What type of sample consists of multiple grab samples combined into one sample for analysis?

• A. Composite sample
• B. Grab sample
• C. Integrated sample
• D. Batch sample

Answer: (A)

A composite sample is formed by combining multiple grab samples taken at different times or locations into a single sample for analysis. This technique is particularly useful in water treatment and environmental monitoring, as it allows for a more representative assessment of the variability in concentrations of pollutants or water quality parameters over a specific time period or spatial range.

By collecting grab samples at different intervals, variances in conditions such as flow rate, concentration of contaminants, and seasonal changes can be accounted for, providing a better overview of the overall quality of the water being tested. This approach is essential for ensuring that the analysis captures a broader picture rather than relying on a single snapshot that might only reflect specific conditions at one moment in time.

In contrast, grab samples are isolated samples taken at one specific time and location, which would not provide an accurate representation of variability. Integrated samples combine aspects of both grab and composite sampling, but this definition specifically points to the method involving multiple grabs, highlighting the unique significance and application of composite sampling in environmental assessments. Batch and integrated sampling refer to different methodologies that do not encapsulate the correct concept being asked in this question.