Undisturbed environment

Undisturbed environment Clear and calm environment, usually under a high pressure system. 

The variability of radiocesium concentration in undisturbed environments such as alpine pastures is very high and a high minimum of soil and plant samples would be required to estimate the radiocesium distribution median with a 95% confidence interval and a tolerable error of at least 20%. Low cost sampling with only a few samples would result in a biased estimate of the real radionuclide contamination. There is some evidence that the high variability is caused more by microscale runoff phenomenon directly after the Chernobyl accident rather than by long-term erosion processes. The high spatial variability of the Cs, the random distribution and the concentration in the first centimeter of the soil possibly causes the missing correlation of the radiocesium activity concentrations in soils and plants and therefore does not allow a soil-to-plant transfer factor to be calculated. 

Although there was no detectable patchiness of the radiocesium distribution in soil within the area, the geostatistical evaluation of the plant data clearly revealed a spatial dependency with a range of about 20 m, which was nearly the same as for the potassium concentration (25 m). This supported the general conclusions that in undisturbed environments with a spatial and vertical irregular distribution of radiocesium in soil, the physiological and ecological properties of special plant communities or individual plants are responsible for the uptake of radiocesium in plants and, if such... 

To gain an understanding of the composition of the reservoir rock, inter-reservoir seals and the reservoir pore system it is desirable to obtain an undisturbed and continuous reservoir core sample. Cores are also used to establish physical rock properties by direct measurements in a laboratory. They allow description of the depositional environment, sedimentary features and the diagenetic history of the sequence. 

Most commercial marine diatomite deposits exploit accumulations resulting from large blooms of diatoms that occurred ia the oceans during the Miocene geological epoch. Diatomite sediments older than the Jurassic period are rare in the fossil record. Commercial deposits of diatomite are accumulations of the fossil skeletons, which can occur in beds as thick as 900 m in some locations (5). Marine deposits must have been formed on the bottom of protected basins or other bodies of quiet water, undisturbed by strong currents, in an environment similar to the existing Santa Barbara Channel or Gulf of California (3,6). 

Typical precautions with trichloroethylene are summarized in Table 5.52. An important factor is that the vapours are much heavier than air they will therefore spread and may accumulate at low levels, particularly in undisturbed areas. Because of its volatility, releases to the environment usually reach the atmosphere. Here it reacts with hydroxyl or other radicals (estimated half-life for reaction with hydroxyl radicals is less than a week) and is not therefore expected to diffuse to the stratosphere to any significant extent. There is some evidence for both aerobic and anaerobic biodegradation of trichloroethylene. 

Askbrant S, Melin J, Sandalls J, et al. 1996. Mobility of radionuclides in undisturbed and cultivated soils in Ukraine, Belarus and Russia six years after the Chernobyl fallout. J Environ Radioact 31(3) 287-312. 

Bunzl K, Forster H, Kracke W, et al. 1994. Residence times of fallout 239l240Pu, 238Pu,241 Am and 137Cs in the upper horizons of an undisturbed grassland soil. J Environ Radioact 22 11-27. 

How to disentangle the two above scenarios Two approaches are useful first, to compare cluster stars with undisturbed analogs evolving in much less environments and second, to look where one of the two mechanism is not allowed to exist. 

Doctor, our apologies for disturbing your solitude and the local social environment here. We can appreciate your wish to be undisturbed in your work. We are anxious to push on to La Chorrera, and we hope that you will help us arrange bearers here to go with us. Also, we are here with a special purpose. I refer to the Virola hallucinogens that you reported to Schultes."... 

In conclusion, we have found that even young unstressed plants of different cultivars show a variation in the chemical composition of their undisturbed root zones. We suggest that this variation shows a genetic potential of the plant in its control of the root zone environment and especially of its rhizosphere microflora. We suspect that this genetic potential will be of importance in selection and adaptation of agricultural crop plants in the future. 

A very different approach is to inundate the land in and around a mine, washing away and/or dissolving out pyrites and other acidforming minerals. These waters are then diverted into large holding ponds where they are allowed to remain undisturbed. When isolated in this way, acid-producing substances are prevented from entering the natural environment. 

Penta- and hexavalent species (of Np and U, respectively) would not be expected to form in undisturbed deep groundwater, as discussed above. In oxidizing environment, however, these valence states would exist and the solubility would be high due to the formation of anionic mixed hydroxy-carbonate complexes. 

By making it possible to produce more food and feed on fewer acres, the triazines have provided a direct benefit to the environment. As a result, much of our more vulnerable and erodible land has remained undisturbed as wildlife refuges, wetlands, or other natural ecosystems because the triazines have been critical in increasing yield on acres already in production. 

Topp, E., W.N. Smith, W.D. Reynolds, and S.U. Khan (1994). Atrazine and metolachlor dissipation in soils incubated in undisturbed cores, repacked cores, and flasks. J. Environ. Qual., 23 693-700. 

Vink, J.P.M. and S.E.A. Vanderzee (1997). Effect of oxygen status on pesticide transformation and sorption in undisturbed soil and lake sediment. Environ. Toxicol. Chem., 16 608-616. 

Kruger, E.L., L. Somasundaram, R.S. Kanwar, and J.R. Coats (1993). Movement and degradation of [14C]atrazine in undisturbed soil columns. Environ. Toxicol. Chem., 12 1969-1975. 

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