Surface slick

Corexit 9527 is a water-and ethylene glycol monobutyl ether-dissolved dispersant. The nature of the surface-active agent has not been disclosed. Laboratory tests were conducted using 0.5-mm thick, fresh Alberta Sweet-Mixed Blend crude oil treated with Corexit 9527 dispersant applied from an overhead spray boom [165]. The effects on dispersion efficiency of mixing jet pressure, mixing jet flow rate, jet standoff distance, and vessel speed were evaluated. The system operates with a nozzle pressure of 7000 kPa, a flow rate of 55 liter/min per nozzle, and nozzles positioned approximately 0.6 m from the water surface. In laboratory tests, such a system was capable of dispersing 80% to 100% of the surface slick. 

Table II. Effect of Exposing Lobsters to a Surface Slick of Oil for Five Months on AHH Activity...

By comparison, Venezuelan crude (exposed to 1-3 mis as a surface slick in a 20 1 aquarium for 3 days) was effective in inducing liver as well as heart, kidney, and spleen tissues (Table V). 

While the nature of the material is important, the surface of the material is also often critical. The human body wants to wrap around or connect to bodies within its domain. In some cases, the desired situation is little or no buildup on the polymer. Here, surface slickness is needed. Siloxanes and fluorinated materials such as PTFE are generally slick materials, but other materials can be made slick through surface treatments that present to the body few voids and irregularities at the atomic level. In other cases, body buildup, and surfaces and materials that assist this growth are preferred. Surface hydrophobicity or hydrophilicity, presence or absence of ionic groups, and chemical and physical (solid or gel) surfaces are all important considerations as one designs a material for a specific application. 

This is generally seen as an indication that wind is an important driving factor for lakes, estuaries, and oceans, ft has been shown that breaking waves and water surface slicks are important (Asher and Wanninkhof, 1998), and there are other parameters -such as mean square water surface slope - that have been proposed as better indicators (Jahne, 1991). The problem is that our ability to predict these indicators from wind velocity measurements have not been developed and tested for liquid film coefficient. 

Jahne et al. (1984,1987) proposed that hquid film coefficient is better related to mean water surface slope. Frew (1997) has found that the Kl relationship using mean square slope can be used to describe gas transfer with and without surface slicks. The problem with mean surface slope is that it cannot be accurately predicted for water bodies, because most investigators have emphasized the larger and longer waves, and the slope is most significant for the small, short waves. This will likely be the subject of future investigations. 

Romano, J. C., Sea-surface slick occurrence in the open sea (Mediterranean, Red Sea, Indian Ocean) in relation to wind-speed , Deep-Sea Research Part 1 - Oceanographic Research Papers, 43,4,411-423 (1996). 

Unique concentrated liquid self-finish. Used as the major softening component in pre-cure and post-cure permanent press processing. Provides full-bodied softness with surface slickness and luster. Effectively reduces "boardiness" on post-cured fabric. Improves fabric drape and surface touch after calendering wash/wear and pre-cure fabrics. 

Barger and Garrett (97) have shown that the organic material found on the aerosol did indeed come from the sea with the jet and film drops and not from any continental source. They found that the aerosol contained a mixture of surface-active compounds and nonpolar hydrocarbons, and specifically identified five fatty acids (C14-C18) to be in the same relative proportions as have been found in sea surface slicks. Further, the film pressure vs. area curves for the surface-active material on the aerosol were of the liquid-expanded type, quite similar in shape to those reported for sea surface samples (36). 

Seba, D. B., Corcoran, E. F., Surface Slicks as Concentrators of Pesticides... 

Gasoline from a tank truck spill has contaminated a small stream that enters a lake. Although the surface slick (NAPL) has evaporated, some gasoline is now dissolved in the lake water. The lake is stratified, and the epilimnion is 4 m thick. Consider the fate of two specific compounds in the fuel pentane (C5H12) and octane (C8H18), both initially present at concentrations of 100 ppb. 

The long-term fate of dispersed oil is not known, although it probably degrades to some extent as it consists primarily of saturate components. Some of the dispersed oil may also rise and form another surface slick or it may become associated with sediment and be precipitated to the bottom. 

Avoidance is another response to oil spills. Some species of fish, seals, and dolphins will avoid surface slicks and move to unoiled areas. Some birds, however, are attracted to oil slicks, mistaking them for calm water. Further research is being done in this area. 

In order to understand how surface slicks are formed and how they are broken up, it is necessary to take into account a number of elementary processes and how they work in combination. This paper does not pretend to present anything like a complete list of these processes, nor does it have much to say about their interaction. What is intended is a simple-minded discussion on a few effects that are felt to be of importance to establish a more coherent description of slicks. 

It is commonly observed that an obstruction on the surface of water flowing gently in an open channel (with free passage underneath the obstruction) causes a spontaneous surface film to accumulate on the upstream side. Although this is not the way a surface slick is generated, there is perhaps something to be learned here. 

The surface motion is of many scales, spanning from mm-waves to meso-scale eddies. In our discussion perhaps the range 10 1 to 103 meters is of interest. Surface slicks are only observed for relatively low and moderate winds. The surface motion during slick conditions may, however, be the result of earlier wind induced turbulence and Langmuir cells in the upper ocean layer. Small scale motion (of the order of 10 cm or less) is probably due to a convective motion in a shallow surface layer (Gemmerich and Hasse 1992). 

