River sediments Rhine

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,... 

The selected case study (Section 7) demonstrates the hazard potential of river sediments. In numerous investigations, pT-values were generated for sediments and dredged material of the rivers Rhine (with its tributaries Moselle and Saar), Ems, Weser, Elbe, Oder and their estuaries, as well as the North and Baltic Seas. Several pT-values were also generated for sediments in the Sepetiba Bay (Federal State of Rio de Janeiro, Brazil) to identify toxic areas. Again, the pT-method was used as an ecotoxicological discriminator to map out sediment quality in polluted zones (Soares and de Freitas, 2000). 

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. 

Sediment > 90% degradation in 14 d using Rhine River sediment as inocula (Kool 1984 quoted, Howard 1990). Soil ... 

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). 

Anaerobic biodegradation of chlorinated aromatics has been conducted using packed columns with sand or sediments. Bosma et al. (1998) studied the biodegradation of chlorinated benzenes on packed columns with Rhine River sediments under methanogenic conditions. This study revealed that Hexachlorobenzene (HCB), Pentachlorobenzene (PCB), Tetrachlorobenzene... 

Following the procedure described above, it is possible to detect down to lOng of both esters, i.e. equivalent to 0.5mg kg-1. Fig. 4.1 shows a typical chromatogram of a hexane extract of sediment taken from the River Rhine. 

The results of analyses of sediment samples taken from the River Rhine are listed in Table 4.1. From Table 4.1 it is seen that for the sediment of the River Rhine di-2-ethylhexyl phthalate and di-ra-butyl phthalate concentrations generally are between 2 and 50ppm. 

Sediments were mainly sampled in autumn. Two samples taken in spring showed concentrations comparable with those found for the same locations in autumn. Significant levels of 0.3—2.8 p-g g-1 dry weight (d.w.) of NPEO were found in the Dommel, a small tributary of the river Meuse, in samples taken downstream from the effluent discharge of a municipal WWTP, and in samples from the Rhine, Scheldt and Meuse rivers. Elevated levels of NP (0.5—3.8 p,g g-1) were... 

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). 

The reduction of sulfone to either sulfoxide or sulfide (i.e., disulfoton) was not observed under the same conditions. Since the bacterial populations in sediments and soils are higher than in typical surface waters (Mossman et al. 1988), biodegradation is expected to play a major role in the loss of disulfoton in soil and sediment, as occurred in the disulfoton spill in the Rhine River (Capel et al. 

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). 

The second example includes the influence of sorption and sediment-water interaction, processes which were not relevant for the case of chloroform. We choose the real case of a chemical pollution of the River Rhine. On November 1, 1986, a fire destroyed a storehouse at Schweizerhalle near Basel (Switzerland). During the fighting of the fire, several tons of various pesticides and other chemicals were flushed into the River Rhine (Wanner et al., 1989). One of the major constituents discharged into the river was disulfoton, an insecticide. An estimated quantity of 3.3 metric tons reached the river within a time period of about 12 hours leading to a massive killing of fish and other aquatic organisms. 

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. 

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

Groundwater estimated t,/2 = 1.0 d in Rhine River in case of a first order reduction process (Zoeteman et al. 1980) t/2 = 48- 9456 h, based on estimated unacclimated aqueous anaerobic biodegradation half-life for 2,4-dinitrotoluene and estimated unacclimated aqueous aerobic biodegradation half-life (Howard et al. 1991). Sediment ... 

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. 

Common tern (Sterna hirundo) breeding in the sedimentation area of Rhine and Meuse rivers, were affected by non- and mono-ortho CB contamination, compared to the clean inland colony near Zeawolde [71]. Studies on double crested cormorants (Phalacrocorax auritus) using CB-126, 2,3,7,8-TCDD, and extract derived from field collected eggs revealed that chicken (Gallus domesti-cus) is at least 70 times more sensitive to developmental abnormalities such as pronounced edema [72],... 

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). 

---