Sedimentation testing

Sediment. The sediment test consists of filtering a definite quantity of milk through a white cotton sediment test disk and observing the character and amount of residue. Efficient use of single-service strainers on dairy farms has reduced the use of sediment tests on milk as deflvered to receiving plants. Although the presence of sediment in milk indicates unsanitary production or handling, its absence does not prove that sanitary conditions always existed. 

Granulation. Before alumination — based on a selective sedimentation test, the phosphorus shall contain a max of 3% of particles of less than 10 microns in diameter. After alumination the powder shall pass thru the following sieves ... 

Calculation to determine xg kg of famoxadone, IN-KZ007, and IN-JS940 found in soil and sediment test samples by linear regression analysis ... 

Esat TM, Yokoyama Y (1999) Rapid fluctuations in the uranium isotope composition of the oceans (abstract). Eos Transactions AGU 80(46(Fall meeting supl)) 581 Fomes WL, DeMaster DJ, Smith CR (2001) A particle introduction experiment in Santa Catalina Basin sediments Testing the age-dependent mixing hypothesis. J Marine Res 59(1) 97-112 Francois R, Bacon MP (1994) Heimich events in the North Atlantic radiochemical evidence. Deep-Sea Res 141 315-334... 

A K is by nature descriptive, but in the Kt approach the value is taken over the range of chemical conditions considered in a model to be constant and predictive. This assumption, of course, cannot hold in the general sense. A K value varies sharply with pH, contaminant concentration, ionic composition of the fluid, and so on its measurement is specific to the fluid and sediment tested. It is imperative that the modeler keep these points in mind. 

OECD (2004) Sediment-water chironomid toxicity test using spiked sediment. Test Guideline 218. OECD, Paris, doi 10.1787/9789264070264-en... 

TableJ Petroleum hydrocarbons in the tissues of English sole exposed to oil-contaminated sediment (test, T) and to nonoiled sediment (control, C) for 2 mo continuously.

Gratzer, H. Ahlf, W. Adjustment of a formulated sediment for sediment testing with Caenorhabditis elegans (nematoda). Acta Hydrochim. Hydrobiol. 2001, 29, 41-46. 

The A. marina bioassay is routinely used in the UK, but only in more saline conditions (Thain and Bifield, 2001). The survival of this polychaete in our study was hardly affected by the sediments tested during the study, but the number of casts produced varied considerably (Table 6). Significant effects with the above sediment in vivo bioassays used here have been demonstrated in other studies, not only in Dutch harbour sediments, but also marine and estuarine environments (Matthiessen et ah, 1998 Kater et al., 2001 Stronkhorst, et al., 2003b). 

Biodegradable in sea water (52 and 73% in OECD 306 tests) 68% TC02 in aerobic river water-sediment test [57]... 

Sedimentation tests are of value particularly for rapid evaluation of the effects of aging, flocculants, vibration, and any other variables that conceivably could affect a rate of filtration. The results may suggest what kinds of equipment to exclude from further consideration and what kind is likely to be worth investigating. For instance, if sedimentation is very rapid, vertical leaves are excluded, and top feed drums or horizontal belts are indicated or it may be indicated that the slurry should be preconcentrated in a thickener before going to filtration. If the settling is very slow, the use of filter aids may be required, etc. Figure 11.1 illustrates typical sedimentation behavior. Figure 11.2 summarizes an experimental routine. 

During exposure to contaminated sediments, test organisms can concentrate chemicals in their tissue and exhibit measurable (sub)lethal effects linked to accumulated substances. In the field of sediment toxicity assessment, it is noteworthy to mention that some studies have been conducted to characterize both exposure and biological effects in parallel. Exposure to contaminants can be gauged by measuring their concentrations in water/sediment and tissue, and effects can be estimated with endpoints such as survival and growth. These studies are important, for example, to detect threshold concentrations at which chemicals begin to exert adverse effects. As such, they can be useful to recommend effective chemical quality standards that will be protective of aquatic life. 

Fuchsman, PC., Barber, T.R. and Sheehan, P.J. (1998) Sediment toxicity evaluation for hexachlorobenzene spiked sediment tests with Leptocheirus plumulosus, Hyalella azteca, and Chironomus tentans, Archives of Environmental Contamination and Toxicology 35 (4), 573-579. 

Suedel, B.C. and Rodgers Jr, J.H. (1994) Development of formulated reference sediments for freshwater and estuarine sediment testing, Environmental Toxicology and Chemistry 13 (7), 1163-1175. 

The general objective, principle, and scope of application of the pT-method are succinctly described in Section 1 and also reported elsewhere in this book (see Chapter 3 of this volume, Section 5.1), where readers will appreciate that this hazard assessment scheme is adaptable to both liquid and solid media. Briefly recalled here in the context of solid-media samples such as dredged material, the pT-value, which relates to a single bioassay, and the pT-index, derived from the most sensitive organism in a test battery, permit a numerical classification of environmental samples on the basis of ecotoxicological principles. Sediment from any aquatic ecosystem (freshwater, brackish, marine) and from any of its phases (whole sediment, porewaters, elutriates or organic extracts) can be appraised provided that the proper standardized toxicity tests are available. There are whole-sediment test protocols standardized for many agencies (e.g., Environment Canada, ASTM). 

McPherson, C.A. and Chapman, P.M. (2000) Copper effects on potential sediment test organisms the importance of appropriate sensitivity, Marine Pollution Bulletin 40, 656-665. 

These discussions at present apply mainly to toxicity data derived from waterdwelling organisms, although in principle they could also apply to sediment toxicity data. Experience is limited with respect to the application of AFs to sediment data, the main problems being the restricted number of sediment test species available and the need to consider multiple exposure pathways. 

Figure 26. Probe calibration in sedimentation tests. Maxwells relation is shown for comparison. (Reproduced with permission from reference 24. Copyright 1987.)...

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