Abiotic processes adsorption

Table 20.5 also indicates whether a process is biotic (mediated or initiated by organisms in the environment), abiotic (not involving biological mediation), or both. Biotic processes are limited to environmental conditions that favor growth of mediating organisms. Abiotic processes occur under a wide range of conditions. Adsorption, precipitation, complexation, and neutralization are abiotic all other processes in Table 20.5 may be either. 

Similarly to N, most S pools are found in organic form in forest floor and soil humus. However, unlike nitrogen, there are important abiotic processes, especially sulfate sorption processes, which play a critical role in regulating sulfate dynamics in forest ecosystems. An example of this type of exposure pathway was shown in the Habbard Brook whole-tree harvesting experiment, where the decrease in sulfate output from the watershed was attributed to sulfate adsorption, which was enhanced by soil acidification from nitrification (see above). 

The abiotic processes based on acid hydrolysis and adsorption have been evaluated for their applicability in the remediation of contaminated water containing fuel oxygenates. 

This chapter reviews the abiotic processes that can lead to the stabilization of organic phosphorus in soils and the aquatic environment. In particular, we examine the role of adsorption to soil minerals, complex-ation reactions, precipitation with polyvalent cations and the incorporation of organic phosphorus into humic substances in stabilizing organic phosphorus. We then discuss the effects of soil solution chemistry on these reactions, as well as the effects of these reactions on the environment. 

The most important removal pathways of PhACs during wastewater treatment are biotransformation/biodegradation and abiotic removal by adsorption to the sludge. The efficiency of their removal at WWTP depends on their physico-chemical properties, especially hydrophobicity and biodegradability, and process operating parameters (i.e., HRT, SRT, and temperature). For certain NSAIDs (e.g., ibuprofen, acetaminophen), high removals (>90%) are consistently reported in literature... 

Processes which generate heat in organic materials are reviewed. At ordinary temperatures, respiration of living cells and particularly the metabolism of microorganisms may cause self-heating, while at elevated temperatures pyrolysis, abiotic oxidation, and adsorption of various gases by charred materials drive temperatures up whenever the released heat is unable to dissipate out of the material. The crucial rate of pyrolytic heat release depends on exothermicity and rates of the pyrolysis process. 

This has been whimsically described as the Great Particle Conspiracy. An important set of these processes involves the incorporation of trace metals into biogenic hard and soft parts. Another involves the adsorption of metals onto the surfaces of particles. Although some metals can theoretically be removed by abiotic precipitation into mineral phases, continuing research confirms that most of the trace metal removal is biologically mediated. 

The existing methods for the removal of heavy metals from the environment can be grouped as biotic and abiotic. Biotic methods are based on the accumulation of heavy metals by plants or microorganisms abiotic methods include physicochemical processes such as precipitation, coprecipitation, and adsorption of heavy metals by a suitable adsorbent. 

Arsenic speciation in anaerobic sediments is controlled by both microbially mediated transformations of species and by abiotic chemical processes including adsorption. The two... 

During production, ds-diaminedichloroplatinum is released, which could leach through soil. Abiotic or biotic processes can convert this to an ionic species, which could enhance its adsorption to soil, cis-Diaminedichloroplatinum will slowly convert to lra s-diaminedichloroplatinum in water. This form will remain dissolved unless it precipitates to the sediment or is adsorbed to suspended particulates. 

MIC may be released to the environment as a result of its manufacture and use as a chemical intermediate. If MIC is released to soil, it will be expected to rapidly hydrolyze if the soil is moist, based upon the rapid hydrolysis observed in aqueous solution. If released to water, it will be expected to rapidly hydrolyze with half-lives of 20 and 9 min at 15°C and 25°C, respectively, calculated from measured overall hydrolysis rate constants. The products of hydrolysis may include N-carboxymethylamine, methylamine, carbon dioxide, and N,N -dimethylurea. Since it rapidly hydrolyzes, bioconcentration, volatilization, and adsorption to sediment and suspended solids are not expected to be significant processes. No data were located concerning biodegradation, but MIC will probably abiotically hydrolyze significantly faster than it will biodegrade. If released to the atmosphere, it will be expected to exist almost entirely in the vapor phase based upon its vapor pressure. It will be susceptible to photooxidation via vapor phase reaction with photochemically produced hydroxyl radicals. Hydrolysis of MIC in moist air may be significant based upon its rapid hydrolysis in aqueous solution. 

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. 

Violante, A., Pigna, M., and Del Gaudio, S. (2005b). Adsorption-desorption processes of arsenate in soil environments. In Soil Abiotic and Biotic Interactions and the Impact on the Ecosystem and Human Welfare, ed. Huang, P. M., Bollag, J.-M., Violante, A., and Vityakon P., Science Publishers, Enfield, NH, 269-299. 

The adsorption to abiotic and biotic surfaces is governed principally by the same processes as lipid diffusion, but with the partition coefficients replaced by the respective adsorption coefficients for the materials. Two principal interactions contribute to adsorption, which may be regarded as like partitioning between an aqueous and a solid phase ... 

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