Variation with sediment depth

Variation with Sediment Depth. This investigation was undertaken to determine the variation of hydrogen sulfide production and associated microorganisms within the upper 8 cm of sediment from East station. Five fractions were examined representing depths of 0-1,1-2, 3-4, 5-6 and 8-9 cm. Results are summarized in Table VI. Maximum values for both sulfate... 

For stations B and C, where the LAS concentrations were higher than for A, the variation in total LAS concentration with sediment depth was determined by the homologues of 12 and 13 carbon atoms (Fig. 6.5.4). These homologues present a strong tendency to sorption and are readily biodegradable. In interstitial water, the vertical profile of the LAS concentration is similar to that observed for the sediment, particularly at stations B and C. The homologue-specific partition coefficient did not vary much with depth, because there is no appreciable variation in the composition of the sediment with depth [34]. 

Variations Between Lakes. Results of a study to evaluate sulfide production variation with water depth is given in Table V. In this experiment, samples were taken from five different sediment depths over a two-day period at each lake in early October. At both lakes sulfate reduction exceeded putrefaction by a factor of approximately 2 with overall mean rates of 0.55 and 0.29 mg S L-kH1 respectively. Sulfate reduction exceeded cysteine decomposition in all samples except one collected from Third Sister Lake at 17 m. Results of this study snow a good correlation at Third Sister Lake between percent hydrogen sulfide production attributable to putrefaction and depth of sampling station (r=0.94) and oxidation-reduction potential (r=0.98). This correlation was not observed at Frains Lake. A possible factor m differences observed may be the physical nature of the sediment at Frains which was less dense and more flocculent than thatofTliird Sister. 

A study of the variation of sulfate reduction and putrefaction with sediment depth of 0-8 cm indicated maximum putrefactive and sulfate reducing activity at a depth of 1-2 cm. The data also suggest that oxidation-reduction potential plays an important part in determining the role of putrefaction. However, the significance of this association must be tempered with the understanding that redox equilibrium is never reached in the aquatic environment and that Eh measurements are of value empirically but not thermodynamically. 

Field Evidence of Biochemical Weathering. PCB congener composition variation with depth in sediment was analyzed for evidence of bio-... 

Sano (1986) and Sano et al. (1986) found He isotopic variations with depth, 3He/4He decreasing toward the surface, in two natural gas wells in northern Taiwan. This relation is interpreted as a mantle flux to the bottom of the well, progressively diluted by radiogenic He released from the surrounding sediment as the gas migrates upward. With a simple mixing model, they obtained mantle He fluxes close to the mean oceanic value (Table 6.4), but the situation in a gas well is rather complicated, and it remains to be seen whether or not the coincidence with the oceanic value is accidental. 

The distribution of calcium carbonate in sediments with ocean depth shows wide variations. In open ocean basins, where rates of detrital sedimentation are moderate to low, sediments above 3000 meters water depth are generally high in calcium carbonate, whereas sediments below 6000 meters generally have very low calcium carbonate content. Between these depths there is a poor correlation between the weight % calcium carbonate and depth (Smith et al., 1968). Turekian... 

Void [52] developed a variety of ballistic deposition models to simulate sedimentation processes. Void used ballistic models to determine deposition densities for spherical particles which traveled via vertical paths and were deposited on horizontal surfaces. Recently, Schmitz et al. [53] used a ballistic aggregation model to describe particle aggregation at the surface of a crossflow microfiltration membrane. Schmitz and co-workers were able to account for interfacial forces empirically, and demonstrated the influence of physical and chemical variables on the resulting morphology of the fouling deposits (such as aggregate density variation with depth, and influence of shear flow and re-entrainment properties on fouling deposit density and porosity). 

Surficial sediments should reflect the weighting function of alkenone production at all seasons and depths throughout the annual cycle—the integrated production temperature (IPT) concept of Conte et al. (1992). Core-top material also provides the benefit of temporal and spatial averaging of other factors, such as genetic variability and variations in growth rate that may influence alkenone systematics. This comes at costs the time averaging varies with sedimentation rate and bioturbation, and much information... 

Figure 23. Variation of the He/ He ratios as a function of depth in basinal natural gas wells in Northern Taiwan. For two localities, Sano et al. (1986) found that the He/Tle ratios increase with increasing depth, a trend attributed to the dilution of a partly mantle-derived He component by radiogenic Me produced in the sediments. These authors concluded that (i) the required Me flux is equivalent to that derived from the whole underlying continental cmst, and (ii) the required Me flux is similar to that originating at mid-ocean ridges.

With drastic variations in sediments, composition as well as types of vanadium complexes vary. Even within a series of samples there is a noticeable variation of the vanadium complexes. For example, as the age or the depth of the fossil remains increases, a transformation of the porphyrin types from philo to etio takes place. This is merely one example of the large variety of reactions and transformations occurring in petroleum as well as other bituminous substances. The study of such effects would reveal much knowledge concerning the migration, maturation, and transformation of a diversity of fossil remains. 

SAEF-N The primary form of SAEF-N was Fe-Mn oxide combined form, whose formation and distribution were affected by the oxidation-reduction characteristics of the sediment environment. The average concentrations in 5 cores were 9.18 pmol/g in Cl, 11.95 j,mol/g in C2, 5.66 pmol/g in C3, 6.27 pmol/g in C4, and 4.71 j,mol/g in C7, reflecting the difference in the oxidation-reduction characteristics in the 5 cores. SAEF-N concentrations presented complex variations with depth, as well as the ratios of NO3-N to NH4-N (Table 3.20). 

Nafe, J.E., and Drake, C.L. 1957. Variation with depth in shallow and deep water marine sediments of porosity, density, and the velodties of compressional and shear waves. Geophysics, 22(3) 523-552. 

The Cenozoic portions of the Gulf Coast sedimentary basins are immature therefore, little cementing of the sediments has taken place. Poisson s ratio varies with depth for such sedimentary columns, reflecting the variation of properties through the column. At great depth (i.e., approaching 20,000 ft), Poisson s ratio approaches that of incompressible, plastic materials (i.e., 0.5) [35]. 

Fig. 10-15 Organic carbon fluxes with depth in the water column normalized to mean annual primary production rates at the sites of sediment trap deployment. The undulating line indicates the base of the euphotic zone the horizontal error bars reflect variations in mean annual productivity as well as replicate flux measurements during the same season or over several seasons vertical error bars are depth ranges of several sediment trap deployments and uncertainities in the exact depth location. (Reproduced with permission from E. Suess (1980). Particulate organic carbon flux in the oceans - surface productivity and oxygen utilization, Nature 288 260-263, Macmillan Magazines.)...

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