Biomarkers parameters

The data described above can be used to predict the location of better source rocks in vertically drained basins, especially in deltaic-type environments with relatively young source rocks. With long-distance vertical migration, some of the biomarker parameters may become skewed. A number of factors must first be considered before applying this approach first, some of the parameters vary with maturity second, C30 steranes are not present in lacustrine samples and so the approach will not work in that situation and finally, it will not work where the oils were deposited prior to land plant evolution, since no vitrinite was present at that time. Oils from mixed source rocks also complicate the issue. The ability to predict source rock properties on the basis of biomarker distributions in cmde oils is a very interesting concept, since most exploration efforts try to discover oil and not source rocks. 

Reservoir geochemical protocols must address the real variations in absolute concentrations of the various commonly used geochemical tracers as lack of variation in some biomarker parameters across oilfields in reservoir geochemical studies where oil admixing has occurred is frequently not apparent using simple peak ratio protocols. 

Crushing of cleansed sands under an organic solvent allows extraction of hydrocarbons from inclusions in quartz and feldspars (cf. Karlsen et al. 1993). Figure 24 illustrates the biomarker parameters (Table 3) recorded from DSTs and fluid inclusions from Smorbukk, Smorbukk Sor and Flalten Vest. 

The sterane distribution of DST and inclusions samples from Halten Vest, Smorbukk and Smorbukk Sor (Fig. 26) suggests that both inclusions and DSTs have been sourced from type II marine source rocks, i.e. the Spekk Formation. There is no statistically relevant difference between the biomarker parameters extracted from inclusions in 6506/12-1, 6506/11-1, 6506/12-4 and Smorbukk Sor. This conclusively shows that inclusions formed in these... 

C4-benzene ratios provide a method to determine the relative maturity of light oils and condensates. The range of usefiilness for C4-benzene parameters appears to extend beyond the thermal maturity limits for all the biomarker parameters. Provided the C4-benzene parameters can be calibrated to another maturity parameter that extends beyond TAS, such as vitrinite reflectance, the C4-benzenes hold great potential as a thermal maturity indicator. 

Develop biomarkers of endocrine disruption. F iirther evidence of endocrine disruption is required in addition to population parameters. Biochemical and histopathological biomarkers are required to identify which hormone systems are affected. 

In predicting the effects of a pollutant on population growth rate, the effects of the chemical on the values of t, I, and n are of central interest. Chemical residue data and biomarker assays that provide measures of toxic effects are relevant here because they can, in concept, be used to relate the effects of a chemical upon the individual organism to a population parameter such as survivorship or fecundity (Figures 4.5 and 4.6). Examples of this are discussed in the second part of the text, including the reduction of survivorship of sparrow hawks caused by dieldrin (Chapter 5), the... 

FIGU RE 4.5 Schematic diagram of the relationship between biomarker response and change in population parameter. 

The development of models incorporating biomarker assays to predict the effects of chemicals upon parameters related to r has obvious attractions from a scientific point of view and is preferable, in theory, to the crude use of ecotoxicity data currently employed in procedures for environmental risk assessment. However, the development of this approach would involve considerable investment in research, and might prove too complex and costly to be widely employed in environmental risk assessment. 

Simmonds PL, Luckhurst CL, Woods JS. 1995. Quantitative evaluation of heme biosynthetic pathway parameters as biomarkers of low-level lead exposure in rats. J Toxicol Environ Health 44 351-367. 

Furthermore, it is necessary to evaluate the isolated and complex physiological effects of some toxic and essential metals on such endpoints (biomarkers) as the neurobehavioral and psycho-physiological parameters and also cardiovascular and immune parameters. The effect depends on metals content in the human body. Moreover, it depends on physiological effects, not only the daily intake. 

No information is available on whether biomarkers for exposure or effect of -hexane validated in adults (exhaled -hexane, 2,5-hexanedion in urine) also are valid for children. Interactions of -hexane with other chemicals have not been reported in children, but have occurred in adults (Altenkirch et al. 1977). Since interactions in adults are dependent on toxickinetic parameters, predicting interactions in children requires greater understanding of the metabolism of -hexane in children. 

For some substances, information on some toxicological endpoints is available from clinical and physiological investigations such as provocation tests for detecting allergy, lung function tests, and analyses of biochemical parameters and biomarkers for exposure or effects. 

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