Anthropogenic fluorine

Readers of this volume may already be more aware than many of the extent to which we are surrounded by the element fluorine. It is present in the air we breathe, the water we drink and the rocks beneath us, as well as in numerous synthetic polymers, pharmaceuticals, agrochemicals and other formulations. Fluorine in the atmosphere, oceans, biosphere and crust might be grouped together as the fluorosphere (Fig. 1), and, in order to understand the effects of human activities on the environment, it is worthwhile briefly considering the reservoirs and flux of fluorine compounds, both natural and anthropogenic, which occur around us [3,4].1... 

The first volume of the series, that is Fluorine and the Environment Atmospheric Chemistry, Emissions Lithosphere covered a wide scope of important issues about our atmospheric environment. The contributions, written by chemists and environmental scientists, mostly dealt with the effects of fluorine-based gases and emissions either from natural or anthropogenic origin. The present volume deals with other topics concerned by Fluorine and the Environment, including Water, Agrochemicals, Green Chemistry, Analytical aspects and Archaeology. 

The presence of halogens (chlorine, fluorine, bromine and perhaps iodine) in the middle atmosphere results from the upward transport from the troposphere of halocarbons which are released at the Earth s surface as a results of natural or anthropogenic processes. These compounds break up in the stratosphere and release halogen atoms. 

Clinical manifestations of fluorosis often occur in the hard tissues of animals, such as bones and teeth, as a result of long-term intake of elevated levels of fluoride, mainly due to industrial fluoride pollution. Evidence also indicates harmful effects of fluoride on soft tissues such as lung, kidney, testis, fiver and brain. Generally, fluorine, in the form of the fluoride ion (F ), is present in soil and water in low concentrations, but it may cause a threat to public and occupational health when its presence in the environment increases due to natural or anthropogenic sources. Excessive intake of F via drinking water is an endemic problem in a number of countries including China, India,... 

Halogens Chlorine, bromine, fluorine and iodine are all present in the atmosphere due to several natural and anthropogenic processes. The most important compounds are the chlorofluorocarbons (CFCs). Besides being greenhouse gases, CFCs were responsible also for the rapid depletion of the Antarctic ozone layer in the 1980s. As a result of international action, the concentration of atmospheric CFCs has declined, which should stabilize the ozone depletion. 

Perfluoroalkyl and polyfluoroalkyl substances (PEASs) are persistent organic pollutants with nearly ubiquitous occmrence in environmental samples. PEASs have anthropogenic origins over the period 1951 to 2004, it has been estimated that up to 7300 tons (i.e., 6.6 x 10 kg) of PEASs have been released into the environment [145]. PEASs are used in the manufacture of industrial materials and consmner products. The compounds are characterized by a nonpolar fluorinated hydrocarbon chain with a polar end group, and they exhibit both lipophobic and hydrophobic properties. Principal applications include uses as srufactants, nonstick coatings, and stain repellants. The compoimds are also precursors in the synthesis of fluoroelastomers and fluoropol)uners and are used in the... 

Chlorofluorocarbons CFCs and hydrochlorofluorocarbons HCFCs are all anthropogenic species and are the causative agents of ozone layer destruction as well as greenhouse gasses. CFCs are the molecules in which aU the hydrogen atoms of hydrocarbons are substituted by chlorine and fluorine atoms. They do not have absorption bands in the tropospheric actinic flux region and also do not react with OH radicals. Therefore, they do not have any dissipation process in the troposphere, and can be photolyzed only after they reached to the stratosphere. On the other hand, HCFCs is molecules in which at least one of chlorine or fluorine atom of CFCs is substituted by hydrogen atom. Since HCFCs react with OH radicals, they are removed in the troposphere, but a portion of them reach the stratosphere and photolyzed, similar to CFCs. 

Fluorine Among halogens, fluorine is very different from Cl, Br and 1 in respect that it does not cause O3 dissipation. Fluorine is transported to the stratosphere in the form of anthropogenic CFCs and HCFCs as described in the following section, and also as CF4 and hydrofluorocarbons (HFCs). From the decomposition processes... 

The presence of ethers in the atmosphere is almost entirely the result of direct emissions from anthropogenic sources (e.g., Arif et al., 1997 Intergovernmental Panel on Climate Change, 2001 Johnson and Andino, 2001 http //en.wikipedia.org/wiki/Ethers and references therein). These sources can be quite varied and species dependent for example, many ethers are commonly used as industrial solvents many are formed as combustion intermediates and in the burning of biomass various branched ethers (e.g., methyl tert-butyl ether) are (or have been) used as fuel additives to increase octane number and reduce CO emissions dimethyl ether has being proposed as an alternative diesel fuel many fluorinated species have been manufactured, evaluated and used as possible chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) replacement compounds some halogenated species are used as inhalation anaesthetics or as chlorofluorocarbon replacements and polybrominated diphenyl ethers (PBDEs) are used as flame retardants. There are no major routes to ether formation in the atmosphere itself. 

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