the inflowing streams. P loading calculations are available for the summer of 2004, while only P concentration data is available for the summer 2003.
Method Analysis:
The sediment samples were digested with sulfuric acid and persulfate in an autoclave. The water samples were digested
with persulfate in an autoclave. Phosphorus concentrations were determined using a uv-vis spectrometer and analyzing
the 625 nm absorption peak based on the association of malachite green with phosphomolybdate under acidic conditions.
Lower detection limit results from this complex having a molar absorptivity constant more than three times greater than
the phosphoantimonylmolybdenum blue in the standard Murphy-Riley method. While the malachite green method does provide
signal at lower concentrations, the Murphy-Riley method provided greater dynamic range and a more reliable standard curve.
Click to see the entire technical bulletin, Pewaukee Lake Phosphorus Monitoring
2003-2004.