Surface waters reference materials

At present, isotope-dilution mass spectrometry provides the best method to certify iron concentration in the recommended deep-water reference material (an expected iron concentration of approximately 0.7 nM) and to obtain an information value for iron in the recommended surface water reference material (an expected iron concentration of approximately 50 pM or less). 

Vapor sorption onto porous solids differs from vapor uptake onto the surfaces of flat materials in that a vapor (in the case of interest, water) will condense to a liquid in a pore structure at a vapor pressure, Pt, below the vapor pressure, P°, where condensation occurs on flat surfaces. This is generally attributed to the increased attractive forces between adsorbate molecules that occur as surfaces become highly curved, such as in a pore or capillary. This phenomenon is referred to as capillary condensation and is described by the Kelvin equation [19] ... 

In existing reference materials the concentrations of several key analytes, including iron, are too high to be useful for scientists making open ocean analysis. For instance, the concentration of iron in seawater standards provided by NRC-Canada is about 100 times greater than expected in surface ocean waters (Table 3.1). 

Many of the analytes of interest for solid phase chemical reference materials are the same as those in seawater, but the need for and the preparation of reference materials for suspended particulate matter and sediments is quite different. The low concentrations of many seawater species and the presence of the salt matrix create particular difficulties for seawater analyses. However while sediments frequently have higher component concentrations than seawater, they also have more complicated matrices that may require unique analytical methods. A number of particulate inorganic and organic materials are employed as paleoceano-graphic proxies, tracers of terrestrial and marine input to the sea, measures of carbon export from the surface waters to the deep sea, and tracers of food-web processes. Some of the most important analytes are discussed below as they relate to important oceanographic research questions. 

A seawater-based reference material with concentration of metals corresponding to open ocean surface water, with an information value for total iron concentration. 

Two trace metal reference materials (one based on surface ocean water and one based on deep ocean water) are urgently needed to further the research community s ability to investigate the role of trace metals in ocean biogeochemistry. Thus these two materials are also assigned a high priority. 

When coal is combusted a number of ash products are produced. In a conventional coal-fired power station the ash that enters the flue gas stream is referred to as the fly ash or pulverized fuel ash. This is volumetrically the most important fraction and although considerable progress has been made in utilizing this material, nevertheless there is an excess production, much of which ends in lagoons or, on a longer term basis, in landfill sites. The potential impacts of fly ash on surface water and groundwater therefore have to be considered both in the short and long term. The annual European production of fly ash in 2000 was 38.96 x 106 t, of which... 

With water treatment technologies, adsorption refers to the removal of contaminants by causing them to attach onto the surfaces of solid materials (adsorbents or sorbents) (Chapters 2 and 3). Sometimes the adsorbed solute is called the adsorbate (Krauskopf and Bird, 1995, 145). Adsorption usually involves ion exchange (Eby, 2004, 345). For example, adsorbing arsenic oxyanions will replace other ions on the surface of the sorbent (Chapter 2). 

Although this chapter focuses on applications with effluent wastewaters, all types of aquatic environmental media (freshwater, brackish, marine) can be appraised with the pT-scale procedure. Testing of liquid samples is virtually unlimited and can include untreated and treated wastewater, surface water, ground water, porewater, elutriates and organic extracts of sediments. Applications could also be extended to assess toxicity of particle-bound substances in suspended matter and sediments. In this case, sample dilutions can be made with reference sediment material (Hoss and Krebs, 2003). The pT-method can also capture the effects of both soluble and particulate toxicity in a sample, provided that appropriate bioassays are employed. 

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