Influence of abiotic factors

The influence of abiotic factors on biocide efficacy has been largely studied on planktonic populations (Bessems, 1998), but can be expected to be also relevant to biofilms. For example, the enhanced efficacy of many biocides with increasing temperature has been described for the treatment of Pseudomonas aeruginosa bio-films thus, a formulation of peracetic acid and hydrogen peroxide caused an increase in killing when the temperature was increased within the temperature range of 10°C to 50°C (Blanchard et al., 1998). 

The incorporation of abiotic particles such as kaolin, calcium carbonate or iron-containing corrosion products into biofilms can result in a reduced biocide efficacy as has been shown for chlorine and monochloramine (LeChevallier, 1991 Srinivasan et al., 1995). This effect has important implications, since biofilms can be dominated by particulate matter in industrial systems such as cooling towers or water pipelines. 

---

Latumus F, Giese B, Wiencke C, Adams FC (2000) Low-Molecular-Weight Organoiodine and Organobromine Compounds Released by Polar Macroalgae - The Influence of Abiotic Factors. Fresenius J Anal Chem 368 297... 

Zhidenko, A.A., Grubinko, V.V., Smolsky, A.S. and Yavonenko, A.F. (1994). Influence of abiotic factors of the environment on the formation of ketone bodies in fish (In Russian). Gydrobiologicheskii Zhumal 30,87-92. 

Zhukinsky, V.N. (1986). The Influence of Abiotic Factors on the Quality and Viability of Fish during early Ontogenesis (In Russian). Agropromizdat, Moscow, 244 pp. 

If all biotic and abiotic factors can be controlled, genetic influence is one of the major features responsible for differences in phytochemical composition. Several reviews on diverse compounds have reported the genetic influence on phytochemicals, sometimes to a surprising order of magnitude. The influence of cultivar can be even greater than the influence of growth conditions, thus complicating the data analyses for plant composition. 

A cadaver exposed to the environment is subject to degradation by various types of animals, of which insects are often the most predominant. Insects can affect the breakdown of the corpse by augmenting the internal decomposition process (Campobasso, Di Vella, and Introna 2001). The succession and development of some insects that visit a corpse can be used to estimate PMI. Succession data are useful in providing a minimum and maximum estimate of time since death. However, biotic and abiotic factors are known to influence carrion insect growth and activity and need to be considered when estimating PMI (Wells and Lamotte 2001). 

Oxidation-reduction (redox) reactions, along with hydrolysis and acid-base reactions, account for the vast majority of chemical reactions that occur in aquatic environmental systems. Factors that affect redox kinetics include environmental redox conditions, ionic strength, pH-value, temperature, speciation, and sorption (Tratnyek and Macalady, 2000). Sediment and particulate matter in water bodies may influence greatly the efficacy of abiotic transformations by altering the truly dissolved (i.e., non-sorbed) fraction of the compounds — the only fraction available for reactions (Weber and Wolfe, 1987). Among the possible abiotic transformation pathways, hydrolysis has received the most attention, though only some compound classes are potentially hydrolyzable (e.g., alkyl halides, amides, amines, carbamates, esters, epoxides, and nitriles [Harris, 1990 Peijnenburg, 1991]). Current efforts to incorporate reaction kinetics and pathways for reductive transformations into environmental exposure models are due to the fact that many of them result in reaction products that may be of more concern than the parent compounds (Tratnyek et al., 2003). 

The growth rate and the onset of maturation are likely to be influenced by a number of abiotic and biotic factors related to the physiology of the host intestine, many of which have been discussed earlier (Chapter 3) or are discussed later (Chapters 10 and 11). 

Table 2. Biotic and abiotic factors which can influence the bioconcentration, bioaccumulation and/or biomagnification of chemicals in fish and other aquatic organisms...

A. (13). Abiotic factors which can also influence the lipid content of the organisms are numbers... 

It is well known that various abiotic factors influence the cyanogenicity of plants. Contradictory findings are reported with regard to the influence of light on cyanogenic potential. On the one hand, light-grown flax plants were... 

A9.7.2.1.2.1 The toxicity of a particular metal in solution, appears to depend primarily on (but is not strictly limited to) the level of dissolved free metal ions. Abiotic factors including alkalinity, ionic strength and pH can influence the toxicity of metals in two ways (i) by influencing the chemical speciation of the metal in water (and hence affecting the availability) and (ii) by influencing the uptake and binding of available metal by biological tissues. 

Because the rates of biotransformation are influenced by a variety of factors related to the size, growth, and substrate utilization rate of the microbial populations involved, they often exhibit a more complex dependence upon substrate concentration than do the rates of abiotic transformation in homogeneous solution (D Adamo et al, 1984). Under many circumstances, however, these more complex relations often simplify to being pseudo first-order with respect to substrate concentration, particularly when the latter is substantially lower than that required to support half the maximum rate of growth of the organisms of interest. At concentrations well above this level, transformation rates may be independent of substrate concentration (Paris et al, 1981). 

Cardinale, M., Casini, M., Arrhenius, E, 2002. The influence of biotic and abiotic factors on the growth of sprat (Sprattus sprattus) in the Baltic Sea. Aquatic Living Resources, 15, 273-281. 

Lake Plussee (Muenster, in preparation) is a eutrophic hardwater lake of the Plon lake district. During the summer, concentrations of dissolved combined phenolic compounds oscillate drastically over short periods of time (as shown in Fig. 17 for epilimnetic waters), although DOC concentrations (measured as COD in glucose-carbon equivalents) were much more stable. Fluctuations in combined phenolic compounds correlate poorly with phytoplankton standing crop (Fig. 17, lowermost panel). Thus, distribution patterns of free phenols and phenolic compounds may result primarily from abiotic factors (e.g., photolysis, allochthonous inputs by rainstorms, or adsorption onto autochthonous calcite) or biotic ones other than release by phytoplankton (e.g., biodegradation after photolysis). These processes, which have not yet been quantified, obviously influence the upper water layers most, since absolute concentrations of phenolic compounds (as well as oscillations within the concentrations) are significantly lower in the deeper-water layers. Perhaps many of the phenols in the deeper strata occur in a particulate state, adsorbed onto sedimentary matter. Alternatively, total phenolic concentrations are really lower in the deeper strata if true, the reasons remain obscure. 

Although the influence of relevant biotic and abiotic variables on the fate and effects of chemicals can, to a certain extent, be explored through controlled experiments and observations of natural systems, the combinations of factors that can be tested in practice are very limited. Mesocosm and field studies are often expensive to perform, can be difficult to replicate sufficiently, and are frequently complicated to interpret. Because they typically represent one unique scenario (species composition and density, temperature, light, nutrient level, and timing of pesticide application in relation to the environmental conditions), questions are often raised about the generality and robustness of the results. Likewise, unexpected or uncontrollable events may occur (e.g., it may have been an unusually rainy, sunny, hot, or cool season), the influence of which on the estimate of risk can be difficult to assess. 

---