How does composite sampling differ from grab sampling?

Composite sampling is characterized by its method of combining multiple individual samples collected from different locations or over a period of time, which helps to obtain a more representative measure of a water body or environment. This approach is particularly useful in assessing variability and averages within a larger area or timeframe, as it can account for fluctuations in contaminant levels or concentrations that might occur at various locations or times.

In contrast, grab sampling involves taking a single sample at a specific point in time, which may not accurately reflect the overall conditions or variability of the water being sampled. Therefore, the defining feature of composite sampling is its ability to aggregate data for better representation, making it essential for effective water quality monitoring and assessment. This ability to capture a broader perspective on water quality rather than just a snapshot is what makes composite sampling valuable in environmental science and regulatory compliance.