Computer Science – Sound
Scientific paper
May 1979
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1979e%26psl..43..241b&link_type=abstract
Earth and Planetary Science Letters, Volume 43, Issue 2, p. 241-259.
Computer Science
Sound
24
Scientific paper
An experiment was designed to assess the relative importance of sediment accumulation and bioturbation in determining the vertical distribution of nuclides in estuarine sediments. A diver-collected core, 120 cm long, was raised from central Long Island Sound and analyzed down its length for: 210Pb and 226Ra; 239, 240Pu; and Mn, Zn, Cu, and Pb. Sampling for chemical analysis was guided by X-radiography of the core. Excess 210Pb (relative to 226Ra) is roughly homogeneous in the top 2-4 cm of the core, then decreases quasi-exponentially to zero at (or above) 15 cm. 239, 240Pu and excess Zn, Cu, and Pb, relative to background values at greater depths in the core, are distributed like excess 210Pb in the top 10-15 cm. The absence of Mn enrichment at the top of the core, in contrast to other cores raised from this station, suggests that 1-3 cm of sediment was lost by erosion at the site of this core sometime prior to sampling. Below 15 cm excess 210Pb and excess Zn, Cu, and Pb are found only in the bulk sample from 25 to 30 cm and in clearly identifiable burrow fillings dissected from 70 cm and 115 cm depth. Infilling of large burrows, excavated and then abandoned by crustaceans, is therefore a mechanism for transfer of surficial material to depth in these sediments. The bioturbation rate in the top several centimeters at this station has been determined previously using 234Th (24-day half-life). The distribution of 239, 240Pu can be used to estimate a bioturbation rate for the underlying layer (to ~10 cm depth); this rate is found to be 1-3% of the maximum mixing rate for the top 2-3 cm. Using these two mixing rates in a composite-layer, mixing + sedimentation model, the distribution of excess 210Pb in the top 15 cm was used to constrain the sediment accumulation rate, ω. While the apparent rate of sediment accumulation (assuming no mixing below 2-4 cm) is 0.11 cm/yr, the model requires ω < 0.05 cm/yr. Thus in an area of slow sediment accumulation, a low rate of bioturbation below the surficial zone of rapid mixing causes an increase of at least a factor of two in apparent accumulation rate.
Aller Robert C.
Benninger Larry K.
Cochran Kirk J.
Turekian Karl K.
No associations
LandOfFree
Effects of biological sediment mixing on the 210Pb chronology and trace metal distribution in a Long Island Sound sediment core does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Effects of biological sediment mixing on the 210Pb chronology and trace metal distribution in a Long Island Sound sediment core, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Effects of biological sediment mixing on the 210Pb chronology and trace metal distribution in a Long Island Sound sediment core will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1702250