And humic substances

In the area of municipal and iadustrial wastewater treatment, the principal environmental issue is the toxicity of residual flocculating agents ia the effluent. Laboratory studies have shown that cationic polymers are toxic to fish because of the iateraction of these polymers with giU. membranes. Nonionic and anionic polymers show no toxicity (82,83). Other studies have shown that ia natural systems the suspended inorganic matter and humic substances substantially reduce the toxicity of added cationic polymer, and the polymers have been used successfully ia fish hatcheries (84—86). Based on these results, the EPA has added a protocol for testing these polymers for toxicity toward fish ia the presence of humic acids (87). The addition of anionic polymers to effluent streams containing cationic polymers to reduce their toxicity has been mentioned ia the patent Hterature (83). 

In the removal of contaminating ions such as (PO or Fe " a precipitate such as Ca2(P0 2 Fe(OH)2, after oxidizing ferrous ion to ferric, is formed and the soHd is removed. The addition of surfactants is usually not essential (nor desirable) since most waters contain natural surfactants that would render the soflds sufficiently hydrophobic for flotation to occur. Such surfactants derive from the degradation of organic matter, and humic substances abundantly available in nature (30). 

NMR has been used in conjunction with NMR in studies on reactions of [ N] hydroxylamine with fulvic and humic substances (Thom et al. 1992). 

J. Gerke, Aluminium and iron (III) species in the soil solution including organic complexes with citrate and humic substances. Z. Pflanzenemarhr. Bodenk. 160 421 (1997). 

G. Cacco, E. Attina, A. Gelsomino, and M. Sidari, Effect of nitrate and humic substances of different molecular size on kinetic parameters of nitrate uptake rate in wheat. seedlings. 3. Plant Nittr. Soil Sci. 763 313 (2000). 

Moulin V, Ouzounian G (1992) Role of colloids and humic substances in the transport of radio-elements through the geosphere. Appl Geochem (Suppl. Issue 1 179-186 Murakami T, Ohnuki T, Isobe H, Sato T (1997) Mobility of uranium during weathering. Am Mineral 82 888-899... 

In natural waters, dissolved zinc speciates into the toxic aquo ion [Zn(H20)6]2+, other dissolved chemical species, and various inorganic and organic complexes zinc complexes are readily transported. Aquo ions and other toxic species are most harmful to aquatic life under conditions of low pH, low alkalinity, low dissolved oxygen, and elevated temperatures. Most of the zinc introduced into aquatic environments is eventually partitioned into the sediments. Zinc bioavailability from sediments is enhanced under conditions of high dissolved oxygen, low salinity, low pH, and high levels of inorganic oxides and humic substances. 

The microorganisms in sewer biofilms are embedded in a matrix of EPS that consists mostly of polysaccharides produced by the bacteria (Characklis and Marshall, 1990). The EPS fraction is the largest organic fraction in the biofilm, i.e., up to about 90% of the total organic content. Only limited studies of the total composition of sewer biofilms in terms of carbohydrates, proteins and humic substances have been undertaken (Figure 3.12). Corresponding information on the composition of anaerobic biofilms in pressure mains does not yet exist. 

Much of the Hgt pool was found in the upper part of the soil, which is rich in organic matter. This pattern is likely due to an elevated atmospheric deposition of Hgt over the extended period and immobilization of mercury by organic functional groups and accumulation of organic matter as part of the soil-forming process. The retention of mercury in the mor humus layer was almost complete due to the very strong association between Hgt and humic substances. 

Looser, P. W., Bertschi, S. and Fent, K. (1998). Bioconcentration and bioavailability of organotin compounds influence of pH and humic substances, Appl. Organomet. Chem., 12, 601-611. 

As with the bulk POM and DOM, the operationally defined fractions of UDOM and humic substances are quantified by elemental analysis and via broad molecular-class detection. Other strategies involve measurement of the natural isotopic composition, both stable and radioactive, of the various fractions. Efforts are underway to develop more sophisticated techniques, such as solid-state NMR and high-resolution mass spectrometry, far identification of specific bonds and functional groups. 

Clay minerals, oxides, and humic substances are the major natural subsurface adsorbents of contaminants. Under natural conditions, when humic substances are present, humate-mineral complexes are formed with surface properties different from those of their constituents. Natural clays may serve also as a basic material for engineering novel organo-clay products with an increased adsorption capacity, which can be used for various reclamation purposes. 

