Nitrate and sulfate

The duoroborate ion has traditionally been referred to as a noncoordinating anion. It has shown Httie tendency to form a coordinate—covalent bond with transition metals as do nitrates and sulfates. A few exceptional cases have been reported (13) in which a coordinated BF was detected by infrared or visible spectroscopy. 

In general, the chemistry of inorganic lead compounds is similar to that of the alkaline-earth elements. Thus the carbonate, nitrate, and sulfate of lead are isomorphous with the corresponding compounds of calcium, barium, and strontium. In addition, many inorganic lead compounds possess two or more crystalline forms having different properties. For example, the oxides and the sulfide of bivalent lead are frequendy colored as a result of their state of crystallisation. Pure, tetragonal a-PbO is red pure, orthorhombic P PbO is yeUow and crystals of lead sulfide, PbS, have a black, metallic luster. 

Coordination Complexes. The abiUty of the various oxidation states of Pu to form complex ions with simple hard ligands, such as oxygen, is, in order of decreasing stabiUty, Pu + > PuO " > Pu + > PuO Thus, Pu(Ill) forms relatively weak complexes with fluoride, chloride, nitrate, and sulfate (105), and stronger complexes with oxygen ligands (Lewis-base donors) such as carbonate, oxalate, and polycarboxylates, eg, citrate, and ethylenediaminetetraacetic acid (106). The complexation behavior of Pu(Ill) is quite similar to that of the light lanthanide(Ill) ions, particularly to Nd(Ill)... 

The acidic character of siUca is shown by its reaction with a large number of basic oxides to form siUcates. The phase relations of numerous oxide systems involving siUca have been summarized (23). Reactions of siUca at elevated temperatures with alkaU and alkaline-earth carbonates result in the displacement of the more volatile acid, CO2, and the formation of the corresponding siUcates. Similar reactions occur with a number of nitrates and sulfates. Sihca at high temperature in the presence of sulfides gives thiosiUcates or siUcon disulfide, SiS2. 

Ion chromatography can be used to determine chloride concentrations of 2—1000 ppb with a carbonate—bicarbonate eluent (23). Eluoride, nitrite, phosphate, bromide, nitrate, and sulfate do not interfere and can be measured simultaneously with a total analysis time of <30 min. 

However, the fertilizing effect of nitrates (and sulfates) may be counterbalanced by the leaching of potassium, magnesium, calcium, and other nutrients from forest soils. There is little evidence that agricultural crops are being injured by exposures to nitrates in precipitation. The amount of nitrates in rainwater is almost always... 

The second subgroup are anaerobes, which oxidize organics in the absence of dissolved oxygen. This is accomplished by using the oxygen which is found in other compounds (such as nitrate and sulfate). Anaerobic behavior can be described by the following reactions ... 

Similarly, the cyanide, acetate and carbonate are unstable in aqueous solution. Hydrolysis of the halides and other salts such as the nitrate and sulfate is incomplete but aqueous solutions are acidic due to the ability of the hydrated cation [AI(H20)6] to act as proton donor giving [A1(H20)5(0H)]-+, (AI(H20)4(0H)2]+, etc. If the pH is gradually increased this deprotonation of the mononuclear species is accompanied by aggregation via OH bridges to give species such as... 

Acid deposition and the associated particulate nitrates and sulfates are implicated in the deterioration of certain sensitive ecosystems, decreased visibility, negative human health effects, and increased degradation of certain stone building materials and cultural resources, especially those made of limestone and marble. Fine particulate nitrate and sulfate particles... 

This half-reaction occurs when the anion cannot be oxidized. Examples include nitrate and sulfate anions, where the nonmetal present is already in its highest oxidation state (+5 for N, +6 for S). 

The solubility of organomercury compounds depends primarily on the nature of the X group nitrates and sulfates tend to be salt-like and relatively water-soluble, whereas chlorides are covalent, nonpolar compounds of low water solubility. Methyl mercury compounds tend to be more volatile than other organomercury compounds. 

In the absence of molecular oxygen, a nnmber of alternative electron acceptors may be used these include nitrate, sulfate, selenate, carbonate, chlorate, Fe(III), Cr(VI), and U(VI), and have already been discussed in Chapter 3, Part 2. In Chapter 14, which deals with applications, attention is directed primarily to the role of nitrate, sulfate, and Fe(III)— with only parenthetical remarks on Cr(VI) and U(VI). The role of nitrate and sulfate as electron acceptors for the degradation of monocyclic aromatic compounds is discnssed, and the particularly broad metabolic versatility of sulfate-reducing bacteria is worthy of notice. 

