Dissolved Oxygen

Dissolved oxygen is essential for the survival of aquatic life, and thus is almost always used in ecological monitoring programs. Oxygen probes can provide continuous and on-line measurements, and are relatively inexpensive. Sudden reductions in oxygen may be indicative of releases of organic constituents by wastewater collection and treatment systems, combined sewer overflows, and surface water runoff. Given that these releases also often include microbial pathogens and other important pollutants, measurement of source water dissolved oxygen can be a relatively easy, though not very specific or sensitive, means of monitoring gross changes in water quality from these sources. In addition, diurnal fluctuations in dissolved oxygen can be indicative of the presence of algae; thus oxygen levels are sometimes used in conjunction with chlorophyll and turbidity measurements to monitor for algal blooms. Most multi-parameter probes include units for measuring dissolved oxygen.