Nitrate measurement

Nitrate (measured as Nitrogen) 10 10 "Blue baby syndrome" in infants under six months -life threatening without immediate medical attention. Symptoms Infant looks blue and has shortness of breath. Runoff from fertilizer use leaching from septic tanks, sewage erosion of natural deposits... 

The bulk viscosities of molten alkali nitrates measured by Ejima s group 140 are shown in Fig. 27, where the bulk viscosity decreases with increasing temperature. The ratios of /r are approximately constant over the temperature range investigated. This suggests that the activation energies of the bulk viscosity and the shear viscosity are much the same. 

Schneider M, O Luxenhofer, A Deissler, K Ballschmiter (1998) Cj-C, alkyl nitrates, benzyl nitrate and bifunctional nitrates measurements in California and South Atlantic air and global comparsion using C2Cj4 and CHBrj as marker molecules. Environ Sci Technol 32 3055-3062. 

Another principle, based on the use of UV photo-oxidation of reduced forms of nitrogen (ammonium and organic) into nitrate (measured by UV spectrophotometry), allows the selective determination of nitrate, ammonium and organic nitrogen, and thus of TKN [26], with a detection limit of 1 mg L This method is commercially available. 

Schneider, M., O. Luxenhofer, A. Deissler, and K. Ballschmiter, C,-C 5 Alkyl Nitrates, Benzyl Nitrate, and Bifunctional Nitrates Measurements in California and South Atlantic Air and Global Comparison Using C2C14 and CHBr3 as Marker Molecules, Enriron. Sci. Technol., 32, 3055-3062 (1998). 

Kleindienst, T. E., P. B. Shepson, E. O. Edney, and L. D. Claxton, Peroxyacetyl Nitrate Measurement of Its Mutagenic Activity Using the Sa/mone/to/Mammalian Microsome Reversion Assay, Mutat. Res., 157, 123-128 (1985b). 

FIGURE 11.27 Ratio of the sum of (NO + N02 + PAN + HNO, + particulate nitrate) measured individually to total measured NO, at three sites in the United States (Whitetop Mountain, Tennessee Bondville, Illinois and Scotia, Pennsylvania) and one in Canada (Egbert, Ontario). The bars represent the range of results and the mid-range lines the median values (adapted from Parrish et al., 1993). 

The nitrate concentration was measured monthly from August 1976 to November 1992. Sampling for nitrate measurements was conducted at the water gauge in Lawitz and... 

Composition Nitric ester of starch. It is not a definite, single compound, but rather a mixture of various esters of different degrees of nitration, measured by the percentage of nitrogen. Like nitrocellulose, nitrostarch is a nitrate and not a nitro compound and the correct chemical name is starch nitrate. However, the term nitrostarch has been generally adopted. 

Despite difficulties, there are a number of studies at both local and regional scales in which SGD of nitrogen (generally only nitrate measurements) has been quantified within the context of whole system N budgets. SGD has been shown to be an important N source in some coral reefs areas (e.g., Corbett et al. 1999 D Elia et al. 1981 Umezawa et al. 2002), shallow coastal lagoons and bays (Capone and Bautista 1985 Capone and Slater, 1990 Gobler and BoneiUo, 2003 Moser, 1997 Valiela and D Elia, 1990 Valiela et al., 1990 2002), and salt marsh dominated systems (Krest et al., 2000). In a number of systems, N inputs from SGD equal or exceed river inputs (Table 9.5). 

As Michalski and Thiemens (2000) have shown, aerosol nitrate possesses an extraordinarily large mass-independent isotopic composition. As for aerosol sulfate, this isotopic signature has already been shown to provide a new means to elucidate source and chemical transformation processes. This has proved to be an important technique by which the nitrate biogeochemical cycle may be understood further. For example, the massive mass-independent isotopic signature observed in Chilean desert nitrates uniquely reveals that these nitrates must be atmospherically derived since all other sources (by measurement) possess mass-dependent isotopic compositions. In addition, these measurements, coupled with contemporary aerosol nitrate measurements reveal that the oxygen isotopic signatures are stable on million year timescales. This is particularly valuable, as this permits measurement of nitrate in polar ice samples to examine paleo-variations in nitrate and in general, chemistry. As... 

