Benthic Flux Sampling Device


The Benthic Flux Sampling Device (BFSD) is an instrument for measuring the flux rates (i.e., rates of change or movement) of contaminants in sediment. (Benthic refers to a narrow zone of water and sediment at the bottom of a body of surface water.) Benthic organisms are bottom feeders and the small organisms that live in sediment. The BFSD collects samples from a sealed volume of water at the sediment/water interface for 2 to 4 days. A flux rate is measured by analyzing the samples for an increase or decrease in contaminant concentration. Increases in concentration indicate that the contaminant is moving out of the sediment; decreases in concentration indicate that the contaminant is moving into the sediment.

Limitations and Concerns

Sampling with this device should be followed with more thorough analysis if contaminants are indicated.

The results should not be relied on to provide information on ecological effects.


BFSD is an on-site screening tool used to determine whether contamination in sediments is moving to surface water. It is primarily used to detect the presence of heavy metals (e.g., lead, mercury, chromium, zinc, and copper), polychlorinated biphenyls (PCBs), dioxins, and petroleum products. It can be used to help determine whether dredging will increase environmental risks or if contaminants are being deposited in the sediment from surface waters.

Technology Status

The technology and methods are well developed. They can be considered commercial.

Web Links

Other Resources and Demonstrations

See for documents on contaminated sediment.