Encyclopedia of Environmental Science and Engineering, Volume I and II

1302 WATER: PROPERTIES, STRUCTURE, AND OCCURRENCE IN NATURE

isotopes aids the quantitative interpretation of biogeochemical

and environmental processes and cycles (Broeker, 1974).

Organic Carbon

The cycle of carbon in natural wastes is especially impor-

tant because it is interrelated with the cycles of all other

elements. Furthermore, the organic material produced in

the oceans constitutes one of man’s most significant marine

resources.

Most of the carbon in the earth’s crust has cycled through

organisms and plants; as a result it has been incorporated into

unstable but long-lived biochemical structures. Information on

the catabolic pathway of organic life substances permits pre-

diction of the type of organic substances to be found in natural

waters. Table 7 gives a greatly condensed and simplified survey

of the decomposition products of life substances and includes

an abbreviated list of specific organic compounds reportedly

found in natural bodies.

In fresh water bodies one typically encounters concentra-

tions of a few milligrams carbon per liter, but occasionally

(e.g., in bog or swamp waters) concentrations may be as high

as 50 mg C per liter. In the oceans the concentrations of organic

carbon range from 0.5 to 1.2 mg C per liter, with the higher

values occurring in the surface waters. Particulate organic

carbon, including planktonic organisms, generally accounts for

TABLE 7

Naturally occurring organic substances

Life substances Decomposition intermediates

Intermediates and products typically found

in nonpolluted natural water

Proteins

Polypeptides RCH(NH ) COOH

RCOOH

RCH OHCOOH

RCH OH

R

aminoacids^2

2

→→ 2

CCH

RCH NH

3

22

⎧

⎨

⎪

⎪⎪

⎩

⎪

⎪

⎪

NH , CO , HS , CH , HPO , 42 4 4^2 peptides,

amino acids, urea, phenols, indole, fatty

acids, mercaptans

Polynucleotides Nucleotides → purine and pyrimidine bases CO 2 , CH 4 , aliphatic acids, acetic, lactic,

citric glycolic, malic, palmitic, steric,

oleic acids, carbohydrates, hydrocarbons

Lipids

Fats

Waxes

Oils

⎫

⎬

⎪

⎭⎪

Hydrocarbons

RCH CH COOH + CH OHCHOHCH OH

RCH OH

RCOOH

Shorter chain acids

R

22 2 2

2

→

CCH

RH

fatty acids glycerol 3

⎧

⎨

⎪

⎪⎪

⎩

⎪

⎪

⎪

Carbohydrates

Cellulose

Sta r ch

Hemicellulose

⎫

⎬

⎪

⎭⎪

C(HO)

monosaccharides

oligosaccharides

chitin

h

xy 2 →

⎧

⎨

⎪

⎩⎪

⎫

⎬

⎪

⎭⎪

→

eexoses

pentoses

glucosamine

⎧

⎨

⎪

⎩⎪

⎫

⎬

⎪

⎭⎪

HPO 42 , CO , CH 24 ,glucose, fructose,

galactose, arabinose, ribose, xylose

Lignin (C 2 H 2 O)x → unsaturated aromatic alcohols → polyhydroxy carboxylic acids

Porphyrins and Plant Pigments

Chlorophyll

Hemin

Carotenes and

Xantophylls

⎫

⎬

⎪⎪

⎭

⎪

⎪

Chlorin→→pheophytin hydrocarbons Phytane

Pristane, carotenoids Isoprenoid, alcohols,

ketones, acids

Porphyrins

breakdown intermediates, e.g., Complex substances formed from → Melanins, melanoidin, gelbstoffe

Phenols + quinines + amino compounds → Humic acids, fulvic acids, “tannic”

Amino compounds + breakdown products of carbohydrates substances

From Stumm and Morgan (1981).

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