Samples were collected weekly at an established sampling location at
each station. Sampling locations were chosen based on adequate
concentration of flow, proximity to weir and staff gage, and low
vulnerability to disturbance. Samples were collected and stored in
polyethylene bottles.
Weekly analyses included nitrate, phosphate, total nitrogen, total
phosphorus, chloride and sulfate.
Samples for anion and cation analysis were filtered (0.45 micron).
Every six weeks, samples were shipped to the Cary Institute of
Ecosystem Studies (CIES) for anion, cation, TN, and TP analysis.
One blank from the laboratory distilled water source was prepared each
week and stored along with the samples. Spike analysis was done as
part of the routine long-term BES stream sampling and analysis.
Samples were stored at 4 degrees C.
Concentrations of nitrate, chloride and sulfate were analyzed on a
Dionex LC20 series ion chromatograph. Concentrations of phosphate were
analyzed on a Lachat Quikchem 8000 flow injection analyzer.
Total nitrogen and phosphorus were analyzed by persulfate digestion
followed by analysis of nitrate and phosphate on a Lachat Quikchem
8000 flow injection analyzer. If the value for total N was more than
0.10 mg N L-1 less than nitrate-N, the total N value for that sample
was set to the nitrate value. If the value for total P was more than
0.01 mg P L-1 less than the phosphate P, the total P value for that
sample was set to the phosphate value.
