Bottom deposit

Abbott et al. [163] described a pyrolysis unit for the determination of Picloram and other herbicides in soil. The determination is effected by electron capture-gas chromatography following thermal decarboxylation of the herbicide. Hall et al. [164] reported further on this method. The decarboxylation products are analysed on a column (5mm i.d.) the first 15cm of which is packed with Vycor chips (2-4mm), the next 1.05m with 3% of SE-30 on Chromosorb W (60-80 mesh) and then 0.6m with 10% of DC-200 on Gas Chrom Q (60-80 mesh). The pyrolysis tube, which is packed with Vycor chips, is maintained at 385°C. The column is operated at 165°C with nitrogen as carrier gas (110ml min-1). The method when applied to ethyl ether extracts of soil gives recoveries of 90 5%. Dennis et al. [165] have reported on the accumulation and persistence of Picloram in bottom deposits. 

Uchiyama [11] has given details of a procedure he developed for the isolation and determination of down to 0.2mg kg 1 of fluorescent whitening agents in extracts of bottom deposits. The fluorescent whitening agents were sodium salts of a sulphonated stilbene derivative and this was measured by fluorescence (excitation 370nm, emission 405nm) with the use of tctra-w-butyl ammonium hydroxide. 

Craig and Morton [64] found 2.2pg L 1 mean total mercury level in 136 samples of bottom deposits from the Mersey Estuary. 

Wastewater from sumps in each toxic cubicle is treated with caustic and then handled as hydrolysate. The 9,540 lbs/ day of bottom deposits from the hydrolysate clarifier is a slurry of solids that is hauled to an off-site hazardous waste treatment facility. The 581,000 lbs/day of effluent from the... 

Heavy metals. The most common heavy-metal pollutants are arsenic, cadmium, chromium, copper, nickel, lead, and mercury. Some metals, such as manganese, iron, copper, and zinc, are essential micronutrients. Each type of heavy metal in its own way affects water ecosystem biochemistry and can accumulate in bottom deposits and in the biomass of living elements. 

Loosening and lifting earth and sand from the bottom of water bodies. Dredging is often carried out to widen the stream of a river, deepen a harbor or navigational channel, or collect earth and sand for landfill it is also carried out to remove contaminated bottom deposit or sludge to improve water quality (PIANC, 2000). Volume 2(9). 

White phosphorus enters the environment when industries make it or use it to make other chemicals and when the military uses it as ammunition. It also enters the environment from spills during storage and transport. Because of the discharge of waste water, white phosphorus is likely to be found in the water and bottom deposits of rivers and lakes near facilities that make or use it. It may also be found at sites where the military uses phosphorus-containing ammunition during training exercises. Rainwater washout of these sites may contaminate nearby waterways and their bottom deposits. Hazardous waste sites that contain white phosphorus are also potential sources of exposure to people. However, because white phosphorus reacts very quickly with oxygen in the air, it may not be found far away from sources of contamination. 

Computer simulation is now used extensively as a tool to help to understand and predict the transport of radionuclides through environmental systems. Most models relate to waste disposal and are based on measured parameters such as water movements, salinity, suspended load and the radionuclide concentration in the solute, suspended particulate matter and bottom deposits. Comparatively few attempts appear to have been made to include chemical speciation into this type of model, presumably because of the added complexity involved. Some modellers have attempted to take into account the characteristics of the major chemical phases such as those present in different particles or coatings (e.g. Martinez-Aquirre et al., 1994). Others have noted the importance of including details of particular chemical species present in industrial waste releases when constructing models to predict dispersion (Abril and Fraga, 1996). 

In the bottom deposits of the Pacific Ocean (Ostroumov and Volkov, 1967) an oxidizing layer from 1 cm to a few meters thick is always recorded. 

The use of °Th and Pa in determining the chronology of deep-sea sediments is based on their production in the oceanic water column from the decay of uranium isotopes (Table 1) dissolved in seawater and their incorporation in the bottom deposit by strong adsorption on particle surfaces followed by the sedimentation of the particles. This combination of the processes leading to removal of particle-reactive radionuchdes such as these from the water column is referred to as chemical scavenging (see Chapter 6.09). At the time of deposition, sediment contains an initial quantity Nq of excess (unsupported) °Th or Pa activity along with small quantities supported by decay of the parent uranium isotopes that are present. The decay of the excess nuclides with time and their burial is governed by Equation (1) and leads to an exponential decrease of the unsupported component as a function of the depth in the sediment. 

In view of this seemingly emerging negative attitude, why then devote a volume of papers specifically to topics on anaerobic treatment processes What is to be gained by a review and iteration of past experiences, some of which have been less than encouraging Can the often rather vaguely appreciated occurrence of anaerobic metabolism in animals and its existence in natural ecosystems—viz., marshes, bottom deposits of lakes and rivers—continue to serve as a sufficient justification for additional research and exploration What characteristics of the process make definition and control so difficult and future application suspect Finally, what does the future hold ... 

Vilenskiy, V.D. and Anikiyev, V.V., 1974. Lead-210 and radium-226 in the bottom deposits of freshwater bodies. Geochem. Intemat., 11 874-877. 

Cappenberg, T.E., 1974a. Interrelations between sulfate-reducing and methane-producing bacteria in bottom deposits of a fresh water lake. I. Field observations. Antonie van Leeuwenhoek J. Microbiol. Serol., 40 285—295. 

Kuznetsov, S.I., 1975. The role of microorganisms in the formation of lake bottom deposits and their diagenesis. Soil Sci. 119 81—88. 

Flat plate 9.4 cm dia. FEP Teflon 1.5 m above ground level, 1.5 m above building roof 0.3 cm rim on stainless steel holder, top and bottom deposition measurements (Figure 1) Davidson, 1977 Davidson and Fried-lander, 1978 Davidson et al., 1985a (U, 15, 16)... 

Accurate use of bulk sedimentary organic matter to reconstruct past UVR penetration requires strong correlations between dissolved and sedimentary organic matter in modern surveys, relatively consistent optical characteristics of DOM, and that these relations remain valid in the past. Positive correlations between water column and sedimentary organic matter may be reinforced by several mechanisms. First, because most water-column C resides in DOM, its sedimentation as colloids or precipitates is a major process increasing the organic matter content of bottom deposits. Second, while sedimentary organic matter is also a function of lake production and catchment erosion [107], these processes will tend to reinforce DOM-sediment relationships due to either... 

Bottom deposits present concentrations of pollntants (Type 1, 3) and past concentrations of pollutants in some cases (Type 2, 3). 

The main differences observed between the calculated elements in a budget are typical in the amounts of organic C from the annual input reaching the ocean bottom. The bottom deposits also contain the segregation products of dissolved OM. Trask (1939), Bogdanov et al. (1971) and other scientists estimated it to be n X 10 g C, where n < 5. River inputs are relatively... 

Notes The so-called FA and HA, isolated from the water and bottom deposits are different in nature from the soil humates common for them is only the method of extraction. 

Bogdanov, Ju.A., Lisitsyn, A.P. and Romankevitsh, E.A., 1971. Organic matter of particles and bottom deposits of seas and oceans. In N.V. Vassoevitsh (Editor), Organic Matter of Recent and Fossil Deposits. Nauka, Moscow, pp. 35—103 (in Russian). 

Vasilevskaya, N.A., Galyashin, B.H., Denisenko, N.M. and Maksimov, O.B., 1977. Chemical study of humic acids from bottom deposits in the west regions of the Paciflc Ocean. Okeanologiya, 17 459—469 (in Russian). 

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