Reinhard M, S Shang, PK Kitanidis, E Orwin, GD Hopkins, CA Lebron (1998) In situ BTEX biotransformation under enhanced nitrate- and sulfate-reducing conditions. Environ Sci Technol 31 28-36. 

Since many ion exchange columns exhibit mixed-mode interactions with analytes, factor analysis has been found to be useful in optimization.84 A 3-year, comprehensive review of inter-laboratory errors in determinations of the anions chloride, nitrate, and sulfate and the cations sodium, potassium, magnesium, and calcium suggested that multipoint calibration is essential and nonlinear calibration desirable.102 The need for nonlinear calibration was confirmed by an extended quality assurance study of chloride, sulfate, and nitrate in rainwater.103... 

Buchholz, A. E., Verplough, C. I., and Smith, J. L., A method for the simultaneous measurement of less than a part-per-million of chloride, nitrate, and sulfate in aqueous samples by nonsuppressed ion chromatography, /. Chromatogr. Sci., 20, 499, 1982. 

In nitrate and sulfate media, Cr(III) is not very stable and the reaction Cr(II) -> Cr tends to be irreversible. The rate constants obtained in these media are tentative because of excessive adsorption of chromous ions in these media. The rate constants have been... 

Adjustment of bacteria following the environmental changes initiated by 02 especially, for example, new nitrogen and carbon dioxide metabolism which frequently took place in particular cells, chemotypes and their species. Novel metabolic paths avoided dangerous intermediate products from nitrate and sulfate on the way to H2S and NH3, using Mo and Fe (see Table 6.8). 

Ionophore-based solvent polymeric membranes were used as sensing layers for the development of LAPS selective for lithium [70], potassium and calcium ions [71]. Anion-selective LAPS for the determination of nitrate and sulfate ions were described [72],... 

Greenland, N03-, Cl , Na+, and A1 or microparticles have usable seasonal variations. Sea salt-derived Na and Cl are useful dating species in East Antarctic snow although the variations are lower than in Greenland and the dating errors are consequently higher. Sea salts are satisfactory seasonal indicators in the inland portion of the Ross Ice Shelf and presumably in West Antarctica. Nitrate and sulfate have good seasonal variations on the Ross Ice Shelf, even at the more seaward locations. 

Fig. 5.2.4. Vertical profiles of nitrate and sulfate concentrations in interstitial water, and total LAS and SPC concentrations in sediment (wet weight) for station C. (Figure taken...

Nitrate and sulfate are readily water soluble and cost-effective electron acceptors ... 

Table IV shows that potassium and sodium salts have been studied much more extensively than ammonium salts. However, we found that, for any one gas, differences in the coefficient between potassium and ammonium salts of the same anion and between sodium and ammonium salts of the same anion are nearly constant. For gases other than carbon dioxide, we have used data on bromides, chlorides, nitrates, and sulfates from a single investigator to obtain average differences (Table V). For carbon dioxide, such data were not available, and we used averages of results on chlorides, nitrates, and sulfates from different investigators.

Estimation of the relative contributions of photochemical and non-photochemical pathways to the formation of inorganic nitrate and sulfate aerosols. 

Cadmium is found naturally deep in the subsurface in zinc, lead, and copper ores, in coal, shales, and other fossil fuels it also is released during volcanic activity. These deposits can serve as sources to ground and surface waters, especially when in contact with soft, acidic waters. Chloride, nitrate, and sulfate salts of cadmium are soluble, and sorption to soils is pH-dependent (increasing with alkalinity). Cadmium found in association with carbonate minerals, precipitated as stable solid compounds, or coprecipitated with hydrous iron oxides is less likely to be mobilized by resuspension of sediments or biological activity. Cadmium absorbed to mineral surfaces (e.g., clay) or organic materials is more easily bioaccumulated or released in a dissolved state when sediments are disturbed, such as during flooding. 

Sorenson, J. (1982) Reduction of ferric iron in anaerobic, marine sediment and interaction with reduction of nitrate and sulfate. Appl. Environ. Microbiol. 43 319—324... 

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