Rhine River sediment from

Beurskens et al. (1995) reported that an anaerobic microbial consortium enriched from Rhine River sediments was able to remove chlorine substituents from CDDs. A model CDD, 1,2,3,4-TCDD, was reductively dechlorinated to both 1,2,3- and 1,2,4-TrCDD. These TrCDD compounds were further dechlorinated to 1,3- and 2,3- DCDD and trace amounts of 2-MCDD. The TrCDD compounds were detected at low concentrations, but the 1,3- and 2,3- DCDD were detected at higher concentrations. The anaerobic culture dechlorinates 1,2,3,4-TCDD at a relatively rapid rate with a half-life value estimated at 15.5 days (first-order kinetics). The formation of metabolites with a conserved 2,3-substitution pattern from 1,2,3,4-TCDD indicates that dechlorination of highly chlorinated CDDs may result in metabolites that are potentially more toxic than the parent compounds. 

For the chlorinated benzenes, a very similar distribution within the sediment core is observed as for some PAHs, e.g. benzo[a]pyrene. An elevated large-scale industrial activity related to these compounds can be deduced for the time between 1947 and 1955. We attribute the decrease in contamination towards the top layers to a reduction of emissions as a result of more efficient sewage treatment plants (Fig. 1A,B) as well as a modified array of products. The concentration profile of HCB (Fig. 6C) and all lower chlorinated benzenes (Tab. 2) suggests the dominance of industrial sources responsible for the contamination as contrasted to agricultural emission derived from pesticide usage. It should be noted that the contamination level of 1,4-dichlorobenzene was elevated in the time period between 1975 and 1980, comparable with concentration levels determined in Rhine river sediments 1982/83. The extensive use of 1,4-dichlorobenzene as an odorous ingredient of toilet cleaners contributed additionally to the contamination via sewage effluents (LWA, 1987/1989). 

Table 7.8 Heavy metal content in exposed and unexposed soils, taken from sediments from the Elbe and Rhine rivers and from sewage sludge [7-15]...

De Voogt et al. [23] analysed marine and estuarine sediments from 22 sites in northwestern Europe (extending from Ireland and France to Norway and Sweden) by HPLC-FL. NP, OP, AgPEO and AgPEO concentration ranges of 0.1-17, highest levels were found in the estuaries of the rivers Seine, Mersey, Rhine/Meuse, Weser and Elbe. 

The transport of disulfoton from water to air can occur due to volatilization. Compounds with a Henry s law constant (H) of <10 atm-m /mol volatilize slowly from water (Thomas 1990). Therefore, disulfoton, with an H value of 2.17x10" atm-m /mol (Domine et al. 1992), will volatilize slowly from water. The rate of volatilization increases as the water temperature and ambient air flow rate increases and decreases as the rate of adsorption on sediment and suspended solids increases (Dragan and Carpov 1987). The estimated gas- exchange half-life for disulfoton volatilization from the Rhine River at an average depth of 5 meters at 11 °C was 900 days (Wanner et al. ] 989). The estimated volatilization half-life of an aqueous suspension of microcapsules containing disulfoton at 20 °C with still air was >90 days (Dragan and Carpov 1987). 

Germany, levels found in sediments from the River Rhine in 1987-88 varied from not detectable to 30-40 pg/kg. At one site, concentrations of 220-2200 jag/kg were measured (WHO, 1996). 

Since in most cases detailed information on the characteristics of the sediments along the river is missing, it is hardly justified to attempt to calculate vsedex from a mechanistic model of the various processes involved. However, there are situations in which we should at least remember that vsedex may depend on the exposure history of the river sediments. In Section 24.3 we will discuss such a case the pollution of the River Rhine by a pesticide after a fire in a storehouse. In this and similar cases,... 

Van Beelen, P. Van Keulen, F. (1990). The kinetics of the degradation of chloroform and benzene in anaerobic sediment from the River Rhine. Hydrobiological Bulletin, 24(1), 13-21. 

Dissanayake CB, Tobschall HJ, Palme H, et al. 1983. The abundance of some major and trace elements in highly polluted sediments from the Rhine river near Mainz, West Germany. Sci Total Environ 29 243-260. 

Some of the DNOC sticks to particles present in water. This process partially transfers DNOC from water to the bottom sediment. When DNOC was accidentally spilled into the Rhine River in Germany, the level of DNOC in water decreased to half its initial value in an estimated 30 days. No known chemical reaction removes significant amounts of DNOC from soil. Microorganisms break down DNOC in soil. The loss of DNOC from soil by evaporation is not significant. DNOC has been found in groundwater from fields where it was applied. The level of DNOC in soil may decrease to half its original level in an estimated 14 days to I month or longer. You will find further information about the fate and movement of DNOC in the environment in Chapter 5. 

Biodegradation > 90% degradation in 3 d using an activated sludge inoculum in 24 h in batch aeration in sewage and 14 d using sediment from the Rhine river as inocula (Howard 1990). 

