Nitrate and sulfate concentrations

The nitrate concentrations and electrical conductivities also recorded the occurrence of a solar flare in 1859/60 which was observed in England. The scope of the stndy by Dreschhoff and Zeller (1994) is unprecedented and demonstrates that large-scale atmospheric events like volcanic eruptions, solar flares, and explosion of large objects from space are recorded by spikes of the nitrate concentrations and electrical conductivities of ice in (jreenland and Antarctica. 

Tephra layers in ice cores are typically overlain by ice that contains elevated sulfate concentrations and excess hydrogen ions (H ). These chemostiatigraphic relationships occur because the sulfur dioxide gas 

The excess acidity and enhanced sulfate concentration of the ice associated with tephra-bearing layers in ice cores enabled Hammer et al. (1981a, b) to obtain a continuous profile of the addity (pH) of ice in a core drilled in 1974 at Station Crete (71°N,37°W) in central Greenland. The profile confirmed that historical volcanic eruptions were represented by acidic layers in the Greenland ice sheet. 

The effect of the volcanic eruptions during the 19th and 20th centuries on the tanperature of the atmosphoe was evaluated in a series of papers by Self et al. (1981), Newell (1981), Robok (1981), and Walker (1981), all of whom published their contribulions in volume 11 of the Journal of Volcanology and Geothermal Research. The occurrence of tephra layers in the East Antarctic ice sheet is the subject of reports by Keys et al. (1977), Koeberl et al. (1987), Palais and Sigurdsson (1989), and Faure et al. (1994, with assistance from Mary Davis and Keith Henderson). 

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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...

The nitrate ion activities in the aqueous phase were measured with a nitrate ion selective electrode taking into account the presence of high hydrogen ion concentration by calibration of the nitrate electrode with nitric acid. The nitrate ion concentration in the organic phase owing to the extraction of neodymium complexes by HDEHP was determined by back-extraction of the organic phase with 3M sulfuric acid, dilution, and analysis with a nitrate ion electrode calibrated for different nitrate and sulfate concentrations. The amount of the nitrate species extracted into the organic phase increases as the initial neodymium nitrate concentration increases. 

The deposition of fog droplets (diameter of a few pm) is sometimes separated from dry and wet deposition. In exposed sites of the higher altitudes of the mountain region (highlands), the precipitations within the forest stand may stem up to 50% from the trapping effect of cloud and fog droplets. Coniferous forests are efficient scavengers of mist and cloud droplets. Compared with rain water, in these deposits trace substances are accumulated (Schemenauer 1986, Kroll and Winkler 1988, Constantin 1993). Fog water contains nitrate- and sulfate-concentrations which are 10- to 100-fold larger than the concentrations in rain or snow. 

The growth of lettuce plants, as measured by dry weight, was affected by changes in the nitrate and sulfate concentrations of simulated rain at pH 3.2 (Table III). Dry weights of apical leaves and roots of plants were significantly increased after exposure to simulated rain with the highest sulfate and lowest nitrate concentrations compared to plants exposed to simulated rain containing lower ratios of sulfate to nitrate at pH 3.2 or 5.7. 

Table III. Dry mass of lettuce plants exposed to simulated rain of different acidity, nitrate and sulfate concentrations.

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. 

The physical and chemical properties of elemental thorium and a few representative water soluble and insoluble thorium compounds are presented in Table 3-2. Water soluble thorium compounds include the chloride, fluoride, nitrate, and sulfate salts (Weast 1983). These compounds dissolve fairly readily in water. Soluble thorium compounds, as a class, have greater bioavailability than the insoluble thorium compounds. Water insoluble thorium compounds include the dioxide, carbonate, hydroxide, oxalate, and phosphate salts. Thorium carbonate is soluble in concentrated sodium carbonate (Weast 1983). Thorium metal and several of its compounds are commercially available. No general specifications for commercially prepared thorium metal or compounds have been established. Manufacturers prepare thorium products according to contractual specifications (Hedrick 1985). 

TABLE 9.15 Mean Concentrations of Ammonium, Nitrate, and Sulfate by Size in Particles in Southern California in 1987 ... 

The large variability of PM2.s infiltration factors reported may further be due to different composition of PM across locations. In locations with relatively high sulfate and EC contributions, higher infiltration factors can be anticipated than in locations with high nitrate and OC concentrations. 

A 250 mL sample of each solution from the polyethylene bottle was filtered through a Millipore filter (0.45 urn pore size). The concentrations of chloride, nitrate and sulfate ions in the filtrate were determined by ion chromatography using a YEW IC 100 of Yokogawa Hokushin Electric Co. Ltd. The concentrations of sodium and potassium were determined by flame emission spectrometry and concentrations of calcium and magnesium by atomic absorption spectrometry using a Hitachi 170-50 Atomic Absorption Spectrophotometer. An aliquot of each filtrate was used for the determination of Sr by ICP emission spectrometry after adding nitric acid (0.1 N), detailed analytical conditions of which are reported elsewhere (3). 

