Freshwater, natural

Methe and Zehr (1999) Freshwater Natural DOC Water chemistry and acidification 16S rRNA cloning and sequencing No N/A N/A p-Proteobacteria and y-Proteobacteria correlated with DOC... 

The European pearl oyster, Margaritifera margaritifera, is of historic interest as it was the source of most of the European freshwater natural pearls. It was native to Europe and parts of North... 

Freshwaters Natural organic chromo-phores and pigments, C C- + H02 or C- + AH- c+ + -o2 c + o2 HOOH H atom transfer to 02 or A Electron transfer to 02 Energy transfer to 02 0,- disproportionation other Numerous... 

Freshwaters Natural organic chromophores and pigments, C- C +HOzOrC+AH- H atom transfer to O2 or A ... 

Other problems occur in the measurement of pH in unbuffered, low ionic strength media such as wet deposition (acid rain) and natural freshwaters (see Airpollution Groundwatermonitoring) (13). In these cases, studies have demonstrated that the principal sources of the measurement errors are associated with the performance of the reference electrode Hquid junction, changes in the sample pH during storage, and the nature of the standards used in caHbration. Considerable care must be exercised in all aspects of the measurement process to assure the quaHty of the pH values on these types of samples. 

High molecular weight polyacrylamides are used as viscosity builders in freshwater muds (53) or as bentonite extenders. The ionic nature of the polyacrylamide may range from nonionic to anionic (30% hydrolyzed) depending on the situation. Molecular weights ranging from >3 x 10 are used for this purpose. Polymer concentrations of 0.7—2.8 kg/m (0.25—1.0 Ib/bbl) are used depending on the appHcation. 

Free ionic silver readily forms soluble complexes or insoluble materials with dissolved and suspended material present in natural waters, such as sediments and sulfide ions (44). The hardness of water is sometimes used as an indicator of its complex-forming capacity. Because of the direct relationship between the availabiUty of free silver ions and adverse environmental effects, the 1980 ambient freshwater criterion for the protection of aquatic life is expressed as a function of the hardness of the water in question. The maximum recommended concentration of total recoverable silver, in fresh water is thus given by the following expression (45) in Fg/L. 

Zinc, like most metals, is found in all natural waters and soils as well as the atmosphere and is an important trace element in plant and animal life (see Mineral nutrients). Rocks of various kinds contain 20—200 ppm zinc and normal soils 10—30 ppm (average ca 50 ppm) in uncontaminated areas. The average zinc content of coal is 33 ppm. Seawater contains 1—27 )-lg/L (median ca 8 p.g/L), and uncontaminated freshwater usually <10 / g/L. 

Clams, mussels, and other bivalves are a serious problem in many cooling water systems. Zebra mussels and freshwater Asiatic clams are relative newcomers to the United States. Because of a lack of natural predators and prodigious reproduction rates, they have rapidly become a serious threat to the operation of many cooling water systems. 

Most petroleum scientists believe that crude oil and natural gas formed over millions to tens of millions of years through the decomposition of organic matter buried by sediments. Generally, marine sediments have led to oil and gas, while freshwater... 

Freshwater Muds—Dispersed Systems. The pH value of low-pH muds may range from 7.0 to 9.5. Low-pH muds include spud muds, bentonite-treated muds, natural muds, phosphate-treated muds, organic thinned muds (red muds, lignite muds, lignosulfate muds), and organic colloid-treated muds. The pH value of high pH muds, such as alkaline tannate-treated mud, is above 9.5. 

Common salt, or sodium chloride, is also present in dissolved form in drilling fluids. Levels up to 3,000 mg/L chloride and sometimes higher are naturally present in freshwater muds as a consequence of the salinity of subterranean brines in drilled formations. Seawater is the natural source of water for offshore drilling muds. Saturated brine drilling fluids become a necessity when drilling with water-based muds through salt zones to get to oil and gas reservoirs below the salt. 

The major source of plutonium in natural waters is the atmospheric fallout from nuclear weapons tests. Fallout plutonium is ubiquitous in marine and freshwater environments of the world with higher concentrations in the northern hemisphere where the bulk of nuclear weapons testing occurred(3). Much of the research on the aquatic chemistry of plutonium takes place in marine and freshwater systems where only fallout is present. 

Manabe, S. and Stouffer, R. J. (1995). Simulation of abrupt climate change induced by freshwater input to the North Atlantic Ocean. Nature 378,165-167. 

Lerman et al. (1975) considered several cases in which mankind s activities perturbed the natural cycle. If we assume that all mined P is supplied to the land as fertilizer and that all of this P is incorporated into land biota, the mass of the land biota will increase by 20%. This amount is small relative to the P stored in the land reservoir. Since P incorporated into land biota must first decompose and be returned to the land reservoir before being transported further, there is essentially no change in the other reservoirs. Thus, although such inputs would significantly alter the freshwater-terrestrial ecosystem locally where the P release is concentrated, the global cycle would be essentially unaffected. 

Meylan S, Odzak N, Behra R, Sigg L (2004) Speciation of copper and zinc in natural freshwater comparison of voltammetric measurements, diffusive gradients in thin Aims (DGT) and chemical equilibrium models. An Chim Acta 510 91... 

Knowles N (2002) Natural and management influences on freshwater inflows and salinity in the San Francisco Estuary at monthly to interannual scales. Water Resour Res 38(12) 1289. doi 10.1029/2001WR000360... 

Acute poisoning of humans by freshwater cyanobacteria as occurs with paralytic shellfish poisoning, while reported, has never been confirmed. Humans are probably just as susceptible as pets, livestock, or wildlife but people naturally avoid contact with heavy waterblooms of cyanobacteria. In addition, there are no known vectors, like shellfish, to concentrate toxins from cyanobacteria into the human food chain. Susceptibility of humans to cyanobacteria toxins is supported mostly by indirect evidence. In many of these cases, however, if a more thorough epidemiological study had been possible these cases probably would have shown direct evidence for toxicity. 

Untreated natural freshwaters from wells, lakes, or rivers commonly contain high levels of MIC-related microbes. These waters shoufd not be used without appropriate treatment. Most potable... 

The cementing technology can be improved in wells with zones containing clays or shales that are sensitive to freshwater cement filtrate. Sodium chloride (i.e., natural salt) and potassium chloride (KCl) have been the primary materials of choice to yield a filtrate that damages these zones less. However, the unfavorable effects of salt on cement have been extensively documented, in particular. 

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