PURPOSE The purpose of this study was to classify brands of bottled water by manufacturer assigned labeling to verify the concentration of fluoride for those brands that claim to contain fluoride, and to determine the existence and concentration of fluoride for those brands that do not cite fluoride or list it as undetermined on the product label. METHODS A convenience sample of bottled drink...

The effect of various substituents on the hydrolysis and condensation reactions, the initial stages of the mechanism to form silsesquioxanes, are investigated with ab initio electronic structure theory including electron correlation effects. In addition, the role of water molecules on the mechanism is also discussed. Disciplines Chemistry Comments Reprinted (adapted) with permission from Journa...

The dynamic interplay between preparation, handling, containment, and analysis of ultrapure chemical standards and reagents for the clinical chemistry laboratory is described. Inorganic as well as organic standards are reviewed. The contamination problems associated with water, acids, and solvents in trace-element analysis are defined and resolved. In addition, less well-known sources of error ...

* Parts of this contribution were presented as a lecture during the annual meeting of the Water Chemistry Division in the German Chemical Society (Fachgruppe Wasserchemie in der GDCh), Lindau, May 1997. ** Dr. Thomas Heberer, Dipl.-Lebensmittelchem. Kathrin Schmidt-Bäumler, Prof. Dr. Hans-Jürgen Stan, Institute of Food Chemistry, Technical University of Berlin, GustavMeyer-Allee 25, D-13355 Ber...

Thick shelled river mussel Unio crassus (included in IUCN Red Data List) is a benthic, filter-feeding animal very susceptible to any changes of water chemistry. In this paper we report on the new sites of this species in the Małopolska region – an area of strong anthropogenic pressure. Physical and chemical parameters have been compared between 8 rivers inhabited and not inhabited by the mussel...

The awareness of the effect of abiotic processes in wastewater treatment and sludge treatment technologies is increasing considerably. However traditionally used mathematical models either do not represent abiotic processes, or use simplified approaches. This paper presents a mathematical model able to represent abiotic processes in the steady-state model developed for the anaerobic reactor in ...

Observations of comets and asteroids show that the Solar Nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth’s surface, seeding its early chemistry. Unlike asteroids, comets preserve a nearly pristine record of the Solar Nebula composition. The presence of cyanides in comets, including 0.01% of methyl cyanide (C...

Atlantic Canada, located in the extreme northeastern portion of North America, receives acid precipitation from all major acid emission sources on the eastern part of the continent. The region was glaciated and has thin soils over a generally poorly acid buffering bedrock. Because of regional topography, large groupings of lakes occur in a number of regions. Environment Canada and the Governmen...

Long term changes in the water quality of rainfall, cloud water and stream waters draining acidic and acid sensitive moorland and forested catchments at Plynlimon, mid-Wales, are examined for the period 1983 to 2001. Atmospheric inputs of chloride and sulphate are influenced by the relative inputs of clean maritime and polluted land based air masses. There is no systematic increase or decrease ...

We developed a numerical model to assess the lithoautotrophic habitability of Mars based on metabolic energy, nutrients, water availability, and temperature. Available metabolic energy and nutrient sources were based on a laboratory-produced Mars-analog inorganic chemistry. For this specific reference chemistry, the most efficient lithoautotrophic microorganisms would use Fe(2+) as a primary me...