The tropospheric air always contains a considerable amount of small submicron particles, the so-called Aitken particles (AP), which are widely spread. Experimental data show that, on the average, not less than 50-75% of the total mass concentration of AP fall on sulfates [43]. The average percentage of the mass concentration of organic and nitrate components in the aerosol of the sub-micron range is estimated at 20-25% [2, 22]. Undoubtedly, nuclear explosions (with a yield of about 10 NO molecules per 1 Mt of trinitrotoluene equivalent [12] should generate great amounts of nitrate and sulfate aerosols, but there are no estimates so far. 

Freezing of waters in the active zone over winter results in the progressive concentration of the residual solution, until first carbonates, then sulfates and chlorides/nitrates precipitate out of solution. These salts can be scavenged by the first waters of the thaw, and these may also become concentrated solutions of chlorides/ nitrates and sulfates in the first instance. Thereafter, both secondary and primary carbonate can be scavenged, since, as Ca concentrations decline, the saturation index of calcium carbonate becomes negative. Hence, groundwaters in proglacial areas may span the spectrum from relatively... 

Anaerobic Metabolism, To examine the extent of anaerobic chloroaromatic metabolism, we undertook a study in which sediments from the upper Hudson River, the lower Hudson River, and the East River were used as inoculum (33, 34). Each monochlorophenol isomer (2-, 3-, and 4-chloro-phenol, CP) and each monochlorobenzoate isomer (2-, 3-, and 4-chloroben-zoate, CB) was used as substrate. Duplicate or triplicate cultures were established under three anaerobic conditions denitrifying, sulfidogenic, and methanogenic. The initial concentration of each of the chloroaromatic compounds was 0.1 mM incubation was at 30 °C in the dark. Substrates were quantified by high-pressure liquid chromatography N2 and CH4 were analyzed by gas chromatography nitrate and sulfate were determined by colorimetric methods or by ion chromatography (33, 34). 

Fig. 3-20. Elution profile of a Fast-Sep anion exchange column. - Eluent 0.00015 mol/L NaHCOj + 0.002 mol/L Na2C03 flow rate 2 mL/min detection suppressed conductivity injection volume 20 pL solute concentrations 1.5 ppm fluoride, 2.5 ppm chloride, 7.5 ppm nitrite and bromide, 10 ppm nitrate and sulfate, 15 ppm orthophosphate.

As can be seen from the chromatogram in Fig. 3-55, a baseline separation between fluoride, acetate, and formate is obtained with this eluent. However, this method has only limited applicability for routine analyses. Ions such as chloride, nitrate, and sulfate have much longer retention times under these chromatographic conditions, which may lead to interferences with subsequent analyses. Therefore, the separator column must be flushed occasionally with carbonate solution of the concentration c = 0.1 mol/L to remove ions that are strongly retained at the stationary phase. However, the relatively long time required for the subsequent reconditioning of the separator column with the tetraborate eluent, which takes at least one to two hours, is a disadvantage. 

The main focus of applications in environmental analytical chemistry is the qualitative and quantitative analysis of anions and cations in all kinds of water [3-8], For example, the anions chloride, nitrite, bromide, nitrate, orthophosphate, and sulfate, from the concentration of which the water quality depends, may be separated and determined in less than ten minutes. In a simple drinking water analysis of the main components (chloride, nitrate, and sulfate), it is possible, as illustrated in Fig. 8-1, to carry out a determination every three minutes. The high sensitivity of this method (detection limit with a direct injection of 50 pL sample ca. 10 ppb) and the possibility for automation contributed much to the rapid spreading of ion chromatography as an analytical tool. 

The chemistry of precipitation is characterized by trace quantities of most substances found in the atmosphere. Concentrations are typically measured in parts per million, parts per billion, and even parts per trillion. When considered as an ionic solution, about 95% of the total ionic strength is accounted for by the analysis of calcium, magnesium, ammonium, sodium, potassium, hydrogen, chloride, nitrate, and sulfate. The hydrogen ion is usually determined from measurements of the sample pH. 

Figure 5.39 Change in transport numbers of bromide, nitrate and sulfate ions relative to chloride ions in anion exchange membranes reacted with various amines. ( ) trimethylamine (H) ethylenediamine and then trimethylamine until electrical resistance of the membrane attained was ca. 10 Qcm2 (2 h) (3) tetraethyle-nepentamine and then trimethylamine until the resistance attained was ca. 10 Qcm2 (32 h) ( ) polyethyleneimine and then trimethylamine until the resistance attained was ca. 10 Qcm2 (64 h). The membranes were immersed in 1.0 N hydrochloric acid solution for 2 h before electrodialysis and PaA was measured by electrodialysis of 1 1 mixed salt solutions (concentration of sodium ions 0.04 N) at 1.0 mA cm 2 at 25.0 °Cfor 60 min.

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