Variation among sites

Other specimens from New World sites. The individual data for these sherds are given in Table I, and in Table II the mean compositions of the sherds from the five sites are compared. The elements which do show some discernible variation among sites are the alkali metals rubidium and sodium. The alkali compounds tend to be water soluble and hence are susceptible to variations during burial. 

Figure 10.9. Principal components analysis of PARAFAC components and water quality parameters for the Horsens catchment data set. Score plots (A-C) showing variation among sites are on the lefL loading plots (i-iii) showing correlations between measured variables are on the right. (See Plate 17.)...

The anaerobic dechlorination of PCBs has been extensively studied both in microcosms and in field samples from heavily contaminated sites in the United States. Three main patterns have been fonnd—N that removed flanked meto-chlorines, P that removed para-chlorines, and LP that removed nnflanked para-chlorines (Bedard et al. 1998). By contrast, ort/to-chlorines were more recalcitrant. These experiments, which have been discussed in Chapter 9, Part 2, laid the fonndation for analysis of a field situation and an appreciation of the effect of long-term exposnre of contaminated lake sediment (Magar et al. 2005a,b). Substantial dechlorination took place in buried sediment cores (35-40 cm) compared with the snrface sediment cores (0-5 cm). Although there were some variations among the cores, the di- and trichlorinated biphenyls were produced at the expense of the... 

Mucus flows in the bronchial airways have not been directly measured. The measurements of particle clearance for radioactively tagged particles depend on a mixture of deposition sites and mucus flow rates. However, such measurements have shown reproducibility in the individual and a large variation among individuals. ... 

Pharmacokinetics Large variation in absorption among sites. Proteinbinding in varying degrees. Metabolized in liver. Primarily excreted in urine. 

Chemical shift variations among N-methyl cations have been related to electron densities and, in the case of fV-methylpyridinium ions, to Hammett substituent constants.126 Upfield shifts of H,126-128 13C,126 and 14N nuclei126 are observed when electron-donating groups increase the electron density at the quaternized site. In instances where shift differences are large, application of these correlations to molecules giving isomeric products will enable conclusive identification of product structures to be made. 

Variation among Sampling Sites. Dissolved humic substance samples from seven end-member environments were isolated for study. Autochthonous inputs to DOM were expected to dominate in Big Soda Lake and in Island Lake, which is a groundwater-sustained eutrophic lake in the sandhills of western Nebraska. Allochthonous inputs to DOM from a swamp environment predominate in the Suwannee River. They also dominate in the Calcasieu River in western Louisiana, but the proportion of swampland is much lower there. The Temi River is a tropical blackwater tributary of the Orinoco River in Venezuela, where allochthonous inputs dominate. The entire Sagavanirktok River basin is located north of the tree line on the North Slope of Alaska a mixture of allochthonous and autochthonous inputs was expected for the various rivers and lakes in this basin. Lastly, Hidden Lake Creek, which is the outlet of Hidden Lake on the Kenai Peninsula of Alaska, was sampled to determine if nutrient inputs from decaying salmon were contributing to primary production and autochthonous inputs to DOM. 

The fractional contribution of the major PCDD and PCDF congeners to their respective total concentrations in Niagara River sediments in Table 3 is shown in Fig. 9. Despite large variations in concentration among sites, the PCDF pattern is remarkably similar along the river. The major congeners are OCDF,... 

Neighbour-joining (NJ) analysis with approximate correction for among-sites rate variation was applied to an alignment, which did not incorporate weakly homologous sequences. Species or even phyla characterized by long branches were additionally excluded. 

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