Literature Review of Chemical Oil Spill Dispersants and Herders in Fresh and Brackish Waters

摘要

The purpose of this research is to document what is currently known about the use of dispersants and chemical herders in fresh and brackish waters to assist decision makers when they are confronted with these conditions. An extensive review of worldwide scientific and technical journals has been undertaken to identify relevant literature on the use of chemical treating agents for oil spill response in fresh and brackish water. Numerous laboratory-scale, meso-scale and field studies, dating back to the late seventies, have been conducted to study the effect of water salinity on the effectiveness of oil spill chemical dispersants. The consistent significant finding of all of these tests is that dispersant designed for use in marine environments (30 to 35 ppt salinity) are considerably less effective when the salinity falls below about 20 ppt or above 40 ppt. Dispersants have been formulated for use in fresh water and these have also been tested for effectiveness over a range of water salinities, although not as extensively as the marine dispersants. The effectiveness of the freshwater dispersants have been shown to generally be much better than the marine products in freshwater but often achieve their best results in waters between 10 and 20 ppt salinity. In theory, water salinity should have only a small influence on the effectiveness of herding agents. Tests using herders in fresh, brackish and salt water consistently have confirmed that salinity has a minimal effect on their performance. France is the only country to have publish information on dispersant use policies and criteria for their use specific to freshwater and it appears to be the only nation to have a list of dispersant products specifically approved for use in fresh water.