Scott JC, Thomas NH (1999) Sea surface slicks - surface chemistry and hydrodynamics in radar remote sensing, in Wind-over-wave couplings. Perspectives... 

The SSSB is deployed in the Atlantic Ocean approximately 40 km northeast of Cape Hatteras (Case 1413) at 35° 26.16 N, 75° 2.90 W and retrieved at 35° 24 N, 75° 4 W. The data collection period is from 13 59 29.14 (t = 0) to 16 09 22.03 (t =7783.15s) UTC. The data for the first 14 minutes or so are onboard the research vessel and not used. On this day, two long internal wave bands several kilometres long and approximately 2 to 4 kilometres apart are spotted on the water surface. The buoy is released into water at 14 13 UTC. The sky is partly cloudy. At 14 49 (t 3000 s) the ship is in a large dark cloudy area. The buoy records a sharp drop in the ambient light at t >2500 s. The dual surface slick bands are visible throughout the morning. The buoy obviously crosses one of them at t 3100 s when a dip of 0.1°C water temperatures is recorded (Fig. lb). Visual confirmation of this encounter is not available due to the large distance between the ship and the buoy. However, similar surface temperature drops (from Jim Edson s onboard met-sensor display) occur when ship crosses slick bands in a few other occasions. 

Infrared imaging a novel tool to investigate the influence of surface slicks on air-sea gas transfer... 

Infrared observations of the effects of surface films on heat and gas transfer have been made in situ (Frew et al. 2004). Figure 10 (upper) shows the instrumented air-sea interaction catamaran LADAS operating within a banded surface slick during the CoOP97 study. Simultaneous infrared imaging and measurements of wave slope and surfactants outside and inside of the slick determined that, when the slick was entered, the surface temperature distribution shifted toward lower temperatures and the spatial scales of the temperature fluctuations at the sea surface increased (Fig. 10, lower), characteristic of reduced surface renewal and an attenuation of mixing in the aqueous boundary layer. The estimated temperature gradient increased from 0.13 Kelvin to 0.24 Kelvin and the net heat flux dropped from 77.2 Watt m 2 to 36.5 Watt m"2. The 80% increase in AT and a 50% decrease in the heat flux lead to a decrease in the estimated heat transfer velocity from 49.7 cm h"1 to 13.1 cm h"1. 

The detection of ocean surface slicks by microwave radars at intermediate incidence angles is well established. The all-weather day-and-night capabilities of microwave remote-sensing has resulted in its wide operational use by harbour authorities for the control of oil pollution in the coastal zone (Attema and Hoogeboom 1978, Sherman 1992). In research, microwave radars can also help further our understanding of air-sea interactions and hydrodynamic processes by providing extensive synoptic two-dimensional maps of the slicks spatial distribution (Espedal et al. 1996, da Silva et al. 1998). 

Table IV. Hydrocarbons Dissolved in Seawater Equilibrated with Oil Samples and Percentage Remaining in Surface Slick (La Rosa crude oil) °...

In Table V the lowest-molecular-weight hydrocarbons are not present in the highest concentrations. Instead, concentrations increase with increase in molecular weight thus, the conclusion that truly dissolved hydrocarbons were minor constituents under the oil slicks was made. The measured hydrocarbons shown in Table V have relative concentrations expected for partly weathered oil and resemble the evaporative loss of volatile hydrocarbons from surface slicks (Figure 5). 

The earliest reported observations of natural films on the sea made use of this simple indicator, and much of this work is described in the papers, and references cited therein, of Ewing (1950), Stommel (1951) and LaFond (1959). When surface slicks are seen, they are usually aligned in long, parallel streaks that may or may not be oriented with respect to the wind (Blanchard,... 

Four groups of workers have independently reported total fatty acid measurements in microlayer and subsurface seawater samples. Their results are collected in Table VII. In surface slicks of Narragansett Bay, adjudged by visual observation to be heavy, continuous but moderate and light respectively, Quinn and Wade (1972) found that microlayer fatty acid concentra-... 

Oily Organic Content. The partition of pesticides from water into oils of petroleum origin in natural waters as surface slicks and sedimented oil have recently been reported (23). The extracting of pesticides from samples containing oil globules which partition pesticides is a new problem which aquatic residue chemists must solve. 

The insoluble surface slicks and thicker films of organic matter are interesting. On the open sea, these thin layers probably are primarily of natural origin and consist of C8-Cj2 fatty acids (both saturated and unsaturated), esters, alcohols, olefins, and alkanes (17, 18, 19, 20,16). Natural petroleum seeps, fats from decaying plants and animals, rainout from air, and coagulation of soluble organics by rising bubbles represent potential sources (21). 

Another source of variability in measurements is due to natural surface active materials that result from biological and chemical processes. Frew et al. [50] found in laboratory studies that surfactant materials from various phytoplankton species could decrease O2 invasion rates by 5-50%. Because of breaking waves and turbulence, intact surface slicks exist only to wind speeds as high as about 6 m s but a surface excess of soluble surface active materials is maintained at considerably higher wind speeds and will influence gas exchange rates accordingly [52,53]. 

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