Which of the following best describes a benefit of conducting sediment sampling alongside water sampling?

Conducting sediment sampling alongside water sampling offers a significant advantage in that it allows for a comprehensive understanding of waterway health. Water and sediment are interconnected in aquatic environments; the sediment often acts as a reservoir for pollutants and nutrients, and it can impact the overall quality of the water. By sampling both, one can assess not only the immediate water quality but also the historical and potential future effects of contaminants that may accumulate in the sediment. This integrated approach provides a more detailed picture of the ecosystem's health, enabling better management and remediation decisions.

In contrast to the other options, focusing solely on sediment quality ignores the critical role water quality plays in an ecosystem. The claim that sediment sampling is less expensive than water sampling does not necessarily hold true, as costs can vary based on the methods and locations used. Lastly, while speed is an important factor in sampling and analysis, the nuance of twinning sediment with water sampling emphasizes depth and breadth of knowledge over mere speed or cost considerations. Thus, the comprehensive understanding garnered through this combined sampling process is key to effective environmental assessment and management.