11. The lack of distinct layering indicates that clams, shrimps, and other burrowing organisms mixed the bottom sediments . 12. In 1928, Pettersson asked her to analyze a sample of sea bottom sediment to determine its radium content. 13. He developed the technique of using explosive charges to determine the type of ocean bottom sediments and their thickness. 14. The EPA estimates there are between 500, 000 and 700, 000 pounds of PCBs still trapped in river-bottom sediment . 15. The major part of the heavy metals transported to Lake Poop?seem to be immobilized in the bottom sediments . 16. The earth s surface soils, water bodies and bottom sediments are thought to be the primary biospheric sinks for mercury. 17. The sinker often had a small container attached to it that would allow for the collection of bottom sediment samples. 18. It was thought that the river's velocity would scour off bottom sediments , deepening the river and decreasing the possibility of flooding. 19. A study commissioned by Polk County in 1994 found the high level of effluent resulted in nutrient recycling from lake bottom sediments . 20. It is the shifting tides, by the way, stirring up the river-bottom sediment that are responsible for the river's characteristic mud-brown color.
