SOME ASPECTS OF THE BIOCHEMISTRY OF MUD 



by 



J. R. Vallentyne 

 Queens University 



Approximately 10^^ grams of organic matter is annually synthesized by 

 plants on the earth's surface. Most of this organic matter is degraded by ani- 

 mals and microorganisms, eventually to carbon dioxide, which is then recycled 

 in the biosphere. A small fraction of the synthesized organic matter is buried 

 in sediments. Biochemical studies on the molecular nature of this fossil organic 

 matter provide data bearing on temperature histories of geologic deposits, bio- 

 chemical evolution, and the conditions of origin of petroleum and coal. Most 

 of the critical work has been done within the past 10 years, and much remains 

 to be done in the future. 



Apart from the demonstration of the presence of trimethylamine in salt 

 marsh deposits by E. C. Shorey in 1913, no one has seriously studied the bio- 

 chemistry of salt marsh sediments. Biochemical data pertaining to other types 

 of sediment are reviewed here, focussing attention on fossil as well as recent 

 materials . 



Degradation products of plant chlorophylls have been isolated from both 

 freshwater and marine sediments by Corcoran, Orr and Brown. These workers 

 agree that chlorophylls a and b and c only rarely occur in recent sediments. 

 The most abundant green pigments in recent sediments are phaeophytin a and 

 phaeophorbide a. Related compounds (desoxophylloerythrin and desoxophyllo- 

 erythroetiophyrin) occur in sedimentary rocks and petroleum. These porphyins, 

 which are chlorophyll derivatives, have been isolated from geologic materials 

 as old as the Ordovician. 



Carotenoids have been found in virtually all recent sediments that contain 

 organic matter. A-carotene, B-carotene, echinenone and rhodoviolascin have 

 been identified. Carotenoids have not been reported to occur in sedimentary 

 rocks or fossils older than the Pleistocene. 



Cellulose and other carbohydrates have been found in recent sediments, 

 and also in lignites as old as the Cretaceous. Polysaccharides are hydrolyzed 

 to polymers of lower molecular weight during the course of geologic time. 



Polypeptides and amino acids have been found in recent sediments and in 

 sedimentary rocks and fossils dating back to the Devonian. As with the poly- 

 saccharides, the molecular weights of proteins decrease during the course of 

 geologic time. 



Recent work by the author has resulted in the isolation of microscopic 



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