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<br />. <br /> <br />002~8' <br /> <br />. <br /> <br />were no apparent differences between the two methods. The samples for <br />total metals were placed in 0.95 i (1 qt.) polyethylene cubitainers, pre- <br />served with HN03' and transported to the EPA laboratory for analysis at <br />the conclusion of each 4-day sampling period. On one occasion (station WR-l <br />on 5/26/76), water samples for dissolved metals analysis were filtered <br />in the field using a 0.45p membrane filter and then preserved with HN03' <br /> <br />All total metal samples were prepared by the digestion procedure <br />establ i shed in the EPA Methods Manual (1974). After di ges tion , all metal <br />analyses were performed by flame atomic absorption, except for the following <br />variations: arsenic and selenium were determined using the graphite furnace <br />technique with the nickel matrix modification as outlined by Ediger (1975); <br />lead was determined in the graphite furnace with the use of ammonium nitrate <br />to volatalize excess sodium chloride (Ediger, 1975); molybdenum was deter- <br />mined in the graphite furnace with no modifications; and lithium and <br />potassium were both analyzed by flame emission spectrometry. All other <br />parameters were analyzed according to approved procedures. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />Duri ng the Spri ng "hi gh fl ow" study water samp 1 es were collected from <br />all stations for nutrient analysis. These grab-type samples were placed <br />in 0.95 i (1 qt.) polyethylene cubitainers, preserved with 40 mg HgC12 per <br />liter, and held on ice until analyzed at the end of each four-day sampling <br />period. <br /> <br />With the exception of TKN, all nutrient samples were analyzed using <br />the Technicon Auto Analyzer II with the Digital Printer Module in accord- <br />ance with approved methods (EPA, 1973a). The specific methods employed <br />in the nutrient analysis were the following: ammonia- automated colori- <br />metric phenolate; nitrite + nitrate- automated cadmium reduction; ortho- <br />phosphorus- automated co lorimetri c ascorbi c aci d reducti on; and total <br />phosphorus- digestion with sulfuric acid-ammonium persulfate, followed <br />by automated colorimetric ascorbic acid reduction. <br /> <br />. <br /> <br />. <br /> <br />The procedure used for TKN analysis was a semi-automated version of <br />the standard TKN digestion and colorimetric method. The digestion pro- <br />cedure util i zed the Techn icon Block Di ges tor in whi ch as many as forty <br />samples at a time were digested under controlled conditions. The digestion <br />converted all organic nitrogen to ammonia which was measured by the auto- <br />mated colorimetric phenolate method. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />10 <br /> <br />. <br /> <br />,j,;,,' <br />