Tribromomethane [75-25-2] (bromoform), CHBr3, is usually sold mixed with up to 3—4% ethanol as a stabilizer. The pure liquid has mp, 7.7°C bp, 149.5°C cP A, 2.8912 g/mL 19D 1.5980 (87). Water solubility is about 0.3 g/100 g at 25°C. Bromoform is prepared from chloroform by the replacement procedures indicated (88). The classical method of preparation involves reaction of acetone and sodium hypobromite the latter may be generated from sodium hypochlorite and a bromide (89). Uses have been found in syntheses, in pharmacy as a sedative and antitussive, in gauge fluids, and as a dense liquid for separating minerals. Traces of bromoform and bromochloroforms are likely to be present in municipal waters and wastes as a result of chlorination in the presence of naturally occurring bromide ions and humic substances (90). Removal can be accomplished by adsorption on activated charcoal. 

Another possibility is that l02 might react with (/DOC to form an en-doperoxide, in a process similar to the furfuryl alcohol reaction (78-81), and with decomposition it would result in the formation of H202 (eq 10). Sturzenegger (15), in studies comparing H202 formation from furfuryl alcohol and humic substances, concluded that this pathway was not significant. 

Silver tends to form complexes with inorganic chemicals and humic substances in soils (Boyle 1968). Since silver is toxic to soil microorganisms and inhibits bacterial enzymes (Domsch 1984), biotransformation is not expected to be a significant process. 

NOM is common in sediments, soils, and near ambient (<50 °C) water. The materials result from the partial decomposition of organisms. They contain a wide variety of organic compounds, including carboxylic acids, carbohydrates, phenols, amino acids, and humic substances (Drever, 1997, 107-119 Wang and Mulligan, 2006, 202). Humic substances are especially important in interacting with arsenic. They result from the partial microbial decomposition of aquatic and terrestrial plants. The major components of humic substances are humin, humic acids, and fulvic acids. By definition, humin is insoluble in water. While fulvic acids are water-soluble under all pH conditions, humic acids are only soluble in water at pH >2 (Drever, 1997, 113-114). 

Cano-Aguilera, I., Haque, N., Morrison, G.M. et al. (2005) Use of hydride generation-atomic absorption spectrometry to determine the effects of hard ions, iron salts and humic substances on arsenic sorption to sorghum biomass. Microchemical Journal, 81(1), 57-60. 

Qualls, R. G., B. L. Haines, and W. T. Swank. 1991. Fluxes of dissolved organic nutrients and humic substances in a deciduous forest. Ecology 72 254-266. 

Thomas, J. D. 1997. The role of dissolved organic matter, particularly free amino acids and humic substances, in freshwater ecosystems. Freshwater Biology 38 1—36. 

Thomas, J. D., and P. Eaton. 1996. The accumulation of amino-acids and humic substances in media conditioned by axenic and non-axenic duckweed (Lemna minor L.) and their possible ecological significance. Hydrobiologia 333 121-128. 

Bushaw-Newton and Humic substances (estuary) Natural Bacterial cell number 0% and +41%... 

TABLE 2.1. Definitions of Environmental Organic Matter and Humic Substances... 

In the past the mineral matrix was considered as inert, only providing stabilization support for enzymes and humic substances however, due to the overwhelming amount of evidence at the molecular level, there is no doubt that minerals participate in abiotic catalysis of humification reactions in soils. Naidja et al. (2000) referred to mineral particles as the Hidden Half of enzyme-clay complexes, which not only prolong the activity of immobilized enzymes but also are readily able to participate in electron transfer reactions. Many environmental factors can negatively affect the... 

Steelink, C. (1994). Application of N-15 NMR spectroscopy to the study of organic nitrogen and humic substances in the soi/. In Humic Substances in the Global Environment, Senesi, N. and Miano, D., eds., Elsevier, Amsterdam, the Netherlands, 405-427. 

Tombacz, E., Gilde, M., Abraham, I. and Szanto, F. (1990). The possibihty of heterocoagulation between montmorillonite and humic substances, Appl. Clay Sci. 5,265-270. 

Kaschl, A., Romheld, V., and Chen, Y. (2002). Cadmium binding by fractions of dissolved organic matter and humic substances from municipal solid waste compost. /. Environ. Qual. 31,1885-1892. 

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