These include the decompositions of many sulfates and nitrates. Measurements of rates and other kinetic parameters for reversible reactions may be subject to the same problems as ttiose described for CaCOj (Chapter 12) unless experimental conditions are carefiiUy designed to ensure that inifluence of the reverse reaction is minimised, as described for the dissociation of BaS04 [93]. 

For natural water, STAC can provide water quality monitoring with continuous multi-parametric determination and nitrate measurements. This online analyser could be also very efficient in case of accidental pollution detection in particular for organic contaminants or in case of urban WWTP dysfunction investigation. 

Zinc. The Zn data were analysed in a similar way to the B data (Table 4.5.7). Again there was a significant effect of transect. Only one (that between transect and time) of the possible interactions between factors had a significant effect on the concentration of Zn, and this is shown in the table. The concentration of nitrate measured with the YSI probe has a non-negligible association with the concentration of Zn. This association was not observed with B. 

At last, the forth dataset for nitrate was obtained by YSI Multiparameter robe 6900 supplied with a specific electrode for nitrate measurements based on the principles of potentiometry (Roig et al., 2006b). 

Flocke, F., A. Volz-Thomas and D. Kley The use of alkyl nitrate measurements for the characterization of the ozone balance at TOR-Station N. 11, Schauinsland, in P. B. Borrell, P. M. Borrell, T. Cvitas, and W. Seiler (eds). Transport and transformation of pollutants in the troposphere - EUROTRAC Symposium, SPB Academie Publishing (1994) 243-247. 

Nitration of Petroleum Oils Nitration by-products can be monitored by measuring the absorbance area from the NO2 symmetric and asymmetric stretch over the range of 1650-1600 cm (Fig. 16.16). The nitration measurement uses the same general baseline as the oxidation measurement. 

The results of the comparison show that the proposed method is well suited for nitrate measurement even in water or wastewater samples with interferences from suspended solids (up to 400 mg /L) or other dissolved compounds, such as humic substances. 

For TKN determination, the photo-oxidation is carried out in the presence of an oxidant solution (potassium peroxodisulphate K2S208 buffered to pH 9). In this case, organic and inorganic nitrogen compounds are converted into nitrate. The concentration of TKN is equal to the difference between nitrate measured after photo-oxidation ([NOX]f), and nitrate measured before ([NOX]/). It is based on the following relation ... 

On the basis of the results of nitrate measurements in the atmosphere Robinson and Robbins (1970) calculated that the total atmospheric nitrate mass is 0.9 x 1061, which is comparable to the nitrate-nitrogen burden (C.5 x 1061) given by Soderlund and Svensson (1976). 

Huebert, B. J. (1980). Nitric acid and aerosol nitrate measurements in the equatorial Pacific region. Geophys. Res. Lett. 7, 325-328. 

Huebert, B. J., and A. L. Lazrus (1980a). Tropospheric gas-phase and particulate nitrate measurements. J. Geophys. Res. 85, 7322-7328. 

Ostling, K., Kelly, B., Bird, S., Bertman, S., and Pippin, M., Fast-turnaround alkyl nitrate measurements during the PROPHET 1998 summer intensive, J. Geophys. Res., 106, 24439-24449, 2001. 

Fignre 6.5 shows typical pore water profiles of oxygen and nitrate measured in organic rich sediments off Namibia summing up the net reactions described above. Due to nitrification, the highest nitrate concentrations are reached approximately at the oxygen penetration depth. At abont 3 cm depth, nitrate is consumed in the process of denitrification. The nitrate profile indicates an npward flnx into the bottom water and a downward flnx to the zone of denitrification. Both profiles are verified by the application of Equations 6.1 and 6.2 within the computer model CoTAM/CoTReM (cf. Chapter 15) as indicated by the solid and dashed lines. 

Under controlled conditions, the nitrite originally present in the seawater sample passes the reductor without further reduction. This amount of nitrite must be considered and subtracted from the total amount of nitrate measured. After the reduction procedure, the nitrate determination is continued exactly as for the determination of nitrite in seawater. 

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