Dated sediment layers

Dated sediment layers (1939-1991) of a small German river were studied for their LAS concentrations and the gathered data were related to political, economic and technical developments in Germany [14]. As expected the sediments corresponding to the period 1939-1945 contained no LAS, since at that time soap was the most important surfactant used for laundry washing. A significantly different picture was obtained in sediments from 1949 to 1951 when a particular LAS was used along with soap. The values determined in the two core samples amounted to 1.4 and 1.3 mg kg-1, respectively. In the sediment horizons from 1954 to 1956 no LASs were detected, which is in accordance with the fact that the less expensive branched alkylbenzene sulfonate (ABS) had replaced the linear one. In the years from 1959 to... 

In a study of dated sediment layers of Central Finland 236 CYMS and 236CYMD were measured and found most abundant in the near recipients of bleaching pulp mills. They were measured as significant contaminants with decreasing gradient in bottoms of the recipient watercourse lakes tens of kilometers downstream from the mill discharge points [24]. An example of the contents is shown in Fig. 1. 

Fig. 1. Analysis results of dated sediment layers at Lake Kuhnamo 1 km downstream from pulp mill discharge at Aanekoski, Central Finland [24]...

For most of the substances the riverine origin was confirmed by a recently reported investigation on surface sediments derived from a longitudinal profile of the Lippe river (Kronimus et al., 2004). Also, the attribution of the individual contaminants to different emission sources in particular municipal, industrial and agricultural effluents was established (LWA, 1982/1987/1991). Furthermore, contaminants derived from superposed emission sources were considered, e.g. polycyclic aromatic compounds. In the following sections, the quantitative results on contaminants and the corresponding concentration profiles obtained for the dated sediment layers are presented in detail. 

In a later study in the Venice lagoon, a dated sediment core was analysed [4]. Seven separate layers were analysed, dating from 1972 back to 1910. 

Sample type Date Bottom sediment layer, radionulclide ... 

Examples of the application of these equations to the activities of and 2 °Th in marine sediments are presented in Figs. 7.4 and 7.5. with a half life of 5730 y is appropriate for dating sediments younger than 4-5 half lives or up to c.30 Iq BP. This includes the late Quaternary through the Holocene. Profiles of versus depth for the carbonate-rich sediment cores shown in Fig. 7.4 reveal a surface layer of constant age in the top 5-10 cm followed by linear decreases with depth that reflect sedimentation rates of 0.25 and 1 cm ky The uniform top section is mixed by bioturbation (mixing... 

A technique used for dating ceramics, bricks, sediment layers, burnt flint, lava, and even cave structures like stalactites and stalagmites, based on the fact that some materials, when heated, give off a flash of light. The intensity of the light is used to date the specimen and is proportional to the quantity of radiation to which it has been exposed and the time span since it was heated. The technique is similar to electron spin resonance (ESR). Good for dates between 10,000 and 230,000 years. 

Layers from sediment cores of up to 2 m length were obtained from selected sampling locations in the urban area of Berlin and in Brandenburg at Lake Quenz (S12, H5, H7, H8, T2, T3) using a deep-freezing method (Schwarzbauer et al., 2001). The sample from station H8 represents a sediment layer of 1984/85 and the sediment sample from station T2b is dated back to 1979/80, as determined by gamma spectrometric measurements of Pb-210 and Cs-137 of sediment core slices. 

Current investigations on dated sediment cores sampled at stations T2 and H8 reveal the occurrence of ASPE with isomeric patterns according to the surface sediment samples in sediment layers of 1979/80 and 1984/85, respectively. 

Preliminary organic geochemical investigations were performed on layers of a formerly dated sediment core taken from a riparian wetland of the Lippe river (Germany). The samples were collected from two distinct depth intervals representing sedimentation periods of 1944-1952 and 1972-1984, respectively. The quantitative distribution of selected persistent lipophilic organic substances characteres municipal as well as... 

To date, only sporadic temporal and spatial measurements exist for atrazine concentration in the surface waters of the Chesapeake Bay, and the quality of the data only allows for an order-of-magnitude estimate of the resident atrazine mass. To obtain this estimate, we assume that the bulk of this herbicide resides in the water column and the sediment layer, with negligible amounts in biota and the surface microlayer, a layer of up to 1 mm thick at the air-water inter ce. 

The oldest of these sedimentation rates, Region I (150 g m 2 yr-1 or 0.063 cm yr-1) represents natural or the pre-cultural sedimentation rates before 1889. Near this location in the lake a volcanic ash layer overlain by 480 cm of sediment has been found, Gould and Budinger [15]. Radiocarbon dating of... 

Figure 11.28 shows the rhenium and osmium isotopic compositions of black shales and sulfide ores from the Yukon Territory (Horan et al., 1994). The black shale and sulfide layers are approximately isochronous. The superimposed reference isochrons bracket the depositional age of the enclosing shales. One reference line represents the minimum age (367 Ma) with an initial ( Os/ Os)q ratio of one, consistent with the mantle isotopic composition at that age (see later). The other reference isochron is drawn for a maximum age of 380 Ma, with ( 870s/ 860s)o = 12 (the maximum value measured in terrigenous sediments). Further examples of application of Re-Os dating of sediments can be found in Ravizza and Turekian (1989). 

The simplest interpretation of the sedimentary profile is that the deepest layer with the first detectable pentachloronaphthalene corresponds to the first release. That puts the date at about 1936. However, you wonder if the first release could have come later (e.g., in 1960) and downward diffusion actually accounts for the appearance of detectable concentrations in the deeper sediments. 

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