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Seawater nutrients

Since certified reference materials for seawater nutrient analysis are currently unavailable, individual laboratories must prepare their own standard solutions for instrument calibration. Standard stock solutions are prepared at high concentrations (mM) so that they can be used for months without significant alterations in concentration. Working low-concentration standard solutions are unstable and need to be prepared daily by diluting stock solutions with distilled water or low-nutrient seawater. In this case, the accuracy of nutrient analysis at a given laboratory is highly dependent upon the accuracy of the daily preparation of the calibration solutions. [Pg.47]

Approaches to the Preparation of Seawater Nutrient Reference Material(s)... [Pg.97]

TTHE BENEFITS OF AUTOMATING NUTRIENT ANALYSES IN SEAWATER have been recognized and utilized for several decades. Automated analyses allow samples to be processed faster and generally with better precision and accuracy than is possible with most manual methods. The only technique that was available at a reasonable cost for the automated analysis of seawater nutrients, until recently, was segmented continuous-flow analysis (CFA). Segmented CFA is characterized by the use of air bubbles to segment the liquid in the reaction tube so that dispersion of the sample is limited. [Pg.7]

U.se of the Technicon AutoAnalyzer in Seawater Nutrient Analyses Ref. No. 71-72, Oregon State Uniy. Corvallis, Oreg., 1971 49 pp. [Pg.448]

Montagna, P., McCulloch, M., Taviani, M., Mazzoli, C. Vendrell, B. 2006. Phosphoms in cold-water corals as a proxy for seawater nutrient chemistry. Science, 312, 1788-1791. [Pg.30]

Sediment, as a seawater nutrient buffer, can continuously receive and release biogenic elements to balance the water chemically or physically. The nitrogen in sediments includes two kinds one is released into water to take part in the cycling, and the other is buried in sediments. In addition, the burial part can also release when environment changed sharply. So the burial part is a potential source of nitrogen for water. [Pg.475]

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. [Pg.396]

Essentially all organic matter in the ocean is ultimately derived from inorganic starting materials (nutrients) converted by photosynthetic algae into biomass. A generalized model for the production of plankton biomass from nutrients in seawater was presented by Redfield, Ketchum and Richards (1963). The schematic "RKR" equation is given below ... [Pg.246]

Silicic acid (H4Si04) is a necessary nutrient for diatoms, who build their shells from opal (Si02 H20). Whether silicic acid becomes limiting for diatoms in seawater depends on the availability of Si relative to N and P. Estimates of diatom uptake of Si relative to P range from 16 1 to 23 1. Dugdale and Wilkerson (1998) and Dunne et al. (1999) have shown that much of the variability in new production in the equatorial Pacific may be tied to variability in diatom production. Diatom control is most important at times of very high nutrient concentrations and during non-steady-state times, perhaps because more iron is available at those times. [Pg.249]

Trace metals can serve as essential nutrients and as toxic substances (Sunda et al, 1991 Frausto da Silva and Williams, 1991). For example, cobalt is a component of vitamin B-12. This vitamin is essential for nitrogen fixing algae. In contrast, copper is toxic to marine phytoplankton at free ion concentrations similar to those found in seawater (Sunda and... [Pg.250]

It follows that deep seawater contains nutrients from two sources. First, it may contain nutrients that were present with the water when it sank from the surface. These are called preformed nutrients." Second, it may contain nutrients derived by the in situ remineralization of organic particles. These are called oxidative nutrients. [Pg.263]

Fortunately, our interest in micro-constituents in the seawater both from the environmental and the nutrient balance points of view has coincided with the availability of advanced instrumentation capable of meeting the analytical needs. [Pg.4]

Flow injection analysis is a rapid method of automated chemical analysis that allows for quasi-continuous recording of nutrient concentrations in a flowing stream of seawater. The apparatus used for flow injection analysis is generally less expensive and more rugged than that used in segmented continuous flow analysis. A modified flow injection analysis procedure, called reverse flow injection analysis, was adopted by Thompson et al. [213] and has been adapted for the analysis of dissolved silicate in seawater. The reagent is injected into the sample stream in reverse flow injection analysis, rather than vice versa as in flow injection analysis. This results in an increase in sensitivity. [Pg.103]

In chemical oceanography, it has been demonstrated that some nutrients required for the survival of microorganisms in seawater contain zinc, iron and manganese as enzyme cofactors. [Pg.288]

Seawater reference materials are recommended for nutrients and for trace metals (especially iron). There is an urgent need for a certified reference material for nutrients. Completed global surveys already suffer from the lack of previously available standards, and the success of future surveys as well as the development of instruments capable of remote time-series measurements will rest on the availability and use of good nutrient reference materials. The reference materials for trace metals— though initially characterized only for the important micronutrient, iron— should ultimately be useful for the analysis of the other metals and some dissolved organic materials. The committee also recommends the devel-... [Pg.18]

This equation describes the ratios with which inorganic nutrients dissolved in seawater are converted by photosynthesis into the biomass of "average marine plankton" and oxygen gas 02. The opposite of this reaction is respiration, or the remineralization process by which organic matter is enzymatically oxidized back to inorganic nutrients and water. The atomic ratios (stoichiometry) of this reaction were established by... [Pg.44]

In the 1970s, the Sagami Chemical Research Center in Japan provided nutrient reference material for the Cooperative Study of the Kuroshio Current (the so-called CSK standards). These solutions were not prepared in seawater, which limits their general utility (see below), however they are still distributed and widely used as a common reference. French and British scientists have conducted some studies on nutrient reference material (Aminot and Keroul, 1991, 1996 Zhang et al., 1999) with limited success. [Pg.47]

Matrix effects in the analysis of nutrients in seawater are caused by differences in background electrolyte composition and concentration (salinity) between the standard solutions and samples. This effect causes several methodological difficulties. First, the effect of ionic strength on the kinetics of colorimetric reactions results in color intensity changes with matrix composition and electrolyte concentration. In practice, analytical sensitivity depends upon the actual sample matrix. This effect is most serious in silicate analysis using the molybdenum blue method. Second, matrix differences can also cause refractive index interference in automated continuous flow analysis, the most popular technique for routine nutrient measurement. To deal with these matrix effects, seawater of... [Pg.47]

The preparation of a reference material requires substantial planning prior to undertaking a specific project (see Box 5.1). The process begins with the definition of the material to be produced, for example, preparation of a seawater-based reference material containing the nutrient elements N03, P04, and Si(OH)4 at concentration levels appropriate to oceanic samples and certified for these constituents." Such definitions arise either from internal decisions by reference material producers (such as NIST or NRC-Canada) typically in response to perceived needs, or through external pressure on these producers from potential users. (This report, for example, explicitly identifies a number of pressing needs for reference materials for the ocean sciences.)... [Pg.94]

The preservation of nutrient solutions at the concentrations occurring in natural seawater is a major challenge to the routine production of a nutrient reference material. Preservation techniques must be developed that maintain concentrations stable for periods of at least one to two years. Gamma radiation will produce nitrite that is unstable. Therefore this method appears to be problematic. The feasibility of other techniques, such as autoclaving, ultra-violet or microwave radiation, freezing, and acidification, should be evaluated. [Pg.97]


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See also in sourсe #XX -- [ Pg.199 , Pg.361 ]

See also in sourсe #XX -- [ Pg.510 , Pg.511 ]




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