CONCLUSIONS 



A number of specific conclusions concerning the levels of AMOCO 

 CADIZ petroleum hydrocarbons in various environmental compartments, the 

 changing chemistry of the hydrocarbon assemblages, and the persistence 

 of petroleum in these compartments are presented here. 



1) Upon introduction into the environment, the oil weathered 

 rapidly with evaporation and biodegradation changing the oil's 

 chemistry markedly even prior to landfall. 



2) Oil impacted a variety of intertidal sedimentary types and a 

 number of secondary impacts were noted at many stations. 



3) Oil was buried in most sedimentary environments with burial 

 and/or penetration down to 15 cm in fine-grained sediments and 

 deeper (^20-30 cm) in sandy sediment. 



4) Oil remained less biodegraded in sandy beach environments than 

 in fine-grained sediments in which heavily biodegraded oil was 

 characteristic. 



5) The presence of UCM material, pentacyclic triterpanes, and 

 alkylated phenanthrene and dibenzothiophene compounds remain 

 as characteristic chemical features of AMOCO CADIZ oil in 

 sediments. 



6) Less weathered oil appeared to be buried (10-20 cm) in fine- 

 grained sediments as evidenced in samples taken one year after 

 the spill. 



7) Offshore sediments were impacted after the shoreline impact, 

 probably through processes involving beaching, sorption on 

 intertidal sediments, and offshore transport of these sedi- 

 ments. Samples taken after the spill in April 1978 do not 

 reveal AMOCO CADIZ oil, thus indicating a lag (weeks to 

 months) in offshore deposition. 



8) Surface intertidal sediments taken in June 1981 show that 

 "normal" background inputs, both of biogenic and chronic 

 pollutant origins, have replaced AMOCO CADIZ oil as major 

 components of the hydrocarbon geochemistry. Only at the most 

 impacted stations at lie Grande marsh and within the sandy 

 beach sediment at AMC-4 (Portsall) do identifiable AMOCO 

 residues persist. At lie Grande the aromatic marker compounds 

 are absent, but hopanoid compounds (triterpanes) and a large 

 UCM persist. 



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