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, turbidity, fecal coliforms,
temperature, dissolved oxygen and pH. Cations, dissolved organic
carbon and nitrogen and metals were measured on selected samples.
Samples for anion and cation analysis were filtered (0.45 micron).
Samples for total N, total P, turbidity, and fecal coliform analysis
were not filtered.
Every six weeks, samples were shipped to the Cary Institute of
Ecosystem Studies (CIES) for anion, cation, TN, and TP analysis. Fecal
coliform analysis was done from October 2001 through September 2004 in
Karin Raedel's laboratory at UMBC. These analyses are described below.
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.
An HF Scientific DRT-15CE turbidimeter was used to analyze turbidity.
Samples were analyzed for fecal coliform concentration using Micrology
Laboratories' Coliscan EasyGel method from October 2001 through
September 2004.
Temperature, pH, conductivity and dissolved oxygen were measured using
a handheld meter during weekly visits for sample collection.
