Organic-rich

Growth faulted deltaic areas are highly prospective since they comprise of thick sections of good quality reservoir sands. Deltas usually overlay organic rich marine clays which can source the structures on maturation. Examples are the Niger, Baram or Mississippi Deltas. Clays, deposited within deltaic sequences may restrict the water expulsion during the rapid sedimentation / compaction. This can lead to the generation of overpressures. 

Consider azeotropic distillation to dehydrate ethanol with benzene. Initial steady-state conditions are as shown in Fig. 13-108. The overhead vapor is condensed and cooled to 298 K to form two hquid phases that are separated in the decanter. The organic-rich phase is returned to the top tray as reflux together with a portion of the water-rich phase and makeup benzene. The other portion of the water-rich phase is sent to a stripper to recover organic compounds. Ordinarily, vapor from that stripper is condensed and recycled to the decanter, but that coupling is ignored here. 

Owing to the stability of the uranyl carbonate complex, uranium is universally present in seawater at an average concentration of ca. 3.2/rgL with a daughter/parent activity ratio U) of 1.14. " In particulate matter and bottom sediments that are roughly 1 x 10 " years old, the ratio should approach unity (secular equilibrium). The principal source of dissolved uranium to the ocean is from physicochemical weathering on the continents and subsequent transport by rivers. Potentially significant oceanic U sinks include anoxic basins, organic rich sediments, phosphorites and oceanic basalts, metalliferous sediments, carbonate sediments, and saltwater marshes. " ... 

A variety of other clinically important infections, such as brucellosis, listeriosis, salmonellosis, and various Mycobacterium infections, are of interest as these are often localized in organs rich in MPS cells. Liposome encapsulation has been demonstrated to improve therapeutic indices of several drugs in a number of infectious models. The natural avidity of macrophages for liposomes can also be exploited in the application of the vesicles as carriers of immunomodulators to activate these cells to an microbicidal, antiviral, or tumoricidal state. These studies were recently reviewed by Emmen and Storm (1987), Popescu et al. (1987), and Alving (1988). In addition to the treatment of "old" infectious diseases, the concept of MPS-directed drug delivery is of considerable interest for the therapy AIDS, possibly enabling control of human immunodeficiency virus replication in human macrophages. 

The question of oxygen concentration is a good deal more complex. The extreme conditions in which oxygen concentration is high, for example in well-mixed surface waters, or essentially absent, for example, in organic-rich deep sediments, are readily visualized. Although these conditions can be realized in laboratory experiments, it is worth drawing attention to a number of less clear-cut situations ... 

The Onnagawa Formation conformably overlies the Nishikurosawa Formation and is composed of siliceous shale and shale. The rocks are characterized by organic-rich laminated diatomaceous deposits, siliceous microfossils, and fish bones, while foraminiferal fossil is poor in amounts. The total thickness is about 3(X) m. The age of base of the Onnagawa Formation is estimated to be 12.9 Ma based on diatoms (Koizumi and Matoba, 1989). The age of the top of the Formation is 5.8 Ma. 

Presently, the precise determination of the true dissolved Th fraction in water samples remains a challenge. Results from ultrafiltration experiments on organic-rich water samples from the Mengong river tend to demonstrate that Th concentration is less than 15 ng/L in absence of DOC (Table 2 and Viers et al. 1997), and that Th is still controlled by organic carbon in the final filtrate of the ultrafiltration experiments. The latter conclusion is also supported by the results obtained for the Kalix river (Porcelli et al. 2001). These results therefore not only raised the question of the determination of the amount of dissolved Th in water but also of the nature of Th chemical speciation. 

Viers J, Dupre B, Polve M, Schott J, Dandurand L, Braun JJ (1997) Chemical weathering in the drainage basin of a tropical watershed (Nsimi-Zoetele site, Cameroon) comparison between organic-poor and organic-rich waters. Chem Geol 140 181-206... 

Honeyman and Santschi 1989). Therefore, flocculation of colloids to form settling particles in estuaries is an important mechanism for trace element removal (Sholkovitz 1977). This is particularly true of Fe, which is a ubiquitous colloidal species and is removed at low salinities. Additional removal may occur by adsorption onto floes, as demonstrated by mixing of organic-rich waters with seawater in the laboratory (Sholkovitz 1977). 

Evidence for the association of U with humic acids has been documented elsewhere. Dearlove et al. (1991) showed that U concentrated by ultrafiltration techniques from organic-rich groundwater samples were associated with humic colloids. Humic and fulvic acids have been shown to strongly complex U. Lienert et al. (1994) modeled the distribution of U species in the Glatt River and concluded that U-humate complexes become important at pH <6.8. These results reinforce the conclusions in the estuarine studies that U humate and fulvate complexes may account for the association of U with colloids. 

Bishop [75] determined barium in seawater by direct injection Zeeman-modulated graphite furnace atomic absorption spectrometry. The V203/Si modifier added to undiluted seawater samples promotes injection, sample drying, graphite tube life, and the elimination of most seawater components in a slow char at 1150-1200 °C. Atomisation is at 2600 °C. Detection is at 553.6 nm and calibration is by peak area. Sensitivity is 0.8 absorbance s/ng (Mo = 5.6 pg 0.0044 absorbance s) at an internal argon flow of 60 ml/min. The detection limit is 2.5 pg barium in a 25 ml sample or 0.5 pg using a 135 ml sample. Precision is 1.2% and accuracy is 23% for natural seawater (5.6-28 xg/l). The method works well in organic-rich seawater matrices and sediment porewaters. 

In soils, lead concentrates in organic-rich surface horizons (NRCC 1973). In one instance, only 17 mg of soluble Pb/kg was found in soils 3 days after the addition of 2784 mg of lead (as lead nitrate)/kg (NRCC 1973). The estimated residence time of lead in soils is about 20 years complete turnover in topsoil is expected every few decades (Nriagu 1978a). In forest litter, however, the mean residence time of lead is lengthy estimates range from 220 years (Turner et al. 1985) to more than 500 years (Friedland and Johnson 1985). 

Kimberlites can be detected in shallow peat groundwater, organic-rich environments using surficial geochemistry. 

---