Dispersal ballast

Subtractive dye precursors (couplers) that could be immobilized in each of the silver containing layers were sought, so that dye formation in all layers could proceed simultaneously rather than successively. The first of these to be commercialized were in Agfacolor Neue and Ansco Color films, introduced soon after Kodachrome film. These reversal working films contained colorless couplers that were immobilized (ballasted) by the attachment of long paraffinic chains. The addition of sulfonic or carboxyUc acid groups provided the necessary hydrophilicity to make them dispersible as micelles in aqueous gelatin. 

An interesting dispersal scenario was described by the authors on the basis of the similarity of southern Finnish chemotypes to chemotypes found in the Netherlands, and other parts of Northern Europe. They suggest that tansy seeds, known to be common components of shipping ballast (Jutila, 1996), may have been transported to... 

The resistant nature of dormant cysts makes them likely candidates for dispersal via dredging operations, shellfish transplants, or boat ballast as well. Each of these is theoretically possible, but there is no direct evidence that demonstrates conclusively that such mechanisms have operated in the past. 

The movement of biological stressors have been described as diffusion and/or jump-dispersal processes. Diffusion involves a gradual spread from the site of introduction and is a function primarily of reproductive rates and motility. Jump-dispersal involves erratic spreads over periods of time, usually by means of a vector. The gypsy moth and zebra mussel have spread this way the gypsy moth via egg masses on vehicles and the zebra mussel via boat ballast water. Biological stressors can use both diffusion and jump-dispersal strategies, which makes it difficult to predict dispersal rates. An additional complication is that biological stressors are influenced by their own survival and reproduction. 

In oil-containing aqueous effluents the oil is present as finely dispersed droplets in a relatively clean water phase, for example oilfield produced water, refinery process water, ballast water from cargo tankers [32]. Factors preventing coalescence include the droplet s negative electrostatic charge, stabilisation by surface active components and steric stability caused by fine solids. 

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