Sediment anaerobic

Sample Preservation Without preservation, many solid samples are subject to changes in chemical composition due to the loss of volatile material, biodegradation, and chemical reactivity (particularly redox reactions). Samples stored at reduced temperatures are less prone to biodegradation and the loss of volatile material, but fracturing and phase separations may present problems. The loss of volatile material is minimized by ensuring that the sample completely fills its container without leaving a headspace where gases can collect. Samples collected from materials that have not been exposed to O2 are particularly susceptible to oxidation reactions. For example, the contact of air with anaerobic sediments must be prevented. 

The fate study of Disperse Blue 79 (262) in anaerobic sediment—water systems shows the following degradation products ... 

E. J. Weber, Fate of Textile Dyes in the Aquatic Environment Degradation of Disperse Blue 79 in Anaerobic Sediment-Water Systems, Environmental Research Laboratory, U.S. EPA, Athens, Ga., Mar. 1988. 

Nelson, M. B., Davis, J. A., Benjamin, M. M. and Leckie, J. O. (1977). The Role of Iron Sulfides in Controlling Trace Heavy Metals in Anaerobic Sediments Oxidative Dissolution of Ferrous Monosulfides and the Behavior of Associated Trace Metals." Air Force Weapons Laboratory, Technical Report 425. 

Although higher chlorinated PCBs are degraded more rapidly than lower chlorinated ones in anaerobic sediments, the reverse is true in terrestrial and aquatic food chains (see Section 6.2.2). As explained earlier, hydroxylations tend to be very slow... 

Lovley DR, JC Woodward (1992) Consumption of freons CFC-11 and CFC-12 by anaerobic sediments and soils. Environ Sci Technol 26 925-929. 

An anaerobic sediment sample was incubated with 2,3,4,6-tetrachlorobiphenyl at various temperatures between 4 and 66°C (Wu et al. 1997a). The main products were 2,4,6- and... 

Peijnenburg WJGM, KGM de Beer, HA den Hollander, MHL Stegeman, H Verboom (1993) Kinetics, products, mechanisms and QSARs for the hydrolytic transformation of aromatic nitriles in anaerobic sediment slurries. Environ Toxicol Chem 12 1149-1161. 

Because of the difficulty in obtaining pure cultures of anaerobic bacteria, use has been made of anaerobic sediment slurries in laboratory experiments. In some of these, although no enrichment was deliberately incorporated, experiments were carried out over long periods of time in the presence of contaminated sediments and adaptation of the natural flora to the xenobiotic during exposure in the laboratory might therefore have taken place. The design of these experiments may also inevitably result in interpretative difficulties. A few illustrations are provided ... 

Bryant FO, DD Hale, JE Rogers (1991) Regiospecific dechlorination of pentachlorphenol by dichlorophenol-adapted microorganisms in freshwater anaerobic sediment slurries. Appl Environ Microbiol 57 2293-2301. 

This is an important parameter particularly for naturally occurring mixed cultures of organisms in the natural environment temperature may result in important changes in the composition of the microbial flora as well as on the rates for different processes. An illustrative example of its importance includes the following. An anaerobic sediment sample was incubated with... 

Interest in the possible persistence of aliphatic sulfides has arisen since they are produced in marine anaerobic sediments, and dimethylsulfide may be implicated in climate alteration (Charlson et al. 1987). Dimethylsnlfoniopropionate is produced by marine algae as an osmolyte, and has aronsed attention for several reasons. It can be the source of climatically active dimethylsulfide (Yoch 2002), so the role of specific bacteria has been considered in limiting its flux from the ocean and deflecting the prodncts of its transformation into the microbial sulfur cycle (Howard et al. 2006). 

An anaerobic sediment sample was incnbated with 2,3,4,6-tetrachlorobiphenyl at various temperatures between 4 and 66°C (Wn et al. 1997). The main products were 2,4,6- and 2,3,6-trichlorobiphenyl and 2,6-dichlorobiphenyl the first of these was produced maximally and discontinnonsly at 12 and 34°C, the second maximally at 18°C, and the third was dominant from 25 to 30°C. Dechlorination was not observed above 37°C. 

Kong, I., Metal toxicity on the dechlorination of monochlorophenols in fresh and acclimated anaerobic sediment slurries, Water Sci Technol, 38 (7), 143-150, 1998. 

CS2 and COS occur in the atmosphere in significant amounts - CS2, 3.8-4.7 Tg S yr-1, COS, 2.7-3.5 Tg S yr-1 one-fifth to one quarter of these amounts are probably anthropogenic. Biogenic CS2 mainly originates in marine settings - anaerobic sediments (bacteria) and salt marshes with a role for Spartina alterniflora.6,10 Some terrestrial plants produce CS2 and tree roots are another source, usually after cutting or wetting. A tree of central America, Stryphnodendron excelsum. can be detected by its CS2 odor.10... 

