Pristine environments

There is an indeterminacy in the term oligotroph, and the dilemma is exacerbated by the fact that it may be impossible to isolate obligate oligotrophs by established procedures. The application of DNA probes should, however, contribute to an understanding of the role of these noncultivable organisms. Oligotrophic bacteria in the marine environment are able to utilize low substrate concentrations, and they may be important in pristine environments. 

Degradation of contaminants may occur with bacteria that have been isolated from pristine environments without established exposure to the contaminants, and exhibit no dependence on substrate concentration. For example, organisms from a previously unexposed forest soil were able to degrade 2,4,6-trichlorophenol at concentrations up to 5000 ppm, and terminal restriction fragment length polymorphism analysis revealed that at concentrations up to 500 ppm, the bacterial community was unaltered (Sanchez et al. 2004). 

Kamagata Y, RR Fulthorpe, K Tamura, H Takami, LJ Forney, JM Tiedje (1997) Pristine environments harbor a new group of oligotrophic 2,4-dichlorophenoxyacetic acid-degrading bacteria. Appl Environ Microbiol 63 2266-2272. 

An appropriate mineral medium supplemented with the organic compound that is to be studied is inoculated with a sample of water, soil, or sediment. In studies of the environmental fate of a xenobiotic in a specific ecosystem, samples are generally taken from the area putatively contaminated with the given compound so that a degree of environmental relevance is automatically incorporated. Attention has, in addition been directed to pristine environments, and the issues of adaptation or preexposure have already been discussed. 

Kitagawa W, S Takami, K Miyauchi, E Masai, Y Kamagata, JM Tiedje, M Fukuda (2002) Novel 2,4-dichlo-rophenoxyacetic acid degradation genes from oligotrophic Bradyrhizobium sp. strain HW 13 isolated from a pristine environment. J Bacterial 184 509-518. 

Marine mammals collected near heavily urbanized or industrialized areas or near zinc pollution point sources usually had elevated zinc concentrations when compared to individuals of the same species and of similar age from relatively pristine environments (Eisler 1984). Zinc concentrations in tissues of the ringed seal (Phoca hispida) were essentially the same in animals near a lead-zinc mine and in those of a distant reference site, although lead and selenium burdens were elevated in the vicinity... 

The pristine environment of the gas phase can give some surprising reactions, viewed from the perspective of condensed-phase chemistry (2). Silver nitrate dissolved in acetonitrile added to a solution of benzenethiol in acetonitrile gives an immediate white precipitate and a brown gas is given off. The insoluble polymeric layered silver thiolate (3) is formed as the solvent abstracts a proton forming nitric acid the acid attacks the solvent. 

Increase in demand and human activity worldwide has seen a reduction in the availability of pristine environments for use as drinking water resources. Raw water for drinking water production is thus obtained from a variety of sources, resulting in variable levels of contamination. Several methods for treatment, on laboratory and field scales and in practice in functioning waterworks, have been summarised here, and in particular rapid sand filtration, subsoil passage and ozonation have been demonstrated as important steps in the removal of undesirable xenobiotics. 

In addition to OH radicals, unsaturated bonds are reactive towards O3 and NO3 radicals and reaction with these species is an important atmospheric degradation mechanism for unsaturated compounds. Table 4 lists rate constants for the reactions of 03 and NO3 radicals with selected alkenes and acetylene. To place such rate constants into perspective we need to consider the typical ambient atmospheric concentrations of O3 and NO3 radicals. Typical ozone concentrations in pristine environments are 20-40 ppb while concentrations in the range 100-200 ppb are experienced in polluted air. The ambient concentration of NO3 is limited by the availability of NO sources. In remote marine environments the NO levels are extremely low (a few ppt) and NO3 radicals do not play an important role in atmospheric chemistry. In continental and urban areas the NO levels are much higher (up to several hundred ppb in polluted urban areas) and NO3 radicals can build up to 5-100 ppt at night (N03 radicals are photolyzed rapidly and are not present in appreciable amounts during the day). For the purposes of the present discussion we have calculated the atmospheric lifetimes of selected unsaturated compounds in Table 4 in the presence of 100 ppb (2.5 x 1012 cm 3) of O3 and 10 ppt (2.5 x 108 cnr3) of NO3. Lifetimes in other environments can be evaluated by appropriate scaling of the data in Table 4. As seen from Table 4, the more reactive unsaturated compounds have lifetimes with respect to reaction with O3 and NO3 radicals of only a few minutes ... 

Wester RC, Maibach HI, Gruenke LD, et al. 1986. Benzene levels in ambient air and breath of smokers and nonsmokers in urban and pristine environments. J Toxicol Environ Health 18 567-573. 

An understanding of the weathering and transport processes controlling the fate and flux of trace metals in pristine environments is important in evaluating the capacity of receiving waters to accommodate wastes without detrimental effects. The Amazon River system, which is relatively free of industrial and agricultural interference. 

Note that these reactions are promoted by acidity (see also Langendorfer et al., 1999). However, as we already mentioned earlier, a newer study found that uptake of HOBr on frozen seal salt leads to the release of dihalogens without the need for acidification (Adams et al., 2002). If this process is significant on a larger scale, it would imply that ODEs can occur in pristine environments like the Hudson Bay area without enough gas phase acids to acidify the aerosol particles. 

In conclusion, the human impact on the salinity of the environment has caused dramatic changes in the chemical composition of soil and water resources. The continued stress on land and water resources has shifted the natural balance and has accelerated the natural salinization process, particularly in arid and semi-arid climatic zones. In addition, direct anthropogenic salinization is expected to modify the environment. The inorganic chemical composition of the pristine environment is now diminishing. 

Foams are ubiquitous in the environment, commonly seen as discolored patches on streams, rivers, lakes, and sea water. They often are assumed to be anthropogenic in origin as they are aesthetically unpleasant, yet they frequently appear in pristine environments indicating a natural origin. The chemical nature of foam, however, is ill defined, and geomorphological and geochemical constraints on natural jfoam formation are not well characterized. 

The chemical and physical evidence presented here shows that aquatic foams collected from pristine environments may have an entirely natural origin. The carboxyl moiety is the dominant anion of the surfactant as foaming ability and stability change dramatically over the pKa range of the carboxyl group (pH 3-5) (25). Most commercial anionic surfactants contain sulfur-containing anions which are not... 

The Seychelles represents a relatively pristine environment, with no local industry for pollution, and are situated more than 1,000 miles from any continent or large population center. 

Sidle WC. 1993. Naturally occuring mercury contamination in a pristine environment Environ Geology 21 42-50. 

Environmental degradation has a starting point. One can present the process in pyramid form where the base of the pyramid represents a pristine environment (Fig. 1). Humans enter the scene and begin to transform nature to meet their needs. 

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