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Conductivity |
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Conductivity is a measure of
the ability of water to pass an electric current, which is proportional to the
nature and quantity of Total Dissolved Solids (TDS) in the sample water. (We
also measure TDS but do not report the results here since TDS and conductivity
are mathematically related.) Conductivity in water is affected by the presence
of inorganic dissolved solids such as chloride, nitrate, sulfate, and phosphate
anions (ions that carry a negative charge) or sodium, magnesium, calcium, iron,
and aluminum cations (ions that carry a positive charge). Conductivity in streams and rivers is affected primarily by the geology
of the area through which the water flows. For example, streams that run through
areas with granite bedrock tend to have lower conductivity because granite is
composed of more inert materials that do not ionize when washed into the water.
On the other hand, streams that run through areas with clay soils tend to have
higher conductivity because of the presence of materials that ionize when washed
into the water. Conductivity may
also be affected by anthropogenic sources such as failing septic systems or
human-caused runoff. We measure conductivity
using an electronic meter (Hanna Meter). The
meter measures the electrical current conducted between electrodes located on
the meter and reports the result in micro-Siemens per centimeter.
(Source: http://bcn.boulder.co.us/basin/data/BACT/info/index.html, http://www.epa.gov/owow/monitoring/volunteer/stream/)
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