The Great Lakes - March-October 2001

Autoanalyzer

An autoanalyzer is a very sophisticated device that automates and standardizes complex analyses of huge numbers of samples for certain “conventional” parameters, such as nitrogen and phosphorus. The autoanalyzer samples small but precise amounts of water and adds appropriate reagents exactly as needed to produce parameter-specific color reactions. The sample is than delivered to a spectrophotometer for measurement. This process may be repeated many hundreds of times during a single lake survey. The equipment makes it possible for a limited number of researchers to characterize the water quality attributes of such immense water bodies such as the Great Lakes.

Water Chemistry

In order to understand all that is happening in the Great Lakes, it is necessary to measure numerous water quality attributes (parameters). Among the more fundamental measurements that are almost always made in an study of water quality are temperature, pH, conductivity, and dissolved oxygen. Some of the instrumentation used in these is presented here.

Conductivity Meter

pH meter
The pH meter measures the water’s acid-base level. Most aquatic organisms require a pH near neutral, or 7. The Great Lakes have a limestone base, which helps buffer the impacts of acid precipitation and industrial or waste treatment plant discharges.

Conductivity Meter
Conductivity measures the free ions dissolved in the water. This is considered a conservative measure of water quality, because it generally doesn’t change unless there are outside inputs, such as road salt runoff..