Sediment origin

An emulsion is a dispersed system of two immiscible phases. Emulsions are present in several food systems. In general, the disperse phase in an emulsion is normally in globules 0.1-10 microns in diameter. Emulsions are commonly classed as either oil in water (O/W) or water in oil (W/O). In sugar confectionery, O/W emulsions are most usually encountered, or perhaps more accurately, oil in sugar syrup. One of the most important properties of an emulsion is its stability, normally referred to as its emulsion stability. Emulsions normally break by one of three processes creaming (or sedimentation), flocculation or droplet coalescence. Creaming and sedimentation originate in density differences between the two phases. Emulsions often break by a mixture of the processes. The time it takes for an emulsion to break can vary from seconds to years. Emulsions are not normally inherently stable since they are not a thermodynamic state of matter. A stable emulsion normally needs some material to make the emulsion stable. Food law complicates this issue since various substances are listed as emulsifiers and stabilisers. Unfortunately, some natural substances that are extremely effective as emulsifiers in practice are not emulsifiers in law. An examination of those materials that do stabilise emulsions allows them to be classified as follows ... 

Chau et al. [19] have described the optimum conditions for extraction of alkyllead compounds from sediments originating in non-saline waters and in saline waters [16]. Analyses of some environmental samples revealed for the... 

For the determination of the repeatability, two sediments originating from coastal areas along the Duteh eoastline were extracted and cleaned up. One ofthe sediments had a low 2,3,7,8-TCDD TEQ eontent, whereas the second sediment had a relatively high 2,3,7,8-TCDD TEQ eontent (4.8 and 26 pg 2,3,7,8-TCDD TEQ/g sediment, respectively). The 2,3,7,8-TCDD TEQ eontent in both extracts was determined by DR CALUX analysis 10 times on the same day. The reprodueibility was determined by analyzing a 3-pM 2,3,7,8-TCDD standard and a cleaned sediment extraet. Both samples were analyzed on 10 different days and by various persons. The results are summarized in Table 1. 

Compound (/iM) Sediment origin Terminal carbon and electron flow Temperature (°C) Metabolite(s) Other remarks References... 

Gorsline D. S. (1984) A review of fine-grained sediment origins, characteristics, transport and deposition. In Finegrained Sediments Deep-water Processes and Facies, Geological Society of America Special Publication 5 (eds. D. A. V. Stow and D. J. W. Piper). Geological Society of America, Boulder, pp. 17-34. 

The dominant form of soil loss in the U.S.A. is caused by water runoff. Some 3.6 Pg of sediment is delivered to waterways annually in the 48 contiguous states, and 50% of the sediment originates from agricultural lands... 

Humic substances in marine sediments originate from both marine and terrestrial sources of organic matter, depending on the nature of sedimentary input. In some cases, a set of criteria based on chemical properties makes it possible to determine their origin. However, these criteria are less clear-cut than those established for kerogens. 

Environmental Samples. Since environmental samples such as airborne particles and sediments originate mainly from constituents of the crust (soils and rocks) and generally contain a high percentage of iron, they can be characterized by TFe Mossbauer spectroscopy. A fairly comprehensive review article has been pubhshed recently on iron oxides and hydroxides in soils (22). 

Li (1995) pointed out that the majority of the sediments in the SYS west area and the area adjacent to the ancient Yellow River came from the ancient Yellow River. However, in the east area, the sediments originated from the modern Yellow River, and the material corralled by the ancient Yellow River had not been conveyed to the east sediments area. The Yangtze River contributed to the sediments distribution to some extent, but the material of sediments in the east of the SYS could not embody the characteristics of Yangtze River material explicitly. Therefore, the sediments in the eastern area of the SYS had several somces, partly from the Yangtze River, partly from Korean Rivers, or from the sediments formed before corrosion, resuspending, and redeposition under the complex hydrodynamic conditions (Li, 1995 Song, 1997). 

---