Field tests provide accurate measurements for which of the following pollutants?

Field tests are designed to provide immediate and reliable measurements of specific parameters within water or wastewater samples. Chlorine residual testing is particularly suited for field testing because it requires quick analysis to ensure that chlorine levels are adequate for disinfection purposes in water treatment systems.

Chlorine residual refers to the amount of chlorine remaining in the water after a certain contact time, which is critical for ensuring that the chlorination process is effective in killing pathogens. Field tests can rapidly give accurate measurements of chlorine, enabling operators to make timely decisions regarding water quality and treatment adjustments on-site.

In contrast, while oxygen levels, heavy metals, and nutrients can also be measured, these tests may require more sophisticated laboratory analysis or specialized equipment for accurate assessment. Measuring oxygen levels is typically more complex and can involve multiple factors, while heavy metals often require precise laboratory methods to detect low concentrations. Nutrients, such as nitrogen and phosphorus, also often necessitate extensive processing and analysis that are better suited for laboratory settings than for instant field measurements.