For what purpose is a clean water sample taken during oil spill sampling?

A clean water sample is taken during oil spill sampling primarily to serve as a baseline or reference point for comparison against polluted water. This allows responders and researchers to measure the extent of contamination and understand the impact of the oil spill on the environment. By having a clean water sample, it becomes possible to quantify how much the pollution has altered the water quality and to assess the effectiveness of remediation efforts.

While the other purposes mentioned could play a role in specific testing scenarios, the fundamental importance of having a clean water sample lies in its role as a reference standard. This comparison helps in evaluating the concentration of various pollutants present in the affected water, thus aiding in environmental assessments and decision-making processes regarding clean-up strategies.