Source and Transformation

In the soil, a continuous addition, degradation, and synthesis of carbohydrates takes place. A particular sample of soil gives a momentary glimpse into a dynamic (partly cyclic) system which might, except for seasonal variations, be in equilibrium. The relatively constant level of soil organic matter and of carbohydrates therein over a long period of time does not, therefore, reflect a long life of the individual carbohydrate molecules. 

The enzymes in the soil may be adsorbed on other soil constituents their activity is, thereby, decreased or increased, as shown by the results of model reactions.  

The degradation of carbohydrates leads, directly or indirectly, to various products, including carbon dioxide, organic acids, microbial polysaccharides, and humic substances. It has often been maintained that carbohydrates are transformed into the dark-colored humic substances by chemical and microbial processes.  

The chemical degradation of carbohydrates, particularly under acidic conditions, produces reductones, furan derivatives, pyruvaldehyde, and so on, which can condense, either among themselves or with amino compounds (Maillard reactions), to produce dark-colored, amorphous products, similar to humic substances. Pyruvaldehyde, which has been held to be an intermediate in Maillard reactions, has been identified in many soils. Such con- 

According to one theory, the synthesis of humic substances is supposed to be brought about, primarily, by the condensation of the autolysis products from micro-organisms growing on carbohydrates (mostly cellulose). The biosynthesis of aromatic compounds from carbohydrates may be of importance in the soil. 

---

Benner, R., and S. Opsahl. 2001. Molecular indicators of the sources and transformations of dissolved organic matter in the Mississippi River plume. Organic Geochemistry 32 597—611. 

Data acquisition is presented in the upper left comer of Figure 1. The information is read from multiple heterogeneous sources and transformed in our standard format. The acquisition mechanism understands the IDMEF format, our private database format, and several dedicated log sources such as firewall logs (Cisco, Netscreen, Checkpoint, IPtables), access control mechanisms (TCP-wrappers, login), VPN concentrators, IDS sensors and routers. 

Gofii, M.A., and Thomas, K.A. (2000) Sources and transformations of organic matter in surface soils and sediments from a tidal estuary (North Inlet, South Carolina, U.S.A). Estuaries 23, 548-564. 

Stable isotope compositions are useful tracers of the sources and transformations of marine materials however, they carry no direct information about the rates and dates of the associated processes. Such temporal distinctions are possible, however, with the many different naturally occurring radioactive isotopes (Fig. 5.1) and their wide range of elemental forms and decay rates. These highly dependable atomic clocks decay by nuclear processes that allow them to be detected at veiy low concentrations. Long-lived and Th... 

The stable isotope composition of sedimentary organic matter has widely been used to describe the state of the oceanic nitrogen cycle as it allows conclusions on nitrogen sources and transformation processes (i.e. assimilation or denitrification), which are subject to isotopic fractionation (i.e. Francois et al. 1992 Altabet and Francois 1994 Altabet et al. 1999 Thunell et al. 2004). We will briefly discuss this issue because early diagenesis... 

Fig.13.1. Soil nitrogen sources and transformations, and fate of end products. (From Allison, 1965.)...

Depending on wetland type, hydrologic regime, and nutrient/contaminant inputs, wetlands can serve as a sink, source, and transformer. 

The tools for developing data warehouses can be grouped into three categories, based on their activities acquisition tools (for inflow), storage tools (for upflow and downflow), and access products (for outflow) (Mattison 1996). Acquisition tools are necessary to perform tasks such as modeling, designing, and populating data warehouses. These tools extract data from various sources (operational databases and external sources) and transform it (i.e., condition it, clean it up, and denormalize it) to make the data usable in the data warehouse. They also establish the metadata, where information about the data in the warehouse is stored (Francett 1994). 

The impact of different surfactants (SDS, DOSS, CTAB and hexadimethrine bromide, bile salts °), nonionic and mixed micelles, and additives (neutral and anionic CDs," " tetraalkylammonium salts, organic solvents in EKC separations has been demonstrated with phenol test mixtures. In addition, phenols have been chosen to introduce the applicability of more exotic EKC secondary phases such as SDS modified by bovine serum albumin, water-soluble calixarene, " starburstdendrimers, " " cationic replaceable polymeric phases, ionenes, amphiphilic block copolymers,polyelectrolye complexes,and liposome-coated capillaries. The separation of phenols of environmental interest as well as the sources and transformations of chlorophenols in the natural environment have been revised. Examples of the investigation of phenols by EKC methodologies in aquatic systems, soil," " and gas phase are compiled in Table 31.3. Figure 31.3 illustrates the electromigration separation of phenols by both CZE and EKC modes. 

M. Czaplicka, Sources and transformations of chlorophenols in the natural environment, ScL Total Environ., 322, 21-39, 2004. 

Pyrrolizidine alkaloids are toxic for animals and possess importance as feeding deterrents (E 5.5.3). Certain insects, however, are able to store pyrrolizidine alkaloids, e.g., senecionine, ingested with the diet for the repellence of potential predators (E 5.1). Some kinds of butterflies hydrolyze pyrrolizidine alkaloids taken up from plant sources and transform the necine bases to pyrrolizidine aldehydes and ketones (Fig. 224) used as sex pheromones (E 4). 

---