Sediment is the material that settles to the bottom of a lake or stream. Sediment may be deposited by weather-related events, soil erosion, illegal discharges, or failures of pipes, dams or other man-made structures. Excessive sediment can smother small aquatic organisms, and it can be contaminated with toxic materials. These toxic materials include organic compounds and heavy metals that bioaccumulate, or build up, within bottom-dwelling or feeding organisms. Sediment contamination can pose a threat to fish and wildlife, degrade aquatic habitat and stress aquatic organisms, as well as present health hazards to humans.
Department staff conduct sediment monitoring around the state to:
- Determine if sediments contain trace substances in concentrations above established or proposed criteria.
- Compare metals levels in sediments with data on distribution of metals concentrations in Missouri to determine background levels.
- Compare metals levels in sediments with data on distribution of metals concentrations in Missouri to determine background levels.
- Determine if sediments are relatively enriched or poorer in metals than soils of the area by analyzing soils and sediment data.
- Identify sediments with anthropogenic sources of metals and state the confidence level of that determination.
Depending upon water depth, sediment characteristics and study objectives, staff will use a variety of equipment such as scooping devices, core samplers and dredge samplers.