Preparing the Hydrocarbon/Crude Oil

Marine Oil Snow, a Microbial Perspective

“…WAF were developed by toxicologists in an attempt to distinguish true chemical toxicity from physical smothering (Widdows et al, 1982;Singer et al, 2000). Essentially the oil is stirred into seawater for a defined time, allowed to "settle" (i.e., for oil droplets to coalesce and float), and then WAF is drawn off from below the slick (see Prince et al, 2016a). If dispersant is also present, the liquid is known as Chemically Enhanced Water Accommodated Fraction (CEWAF), and other abbreviations abound to describe dilutions, higher energies of mixing, etc.…”

“…The concentration of the latter depends on the mixing energy and the "settling time, " which in turn defines how much of a reservoir the drops provide for resupplying soluble compounds should they be consumed from the aqueous phase by biodegradation or evaporation. WAF with nominally similar concentrations have significantly different concentrations of soluble compounds if they are made directly at the nominal concentration, or by dilution from a more concentrated "stock" (Prince et al, 2016a), and one cannot readily predict the chemical composition of either. In contrast, while oil-in-water dispersions may have variable droplet sizes depending on the energy used to generate the dispersion, the chemical composition of what is in the vessel is reproducible anywhere, and is readily calculated.…”