Biota

Phenols. The first stable ozone oxidation product of phenol in water is ds ds-raucomc acid, which requires - 2 mol O /mol phenol. In practice, larger dosage levels of ozone are required because other ozone-reactive substances are present in most wastes. Ozone oxidation of phenoHc effluents is employed in paper mills, coke mills, oil refineries, and thermoplastic resin manufacture, producing effluents that are safe to freshwater biota (122,123) (see Lignin Pulp). 

Acquisition of Solutes and Circulation of Water with Rocks, Atmosphere, and Biota... 

Fig. 8. Steady-state model for the earth s surface geochemical system. The kiteraction of water with rocks ki the presence of photosynthesized organic matter contkiuously produces reactive material of high surface area. This process provides nutrient supply to the biosphere and, along with biota, forms the array of small particles (sods). Weatheriag imparts solutes to the water, and erosion brings particles kito surface waters and oceans.

Fig. 11. Elements ia natural waters, their form of occurrence, and concentration. Elements whose distribution is significantly affected by biota ate shaded ...

The solubihty of hydrophobic substances in, or their absorbabiUty on suspended particles, on sediments, on biota, or on soil particles can be related to the solubihty of these substances in organic solvents. The solvent -octanol, CH2(CH2)yOH, is a kind of surrogate for many kinds of environmental and physiological organic substances and has become a reference phase for organic phase water partitioning of organic solutes. 

Both calcium and chloride ions are essential to plant biota, although only small amounts of chloride ion are needed. The average concentration of calcium in plant shoot dry matter sufficient for adequate growth is 0.5%. The corresponding number for chloride is 100 mg/kg (42). 

The identification of PCB residues in fish, wildlife, and human tissues has been reported since the 1970s (9—13,20—26). The results of these analytical studies led to the ultimate ban on further use and production of these compounds. The precise composition of PCB extracts from biota samples is highly variable and depends, in part, on the specific analyte and the commercial PCB preparations associated with a contaminated area (14). PCBs found in a composite human milk sample from Michigan (26) were highly complex, and the congener composition and their relative concentrations did not resemble any of the commercial PCB preparations. This fact raises obvious problems with regard to the ha2ard assessment of PCB mixtures (27). 

The existing variety of means and methods of micro-element analysis is used worldwide for the determination of element contents in atmospheric aerosols when they ai e collected at aspiration filters, sediment and natural surfaces and biota objects where toxic substances migration can be observed. 

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) ai e toxic compounds of anthropogenous origin, able to accumulate in tissues of alive organisms and to cause different diseases. These compounds ai e the most dangerous for aquatic ecosystems as they easily adsorb in sludge and ai e included in food chains of biota. Humans consume PCBs and OCPs mostly with fish. 

Hydrophilic substances and/or compounds with a relatively high reactivity, present at a steady-state concentration in biota due to high external exposures. 

Figures 16-3 through 16-5 present the decision network for screening contaminant fate in air, surface water, ground water, and biota. Pathways must be further evaluated to determine the likelihood of population exposure.

If areas identified as likely to receive significant atmospheric contaminant concentrations include areas supporting edible biota, the biouptake of contaminants must be considered as a possible environmental fate pathway. Direct biouptake from the atmosphere is a potential fate mechanism for lipophilic contaminants. Biouptake from soil or water following transfer of contaminants to these media must also be considered as part of the screening assessments of these media. 

Important intermedia transfer mechanisms that must be considered where significant surface water contamination is expected include transfers to ground water where hydrogeology of the area indicates significant surface water-ground water exchange, transfers to biota where waters contaminated with lipophilic substances support edible biotic species, and transfer... 

Contaminant transfer to bed sediments represents another significant transfer mechanism, especially in cases where contaminants are in the form of suspended solids or are dissolved hydrophobic substances that can become adsorbed by organic matter in bed sediments. For the purposes of this chapter, sediments and water are considered part of a single system because of their complex interassociation. Surface water-bed sediment transfer is reversible bed sediments often act as temporary repositories for contaminants and gradually rerelease contaminants to surface waters. Sorbed or settled contaminants are frequently transported with bed sediment migration or flow. Transfer of sorbed contaminants to bottomdwelling, edible biota represents a fate pathway potentially resulting in human exposure. Where this transfer mechanism appears likely, the biotic fate of contaminants should be assessed. 

Nowel, L.H. et al. (1999) Pesticides in Stream Sediment and Aquatic Biota, CRC Press. 

Figure 1. Conceptual model illustrating examples of major anthropogenic contaminant sources and contaminants, their distribution within the abiotic environmental media, their movement into biota with potential food chain contamination, and potential effects at the organismal, population, conmiunity and ecosystem level of organization.

Durham, R.W. Oliver, B.G. J. Great Lakes Res. 1983, P, 160-168. Thomas, R.L. Veik. Intemat. Verein. Limnol. 1981, 21, 1666-1680. Literature Review of the Effects of Persistent Toxic Substances on Great Lakes Biota Fitchko, J., Ed. Report to the Great Lakes Science Advisory Board, International Joint Commission, Windsor, Ontario, 1986, 256p. Allan, R.J. Symp. Biol. Hung. 1989, 38, 217-243. 

Biota of metal forms in natural waters. International Joint Commission Duluth, MN, 1976. 

Bjorkstrom, A. 1979. A model of CO2 interaction between atmosphere,oceans, and land biota. In The Global Carbon Cycle, Bolin, B. Degens, E. T. Kempe, S. Ketner, P., Eds. SCOPE 13 J Wiley Sons New York, NY, 1979 pp 403-457. 

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