Spatial variations and chronologies of aliphatic hydrocarbons in Lake Michigan sediments.
Four sediment cores were collected in fine-grained depositional areas of the southern basin of Lake Michigan. Spatial variations of aliphatic hydrocarbons in surficial sediments were consistent with a lakeward movement of riverine sediments in a series of resuspension-settling cycles in which an unresolved complex mixture (UCM) of hydrocarbons associated with dense sediments is deposited in nearshore areas, fine-grained sediments of terrestrial origin accumulate in the deep basin, and planktonic hydrocarbons are depleted by microbial degradation during transport to the deep basin. The rate of accumulation of the UCM (a marker of petroleum residues) in deep basin sediments has increased by more than an order of magnitude since 1880, from 60 {mu}g m{sup -2}{center_dot}a{sup -1} to approximately 960 {mu}g m{sup -2}{center_dot}a{sup -1} in 1980. Crude estimates of the atmospheric loading of the UCM (1100 {mu}g m{sup -2}{center_dot}a{sup -1}) indicate that accumulations in deep-basin sediments might be supported by atmospheric deposition. Agreement was poor between the atmospheric flux of the terrestrial n-alkanes ({Sigma}C{sub 25}, C{sub 27}, C{sub 29}, C{sub 31}) to the deep basin (3200 {mu}g m{sup -2}{center_dot}a{sup -1}) and the sediment accumulation rate (660 {mu}g m{sup -2}{center_dot}a{sup -1}). Understanding of atmospheric fluxes, estimated from the very few available data, would be improved by more frequent measurement of the levels of aliphatic hydrocarbons in air and precipitation and a better knowledge of the particle deposition velocities and precipitation scavenging coefficients.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); NOAA
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 942960
- Report Number(s):
- ANL/ER/JA-36279; ESTHAG; TRN: US201002%%464
- Journal Information:
- Environ. Sci. Technol., Vol. 35, Issue 2 ; Jan. 15, 2001; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- ENGLISH
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