Chemical Analyses of Waters from Crater Lake, Oregon, and Nearby Springs
by J. Michael Thompson, L. Douglas White and Manuel Nathenson
Sampling and Analysis
Spring waters were collected using methods similar to those described in Thompson (1975). Temperatures of springs were determined using a conventional, total immersion, mercury-in-glass thermometer. In 1981 and 1982 field measurements of the spring water pH were made with non-bleeding, low-ionic-strength, pH-indicating dyes (E. M. Colorphast pH strips*). Beginning in 1983 all field pH measurements were made with a gel-filled pH electrode and a portable pH meter. Temperature and pH were generally determined at each spring site. The alkalinity of the 1984 and the few 1985 samples was also determined in the field. At each spring site a filtered, unacidified CFU) water sample for anion analysis was collected by passing the water through a 0.45 pm membrane filter. Additionally, a filtered, acidified sample (FA) for cation analysis was collected by adding concentrated, trace-metal quality HCI to the filtered water. An untreated sample for deuterium and oxygen-18 analysis was also collected at each site.
Samples of lake water were collected in 2 liter Van Dorn sample bottles attached to a metal cable and retrieved either by hand (1981 samples) or mechanically (all others). The depth of sampling in 1983 was limited to 300 m by the available cable; in 1984 the winch and cable were replaced, permitting us to retrieve samples from the bottom of the lake. Samples were collected and treated similar to the spring water ones: one bottle for anion analysis, FU, another for cation analysis, FA, and a third for isotopic analysis, untreated. In 1985 a one-liter raw sample was collected and evaporated to approximately 50 mL for B and Li analysis.