Colloids can be organic or inorganic. Even if they are not separated from the dissolved load by classical filtration, colloids have the physicochemical properties of a solid. Colloids are finely divided amorphous substances or sohds with very high specific surface areas and strong adsorption capacities. It is shown by Ferret et al. (1994) for the Rhine River that the colloids contribute less than 2% of the total particle volume and mass, but represent a dominant proportion of the available surface area for adsorption of pollutants. The abundance of colloids, their fate, through coagulation and sedimentation processes in natural waters therefore control the abundance of a number of elements. 

Gocht T., Moldenhauer K.-M., and Puttmann W. (2001) Historical record of polycyclic aromatic hydrocarbons (PAH) and heavy metals in floodplain sediments from the Rhine River (Hessisches Ried, Germany). Appi Geochem. 16, 1707-1721. 

A sediment core from a floodplain of the Lippe river, a tributary of the Rhine river (Germany) was taken in 1989/90 by the North-Rhine Westphalian Environment Agency. 

Evers EHG, Re KCM, Olie K (1988) Spatial variations and correlations in the distribution of PCDDs, PCDFs and related compounds in sediments from the River Rhine - Western Europe. Chemosphere 17, 2271-2288. 

Fdrstner, U. Patchineelam, S.R. (1980) Chemical associations of heavy metals in polluted sediments from the lower Rhine River. In Particulates in Water, eds. M.C. Kavaunagh J.0. Leckie. Adv. Chem. Ser. Amer. Chem. Soc. 189. 177-193. 

Chemical Associations of Heavy Metals in Polluted Sediments from the Lower Rhine River... 

Differentiation of sedimentary metal phases was performed on grain size fractionated samples from the lower Rhine River by successive chemical leaching (review). Pollution affects the significant increase of nonresidual associations of chromium, cop er, lead, and zinc. Except for manganese the metal contents in most of the extracted phases decrease as the grain size increases. Phase concentration factors (PCF relative enrichment of metal content in major carrier substances) are high for chromium in moderately reducible phases (20-fold increase in clay-sized particles), for manganese and zinc in the easily reducible sediment fraction (30- and 55-fold enrichment), and for copper and zinc in the carbonates (15 or 25 times compared with total sediment). 

Results of studies on recent mud deposits of the heavily polluted lower Rhine River 31, 33) near the German/Dutch border (13) are compared with the data from a sediment study on Lake Constance (33), where the contamination by heavy metals is still relatively low (34). 

Some properties of the sediment samples from Lake Constance and the Rhine River, possibly relevant for the study of the accumulative eflFects on heavy metals, are summarized in Figure 1. The concentrations of the metals in both samples (13,33) indicate an increase from coarser to fine grained fractions, as exemplified by zinc. Elevated concentrations of metals in the sand-sized material probably originate from heavy minerals or from corrosion products. An even greater grain size effect occurs for phosphorus approximately 0.35% (dry weight) has been... 

Figure 1, Percentages and concentrations of zinc, various sedimentary phases, and specific surface area in different grain size intervals of sediments from the Rhine River and Lake Constance...

The ratio of residual and nonresidual associations in a sediment sample will allow early estimations of the bioavailability of trace metals. In Table II, we compare the metal concentrations in the total sediment samples and within the nonresidual phases, with the latter as average values from the grain size fractionated samples. It is shown that as the metal concentrations in the Rhine River sample are enriched because of pollution influences (except for manganese where diagenetic effects are probably involved), there is a distinct increase in the nonresidual metal fraction. This is mainly valid for copper, lead, and zinc, of which more than 90% in the Rhine River sample can be considered as being potentially remobilizable under natural conditions. Most readily available for biological processes are the metal cations in water-soluble and easily extractable forms copper is typically enriched in these chemical phases in both samples. 

Of the other forms of nonresidual associations, some metal-organic compounds, for example, fulvic and humic acids, have been shown to be particularly effective in the transfer of (toxic) metals from inorganic matter into organisms 51). According to Table II, where data of humate extractions with O.IN NaOH are compared, these effects should be more relevant for iron, copper, zinc, and lead in the sample from the Rhine River than in the sediment material from Lake Constance. The other nonresidual metal associations (easily reducible, carbonates, moderately reducible forms) partly indicate higher percentages in Lake Constance sediments (Mn and Pb), whereas others (chromium, copper, and zinc) are enriched in the Rhine sample. 

Enrichment (or Reduction) of Metal Concentrations in Major Sediment Particles from the Rhine River ... 

Zinc concentrations in the sediments of the Rhine River have increased about sixfold between 1900 and 1950 - and have remained stable since then. But migratory waterfowl from this collection locale do not have elevated zinc concentrations in their primary feathers. Zinc content in feathers of the hoopoe Upupa epops) increased from 200.0mg/kg DW at age 7 days to 1000.0 mg/kg DW at age 35 days. Hoopoe populations are declining in India and this decline is said to be associated with increasing zinc concentrations... 

TCE 1,2 dibromoethane, and PCE are transformed in methanogenic environments. Anaerobic habitats, supporting reductive transformation, include continuous flow methanogenic fixed-film reactors [3,4,30,31], organic sediment-muck [24,27,32-34], anaerobic aquifer microcosms [28], anaerobic sediment from the Rhine river [35], enrichments [26], and pure cultures [36-39]. 

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