Natural Factors

The natural factors cover dispersion conditions, which are influenced by climate and (regional and local) topography, and natural PM10 sources. 

Of the selected cities, the following cities have a continental or Mediterranean climate, characterised by low wind speeds and frequent high-pressure situations  

The following cities have a more or less oceanic climate  

The following cities are severely affected by adverse dispersion conditions, due to the local or regional topography of the surrounding area  

Natural sources (Sahara dust) contribute significantly to PM10 levels in Lisbon, a factor which can be considered (deducted) in the air quality assessment. 

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Outdoor inhalation exposure is mainly due to traffic, energy production, heating, and natural factors such as pollen and mineral dusts. These outdoor sources of pollution also affect indoor air quality. The indoor concentration is typically 20-70% of the corresponding outdoor concentration. Occasionally the indoor concentrations of an external pollutant (especially radon) may even exceed the concentrations outdoors. ... 

The term natural ventilation relates to the airflow in a building that is caused by three natural factors ... 

Basically corrosion resistance is the ability of a material to withstand contact with ambient natural factors or those of a particular artificially created atmosphere without degra-... 

Obviously, one looks for causes. That declines in one or another species have natural factor etiologies is unequivocal. The demise of American elms and of the chestnut were due to natural factors. Insect infestations, bacterial and fungal diseases, hurricanes, floods, freezes, droughts and many other stresses can cause extensive tree death (5). But in such declines typically only a single species is affected or climatic events caused decline in a delimited area. In almost all declines caused by natural events, the causal factors can be identified we know their precise etiologies. Natural events are always part of the natural environment and must be factored in when evaluating forest declines (Table I). 

A problem with the simplex-guided experiment (right panel) is that it does not take advantage of the natural factor levels, e.g., molar ratios of 1 0.5, 1 1, 1 2, but would prescribe seemingly arbitrary factor combinations, even such ones that would chemically make no sense, but the optimum is rapidly approached. If the system can be modeled, simulation might help. The dashed lines indicate ridges on the complex response surface. The two figures are schematic. 

Also, the alterations can be classified depending on their intensity. The more intense or frequent the intensity, the easier to predict the consequences. When the alterations are slighter or less frequent, it may occur that the natural factors are more important than the alteration itself [3]. The effect produced by the reservoirs depends on different factors, like the size of the reservoir, the residence time, the stability of the thermal stratification and the withdrawal depth. Moreover, there is a certain interannual variability in the magnitude as well as in the timing of the alterations [4]. Among these factors, the most important one is the depth at which water is released. 

The most dangerous in their long-term effects are the tailing dumps containing radio-active waste, which are also located in the vicinity of the Dnepr bed or near smaller rivers in the Dnepr catchment basin. Many tailing dump levees and toxic radio-active waste hoarder dams are in extremely poor condition. They can be easily destroyed by natural factors (minor earthquakes, floods, rise of subterranean waters) or by man-made acts (like a terrorist act with the use of explosives), with all ensuing consequences. 

Development of models to assess chemical-induced allergic or autoimmune reactions is difficult in that both types of reactions are subject to complex processes, and are idiosyncratic in nature. Factors that must be considered include a large number of genetic as well as phenotypic, neuroendocrine, or environmental factors that are only in part related to the immune system. 

Research on global climate change poses some of the most daunting challenges to scientists of any environmental problem. It involves many complex human and natural factors interacting in ways that are often poorly understood by scientists, requiring researchers to... 

Earth resistance depends on the type of soil, its mineral composition, moisture content, and temperature. Table 5.2 provides the resistivity of various types of soils Table 5.3, the effect of moisture on soil resistivity and Table 5.4, the effect of temperature on soil resistivity. The information contained in the tables is used to illustrate the effect of various natural factors on soil resistivity. Table 5.5 shows the changes in earth resistance by using multiple ground rods. Note that, to realize the full benefits of multiple rods, the rods should be spaced an adequate distance apart. 

Heuer, H., Kroppenstedt, R. M., Lottmann, J., and Smalla, K. (2002). Effects of T4-lysozyme release from transgenic potato roots on bacterial rhizosphere communities are negligible relative to natural factors. Appl. Environ. Microb. 68,1325-1335. 

Legras, S., S. Mouneyrac, J.-C. Amiard, C. Amiard-Triquet, and P.S. Rainbow. 2000. Changes in metallothionein concentrations in response to variation in natural factors (salinity, sex, weight) and metal contamination in crabs from a metal-rich estuary. J. Exp. Mar. Biol. Ecol. 246 259-279. 

It is very important in environmental studies to identify the nature of a PC. A retained PC that does not represent real anthropogenic or natural factors governing an environmental system is useless and does not provide any useful information about the data set under scrutiny. 

The total concentrations of elements in air, water, soil, and sediment may vary depending on natural factors and also for the human impact. 

The successful establishment of such species in the Black Sea is favored by natural factors such as the diversity of habitats both in the sea proper and in its bays, lagoons, and river mouths the favorable food conditions for benthofagous, planktivorous, and predator species and the existence of free ecological niches because of the low species diversity of the Black Sea flora and fauna both in the near-shore benthic zone and in the pelagic area of the basin. 

In a previous section, data and plots were given showing the rapid rise in consumption and production of manufactured fibers at the expense of natural fibers. The principal reason for this has been the wide range of manufactured fiber variants that can be produced from a single fiber-forming polymer. The wide range of polymers available, each with its particular properties, adds yet another dimension. This is not to say that there is only one type of cotton, wool, silk, or asbestos fiber there are many varieties of natural fibers, but their supply is limited by natural factors such as climate and genetics. The relative availabilities of manufactured fiber types can be altered by controlled chemical-process... 

Gamma EDR in air and water was entirely determined by cosmic rays, whereas in bottom sediments - by natural-origin radionuclides. Depth-depending increase in the counting rate of PRM-K scintillation sensor (from 50-m depth and below) within all energy ranges (Fig.3), save for 1.8-2.5 MeV (Fig. 4b), was due to natural factors -namely to increase in salinity, thus of concentration, with depth. 

Table 5.34 Simplex regular plan with values of natural factors (second step of example 5.5.6.1).

The pear sucker species overwinter both in and outside the orchard. On the first warm days in March they emerge from their hiding-places and mate. At the end of March they start to lay their oval, yellow eggs, first on the fruit spurs and later on the inflorescences and leaves. The first larvae appear before flowering and begin immediately to suck on leaves and blossoms. From the third larval stage onwards they start to secrete honeydew. Two or three generations develop. Particularly between the end of May and middle of June the pear sucker population can increase dramatically or else completely collapse because of natural factors (predators and/or weather). Newly hatched pear suckers are very sensitive to cool, damp weather. 

Deposition of primary iron sulfides depends on many natural factors—pH, Eh, concentration of iron and sulfur, presence of reactive forms of carbon dioxide and silicic acid, etc. To ascertain the conditions of chemogenic formation of iron sulfides, a special examination of the effect of all these factors is needed. We will limit ourselves to determining the conditions of formation of sulfide iron sediments from waters with a constant sulfur content, and then we will examine the effect of a change in its concentration. 

Such a situation can be explained not only by the complexity and differences in the interpretation of observed natural factors, but also by the inadequate development of the physicochemical side of the theory of ultra-... 

The present forest decline cannot be explained by natural factors but has to be seen as the result of increasing chemical impact. These chemicals are produced by burning fossil fuels, intentionally brought into the environment as pest control e.g., released as by-product, or left as waste somewhere. 

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