Organo-mineral complexes and their study by radiocarbon dating

Journal Article · · Soil Sci. Soc. Am. J.; (United States)

OSTI ID:6414968

Anderson, D W; Paul, E A

The objective of this study was to investigate the long-term cycling of organic C in cultivated soils by radiocarbon dating. Samples from a clayey Haplorboroll soil (Indian Head) taken in 1963 and 1978 showed a general reduction in radiocarbon age of the whole soils of 20%. This was attributed to the enrichment of /sup 14/C in the atmosphere because of nuclear explosions in the 1960s, and its subsequent incorporation into organic matter. Relative decreases in age were least active fractions. The apparent age of the humin and clay-associated HA-B decreased much more, indicating their greater involvement in short-term cycling. A second clayey Haploboroll soil (Melfort) was studied by chemical fractionation and separation into size fractions after ultrasonic dispersion. The HA-A and coarse clay-associated organic C were oldest, with a much younger date for fine-clay-associated organic C. Fulvic acids purified by dialysis to eliminate materials less than 2000 molecular weight had an old date of 1140 +/- 35 yr. Size fractionation of two other Boroll soils indicated young radiocarbon ages (radiocarbon enrichment) of fine clay-associated organic C. These finding are discussed in terms of the cycling of organic matter and nutrients. Particular attention is given to clay-humus interactions and their importance in protecting otherwise labile humic materials to provide a substantial pool of moderately available nutrients.

• Research Organization: Univ. of Saskatchewan, Saskatoon
• OSTI ID: 6414968
• Journal Information: Soil Sci. Soc. Am. J.; (United States), Journal Name: Soil Sci. Soc. Am. J.; (United States) Vol. 48:2; ISSN SSSJD
• Country of Publication: United States
• Language: English

Related Subjects

510101* -- Environment
Terrestrial-- Basic Studies-- Radiometric Techniques-- (-1989)
54 ENVIRONMENTAL SCIENCES
AGE ESTIMATION
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BUILDUP
CARBON 14
CARBON CYCLE
CARBON ISOTOPES
CHEMICAL ANALYSIS
CLAYS
EVEN-EVEN NUCLEI
EXPLOSIONS
FALLOUT
HUMUS
ISOTOPE DATING
ISOTOPES
LIGHT NUCLEI
NUCLEAR EXPLOSIONS
NUCLEI
ORGANIC MATTER
RADIOISOTOPES
SOILS
YEARS LIVING RADIOISOTOPES