2. Primary ecological alterations 



Alterations will vary according the spill size, toxicity of the 

 chemical substances released, and cleanup methodology utilized. 



2.1 Introduction of toxic materials into v/ater and soil systems 



2.2 Complete above-ground removal of vegetation in spill zone 



2.3 Partial vegetation removal in adjacent areas during access and 

 cleanup phases 



2.4 Complete removal of selected consumer species in spill area 



2.5 Increased concentration of suspended sediments and dissolved 

 nutrients 



2.6 Creation of pathways for increased saltwater inundation 



2.7 Creation of pathways which increase freshwater runoff 



2.8 Alterations of existing tidal drainage patterns 

 3. Attribute alterations 



Plant assemblages are removed or altered by either (1) the toxic 

 effects of spilled petrochemicals or brine or (2) the cleanup 

 processes which follow. 



Toxicity of oil pollutants varies with the petroleum fraction in- 

 volved. In a decreasing order of toxicity are gasoline, diesel, 

 bunker C, and crude. The most toxic oil products have the largest 

 percentage of volatiles; therefore, they become less toxic very 

 rapidly as the volatiles evaporate. Ironically, the detergents used 

 to disperse oil spills are often more toxic than the spilled mate- 

 rial. 



Natural decomposition of an oil spill begins immediately and pro- 

 ceeds via several means. Depending on the temperature and wind 

 velocity, the volatile fraction evaporates rapidly. Within 12 hr 

 of crude oil spill, roughly 40 percent is evaporated or in the water 

 column while 60 percent remains as a tarry slick. The oil can be 



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