Sediment Sedimentation

Sediment. Sediment is most commonly used as an operational check of filter efficiency and leakage, although some customers, especially those who iatend to melt the sugar iato clear solutions, write sediment restrictions. The measurement is normally done by passiag the 50% solution used for the color determination through a half black—half white filter pad and visually counting the white and black specks. 

If Vtii/Ptii = 1 then the accumulation of °Thxs in marine sediments would provide an assessment of their sedimentation rate. For instance, if Pm is N dpm m yr , and N dpm are found in the upper 1 cm of 1 m of seafloor, then the sedimentation rate must be lcmyr Sedimentation rate is an important variable in paleoceanographic reconstruction as it provides the timescale for the continuous record of environmental change recorded in marine sediments. Sedimentation rate is also a key geochemical variable as sediments are the major sink for most chemical species in the ocean. A tool allowing assessment of past sedimentation rates is therefore an appealing prospect. 

Compartment Air Water Soil Sediment sediment Fish... 

Soil-Air Water-Sediment Sediment-Water Soil-Water... 

Determination of the persistence and mobility of organotin compounds — especially in aquatic abiotic materials, such as sediments, sediment interstitial waters, suspended particulates, and the water column — and on the partitioning of these compounds between the surface microlayer and subsurface waters (Wilkinson 1984 Thompson et al. 1985). 

Figure 5.2.4 shows the variation of the concentration of LAS and long-chain SPCs with depth, with reference to the wet sediment (sediment + interstitial water), versus the variation of NO3 and SO4-, in the interstitial water. A very sharp decrease in the concentration of LAS and low concentrations of SPC are observed in the oxic zone, the lower... 

Biogenous sediments Sediments that are composed of hard or soft parts, such as shells and tissues that were synthesized by marine organisms. 

Hemipelagic sediments Sediments that lie in water depths of 200 to 3000 m (roughly encompassing the continental slope and upper part of the rise). 

Pelagic sedimentation Sedimentation that occurs at rates less than 1 cm/lOOOy. This is characteristic of sediment on the abyssal plains and mid-ocean ridges. 

Poorly soiTed sediments Sediments that contain a wide range of different size class particles, such as clays, sands, and pebbles. 

Relict sediment Sediments that are no longer forming. Most of the sediments on the continental margins are presently relict. Some are even eroding. 

Unsorted sediments Sediments that contain unconsolidated grains exhibiting a wide range of particle sizes. Same as poorly sorted sediments. 

Well-sorted sediments Sediments composed of one size class of particles, e.g., a deep-sea clay. 

Sorption onto suspended sediments Turbulent mixing exposes chemicals to sediment Sediment-water partitioning... 

Paleolimnological Conditions. Because of the interplay between primary production, oxygen content of bottom waters, and the sulfur content and speciation of sediments, sediment profiles of S probably preserve records of paleolimnological conditions. Several studies (23-25, 205) point to increased S content of sediments as a result of eutrophication. Mechanisms involve both rates of S supply to sediments (seston deposition and diffusive gradients) and rates of S reduction and oxidation. The relative S enrichment... 

Profundal Sediments. Sediment cores were collected in precleaned acrylic tubes by scuba divers following similar clean sampling procedures... 

---