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Baltimore Ecosystem Study Stream Chemistry Metadata
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Field Sampling
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Samples are 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 are collected and stored in polyethylene bottles.
Weekly analyses includes nitrate, phosphate, total nitrogen, total phosphorus, chloride and sulfate, total suspended solids, turbidity, fecal coliforms, temperature, dissolved oxygen and pH. Cations, dissolved organic carbon and nitrogen and metals are measured on selected samples.
Samples for anion and cation analysis are filtered (0.45 micron). Samples for total suspended solids, total N, total P, turbidity, and fecal coliform analysis are not filtered.
During weekly visits for sample collection, a handheld meter is used to get instantaneous measures of temperature, pH, conductivity and dissolved oxygen.
Every six weeks, samples are shipped to IES for anion, cation, TN, and TP analysis. TSS and turbidity analysis is done at the BES laboratory at the University of Maryland Baltimore County (UMBC). Fecal coliform analysis is done in Karin Raedel's laboratory at UMBC. These analyses are described below.
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Blanks and Spikes
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One blank from the laboratory distilled water source is prepared each week and stored along with the samples. Once every six weeks one extra filtered sample is collected at three stations, Carroll Park, Villanova, and Glyndon, for percent recovery (spike) analysis. Back at the UMBC lab, the extra bottle is spiked with one mL each of a 1000 ppm NO3- and a 1000 ppb PO4- standard per 100 ml of solution; the cation bottle is spiked with a combined nitrate and phosphate standard and stored and analyzed with other samples. Samples are stored at 4°C.
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Chemical Analyses
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Anions. Concentrations of nitrate, chloride and sulfate are analyzed on a Dionex LC20 series ion chromatograph. Concentrations of phosphate are analyzed on a Lachat Quikchem 8000 flow injection analyzer.
Total nitrogen and phosphorus are 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 is more than 0.10 mg N L-1 less than nitrate-N, the total N value for that sample is set to the nitrate value. If the value for total P is more than 0.01 mg P L-1 less than the phosphate P, the total P value for that sample is set to the phosphate value.
TSS is analyzed by filtering and weighing.
Turbidity. An HF Scientific DRT-15CE turbidimeter is used to analyze turbidity samples.
Fecal coliforms. Samples are analyzed for fecal coliform concentration using Micrology Laboratories' Coliscan EasyGel method.
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