Ionic composition of acid lakes in relation to airborne inputs and watershed characteristics

Ion and temperature dependence of electrical conductance for natural waters

“…Figure 4 shows the percent difference between this result and the originally reported conductivity plotted as a function of lake temperature. The plot illustrates three points: (1) The effect of the variation in R values from lake to lake is expressed by the spread in the vertical direction at a given temperature. (2) The general error in the temperature conversion method used by Birge and Juday is shown by the overall shape of the curve, similar to Figure 1. (3) The average absolute percent difference is roughly 0.3% and is within the precision of the original measurements.…”

“…The assay of selenium (Se) in biological specimens including blood is commonly undertaken to determine the Se status of man and animals. In a recent survey (1) of the determination of Se in blood, it was found that the interlaboratory coefficient of variation (CV) was unsatisfactory at blood Se concentrations below 0.5 µ /L and that at about 0.2 µ /L, the CV was up to 57%. This analytical variation is of concern in the diagnosis of marginal Se deficiency in livestock where the blood Se concentrations of interest are in the range 0.15-0.50 µ /L (2).…”

“…EXPERIMENTAL SECTION Preparation of Blood Samples. Four blood samples from the previous survey (1) were used as a common set of blood standards for all laboratories. On the basis of the results reported in the survey, the mean blood Se concentrations (µ /L) of these four samples, namely, RMl-Se-A, RMl-Se-B, RMl-SeC, and…”

“…One of the most common of all measurements of water quality is electrical conductance. The usefulness of such a measure has been exploited recently as a powerful tool used for the quality assurance of ion concentration measurements in the USEPA ERL-D water quality acid rain database (1) and has been used to evaluate historical data (2-4). Since electrical conductance is a strong function of temperature and measurements cannot always be at a standard temperature (usually 25 °C) it is necessary to apply a temperature conversion formula before meaningful comparisons can be made for most applications.…”