Final answer:
Grab samples are used to measure a variety of water quality indicators like temperature, pH, conductivity, dissolved oxygen and specific chemicals such as H+, NH4/NH3, and K+. These measures help ensure compliance with National Primary Standards for Drinking Water, by examining both primary and secondary contaminants.
Step-by-step explanation:
Grab samples are commonly used when measuring water quality indicators such as temperature, pH, conductivity, dissolved oxygen, and the presence of specific chemical species. These samples are taken at a specific point in time and location, and they allow for the immediate measurement of water characteristics, which can capture transient variations in water quality.
For example, grab samples can be used to test for the concentration of H+ in laboratory samples, blood, soil, and ground and surface water. Similarly, other species like NH4/NH3 (ammonia) can be measured in wastewater and runoff water, or K+ (potassium) in samples like blood and wine. Other water quality indicators such as specific gravity are also measured using grab samples with equipment like a hydrometer.
According to the National Primary Standards for Drinking Water, water quality standards include designated uses of the water body and water quality criteria that protect these uses, which might involve both primary contaminants, which can be toxic in small amounts like Hg, As, and U, and secondary concerns such as Fe and Zn that affect color, taste, and odor.
The process of evaluating water clarity involves both visual examination for clarity or cloudiness and more detailed assessments such as microscopic examination and pH testing. The EPA also recommends adding varying amounts of chlorine to water samples to determine chlorine residuals, which are important for maintaining safe drinking water quality.