Water occurrence

Mann DK, Wong GTF (1993) Strongly bound uranium in marine waters occurrence and analytical implications. Marine Chem 42 25-37... 

Keywords Drinking water. Occurrence, Pharmaceuticals, Removal... 

Keywords Chloramination, Chlorination, Chlorine dioxide, DBFs, Disinfection by-products, Drinking water. Occurrence, Ozonation, Swimming pools. Toxicity... 

Since volatilization is restricted in groundwater, concentrations of dichloromethane are often higher there than in surface water. Occurrence of dichloromethane in ground-water has been reported in several surveys across the United States, with concentrations ranging from 0 to 3600 pg/L (Agency for Toxic Substances and Disease Registry, 1993). 

G.A. Codd, W.P. Brooks, L.A. Lawton and K.A. Beattie, Cyanobacterial toxins in European waters occurrence, properties, problems and requirements. In D. Wheeler, M.L. Richardson and J. Bridges (Eds.), Water-shed 89. The Future for Water Quality in Europe, Vol. II, Pergamon, Oxford, 1989, pp. 211-220. 

New drillings are traditionally conducted to check water occurrences, to establish the depth of water tables, and to be equipped for pumping new niches of known aquifers. Inclusion of hydrochemical studies as an integral part of the drilling operation may double or triple the amount and quality of information gained, with only a small increase in costs. A number of examples are given below. 

Answer 2.5 The first water occurrence indicates the existence of a phreatic aquifer, and the second occurrence of water may indicate the existence of an underlying confined aquifer. However, the drillers could have difficulties in telling water occurrences apart if the drilling itself is conducted with water. Additional data are always needed—water table, water temperature, and water chemistry. Differences between the properties of the deeper and shallower waters will establish that two separated aquifers exist and that the deeper one is confined. 

Abstract Monitoring of Phaeocystis since 1948 during the Continuous Plankton Recorder survey indicates that over the last 5.5 decades the distribution of its colonies in the North Atlantic Ocean was not restricted to neritic waters occurrence was also recorded in the open Atlantic regions sampled, most frequently in the spring. Apparently, environmental conditions in open ocean waters, also those far offshore, are suitable for complete lifecycle development of colonies (the only stage recorded in the survey). 

However, as a science expands and changes, so must the types of systems used to describe those characteristics which need to be studied. The field of hydrogeology is one area of geology which has only been overtly recognized since the term was coined by Lucas in 1879 (2). Since that time hydrogeology has expanded, from a discipline devoted to water occurrence and availability, to include the broad aspect of water quality and solute chemistry. Definition of water quality is fundamental to the protection of the ground-water resource from pollution. 

Keywords MTBE Source Water Drinking Water Occurrence Fuel Oxygenates... 

Table 3.32. Sources of normal water occurrence on the Earth [3]...

C, IH, gO, Mr 164.25. a pale yellow oil with a jasmin(e) odor resembling that of celery. Bp. 134-135 °C (1.6 kPa), LD50 (rat p. o.) 5 g/kg, soluble in alcohol and other organic solvents, practically insoluble in water. Occurrence With ca. 3% content in jasmin(e) absolute J. is one of the decisive compounds for jasmin(e) odor and is also contained, among others, in orange flower absolute, peppermint oils, and tea flavor. For synthesis, see LiV. ... 

Name Structure Odor threshold (pg/kg, water) Occurrence... 

When the temperature decreases, water becomes less soluble (see Figure 5.15) and deposits as fine droplets that begin to freeze as the temperature reaches 0°C. To prevent this occurrence, it is possible to use anti-freeze additives that absorb the water and lower the freezing point. These products, used at maximum levels of 1500 ppm, are ethers-alcohols for example, 2-methoxy... 

Lattice models have been studied in mean field approximation, by transfer matrix methods and Monte Carlo simulations. Much interest has focused on the occurrence of a microemulsion. Its location in the phase diagram between the oil-rich and the water-rich phases, its structure and its wetting properties have been explored [76]. Lattice models reproduce the reduction of the surface tension upon adsorption of the amphiphiles and the progression of phase equilibria upon increasmg the amphiphile concentration. Spatially periodic (lamellar) phases are also describable by lattice models. Flowever, the structure of the lattice can interfere with the properties of the periodic structures. 

Aflatoxki B (1) is of greatest occurrence ki nature, followed by G, B2, and G2. Water content of medium, temperature, pH, and tight are among those environmental factors that affect aflatoxki production. 

A comprehensive search (295) of the STORET water quaUty database, maintained by the U.S. EPA Office of Water, is used to evaluate the potential water quaUty implications of various herbicides. This database contains information on contamination of surface water (SW) and groundwater (GW) suppUes. The data are provided to give a general impression of the occurrence of a given herbicide in SW and GW (269). The U.S. EPA scheme for categorizing a chemical s carcinogenic potential is used for herbicides for which healthy advisory information (HA) is available. The U.S. EPA is continually issuing HAs for various environmental contaminants HAs available in Reference 269 were used in preparation of this article. 

Although not abundant in quantity, iodine is distributed in rocks, soils, waters, plants, animal tissues, and foodstuffs (3,4). Excepting the possible occurrence of elemental iodine vapor in the air near certain iodine-rich springs, iodine never occurs free in nature. It is always found combined with other elements. 

In the petroleum industry, the size of an underground oil deposit is deterrnined by the injection of radiolabeled substances into a well head. The occurrence of radioactivity in the oil—water mixture, which is pumped out of adjoining wells, gives an indication of the pocket size of the oil deposit (see Petroleum). 

The documented occurrence of pesticides in surface water is indicative that mnoff is an important pathway for transport of pesticide away from the site of appHcation. An estimated 160 t of atra2ine, 71 t of sima2ine, 56 t of metolachlor, and 18 t of alachlor enter the Gulf of Mexico from the Mississippi River annually as the result of mnoff (47). Field appHcation of pesticides inevitably leads to pesticide contamination of surface mnoff water unless mnoff does not occur while pesticide residues remain on the surface of the soil. The amount of pesticides transported in a field in mnoff varies from site to site. It is controUed by the timing of mnoff events, pesticide formulation, physical—chemical properties of the pesticide, and properties of the soil surface (48). Under worst-case conditions, 10% or more of the appHed pesticide can leave the edge of the field where it was appHed. 

Dimethyl sulfoxide occurs widely at levels of <3 ppm. It has been isolated from spearmint oil, com, barley, malt, alfalfa, beets, cabbage, cucumbers, oats, onion, Swiss chard, tomatoes, raspberries, beer, coffee, milk, and tea (5). It is a common constituent of natural waters, and it occurs in seawater in the 2one of light penetration where it may represent a product of algal metaboHsm (6). Its occurrence in rainwater may result from oxidation of atmospheric dimethyl sulfide, which occurs as part of the natural transfer of sulfur of biological origin (7,8). 

Fig. 11. Elements ia natural waters, their form of occurrence, and concentration. Elements whose distribution is significantly affected by biota ate shaded ...

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