Nitrate and phosphate

T)rree and Bynum [55] describe an ion chromatographic method for the determination of nitrate and phosphate in seawater The pretreatment comprised vigorous mixing of the sample with a silver-based cation exchange resin, followed by filtration to remove the precipitated silver Scdt. 

Peschet and Tinet [102] have also discussed the determination of phosphate in seawater. 

Singh et al. [72] have determined sulphate in deep sub-surface waters by suppressed ion chromatography. 

Cation Stationary phase Eluent Comments Detection ID Ref. 

Xiao-Hua Yang ef al. [103] determined nanomolar concentrations of individual low molecular weight-carboxylic acids (and amines) in seawater. Diffusion of the acids across a hydrophobic membrane was used to concentrate and separate carboxylic acids from inorganic salts and most other organic compounds prior to the application of ion chromatography. Acetic acid, propionic acid, butyric acid-1, butyric acid-2, valeric and pyruvic acid, acrylic acid and benzoic acid were all found in reasonable concentrations in seawater. 

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Other limitations on phytoplankton growth are chemical in nature. Nitrogen, in the form of nitrate, nitrite and ammonium ions, forms a basic building material of a plankton s cells. In some species silicon, as silicate, takes on this role. Phosphorus, in the form of phosphate, is in both cell walls and DNA. Iron, in the form of Fe(III) hydroxyl species, is an important trace element. Extensive areas of the mixed layer of the upper ocean have low nitrate and phosphate levels during... 

Table 1 Discharge, nutrient concentrations, and nutrient uptake lengths for ammonium, nitrate, and phosphate measured at reaches located upstream (UP) and downstream (DW) of WWTP effluent inputs in flve European streams... 

Cyanides can be fatal to fish at <1 ppm. Because of concern over the possible in vivo conversion of nitrate into carcinogenic nitrosamines, the nitrate content of drinking water must be strictly controlled. Nitrate and phosphate pollution can also cause eutrophication in still or slow-moving warm waters by stimulation of algae growth in the presence of... 

R. B. Jackson and M. M. Caldwell, Integrating resource heterogeneity and plant plasticity modelling nitrate and phosphate uptake in a patchy soil environment. J. Ecol. 84 891 (1996). 

The carbonates, sulfates, nitrates, and phosphates of the group IA and IIA metals are important materials in inorganic chemistry. Some of the most important compounds of the group IA and IIA elements are organometallic compounds, particularly for lithium, sodium, and magnesium, and Chapter 12 will be devoted to this area of chemistry. 

Fig. 3 Nitrate and phosphate river water concentrations for the period 1981-2009 at the main Ebro channel (Sastago and Tortosa sites), at Aragon Gallego and Segre left margin tributaries, and at the Jalon and Matarranya right margin tributaries. Data are monthly values...

The two important oxyanions in soil are nitrate and phosphate. Nitrate (N03 ) is the predominant oxyanion of nitrogen however, nitrite (N02 ) can also occur in the soil solution. Phosphate can exist as one of three species,... 

Anions play key roles in chemical and biological processes. Many anions act as nucleophiles, bases, redox agents or phase transfer catalysts. Most enzymes bind anions as either substrates or cofactors. The chloride ion is of special interest because it is crucial in several phases of human biology and in disease regulation. Moreover, it is of great interest to detect anionic pollutants such as nitrates and phosphates in ground water. Design of selective anion molecular sensors with optical or electrochemical detection is thus of major interest, however it has received much less attention than molecular sensors for cations. 

Aminot, A., and R. Keroul. 1991. Autoclaved seawater as a reference material for the determination of nitrate and phosphate in seawater. Analytical Chimica Acta 248 277-283. 

As exemplified by the silicate profile, all biolimiting elements do not behave identically. In the case of dissolved silicon and TDIC, their concentration maxima lie below the nitrate and phosphate maxima. This reflects the different mechanisms by which the elements are resolubilized. Nitrate and phosphate are regenerated from soft parts. This process seems to occur more readily than the dissolution of hard parts, which releases silicate causing the nitrate and phosphate concentration maxima to lie at shallower depths. Since TDIC is released in nearly equal amounts from soft parts as CO2 and the dissolution of calcareous hard parts as CO3, the resulting concentration maximmn lies below that of nitrate and phosphate. 

Depth profiles from the eastern tropical North Pacific (Figure 24.8) show the effects of nitrogen metabolism under 02-deficient conditions. The thermocline is characterized by a sharp decline in O2 concentrations that coincides with increasing nitrate and phosphate concentrations. The oxycline is produced by the respiration of sinking POM under vertically stagnant conditions. Below the oxycline, in depths where O2 concentrations are suboxic, phosphate concentrations continue to increase, but at a slower rate. In contrast, nitrate concentrations decline and reach a mid-water minimum that coincides with a nitrite maximum. The latter is referred to as the secondary nitrite maximum. (At this site the primary nitrite maximum is located at 50 m.)... 

Nutrient regeneration The process whereby particulate organic nitrogen and phosphorous are transformed into dissolved inorganic species, such as nitrate and phosphate. Microorganisms are largely responsible for this process. 

Riparian wetlands are effective though not infinite sinks for nitrate and phosphate from agricultural runoff. Strips of wetland a few tens of metres wide have been shown to remove the bulk of nitrate and phosphate entering in runoff and groundwater, though the limits to this under different circumstances are not well quantified (Baker and Malfby, 1995 Mitsch and Gosselink, 2000). 

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