What does the term "head space" refer to?

The term "head space" specifically refers to the air or empty space in a sampling bottle. In field sampling, this space is crucial because it can impact the quality of the sample being collected and analyzed. Too much head space can lead to issues such as evaporation of volatile substances or contamination from atmospheric gases that may alter the chemical composition of the sample. Therefore, understanding and controlling the head space is essential for maintaining the integrity of the sample in water quality testing and other environmental analyses.