Biological population

Axenic Literally "without strangers." A system in which all biological populations are defined, such as a pure culture. 

We will also see that residence time distribution notions lead to some interesting examples of pollution reactions, biological populations, and environmental modeling. 

Finally, when we need accurate predictions of a chemical reactor, we must do the complete simulations by solving the differential equations written at the start of this chapter. This almost always requires numerical solutions. However, whenever we are dealing with complex systems (which environmental and biological population problems certainly are), we must always resort to approximations and intuition. A wrong or inadequate set of approximations can lead to inaccurate or nonsensical solutions, and we must always be creative in our models and skeptical of our calculations. 

Yu.M. Svirezhev and D.O. Logofet, Stability of Biological Populations, Nauka, Moscow, 1978 (in Russian). 

May RM. 1974a. Biological populations with nonoverlapping generations stable points, stable cycles and chaos. Science 186 645-647. 

The types of biological methods that need to be carefully evaluated and, if appropriate, standardized for field use include (1) laboratory screening tests to assess the relative hazard of chemical mixtures, (2) field survey methods to detect changes in biological populations, and (3) monitoring techniques to detect... 

Dynamics of development of biological populations in general case and cells populations in particular may be formally described by various empirical equations. 

May, R.M. (1987). Chaos and the dynamics of biological populations, in Dynamical Chaos, eds. M.V. Berry, I.C. Percival and N.O. Weiss (Princeton University Press, Princeton). 

Whitledge, T. E. (1981). Nitrogen recycling and biological populations in upweUing ecosystems. In Coastal UpweUing. (Richards, F. A., ed.). American Geophysical Union, pp. 257-274. 

Eric Renshaw Modelling biological populations in space and time... 

Acclimation. The magnitude of the toxic effect generated by a substance can often be reduced significantly if the concentration is increased slowly. This is the phenomenon of acclimation which represents an adjustment of the biological population to the adverse effects of the toxin. In a waste treatment system this does not usually represent either a mutation or a selection of the fittest because rarely is all of the toxic effect eliminated. Rather acclimation represents a rearrangement of the metabolic resources of the organism to overcome the metabolic block produced by the toxic substance. Significant reductions in toxicity may be obtained if the concentration of the toxic substance is increased slowly rather than increased all at once. 

If a normal biological population is surveyed for sixteen independent factors and each factor is a normally distributed (Gaussian) factor, then, describing any result outside 2 SD of the mean as abnormal will result in 40% of the population having at least one abnormal result. 

Ramkrishna [93, 94] adopted the concepts of Randolph and Larson to investigate biological populations. An outline of the population balance model derivation from the continuum mechanics point of view was discussed. 

While ranges of total concentration serve to set bounds for experimentally determining effects on marine populations, the actual species of metal ion available to the biological population is of importance. Sillen, in a classic paper, has computed the stable species of many metals in sea water21). He concluded, for example, that Hg+2, Cd+2, and Pb+2 exist primarily as chloride complexes. pH determines the availability of the hydroxide ion and thereby the solubility of metal hydroxides. Sillen assumed a pH of 8.1 0.2 as representative. Significant variations could occur, however, in estuarine waters. When concentrations of trace elements were compared with calculations of their solubility products and stability constants, the observed values were considerably less than the calculated values. The implication is that the heavy metals are not in equilibrium with solid phases of their salts, but that other processes, such as chelation and adsorption, control their concentration. 

The major disposal alternatives for dredged sediments and their modifications are listed in Table 7-3 (Gambrell et al., 1978) These categories differ primarily in the biological population exposed to the contaminated sediments, oxidation-reduction conditions, and transport pro-... 

In the case of biological populations, a simple example in this category is the logistic population dynamics (Sect. 3.2.1) of oceanic plankton in an environment with spatially non-uniform carrying capacity (e.g. due to non-uniform light, temperature or nutrient availability)... 

E. Renshaw. Modelling Biological Populations in Space and Time. Cambridge University Press, Cambridge, 1991. 

When biochemical reactions are studied with time, two situations commonly occur. One is when enzyme concentrations remain constant (the biological population... 

The rate of hydrolysis is influenced by pH, temperature and calcium concentration. Calcium shifts the chemical equilibrium of this reaction to the right as it bonds the orthophosphate ions formed. In addition to chemical hydrolysis, biochemical hydrolysis also takes place in waters, particularly in sewage with a dense biological population. A considerable part of polyphosphates in sewage fed into wastewater treatment plants is hydrolysed. The half-time of polyphosphates in surface waters is given in days and tens of days. 

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