Huber and coworkers123 also reported biomethylation of Pb2+ and of Me3PbX. They followed the redistribution of Me3PbX in anaerobic cultures (bacteria from the surface of a natural lake gron under N2, or from the anaerobic sediment of a small pond), and observed a rate increase, but less Pb2+ and more Me4Pb were obtained than were expected from equation 4 ... 

Brannon and Patrick [129] reported on the transformation and fixation of arsenic V in anaerobic sediment, the long term release of natural and added arsenic, and sediment properties which affected the mobilization of arsenic V, arsenic III and organic arsenic. Arsenic in sediments was determined by extraction with various solvents according to conventional methods. Added arsenic was associated with iron and aluminium compounds. Addition of arsenic V prior to anaerobic incubation resulted in accumulation of arsenic III and organic arsenic in the interstitial water and the exchangeable phases of the anaerobic sediments. Mobilization of... 

To elucidate the fate of these compounds at sediment-water interfaces, sediment/water mixtures (Lake Macatawa, Holland, MI) were spiked with DCB and incubated at 20 °C for 12 months under anaerobic conditions [72]. Dehalogenation of DCB to benzidine appeared to take place through a transient intermediate, 3-monochlorobenzidine (Fig. 27), which was observed in time-course analyses of the sediment/water mixtures. No metabolites were observed in autoclaved samples, suggesting that dehalogenation of DCB in anaerobic sediment/water systems was mediated by microbial activity. The product of dehalogenation (benzidine, Fig. 27) is more toxic to humans than the parent compound, DCB. From sediment/water distribution experiments, DCB showed greater affinity for the sediment phase than its non-chlorinated derivative,... 

Reductive dechlorination of PCBs is important because it reduces their potential toxicity and persistence. In situ dechlorination of PCBs attributed to microorganisms in the anaerobic sediments has been documented in the Hudson River, Silver Lake (MA), the St. Lawrence River (NY), and New Bedford Harbor (MA) [76,371,451,454-456]. 

Ellis et al. (2003) reduced Se(Vl) with anaerobic sediment slurries in order to approximate conditions in natural wetlands. Sediments and waters from the northern reach of the San Francisco estuary, the San Luis Drain, and a man-made wetland, all in California, were used. Reduction was apparently carried out by microbes, as autoclaved control experiments exhibited little reduction. Despite differences between the sediments and concentrations of Se(Vl) used in the various experiments, ese(vi)-se(iv) varied little, from 2.6%o to 3.1%o. The starting Se(Vl) concentrations of three experiments ranged from 230 nmol/L to 430 nmol/L that of a fourth experiment was much greater, at 100 pmol/L. Thus, it appears based on these few data that signihcant Se isotope fractionations persist to very low concentrations, though extrapolation to seawater concentrations (e.g., 1 nmol/L) would be risky. 

Dacey JWH. 1980. Internal winds in water lilies an adaptation for life in anaerobic sediments. Science 210 1017-1019. 

Biological. Ethyl mercaptan did not degrade in anaerobic sediments and sludges nor in anaerobic freshwater conditions (van Leerdam et al., 2006). 

Biological. After 20 d, methyl mercaptan started to degrade in anaerobic sediments and sludges producing stoichiometric amounts of methane. Complete degradation was achieved after 20 d. Under anaerobic freshwater conditions, methyl mercaptan were degraded by methanogenic archea (van... 

Weber EJ, Wolfe NL. 1986. Kinetic studies of aromatic azo compounds in anaerobic sediment/water systems abstract. In 191st National meeting American Chemical Society Division of Environmental Chemistry 26 239-40. 

Anaerobic conditions often develop in hydrocarbon-contaminated subsurface sites due to rapid aerobic biodegradation rates and limited supply of oxygen. In the absence of O, oxidized forms or natural organic materials, such as humic substances, are used by microorganisms as electron acceptors. Because many sites polluted by petroleum hydrocarbons are depleted of oxygen, alternative degradation pathways under anaerobic conditions tend to develop. Cervantes et al. (2001) tested the possibility of microbially mediated mineralization of toluene by quinones and humus as terminal electron acceptors. Anaerobic microbial oxidation of toluene to CO, coupled to humus respiration, was demonstrated by use of enriched anaerobic sediments (e.g., from the Amsterdam petroleum harbor). Natural humic acids and... 

Sanders PF, Wolfe NL. 1985. Reduction of nitroaromatic compounds in anaerobic sediment/water systems. Amer Chem Soc 25 225-226. 

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