What are field blanks used for in water sampling?

Field blanks are an essential tool in water sampling that help to ensure the integrity of the data collected. Specifically, they are used to check for cross-contamination during the sample collection process. When collecting water samples, it is crucial to ensure that any detected contaminants are actually present in the water source and not introduced from external sources or equipment.

Field blanks are typically created by filling a clean container with deionized water that has not been in contact with the sample site or sampling equipment. This blank sample is then treated in the same manner as the actual samples, including transportation, storage, and analysis. By comparing the results of the field blank with those of the actual water samples, researchers can determine if any contamination has occurred during the sampling process. If impurities are found in the field blank, it indicates that there was likely cross-contamination, which would affect the reliability of the sample results.

Using field blanks is a standard practice in environmental monitoring and ensures that the data collected can be trusted to reflect the true conditions of the water body being studied.