New Method for Electrical Conductivity Temperature
Compensation
- Publication date
- Publisher
Abstract
Electrical
conductivity (κ) measurements of natural waters
are typically referenced to 25 °C (κ<sub>25</sub>) using
standard temperature compensation factors (α). For acidic waters
(pH < 4), this can result in a large κ<sub>25</sub> error
(δκ<sub>25</sub>). The more the sample temperature departs
from 25 °C, the larger the potential δκ<sub>25</sub>. For pH < 4, the hydrogen ion transport number becomes substantial
and its mode of transport is different from most other ions resulting
in a different α. A new method for determining α as a
function of pH and temperature is presented. Samples with varying
amounts of H<sub>2</sub>SO<sub>4</sub> and NaCl were used to develop
the new α, which was then applied to 65 natural water samples
including acid mine waters, geothermal waters, seawater, and stream
waters. For each sample, the κ and pH were measured at several
temperatures from 5 to 90 °C and κ<sub>25</sub> was calculated.
The δκ<sub>25</sub> ranged from −11 to 9% for the
new method as compared to −42 to 25% and −53 to 27%
for the constant α (0.019) and ISO-7888 methods, respectively.
The new method for determining α is a substantial improvement
for acidic waters and performs as well as or better than the standard
methods for circumneutral waters