No abstract

The technical aspects of oil spill remote sensing are examined and the practical uses and drawbacks of each technology are given with a focus on unfolding technology. The use of visible techniques is ubiquitous, but limited to certain observational conditions and simple applications. Infrared cameras offer some potential as oil spill sensors but have several limitations. Both techniques, although limited in capability, are widely used because of their increasing economy. The laser fluorosensor uniquely detects oil on substrates that include shoreline, water, soil, plants, ice, and snow. New commercial units have come out in the last few years. Radar detects calm areas on water and thus oil on water, because oil will reduce capillary waves on a water surface given moderate winds. Radar provides a unique option for wide area surveillance, all day or night and rainy/cloudy weather. Satellite-carried radars with their frequent overpass and high spatial resolution make these day-night and all-weather sensors essential for delineating both large spills and monitoring ship and platform oil discharges. Most strategic oil spill mapping is now being carried out using radar. Slick thickness measurements have been sought for many years. The operative technique at this time is the passive microwave. New techniques for calibration and verification have made these instruments more reliable.

No abstract

No abstract

No abstract

No abstract

Multicomponent composition and corresponding physical properties data of crude oils and petroleum products are needed as input to environmental fate simulations. Complete sets of such data, however, are not available in the literature due to the complexity and expense of making the measurements. Environment Canada has previously developed a database of various physical and chemical properties of crude oils and petroleum products. In this cooperative project, ten “typical” crude oils and refined products in common use or transport were identified for subsequent characterization. Measured oil physical properties include API gravity, density, sulphur content, water content, flash point, pour point, viscosity, surface and interfacial tension, adhesion, the equation for predicting evaporation, emulsion formation, and simulated boiling point distribution. The chemical composition of the oils are quantified for hydrocarbon groups, volatile organic compounds, n-alkane distribution, distribution of alkylated polyaromatic hydrocarbon (PAH) homologues and other EPA priority PAHs, and biomarker concentrations. This project will provide the most complete and comprehensive database for the selected oils to date. The new composition data will be integrated into the existing Environment Canada oil properties database. The results will be made available to the public both on the world wide web and as a database on disc.

Extensive experimentation was conducted on oil evaporation. The results of the regulation nature of oil evaporation experiments, show that oil is not strictly boundary-layer regulated specifically: (1) the evaporation rate of several oils with increasing wind speed shows that, unlike water, the evaporation rate does not change significantly except for the initial step over 0-level wind; (2) increasing area does not significantly change oil evaporation rate; (3) decreasing thickness does not increase oil evaporation rate; (4) the volume or mass of oil evaporating correlates with the evaporation rate; (5) evaporation of pure hydrocarbons with and without wind (turbulence) shows that compounds larger than nonane and decane are not boundary-layer regulated. The fact that oil evaporation is not strictly boundary-layer regulated implies a simplistic evaporation equation will suffice to describe the process. A simple equation of the form, evaporation = constant × logarithm of time, is sufficient to describe evaporation. The following processes do not require consideration: wind velocity, turbulence level, area, thickness, and scale size. The factors found to be important to evaporation are time and temperature. The equation parameters found experimentally for the evaporation of oils can be related to commonly-available distillation data for the oil. Specifically, it has been found that the distillation percentage at 180°C correlates well with the equation parameters. Relationships enabling calculation of evaporation equations directly from distillation data have been developed. These equations were combined with the equations generated to account for the temperature variations. The results have application in oil spill prediction and modelling. The simple equations can be applied using readily-available data such as sea temperature and time. Old equations required oil vapour pressure, specialised distillation data, spill area, wind speed, and mass transfer coefficients, all of which are difficult to obtain.